1 | /* |
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2 | * gzlog.c |
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3 | * Copyright (C) 2004, 2008 Mark Adler, all rights reserved |
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4 | * For conditions of distribution and use, see copyright notice in gzlog.h |
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5 | * version 2.0, 25 Apr 2008 |
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6 | */ |
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7 | |
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8 | /* |
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9 | gzlog provides a mechanism for frequently appending short strings to a gzip |
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10 | file that is efficient both in execution time and compression ratio. The |
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11 | strategy is to write the short strings in an uncompressed form to the end of |
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12 | the gzip file, only compressing when the amount of uncompressed data has |
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13 | reached a given threshold. |
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14 | |
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15 | gzlog also provides protection against interruptions in the process due to |
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16 | system crashes. The status of the operation is recorded in an extra field |
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17 | in the gzip file, and is only updated once the gzip file is brought to a |
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18 | valid state. The last data to be appended or compressed is saved in an |
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19 | auxiliary file, so that if the operation is interrupted, it can be completed |
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20 | the next time an append operation is attempted. |
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21 | |
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22 | gzlog maintains another auxiliary file with the last 32K of data from the |
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23 | compressed portion, which is preloaded for the compression of the subsequent |
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24 | data. This minimizes the impact to the compression ratio of appending. |
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25 | */ |
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26 | |
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27 | /* |
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28 | Operations Concept: |
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29 | |
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30 | Files (log name "foo"): |
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31 | foo.gz -- gzip file with the complete log |
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32 | foo.add -- last message to append or last data to compress |
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33 | foo.dict -- dictionary of the last 32K of data for next compression |
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34 | foo.temp -- temporary dictionary file for compression after this one |
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35 | foo.lock -- lock file for reading and writing the other files |
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36 | foo.repairs -- log file for log file recovery operations (not compressed) |
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37 | |
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38 | gzip file structure: |
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39 | - fixed-length (no file name) header with extra field (see below) |
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40 | - compressed data ending initially with empty stored block |
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41 | - uncompressed data filling out originally empty stored block and |
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42 | subsequent stored blocks as needed (16K max each) |
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43 | - gzip trailer |
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44 | - no junk at end (no other gzip streams) |
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45 | |
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46 | When appending data, the information in the first three items above plus the |
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47 | foo.add file are sufficient to recover an interrupted append operation. The |
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48 | extra field has the necessary information to restore the start of the last |
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49 | stored block and determine where to append the data in the foo.add file, as |
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50 | well as the crc and length of the gzip data before the append operation. |
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51 | |
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52 | The foo.add file is created before the gzip file is marked for append, and |
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53 | deleted after the gzip file is marked as complete. So if the append |
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54 | operation is interrupted, the data to add will still be there. If due to |
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55 | some external force, the foo.add file gets deleted between when the append |
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56 | operation was interrupted and when recovery is attempted, the gzip file will |
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57 | still be restored, but without the appended data. |
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58 | |
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59 | When compressing data, the information in the first two items above plus the |
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60 | foo.add file are sufficient to recover an interrupted compress operation. |
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61 | The extra field has the necessary information to find the end of the |
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62 | compressed data, and contains both the crc and length of just the compressed |
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63 | data and of the complete set of data including the contents of the foo.add |
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64 | file. |
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65 | |
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66 | Again, the foo.add file is maintained during the compress operation in case |
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67 | of an interruption. If in the unlikely event the foo.add file with the data |
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68 | to be compressed is missing due to some external force, a gzip file with |
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69 | just the previous compressed data will be reconstructed. In this case, all |
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70 | of the data that was to be compressed is lost (approximately one megabyte). |
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71 | This will not occur if all that happened was an interruption of the compress |
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72 | operation. |
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73 | |
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74 | The third state that is marked is the replacement of the old dictionary with |
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75 | the new dictionary after a compress operation. Once compression is |
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76 | complete, the gzip file is marked as being in the replace state. This |
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77 | completes the gzip file, so an interrupt after being so marked does not |
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78 | result in recompression. Then the dictionary file is replaced, and the gzip |
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79 | file is marked as completed. This state prevents the possibility of |
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80 | restarting compression with the wrong dictionary file. |
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81 | |
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82 | All three operations are wrapped by a lock/unlock procedure. In order to |
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83 | gain exclusive access to the log files, first a foo.lock file must be |
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84 | exclusively created. When all operations are complete, the lock is |
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85 | released by deleting the foo.lock file. If when attempting to create the |
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86 | lock file, it already exists and the modify time of the lock file is more |
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87 | than five minutes old (set by the PATIENCE define below), then the old |
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88 | lock file is considered stale and deleted, and the exclusive creation of |
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89 | the lock file is retried. To assure that there are no false assessments |
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90 | of the staleness of the lock file, the operations periodically touch the |
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91 | lock file to update the modified date. |
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92 | |
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93 | Following is the definition of the extra field with all of the information |
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94 | required to enable the above append and compress operations and their |
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95 | recovery if interrupted. Multi-byte values are stored little endian |
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96 | (consistent with the gzip format). File pointers are eight bytes long. |
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97 | The crc's and lengths for the gzip trailer are four bytes long. (Note that |
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98 | the length at the end of a gzip file is used for error checking only, and |
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99 | for large files is actually the length modulo 2^32.) The stored block |
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100 | length is two bytes long. The gzip extra field two-byte identification is |
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101 | "ap" for append. It is assumed that writing the extra field to the file is |
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102 | an "atomic" operation. That is, either all of the extra field is written |
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103 | to the file, or none of it is, if the operation is interrupted right at the |
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104 | point of updating the extra field. This is a reasonable assumption, since |
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105 | the extra field is within the first 52 bytes of the file, which is smaller |
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106 | than any expected block size for a mass storage device (usually 512 bytes or |
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107 | larger). |
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108 | |
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109 | Extra field (35 bytes): |
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110 | - Pointer to first stored block length -- this points to the two-byte length |
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111 | of the first stored block, which is followed by the two-byte, one's |
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112 | complement of that length. The stored block length is preceded by the |
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113 | three-bit header of the stored block, which is the actual start of the |
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114 | stored block in the deflate format. See the bit offset field below. |
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115 | - Pointer to the last stored block length. This is the same as above, but |
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116 | for the last stored block of the uncompressed data in the gzip file. |
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117 | Initially this is the same as the first stored block length pointer. |
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118 | When the stored block gets to 16K (see the MAX_STORE define), then a new |
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119 | stored block as added, at which point the last stored block length pointer |
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120 | is different from the first stored block length pointer. When they are |
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121 | different, the first bit of the last stored block header is eight bits, or |
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122 | one byte back from the block length. |
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123 | - Compressed data crc and length. This is the crc and length of the data |
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124 | that is in the compressed portion of the deflate stream. These are used |
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125 | only in the event that the foo.add file containing the data to compress is |
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126 | lost after a compress operation is interrupted. |
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127 | - Total data crc and length. This is the crc and length of all of the data |
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128 | stored in the gzip file, compressed and uncompressed. It is used to |
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129 | reconstruct the gzip trailer when compressing, as well as when recovering |
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130 | interrupted operations. |
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131 | - Final stored block length. This is used to quickly find where to append, |
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132 | and allows the restoration of the original final stored block state when |
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133 | an append operation is interrupted. |
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134 | - First stored block start as the number of bits back from the final stored |
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135 | block first length byte. This value is in the range of 3..10, and is |
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136 | stored as the low three bits of the final byte of the extra field after |
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137 | subtracting three (0..7). This allows the last-block bit of the stored |
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138 | block header to be updated when a new stored block is added, for the case |
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139 | when the first stored block and the last stored block are the same. (When |
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140 | they are different, the numbers of bits back is known to be eight.) This |
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141 | also allows for new compressed data to be appended to the old compressed |
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142 | data in the compress operation, overwriting the previous first stored |
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143 | block, or for the compressed data to be terminated and a valid gzip file |
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144 | reconstructed on the off chance that a compression operation was |
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145 | interrupted and the data to compress in the foo.add file was deleted. |
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146 | - The operation in process. This is the next two bits in the last byte (the |
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147 | bits under the mask 0x18). The are interpreted as 0: nothing in process, |
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148 | 1: append in process, 2: compress in process, 3: replace in process. |
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149 | - The top three bits of the last byte in the extra field are reserved and |
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150 | are currently set to zero. |
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151 | |
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152 | Main procedure: |
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153 | - Exclusively create the foo.lock file using the O_CREAT and O_EXCL modes of |
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154 | the system open() call. If the modify time of an existing lock file is |
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155 | more than PATIENCE seconds old, then the lock file is deleted and the |
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156 | exclusive create is retried. |
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157 | - Load the extra field from the foo.gz file, and see if an operation was in |
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158 | progress but not completed. If so, apply the recovery procedure below. |
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159 | - Perform the append procedure with the provided data. |
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160 | - If the uncompressed data in the foo.gz file is 1MB or more, apply the |
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161 | compress procedure. |
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162 | - Delete the foo.lock file. |
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163 | |
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164 | Append procedure: |
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165 | - Put what to append in the foo.add file so that the operation can be |
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166 | restarted if this procedure is interrupted. |
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167 | - Mark the foo.gz extra field with the append operation in progress. |
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168 | + Restore the original last-block bit and stored block length of the last |
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169 | stored block from the information in the extra field, in case a previous |
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170 | append operation was interrupted. |
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171 | - Append the provided data to the last stored block, creating new stored |
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172 | blocks as needed and updating the stored blocks last-block bits and |
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173 | lengths. |
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174 | - Update the crc and length with the new data, and write the gzip trailer. |
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175 | - Write over the extra field (with a single write operation) with the new |
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176 | pointers, lengths, and crc's, and mark the gzip file as not in process. |
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177 | Though there is still a foo.add file, it will be ignored since nothing |
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178 | is in process. If a foo.add file is leftover from a previously |
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179 | completed operation, it is truncated when writing new data to it. |
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180 | - Delete the foo.add file. |
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181 | |
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182 | Compress and replace procedures: |
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183 | - Read all of the uncompressed data in the stored blocks in foo.gz and write |
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184 | it to foo.add. Also write foo.temp with the last 32K of that data to |
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185 | provide a dictionary for the next invocation of this procedure. |
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186 | - Rewrite the extra field marking foo.gz with a compression in process. |
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187 | * If there is no data provided to compress (due to a missing foo.add file |
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188 | when recovering), reconstruct and truncate the foo.gz file to contain |
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189 | only the previous compressed data and proceed to the step after the next |
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190 | one. Otherwise ... |
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191 | - Compress the data with the dictionary in foo.dict, and write to the |
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192 | foo.gz file starting at the bit immediately following the last previously |
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193 | compressed block. If there is no foo.dict, proceed anyway with the |
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194 | compression at slightly reduced efficiency. (For the foo.dict file to be |
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195 | missing requires some external failure beyond simply the interruption of |
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196 | a compress operation.) During this process, the foo.lock file is |
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197 | periodically touched to assure that that file is not considered stale by |
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198 | another process before we're done. The deflation is terminated with a |
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199 | non-last empty static block (10 bits long), that is then located and |
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200 | written over by a last-bit-set empty stored block. |
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201 | - Append the crc and length of the data in the gzip file (previously |
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202 | calculated during the append operations). |
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203 | - Write over the extra field with the updated stored block offsets, bits |
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204 | back, crc's, and lengths, and mark foo.gz as in process for a replacement |
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205 | of the dictionary. |
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206 | @ Delete the foo.add file. |
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207 | - Replace foo.dict with foo.temp. |
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208 | - Write over the extra field, marking foo.gz as complete. |
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209 | |
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210 | Recovery procedure: |
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211 | - If not a replace recovery, read in the foo.add file, and provide that data |
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212 | to the appropriate recovery below. If there is no foo.add file, provide |
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213 | a zero data length to the recovery. In that case, the append recovery |
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214 | restores the foo.gz to the previous compressed + uncompressed data state. |
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215 | For the the compress recovery, a missing foo.add file results in foo.gz |
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216 | being restored to the previous compressed-only data state. |
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217 | - Append recovery: |
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218 | - Pick up append at + step above |
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219 | - Compress recovery: |
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220 | - Pick up compress at * step above |
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221 | - Replace recovery: |
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222 | - Pick up compress at @ step above |
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223 | - Log the repair with a date stamp in foo.repairs |
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224 | */ |
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225 | |
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226 | #include <sys/types.h> |
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227 | #include <stdio.h> /* rename, fopen, fprintf, fclose */ |
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228 | #include <stdlib.h> /* malloc, free */ |
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229 | #include <string.h> /* strlen, strrchr, strcpy, strncpy, strcmp */ |
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230 | #include <fcntl.h> /* open */ |
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231 | #include <unistd.h> /* lseek, read, write, close, unlink, sleep, */ |
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232 | /* ftruncate, fsync */ |
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233 | #include <errno.h> /* errno */ |
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234 | #include <time.h> /* time, ctime */ |
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235 | #include <sys/stat.h> /* stat */ |
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236 | #include <sys/time.h> /* utimes */ |
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237 | #include "zlib.h" /* crc32 */ |
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238 | |
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239 | #include "gzlog.h" /* header for external access */ |
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240 | |
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241 | #define local static |
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242 | typedef unsigned int uint; |
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243 | typedef unsigned long ulong; |
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244 | |
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245 | /* Macro for debugging to deterministically force recovery operations */ |
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246 | #ifdef DEBUG |
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247 | #include <setjmp.h> /* longjmp */ |
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248 | jmp_buf gzlog_jump; /* where to go back to */ |
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249 | int gzlog_bail = 0; /* which point to bail at (1..8) */ |
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250 | int gzlog_count = -1; /* number of times through to wait */ |
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251 | # define BAIL(n) do { if (n == gzlog_bail && gzlog_count-- == 0) \ |
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252 | longjmp(gzlog_jump, gzlog_bail); } while (0) |
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253 | #else |
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254 | # define BAIL(n) |
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255 | #endif |
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256 | |
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257 | /* how old the lock file can be in seconds before considering it stale */ |
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258 | #define PATIENCE 300 |
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259 | |
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260 | /* maximum stored block size in Kbytes -- must be in 1..63 */ |
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261 | #define MAX_STORE 16 |
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262 | |
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263 | /* number of stored Kbytes to trigger compression (must be >= 32 to allow |
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264 | dictionary construction, and <= 204 * MAX_STORE, in order for >> 10 to |
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265 | discard the stored block headers contribution of five bytes each) */ |
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266 | #define TRIGGER 1024 |
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267 | |
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268 | /* size of a deflate dictionary (this cannot be changed) */ |
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269 | #define DICT 32768U |
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270 | |
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271 | /* values for the operation (2 bits) */ |
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272 | #define NO_OP 0 |
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273 | #define APPEND_OP 1 |
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274 | #define COMPRESS_OP 2 |
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275 | #define REPLACE_OP 3 |
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276 | |
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277 | /* macros to extract little-endian integers from an unsigned byte buffer */ |
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278 | #define PULL2(p) ((p)[0]+((uint)((p)[1])<<8)) |
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279 | #define PULL4(p) (PULL2(p)+((ulong)PULL2(p+2)<<16)) |
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280 | #define PULL8(p) (PULL4(p)+((off_t)PULL4(p+4)<<32)) |
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281 | |
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282 | /* macros to store integers into a byte buffer in little-endian order */ |
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283 | #define PUT2(p,a) do {(p)[0]=a;(p)[1]=(a)>>8;} while(0) |
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284 | #define PUT4(p,a) do {PUT2(p,a);PUT2(p+2,a>>16);} while(0) |
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285 | #define PUT8(p,a) do {PUT4(p,a);PUT4(p+4,a>>32);} while(0) |
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286 | |
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287 | /* internal structure for log information */ |
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288 | #define LOGID "\106\035\172" /* should be three non-zero characters */ |
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289 | struct log { |
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290 | char id[4]; /* contains LOGID to detect inadvertent overwrites */ |
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291 | int fd; /* file descriptor for .gz file, opened read/write */ |
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292 | char *path; /* allocated path, e.g. "/var/log/foo" or "foo" */ |
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293 | char *end; /* end of path, for appending suffices such as ".gz" */ |
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294 | off_t first; /* offset of first stored block first length byte */ |
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295 | int back; /* location of first block id in bits back from first */ |
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296 | uint stored; /* bytes currently in last stored block */ |
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297 | off_t last; /* offset of last stored block first length byte */ |
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298 | ulong ccrc; /* crc of compressed data */ |
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299 | ulong clen; /* length (modulo 2^32) of compressed data */ |
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300 | ulong tcrc; /* crc of total data */ |
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301 | ulong tlen; /* length (modulo 2^32) of total data */ |
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302 | time_t lock; /* last modify time of our lock file */ |
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303 | }; |
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304 | |
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305 | /* gzip header for gzlog */ |
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306 | local unsigned char log_gzhead[] = { |
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307 | 0x1f, 0x8b, /* magic gzip id */ |
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308 | 8, /* compression method is deflate */ |
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309 | 4, /* there is an extra field (no file name) */ |
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310 | 0, 0, 0, 0, /* no modification time provided */ |
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311 | 0, 0xff, /* no extra flags, no OS specified */ |
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312 | 39, 0, 'a', 'p', 35, 0 /* extra field with "ap" subfield */ |
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313 | /* 35 is EXTRA, 39 is EXTRA + 4 */ |
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314 | }; |
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315 | |
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316 | #define HEAD sizeof(log_gzhead) /* should be 16 */ |
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317 | |
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318 | /* initial gzip extra field content (52 == HEAD + EXTRA + 1) */ |
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319 | local unsigned char log_gzext[] = { |
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320 | 52, 0, 0, 0, 0, 0, 0, 0, /* offset of first stored block length */ |
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321 | 52, 0, 0, 0, 0, 0, 0, 0, /* offset of last stored block length */ |
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322 | 0, 0, 0, 0, 0, 0, 0, 0, /* compressed data crc and length */ |
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323 | 0, 0, 0, 0, 0, 0, 0, 0, /* total data crc and length */ |
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324 | 0, 0, /* final stored block data length */ |
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325 | 5 /* op is NO_OP, last bit 8 bits back */ |
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326 | }; |
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327 | |
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328 | #define EXTRA sizeof(log_gzext) /* should be 35 */ |
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329 | |
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330 | /* initial gzip data and trailer */ |
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331 | local unsigned char log_gzbody[] = { |
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332 | 1, 0, 0, 0xff, 0xff, /* empty stored block (last) */ |
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333 | 0, 0, 0, 0, /* crc */ |
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334 | 0, 0, 0, 0 /* uncompressed length */ |
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335 | }; |
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336 | |
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337 | #define BODY sizeof(log_gzbody) |
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338 | |
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339 | /* Exclusively create foo.lock in order to negotiate exclusive access to the |
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340 | foo.* files. If the modify time of an existing lock file is greater than |
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341 | PATIENCE seconds in the past, then consider the lock file to have been |
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342 | abandoned, delete it, and try the exclusive create again. Save the lock |
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343 | file modify time for verification of ownership. Return 0 on success, or -1 |
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344 | on failure, usually due to an access restriction or invalid path. Note that |
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345 | if stat() or unlink() fails, it may be due to another process noticing the |
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346 | abandoned lock file a smidge sooner and deleting it, so those are not |
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347 | flagged as an error. */ |
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348 | local int log_lock(struct log *log) |
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349 | { |
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350 | int fd; |
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351 | struct stat st; |
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352 | |
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353 | strcpy(log->end, ".lock"); |
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354 | while ((fd = open(log->path, O_CREAT | O_EXCL, 0644)) < 0) { |
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355 | if (errno != EEXIST) |
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356 | return -1; |
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357 | if (stat(log->path, &st) == 0 && time(NULL) - st.st_mtime > PATIENCE) { |
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358 | unlink(log->path); |
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359 | continue; |
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360 | } |
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361 | sleep(2); /* relinquish the CPU for two seconds while waiting */ |
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362 | } |
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363 | close(fd); |
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364 | if (stat(log->path, &st) == 0) |
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365 | log->lock = st.st_mtime; |
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366 | return 0; |
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367 | } |
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368 | |
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369 | /* Update the modify time of the lock file to now, in order to prevent another |
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370 | task from thinking that the lock is stale. Save the lock file modify time |
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371 | for verification of ownership. */ |
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372 | local void log_touch(struct log *log) |
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373 | { |
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374 | struct stat st; |
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375 | |
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376 | strcpy(log->end, ".lock"); |
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377 | utimes(log->path, NULL); |
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378 | if (stat(log->path, &st) == 0) |
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379 | log->lock = st.st_mtime; |
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380 | } |
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381 | |
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382 | /* Check the log file modify time against what is expected. Return true if |
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383 | this is not our lock. If it is our lock, touch it to keep it. */ |
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384 | local int log_check(struct log *log) |
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385 | { |
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386 | struct stat st; |
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387 | |
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388 | strcpy(log->end, ".lock"); |
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389 | if (stat(log->path, &st) || st.st_mtime != log->lock) |
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390 | return 1; |
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391 | log_touch(log); |
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392 | return 0; |
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393 | } |
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394 | |
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395 | /* Unlock a previously acquired lock, but only if it's ours. */ |
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396 | local void log_unlock(struct log *log) |
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397 | { |
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398 | if (log_check(log)) |
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399 | return; |
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400 | strcpy(log->end, ".lock"); |
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401 | unlink(log->path); |
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402 | log->lock = 0; |
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403 | } |
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404 | |
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405 | /* Check the gzip header and read in the extra field, filling in the values in |
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406 | the log structure. Return op on success or -1 if the gzip header was not as |
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407 | expected. op is the current operation in progress last written to the extra |
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408 | field. This assumes that the gzip file has already been opened, with the |
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409 | file descriptor log->fd. */ |
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410 | local int log_head(struct log *log) |
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411 | { |
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412 | int op; |
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413 | unsigned char buf[HEAD + EXTRA]; |
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414 | |
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415 | if (lseek(log->fd, 0, SEEK_SET) < 0 || |
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416 | read(log->fd, buf, HEAD + EXTRA) != HEAD + EXTRA || |
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417 | memcmp(buf, log_gzhead, HEAD)) { |
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418 | return -1; |
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419 | } |
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420 | log->first = PULL8(buf + HEAD); |
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421 | log->last = PULL8(buf + HEAD + 8); |
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422 | log->ccrc = PULL4(buf + HEAD + 16); |
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423 | log->clen = PULL4(buf + HEAD + 20); |
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424 | log->tcrc = PULL4(buf + HEAD + 24); |
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425 | log->tlen = PULL4(buf + HEAD + 28); |
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426 | log->stored = PULL2(buf + HEAD + 32); |
---|
427 | log->back = 3 + (buf[HEAD + 34] & 7); |
---|
428 | op = (buf[HEAD + 34] >> 3) & 3; |
---|
429 | return op; |
---|
430 | } |
---|
431 | |
---|
432 | /* Write over the extra field contents, marking the operation as op. Use fsync |
---|
433 | to assure that the device is written to, and in the requested order. This |
---|
434 | operation, and only this operation, is assumed to be atomic in order to |
---|
435 | assure that the log is recoverable in the event of an interruption at any |
---|
436 | point in the process. Return -1 if the write to foo.gz failed. */ |
---|
437 | local int log_mark(struct log *log, int op) |
---|
438 | { |
---|
439 | int ret; |
---|
440 | unsigned char ext[EXTRA]; |
---|
441 | |
---|
442 | PUT8(ext, log->first); |
---|
443 | PUT8(ext + 8, log->last); |
---|
444 | PUT4(ext + 16, log->ccrc); |
---|
445 | PUT4(ext + 20, log->clen); |
---|
446 | PUT4(ext + 24, log->tcrc); |
---|
447 | PUT4(ext + 28, log->tlen); |
---|
448 | PUT2(ext + 32, log->stored); |
---|
449 | ext[34] = log->back - 3 + (op << 3); |
---|
450 | fsync(log->fd); |
---|
451 | ret = lseek(log->fd, HEAD, SEEK_SET) < 0 || |
---|
452 | write(log->fd, ext, EXTRA) != EXTRA ? -1 : 0; |
---|
453 | fsync(log->fd); |
---|
454 | return ret; |
---|
455 | } |
---|
456 | |
---|
457 | /* Rewrite the last block header bits and subsequent zero bits to get to a byte |
---|
458 | boundary, setting the last block bit if last is true, and then write the |
---|
459 | remainder of the stored block header (length and one's complement). Leave |
---|
460 | the file pointer after the end of the last stored block data. Return -1 if |
---|
461 | there is a read or write failure on the foo.gz file */ |
---|
462 | local int log_last(struct log *log, int last) |
---|
463 | { |
---|
464 | int back, len, mask; |
---|
465 | unsigned char buf[6]; |
---|
466 | |
---|
467 | /* determine the locations of the bytes and bits to modify */ |
---|
468 | back = log->last == log->first ? log->back : 8; |
---|
469 | len = back > 8 ? 2 : 1; /* bytes back from log->last */ |
---|
470 | mask = 0x80 >> ((back - 1) & 7); /* mask for block last-bit */ |
---|
471 | |
---|
472 | /* get the byte to modify (one or two back) into buf[0] -- don't need to |
---|
473 | read the byte if the last-bit is eight bits back, since in that case |
---|
474 | the entire byte will be modified */ |
---|
475 | buf[0] = 0; |
---|
476 | if (back != 8 && (lseek(log->fd, log->last - len, SEEK_SET) < 0 || |
---|
477 | read(log->fd, buf, 1) != 1)) |
---|
478 | return -1; |
---|
479 | |
---|
480 | /* change the last-bit of the last stored block as requested -- note |
---|
481 | that all bits above the last-bit are set to zero, per the type bits |
---|
482 | of a stored block being 00 and per the convention that the bits to |
---|
483 | bring the stream to a byte boundary are also zeros */ |
---|
484 | buf[1] = 0; |
---|
485 | buf[2 - len] = (*buf & (mask - 1)) + (last ? mask : 0); |
---|
486 | |
---|
487 | /* write the modified stored block header and lengths, move the file |
---|
488 | pointer to after the last stored block data */ |
---|
489 | PUT2(buf + 2, log->stored); |
---|
490 | PUT2(buf + 4, log->stored ^ 0xffff); |
---|
491 | return lseek(log->fd, log->last - len, SEEK_SET) < 0 || |
---|
492 | write(log->fd, buf + 2 - len, len + 4) != len + 4 || |
---|
493 | lseek(log->fd, log->stored, SEEK_CUR) < 0 ? -1 : 0; |
---|
494 | } |
---|
495 | |
---|
496 | /* Append len bytes from data to the locked and open log file. len may be zero |
---|
497 | if recovering and no .add file was found. In that case, the previous state |
---|
498 | of the foo.gz file is restored. The data is appended uncompressed in |
---|
499 | deflate stored blocks. Return -1 if there was an error reading or writing |
---|
500 | the foo.gz file. */ |
---|
501 | local int log_append(struct log *log, unsigned char *data, size_t len) |
---|
502 | { |
---|
503 | uint put; |
---|
504 | off_t end; |
---|
505 | unsigned char buf[8]; |
---|
506 | |
---|
507 | /* set the last block last-bit and length, in case recovering an |
---|
508 | interrupted append, then position the file pointer to append to the |
---|
509 | block */ |
---|
510 | if (log_last(log, 1)) |
---|
511 | return -1; |
---|
512 | |
---|
513 | /* append, adding stored blocks and updating the offset of the last stored |
---|
514 | block as needed, and update the total crc and length */ |
---|
515 | while (len) { |
---|
516 | /* append as much as we can to the last block */ |
---|
517 | put = (MAX_STORE << 10) - log->stored; |
---|
518 | if (put > len) |
---|
519 | put = (uint)len; |
---|
520 | if (put) { |
---|
521 | if (write(log->fd, data, put) != put) |
---|
522 | return -1; |
---|
523 | BAIL(1); |
---|
524 | log->tcrc = crc32(log->tcrc, data, put); |
---|
525 | log->tlen += put; |
---|
526 | log->stored += put; |
---|
527 | data += put; |
---|
528 | len -= put; |
---|
529 | } |
---|
530 | |
---|
531 | /* if we need to, add a new empty stored block */ |
---|
532 | if (len) { |
---|
533 | /* mark current block as not last */ |
---|
534 | if (log_last(log, 0)) |
---|
535 | return -1; |
---|
536 | |
---|
537 | /* point to new, empty stored block */ |
---|
538 | log->last += 4 + log->stored + 1; |
---|
539 | log->stored = 0; |
---|
540 | } |
---|
541 | |
---|
542 | /* mark last block as last, update its length */ |
---|
543 | if (log_last(log, 1)) |
---|
544 | return -1; |
---|
545 | BAIL(2); |
---|
546 | } |
---|
547 | |
---|
548 | /* write the new crc and length trailer, and truncate just in case (could |
---|
549 | be recovering from partial append with a missing foo.add file) */ |
---|
550 | PUT4(buf, log->tcrc); |
---|
551 | PUT4(buf + 4, log->tlen); |
---|
552 | if (write(log->fd, buf, 8) != 8 || |
---|
553 | (end = lseek(log->fd, 0, SEEK_CUR)) < 0 || ftruncate(log->fd, end)) |
---|
554 | return -1; |
---|
555 | |
---|
556 | /* write the extra field, marking the log file as done, delete .add file */ |
---|
557 | if (log_mark(log, NO_OP)) |
---|
558 | return -1; |
---|
559 | strcpy(log->end, ".add"); |
---|
560 | unlink(log->path); /* ignore error, since may not exist */ |
---|
561 | return 0; |
---|
562 | } |
---|
563 | |
---|
564 | /* Replace the foo.dict file with the foo.temp file. Also delete the foo.add |
---|
565 | file, since the compress operation may have been interrupted before that was |
---|
566 | done. Returns 1 if memory could not be allocated, or -1 if reading or |
---|
567 | writing foo.gz fails, or if the rename fails for some reason other than |
---|
568 | foo.temp not existing. foo.temp not existing is a permitted error, since |
---|
569 | the replace operation may have been interrupted after the rename is done, |
---|
570 | but before foo.gz is marked as complete. */ |
---|
571 | local int log_replace(struct log *log) |
---|
572 | { |
---|
573 | int ret; |
---|
574 | char *dest; |
---|
575 | |
---|
576 | /* delete foo.add file */ |
---|
577 | strcpy(log->end, ".add"); |
---|
578 | unlink(log->path); /* ignore error, since may not exist */ |
---|
579 | BAIL(3); |
---|
580 | |
---|
581 | /* rename foo.name to foo.dict, replacing foo.dict if it exists */ |
---|
582 | strcpy(log->end, ".dict"); |
---|
583 | dest = malloc(strlen(log->path) + 1); |
---|
584 | if (dest == NULL) |
---|
585 | return -2; |
---|
586 | strcpy(dest, log->path); |
---|
587 | strcpy(log->end, ".temp"); |
---|
588 | ret = rename(log->path, dest); |
---|
589 | free(dest); |
---|
590 | if (ret && errno != ENOENT) |
---|
591 | return -1; |
---|
592 | BAIL(4); |
---|
593 | |
---|
594 | /* mark the foo.gz file as done */ |
---|
595 | return log_mark(log, NO_OP); |
---|
596 | } |
---|
597 | |
---|
598 | /* Compress the len bytes at data and append the compressed data to the |
---|
599 | foo.gz deflate data immediately after the previous compressed data. This |
---|
600 | overwrites the previous uncompressed data, which was stored in foo.add |
---|
601 | and is the data provided in data[0..len-1]. If this operation is |
---|
602 | interrupted, it picks up at the start of this routine, with the foo.add |
---|
603 | file read in again. If there is no data to compress (len == 0), then we |
---|
604 | simply terminate the foo.gz file after the previously compressed data, |
---|
605 | appending a final empty stored block and the gzip trailer. Return -1 if |
---|
606 | reading or writing the log.gz file failed, or -2 if there was a memory |
---|
607 | allocation failure. */ |
---|
608 | local int log_compress(struct log *log, unsigned char *data, size_t len) |
---|
609 | { |
---|
610 | int fd; |
---|
611 | uint got, max; |
---|
612 | ssize_t dict; |
---|
613 | off_t end; |
---|
614 | z_stream strm; |
---|
615 | unsigned char buf[DICT]; |
---|
616 | |
---|
617 | /* compress and append compressed data */ |
---|
618 | if (len) { |
---|
619 | /* set up for deflate, allocating memory */ |
---|
620 | strm.zalloc = Z_NULL; |
---|
621 | strm.zfree = Z_NULL; |
---|
622 | strm.opaque = Z_NULL; |
---|
623 | if (deflateInit2(&strm, Z_DEFAULT_COMPRESSION, Z_DEFLATED, -15, 8, |
---|
624 | Z_DEFAULT_STRATEGY) != Z_OK) |
---|
625 | return -2; |
---|
626 | |
---|
627 | /* read in dictionary (last 32K of data that was compressed) */ |
---|
628 | strcpy(log->end, ".dict"); |
---|
629 | fd = open(log->path, O_RDONLY, 0); |
---|
630 | if (fd >= 0) { |
---|
631 | dict = read(fd, buf, DICT); |
---|
632 | close(fd); |
---|
633 | if (dict < 0) { |
---|
634 | deflateEnd(&strm); |
---|
635 | return -1; |
---|
636 | } |
---|
637 | if (dict) |
---|
638 | deflateSetDictionary(&strm, buf, (uint)dict); |
---|
639 | } |
---|
640 | log_touch(log); |
---|
641 | |
---|
642 | /* prime deflate with last bits of previous block, position write |
---|
643 | pointer to write those bits and overwrite what follows */ |
---|
644 | if (lseek(log->fd, log->first - (log->back > 8 ? 2 : 1), |
---|
645 | SEEK_SET) < 0 || |
---|
646 | read(log->fd, buf, 1) != 1 || lseek(log->fd, -1, SEEK_CUR) < 0) { |
---|
647 | deflateEnd(&strm); |
---|
648 | return -1; |
---|
649 | } |
---|
650 | deflatePrime(&strm, (8 - log->back) & 7, *buf); |
---|
651 | |
---|
652 | /* compress, finishing with a partial non-last empty static block */ |
---|
653 | strm.next_in = data; |
---|
654 | max = (((uint)0 - 1) >> 1) + 1; /* in case int smaller than size_t */ |
---|
655 | do { |
---|
656 | strm.avail_in = len > max ? max : (uint)len; |
---|
657 | len -= strm.avail_in; |
---|
658 | do { |
---|
659 | strm.avail_out = DICT; |
---|
660 | strm.next_out = buf; |
---|
661 | deflate(&strm, len ? Z_NO_FLUSH : Z_PARTIAL_FLUSH); |
---|
662 | got = DICT - strm.avail_out; |
---|
663 | if (got && write(log->fd, buf, got) != got) { |
---|
664 | deflateEnd(&strm); |
---|
665 | return -1; |
---|
666 | } |
---|
667 | log_touch(log); |
---|
668 | } while (strm.avail_out == 0); |
---|
669 | } while (len); |
---|
670 | deflateEnd(&strm); |
---|
671 | BAIL(5); |
---|
672 | |
---|
673 | /* find start of empty static block -- scanning backwards the first one |
---|
674 | bit is the second bit of the block, if the last byte is zero, then |
---|
675 | we know the byte before that has a one in the top bit, since an |
---|
676 | empty static block is ten bits long */ |
---|
677 | if ((log->first = lseek(log->fd, -1, SEEK_CUR)) < 0 || |
---|
678 | read(log->fd, buf, 1) != 1) |
---|
679 | return -1; |
---|
680 | log->first++; |
---|
681 | if (*buf) { |
---|
682 | log->back = 1; |
---|
683 | while ((*buf & ((uint)1 << (8 - log->back++))) == 0) |
---|
684 | ; /* guaranteed to terminate, since *buf != 0 */ |
---|
685 | } |
---|
686 | else |
---|
687 | log->back = 10; |
---|
688 | |
---|
689 | /* update compressed crc and length */ |
---|
690 | log->ccrc = log->tcrc; |
---|
691 | log->clen = log->tlen; |
---|
692 | } |
---|
693 | else { |
---|
694 | /* no data to compress -- fix up existing gzip stream */ |
---|
695 | log->tcrc = log->ccrc; |
---|
696 | log->tlen = log->clen; |
---|
697 | } |
---|
698 | |
---|
699 | /* complete and truncate gzip stream */ |
---|
700 | log->last = log->first; |
---|
701 | log->stored = 0; |
---|
702 | PUT4(buf, log->tcrc); |
---|
703 | PUT4(buf + 4, log->tlen); |
---|
704 | if (log_last(log, 1) || write(log->fd, buf, 8) != 8 || |
---|
705 | (end = lseek(log->fd, 0, SEEK_CUR)) < 0 || ftruncate(log->fd, end)) |
---|
706 | return -1; |
---|
707 | BAIL(6); |
---|
708 | |
---|
709 | /* mark as being in the replace operation */ |
---|
710 | if (log_mark(log, REPLACE_OP)) |
---|
711 | return -1; |
---|
712 | |
---|
713 | /* execute the replace operation and mark the file as done */ |
---|
714 | return log_replace(log); |
---|
715 | } |
---|
716 | |
---|
717 | /* log a repair record to the .repairs file */ |
---|
718 | local void log_log(struct log *log, int op, char *record) |
---|
719 | { |
---|
720 | time_t now; |
---|
721 | FILE *rec; |
---|
722 | |
---|
723 | now = time(NULL); |
---|
724 | strcpy(log->end, ".repairs"); |
---|
725 | rec = fopen(log->path, "a"); |
---|
726 | if (rec == NULL) |
---|
727 | return; |
---|
728 | fprintf(rec, "%.24s %s recovery: %s\n", ctime(&now), op == APPEND_OP ? |
---|
729 | "append" : (op == COMPRESS_OP ? "compress" : "replace"), record); |
---|
730 | fclose(rec); |
---|
731 | return; |
---|
732 | } |
---|
733 | |
---|
734 | /* Recover the interrupted operation op. First read foo.add for recovering an |
---|
735 | append or compress operation. Return -1 if there was an error reading or |
---|
736 | writing foo.gz or reading an existing foo.add, or -2 if there was a memory |
---|
737 | allocation failure. */ |
---|
738 | local int log_recover(struct log *log, int op) |
---|
739 | { |
---|
740 | int fd, ret = 0; |
---|
741 | unsigned char *data = NULL; |
---|
742 | size_t len = 0; |
---|
743 | struct stat st; |
---|
744 | |
---|
745 | /* log recovery */ |
---|
746 | log_log(log, op, "start"); |
---|
747 | |
---|
748 | /* load foo.add file if expected and present */ |
---|
749 | if (op == APPEND_OP || op == COMPRESS_OP) { |
---|
750 | strcpy(log->end, ".add"); |
---|
751 | if (stat(log->path, &st) == 0 && st.st_size) { |
---|
752 | len = (size_t)(st.st_size); |
---|
753 | if (len != st.st_size || (data = malloc(st.st_size)) == NULL) { |
---|
754 | log_log(log, op, "allocation failure"); |
---|
755 | return -2; |
---|
756 | } |
---|
757 | if ((fd = open(log->path, O_RDONLY, 0)) < 0) { |
---|
758 | log_log(log, op, ".add file read failure"); |
---|
759 | return -1; |
---|
760 | } |
---|
761 | ret = read(fd, data, len) != len; |
---|
762 | close(fd); |
---|
763 | if (ret) { |
---|
764 | log_log(log, op, ".add file read failure"); |
---|
765 | return -1; |
---|
766 | } |
---|
767 | log_log(log, op, "loaded .add file"); |
---|
768 | } |
---|
769 | else |
---|
770 | log_log(log, op, "missing .add file!"); |
---|
771 | } |
---|
772 | |
---|
773 | /* recover the interrupted operation */ |
---|
774 | switch (op) { |
---|
775 | case APPEND_OP: |
---|
776 | ret = log_append(log, data, len); |
---|
777 | break; |
---|
778 | case COMPRESS_OP: |
---|
779 | ret = log_compress(log, data, len); |
---|
780 | break; |
---|
781 | case REPLACE_OP: |
---|
782 | ret = log_replace(log); |
---|
783 | } |
---|
784 | |
---|
785 | /* log status */ |
---|
786 | log_log(log, op, ret ? "failure" : "complete"); |
---|
787 | |
---|
788 | /* clean up */ |
---|
789 | if (data != NULL) |
---|
790 | free(data); |
---|
791 | return ret; |
---|
792 | } |
---|
793 | |
---|
794 | /* Close the foo.gz file (if open) and release the lock. */ |
---|
795 | local void log_close(struct log *log) |
---|
796 | { |
---|
797 | if (log->fd >= 0) |
---|
798 | close(log->fd); |
---|
799 | log->fd = -1; |
---|
800 | log_unlock(log); |
---|
801 | } |
---|
802 | |
---|
803 | /* Open foo.gz, verify the header, and load the extra field contents, after |
---|
804 | first creating the foo.lock file to gain exclusive access to the foo.* |
---|
805 | files. If foo.gz does not exist or is empty, then write the initial header, |
---|
806 | extra, and body content of an empty foo.gz log file. If there is an error |
---|
807 | creating the lock file due to access restrictions, or an error reading or |
---|
808 | writing the foo.gz file, or if the foo.gz file is not a proper log file for |
---|
809 | this object (e.g. not a gzip file or does not contain the expected extra |
---|
810 | field), then return true. If there is an error, the lock is released. |
---|
811 | Otherwise, the lock is left in place. */ |
---|
812 | local int log_open(struct log *log) |
---|
813 | { |
---|
814 | int op; |
---|
815 | |
---|
816 | /* release open file resource if left over -- can occur if lock lost |
---|
817 | between gzlog_open() and gzlog_write() */ |
---|
818 | if (log->fd >= 0) |
---|
819 | close(log->fd); |
---|
820 | log->fd = -1; |
---|
821 | |
---|
822 | /* negotiate exclusive access */ |
---|
823 | if (log_lock(log) < 0) |
---|
824 | return -1; |
---|
825 | |
---|
826 | /* open the log file, foo.gz */ |
---|
827 | strcpy(log->end, ".gz"); |
---|
828 | log->fd = open(log->path, O_RDWR | O_CREAT, 0644); |
---|
829 | if (log->fd < 0) { |
---|
830 | log_close(log); |
---|
831 | return -1; |
---|
832 | } |
---|
833 | |
---|
834 | /* if new, initialize foo.gz with an empty log, delete old dictionary */ |
---|
835 | if (lseek(log->fd, 0, SEEK_END) == 0) { |
---|
836 | if (write(log->fd, log_gzhead, HEAD) != HEAD || |
---|
837 | write(log->fd, log_gzext, EXTRA) != EXTRA || |
---|
838 | write(log->fd, log_gzbody, BODY) != BODY) { |
---|
839 | log_close(log); |
---|
840 | return -1; |
---|
841 | } |
---|
842 | strcpy(log->end, ".dict"); |
---|
843 | unlink(log->path); |
---|
844 | } |
---|
845 | |
---|
846 | /* verify log file and load extra field information */ |
---|
847 | if ((op = log_head(log)) < 0) { |
---|
848 | log_close(log); |
---|
849 | return -1; |
---|
850 | } |
---|
851 | |
---|
852 | /* check for interrupted process and if so, recover */ |
---|
853 | if (op != NO_OP && log_recover(log, op)) { |
---|
854 | log_close(log); |
---|
855 | return -1; |
---|
856 | } |
---|
857 | |
---|
858 | /* touch the lock file to prevent another process from grabbing it */ |
---|
859 | log_touch(log); |
---|
860 | return 0; |
---|
861 | } |
---|
862 | |
---|
863 | /* See gzlog.h for the description of the external methods below */ |
---|
864 | gzlog *gzlog_open(char *path) |
---|
865 | { |
---|
866 | size_t n; |
---|
867 | struct log *log; |
---|
868 | |
---|
869 | /* check arguments */ |
---|
870 | if (path == NULL || *path == 0) |
---|
871 | return NULL; |
---|
872 | |
---|
873 | /* allocate and initialize log structure */ |
---|
874 | log = malloc(sizeof(struct log)); |
---|
875 | if (log == NULL) |
---|
876 | return NULL; |
---|
877 | strcpy(log->id, LOGID); |
---|
878 | log->fd = -1; |
---|
879 | |
---|
880 | /* save path and end of path for name construction */ |
---|
881 | n = strlen(path); |
---|
882 | log->path = malloc(n + 9); /* allow for ".repairs" */ |
---|
883 | if (log->path == NULL) { |
---|
884 | free(log); |
---|
885 | return NULL; |
---|
886 | } |
---|
887 | strcpy(log->path, path); |
---|
888 | log->end = log->path + n; |
---|
889 | |
---|
890 | /* gain exclusive access and verify log file -- may perform a |
---|
891 | recovery operation if needed */ |
---|
892 | if (log_open(log)) { |
---|
893 | free(log->path); |
---|
894 | free(log); |
---|
895 | return NULL; |
---|
896 | } |
---|
897 | |
---|
898 | /* return pointer to log structure */ |
---|
899 | return log; |
---|
900 | } |
---|
901 | |
---|
902 | /* gzlog_compress() return values: |
---|
903 | 0: all good |
---|
904 | -1: file i/o error (usually access issue) |
---|
905 | -2: memory allocation failure |
---|
906 | -3: invalid log pointer argument */ |
---|
907 | int gzlog_compress(gzlog *logd) |
---|
908 | { |
---|
909 | int fd, ret; |
---|
910 | uint block; |
---|
911 | size_t len, next; |
---|
912 | unsigned char *data, buf[5]; |
---|
913 | struct log *log = logd; |
---|
914 | |
---|
915 | /* check arguments */ |
---|
916 | if (log == NULL || strcmp(log->id, LOGID) || len < 0) |
---|
917 | return -3; |
---|
918 | |
---|
919 | /* see if we lost the lock -- if so get it again and reload the extra |
---|
920 | field information (it probably changed), recover last operation if |
---|
921 | necessary */ |
---|
922 | if (log_check(log) && log_open(log)) |
---|
923 | return -1; |
---|
924 | |
---|
925 | /* create space for uncompressed data */ |
---|
926 | len = ((size_t)(log->last - log->first) & ~(((size_t)1 << 10) - 1)) + |
---|
927 | log->stored; |
---|
928 | if ((data = malloc(len)) == NULL) |
---|
929 | return -2; |
---|
930 | |
---|
931 | /* do statement here is just a cheap trick for error handling */ |
---|
932 | do { |
---|
933 | /* read in the uncompressed data */ |
---|
934 | if (lseek(log->fd, log->first - 1, SEEK_SET) < 0) |
---|
935 | break; |
---|
936 | next = 0; |
---|
937 | while (next < len) { |
---|
938 | if (read(log->fd, buf, 5) != 5) |
---|
939 | break; |
---|
940 | block = PULL2(buf + 1); |
---|
941 | if (next + block > len || |
---|
942 | read(log->fd, (char *)data + next, block) != block) |
---|
943 | break; |
---|
944 | next += block; |
---|
945 | } |
---|
946 | if (lseek(log->fd, 0, SEEK_CUR) != log->last + 4 + log->stored) |
---|
947 | break; |
---|
948 | log_touch(log); |
---|
949 | |
---|
950 | /* write the uncompressed data to the .add file */ |
---|
951 | strcpy(log->end, ".add"); |
---|
952 | fd = open(log->path, O_WRONLY | O_CREAT | O_TRUNC, 0644); |
---|
953 | if (fd < 0) |
---|
954 | break; |
---|
955 | ret = write(fd, data, len) != len; |
---|
956 | if (ret | close(fd)) |
---|
957 | break; |
---|
958 | log_touch(log); |
---|
959 | |
---|
960 | /* write the dictionary for the next compress to the .temp file */ |
---|
961 | strcpy(log->end, ".temp"); |
---|
962 | fd = open(log->path, O_WRONLY | O_CREAT | O_TRUNC, 0644); |
---|
963 | if (fd < 0) |
---|
964 | break; |
---|
965 | next = DICT > len ? len : DICT; |
---|
966 | ret = write(fd, (char *)data + len - next, next) != next; |
---|
967 | if (ret | close(fd)) |
---|
968 | break; |
---|
969 | log_touch(log); |
---|
970 | |
---|
971 | /* roll back to compressed data, mark the compress in progress */ |
---|
972 | log->last = log->first; |
---|
973 | log->stored = 0; |
---|
974 | if (log_mark(log, COMPRESS_OP)) |
---|
975 | break; |
---|
976 | BAIL(7); |
---|
977 | |
---|
978 | /* compress and append the data (clears mark) */ |
---|
979 | ret = log_compress(log, data, len); |
---|
980 | free(data); |
---|
981 | return ret; |
---|
982 | } while (0); |
---|
983 | |
---|
984 | /* broke out of do above on i/o error */ |
---|
985 | free(data); |
---|
986 | return -1; |
---|
987 | } |
---|
988 | |
---|
989 | /* gzlog_write() return values: |
---|
990 | 0: all good |
---|
991 | -1: file i/o error (usually access issue) |
---|
992 | -2: memory allocation failure |
---|
993 | -3: invalid log pointer argument */ |
---|
994 | int gzlog_write(gzlog *logd, void *data, size_t len) |
---|
995 | { |
---|
996 | int fd, ret; |
---|
997 | struct log *log = logd; |
---|
998 | |
---|
999 | /* check arguments */ |
---|
1000 | if (log == NULL || strcmp(log->id, LOGID) || len < 0) |
---|
1001 | return -3; |
---|
1002 | if (data == NULL || len == 0) |
---|
1003 | return 0; |
---|
1004 | |
---|
1005 | /* see if we lost the lock -- if so get it again and reload the extra |
---|
1006 | field information (it probably changed), recover last operation if |
---|
1007 | necessary */ |
---|
1008 | if (log_check(log) && log_open(log)) |
---|
1009 | return -1; |
---|
1010 | |
---|
1011 | /* create and write .add file */ |
---|
1012 | strcpy(log->end, ".add"); |
---|
1013 | fd = open(log->path, O_WRONLY | O_CREAT | O_TRUNC, 0644); |
---|
1014 | if (fd < 0) |
---|
1015 | return -1; |
---|
1016 | ret = write(fd, data, len) != len; |
---|
1017 | if (ret | close(fd)) |
---|
1018 | return -1; |
---|
1019 | log_touch(log); |
---|
1020 | |
---|
1021 | /* mark log file with append in progress */ |
---|
1022 | if (log_mark(log, APPEND_OP)) |
---|
1023 | return -1; |
---|
1024 | BAIL(8); |
---|
1025 | |
---|
1026 | /* append data (clears mark) */ |
---|
1027 | if (log_append(log, data, len)) |
---|
1028 | return -1; |
---|
1029 | |
---|
1030 | /* check to see if it's time to compress -- if not, then done */ |
---|
1031 | if (((log->last - log->first) >> 10) + (log->stored >> 10) < TRIGGER) |
---|
1032 | return 0; |
---|
1033 | |
---|
1034 | /* time to compress */ |
---|
1035 | return gzlog_compress(log); |
---|
1036 | } |
---|
1037 | |
---|
1038 | /* gzlog_close() return values: |
---|
1039 | 0: ok |
---|
1040 | -3: invalid log pointer argument */ |
---|
1041 | int gzlog_close(gzlog *logd) |
---|
1042 | { |
---|
1043 | struct log *log = logd; |
---|
1044 | |
---|
1045 | /* check arguments */ |
---|
1046 | if (log == NULL || strcmp(log->id, LOGID)) |
---|
1047 | return -3; |
---|
1048 | |
---|
1049 | /* close the log file and release the lock */ |
---|
1050 | log_close(log); |
---|
1051 | |
---|
1052 | /* free structure and return */ |
---|
1053 | if (log->path != NULL) |
---|
1054 | free(log->path); |
---|
1055 | strcpy(log->id, "bad"); |
---|
1056 | free(log); |
---|
1057 | return 0; |
---|
1058 | } |
---|