1 | /* |
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2 | * COPYRIGHT (c) 2012, 2018 Chris Johns <chrisj@rtems.org> |
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3 | * |
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4 | * The license and distribution terms for this file may be |
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5 | * found in the file LICENSE in this distribution or at |
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6 | * http://www.rtems.org/license/LICENSE. |
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7 | */ |
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8 | /** |
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9 | * @file |
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10 | * |
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11 | * @ingroup rtems_rtl |
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12 | * |
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13 | * @brief RTEMS Run-Time Linker Object File cache buffers a section of the |
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14 | * object file in a buffer to localise read performance. |
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15 | */ |
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16 | |
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17 | #if HAVE_CONFIG_H |
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18 | #include "config.h" |
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19 | #endif |
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20 | |
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21 | #include <errno.h> |
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22 | #include <stdio.h> |
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23 | #include <string.h> |
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24 | #include <unistd.h> |
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25 | #include <inttypes.h> |
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26 | #include <rtems/inttypes.h> |
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27 | |
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28 | #include <rtems/rtl/rtl-allocator.h> |
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29 | #include <rtems/rtl/rtl-obj-cache.h> |
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30 | #include "rtl-error.h" |
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31 | #include <rtems/rtl/rtl-trace.h> |
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32 | |
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33 | bool |
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34 | rtems_rtl_obj_cache_open (rtems_rtl_obj_cache* cache, size_t size) |
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35 | { |
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36 | cache->fd = -1; |
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37 | cache->file_size = 0; |
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38 | cache->offset = 0; |
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39 | cache->size = size; |
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40 | cache->level = 0; |
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41 | cache->buffer = rtems_rtl_alloc_new (RTEMS_RTL_ALLOC_OBJECT, size, false); |
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42 | if (!cache->buffer) |
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43 | { |
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44 | rtems_rtl_set_error (ENOMEM, "no memory for cache buffer"); |
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45 | return false; |
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46 | } |
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47 | return true; |
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48 | } |
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49 | |
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50 | void |
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51 | rtems_rtl_obj_cache_close (rtems_rtl_obj_cache* cache) |
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52 | { |
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53 | if (rtems_rtl_trace (RTEMS_RTL_TRACE_CACHE)) |
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54 | printf ("rtl: cache: %2d: close\n", cache->fd); |
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55 | rtems_rtl_alloc_del (RTEMS_RTL_ALLOC_OBJECT, cache->buffer); |
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56 | cache->buffer = NULL; |
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57 | cache->fd = -1; |
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58 | cache->file_size = 0; |
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59 | cache->level = 0; |
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60 | } |
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61 | |
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62 | void |
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63 | rtems_rtl_obj_cache_flush (rtems_rtl_obj_cache* cache) |
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64 | { |
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65 | if (rtems_rtl_trace (RTEMS_RTL_TRACE_CACHE)) |
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66 | printf ("rtl: cache: %2d: flush\n", cache->fd); |
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67 | cache->fd = -1; |
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68 | cache->file_size = 0; |
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69 | cache->offset = 0; |
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70 | cache->level = 0; |
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71 | } |
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72 | |
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73 | bool |
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74 | rtems_rtl_obj_cache_read (rtems_rtl_obj_cache* cache, |
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75 | int fd, |
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76 | off_t offset, |
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77 | void** buffer, |
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78 | size_t* length) |
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79 | { |
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80 | struct stat sb; |
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81 | |
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82 | if (rtems_rtl_trace (RTEMS_RTL_TRACE_CACHE)) |
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83 | printf ("rtl: cache: %2d: fd=%d offset=%" PRIdoff_t "length=%zu area=[%" |
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84 | PRIdoff_t ",%" PRIdoff_t "] cache=[%" PRIdoff_t ",%" PRIdoff_t "] size=%zu\n", |
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85 | fd, cache->fd, offset, *length, |
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86 | offset, offset + *length, |
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87 | cache->offset, cache->offset + cache->level, |
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88 | cache->file_size); |
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89 | |
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90 | if (*length > cache->size) |
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91 | { |
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92 | rtems_rtl_set_error (EINVAL, "read size larger than cache size"); |
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93 | return false; |
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94 | } |
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95 | |
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96 | if (cache->fd == fd) |
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97 | { |
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98 | if (offset > cache->file_size) |
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99 | { |
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100 | rtems_rtl_set_error (EINVAL, "offset past end of file: offset=%i size=%i", |
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101 | (int) offset, (int) cache->file_size); |
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102 | return false; |
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103 | } |
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104 | |
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105 | /* |
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106 | * We sometimes are asked to read strings of a length we do not know. |
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107 | */ |
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108 | if ((offset + *length) > cache->file_size) |
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109 | { |
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110 | *length = cache->file_size - offset; |
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111 | if (rtems_rtl_trace (RTEMS_RTL_TRACE_CACHE)) |
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112 | printf ("rtl: cache: %2d: truncate length=%d\n", fd, (int) *length); |
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113 | } |
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114 | } |
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115 | |
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116 | while (true) |
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117 | { |
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118 | size_t buffer_offset = 0; |
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119 | size_t buffer_read = cache->size; |
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120 | |
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121 | /* |
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122 | * Is the data in the cache for this file ? |
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123 | */ |
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124 | if (fd == cache->fd) |
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125 | { |
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126 | /* |
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127 | * Do not read past the end of the file. |
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128 | */ |
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129 | if ((offset + buffer_read) > cache->file_size) |
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130 | buffer_read = cache->file_size - offset; |
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131 | |
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132 | /* |
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133 | * Is any part of the data in the cache ? |
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134 | */ |
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135 | if ((offset >= cache->offset) && |
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136 | (offset < (cache->offset + cache->level))) |
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137 | { |
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138 | size_t size; |
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139 | |
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140 | buffer_offset = offset - cache->offset; |
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141 | size = cache->level - buffer_offset; |
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142 | |
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143 | /* |
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144 | * Return the location of the data in the cache. |
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145 | */ |
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146 | *buffer = cache->buffer + buffer_offset; |
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147 | |
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148 | /* |
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149 | * Is all the data in the cache or just a part ? |
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150 | */ |
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151 | if (*length <= size) |
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152 | return true; |
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153 | |
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154 | if (rtems_rtl_trace (RTEMS_RTL_TRACE_CACHE)) |
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155 | printf ("rtl: cache: %2d: copy-down: buffer_offset=%d size=%d level=%d\n", |
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156 | fd, (int) buffer_offset, (int) size, (int) cache->level); |
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157 | |
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158 | /* |
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159 | * Copy down the data in the buffer and then fill the remaining space |
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160 | * with as much data we are able to read. |
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161 | */ |
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162 | memmove (cache->buffer, cache->buffer + buffer_offset, size); |
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163 | |
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164 | cache->offset = offset; |
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165 | cache->level = size; |
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166 | buffer_read = cache->size - cache->level; |
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167 | buffer_offset = size; |
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168 | |
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169 | /* |
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170 | * Do not read past the end of the file. |
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171 | */ |
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172 | if ((offset + buffer_offset + buffer_read) > cache->file_size) |
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173 | buffer_read = cache->file_size - (offset + buffer_offset); |
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174 | } |
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175 | } |
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176 | |
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177 | if (rtems_rtl_trace (RTEMS_RTL_TRACE_CACHE)) |
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178 | printf ("rtl: cache: %2d: seek: offset=%" PRIdoff_t "buffer_offset=%zu" |
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179 | "read=%zu cache=[%" PRIdoff_t ",%" PRIdoff_t "] " |
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180 | "dist=%" PRIdoff_t "\n", |
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181 | fd, offset + buffer_offset, buffer_offset, buffer_read, |
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182 | offset, offset + buffer_read, |
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183 | (cache->file_size - offset)); |
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184 | |
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185 | if (lseek (fd, offset + buffer_offset, SEEK_SET) < 0) |
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186 | { |
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187 | rtems_rtl_set_error (errno, "file seek failed"); |
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188 | return false; |
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189 | } |
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190 | |
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191 | /* |
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192 | * Loop reading the data from the file until either an error or 0 is |
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193 | * returned and if data has been read check if the amount is what we |
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194 | * want. If not it is an error. A POSIX read can read data in fragments. |
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195 | */ |
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196 | |
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197 | cache->level = buffer_offset + buffer_read; |
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198 | |
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199 | while (buffer_read) |
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200 | { |
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201 | int r = read (fd, cache->buffer + buffer_offset, buffer_read); |
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202 | if (r < 0) |
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203 | { |
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204 | rtems_rtl_set_error (errno, "file read failed"); |
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205 | return false; |
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206 | } |
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207 | if ((r == 0) && buffer_read) |
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208 | { |
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209 | if (rtems_rtl_trace (RTEMS_RTL_TRACE_CACHE)) |
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210 | printf ("rtl: cache: %2d: read: past end by=%d\n", fd, (int) buffer_read); |
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211 | cache->level = cache->level - buffer_read; |
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212 | buffer_read = 0; |
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213 | } |
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214 | else |
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215 | { |
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216 | buffer_read -= r; |
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217 | buffer_offset += r; |
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218 | } |
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219 | } |
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220 | |
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221 | cache->offset = offset; |
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222 | |
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223 | if (cache->fd != fd) |
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224 | { |
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225 | cache->fd = fd; |
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226 | |
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227 | if (fstat (cache->fd, &sb) < 0) |
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228 | { |
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229 | rtems_rtl_set_error (errno, "file stat failed"); |
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230 | return false; |
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231 | } |
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232 | |
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233 | cache->file_size = sb.st_size; |
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234 | } |
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235 | } |
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236 | |
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237 | return false; |
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238 | } |
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239 | |
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240 | bool |
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241 | rtems_rtl_obj_cache_read_byval (rtems_rtl_obj_cache* cache, |
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242 | int fd, |
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243 | off_t offset, |
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244 | void* buffer, |
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245 | size_t length) |
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246 | { |
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247 | void* cbuffer = 0; |
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248 | size_t len = length; |
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249 | bool ok = rtems_rtl_obj_cache_read (cache, fd, offset, &cbuffer, &len); |
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250 | if (ok && (len != length)) |
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251 | ok = false; |
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252 | if (ok) |
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253 | memcpy (buffer, cbuffer, length); |
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254 | return ok; |
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255 | } |
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