1 | .\" Copyright (c) 2009 Joseph Koshy. All rights reserved. |
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2 | .\" |
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3 | .\" Redistribution and use in source and binary forms, with or without |
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4 | .\" modification, are permitted provided that the following conditions |
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5 | .\" are met: |
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6 | .\" 1. Redistributions of source code must retain the above copyright |
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7 | .\" notice, this list of conditions and the following disclaimer. |
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8 | .\" 2. Redistributions in binary form must reproduce the above copyright |
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9 | .\" notice, this list of conditions and the following disclaimer in the |
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10 | .\" documentation and/or other materials provided with the distribution. |
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11 | .\" |
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12 | .\" This software is provided by Joseph Koshy ``as is'' and |
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13 | .\" any express or implied warranties, including, but not limited to, the |
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14 | .\" implied warranties of merchantability and fitness for a particular purpose |
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15 | .\" are disclaimed. in no event shall Joseph Koshy be liable |
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19 | .\" however caused and on any theory of liability, whether in contract, strict |
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20 | .\" liability, or tort (including negligence or otherwise) arising in any way |
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21 | .\" out of the use of this software, even if advised of the possibility of |
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22 | .\" such damage. |
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23 | .\" |
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24 | .\" $Id: dwarf_init.3 2122 2011-11-09 15:35:14Z jkoshy $ |
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25 | .\" |
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26 | .Dd November 9, 2011 |
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27 | .Os |
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28 | .Dt DWARF_INIT 3 |
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29 | .Sh NAME |
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30 | .Nm dwarf_init , |
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31 | .Nm dwarf_elf_init |
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32 | .Nd allocate a DWARF debug descriptor |
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33 | .Sh LIBRARY |
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34 | .Lb libdwarf |
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35 | .Sh SYNOPSIS |
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36 | .In libdwarf.h |
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37 | .Ft int |
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38 | .Fo dwarf_init |
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39 | .Fa "int fd" |
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40 | .Fa "int mode" |
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41 | .Fa "Dwarf_Handler errhand" |
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42 | .Fa "Dwarf_Ptr errarg" |
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43 | .Fa "Dwarf_Debug *ret" |
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44 | .Fa "Dwarf_Error *err" |
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45 | .Fc |
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46 | .Ft in |
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47 | .Fo dwarf_elf_init |
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48 | .Fa "Elf *elf" |
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49 | .Fa "int mode" |
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50 | .Fa "Dwarf_Handler errhand" |
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51 | .Fa "Dwarf_Ptr errarg" |
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52 | .Fa "Dwarf_Debug *ret" |
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53 | .Fa "Dwarf_Error *err" |
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54 | .Fc |
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55 | .Sh DESCRIPTION |
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56 | These functions allocate and return a |
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57 | .Vt Dwarf_Debug |
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58 | instance for the object denoted by argument |
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59 | .Ar fd |
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60 | or |
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61 | .Ar elf . |
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62 | This instance would be used for subsequent access to debugging information in the object by other functions in the DWARF(3) library. |
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63 | .Pp |
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64 | For function |
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65 | .Fn dwarf_init , |
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66 | argument |
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67 | .Ar fd |
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68 | denotes an open file descriptor referencing a compilation object. |
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69 | Function |
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70 | .Fn dwarf_init |
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71 | implicitly allocates an |
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72 | .Vt Elf |
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73 | descriptor for argument |
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74 | .Ar fd . |
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75 | .Pp |
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76 | For function |
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77 | .Fn dwarf_elf_init , |
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78 | argument |
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79 | .Ar elf |
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80 | denotes a descriptor returned by |
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81 | .Xr elf_begin 3 |
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82 | or |
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83 | .Xr elf_memory 3 . |
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84 | .Pp |
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85 | Argument |
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86 | .Ar mode |
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87 | specifies the access mode desired. |
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88 | It should be at least as permissive as the mode with which |
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89 | the file descriptor |
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90 | .Ar fd |
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91 | or the ELF descriptor |
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92 | .Ar elf |
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93 | was created with. |
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94 | Legal values for argument |
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95 | .Ar mode |
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96 | are: |
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97 | .Pp |
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98 | .Bl -tag -width "DW_DLC_WRITE" -compact |
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99 | .It DW_DLC_RDWR |
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100 | Permit reading and writing of DWARF information. |
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101 | .It DW_DLC_READ |
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102 | Operate in read-only mode. |
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103 | .It DW_DLC_WRITE |
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104 | Permit writing of DWARF information. |
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105 | .El |
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106 | .Pp |
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107 | Argument |
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108 | .Ar errhand |
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109 | denotes a function to be called in case of an error. |
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110 | If this argument is |
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111 | .Dv NULL |
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112 | then a default error handling scheme is used. |
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113 | See |
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114 | .Xr dwarf 3 |
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115 | for a description of the error handling scheme used by the |
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116 | DWARF(3) library. |
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117 | .Pp |
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118 | Argument |
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119 | .Ar errarg |
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120 | is passed to the error handler function denoted by argument |
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121 | .Ar errhand |
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122 | when it is invoked. |
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123 | .Pp |
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124 | Argument |
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125 | .Ar ret |
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126 | points to the memory location that will hold a |
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127 | .Vt Dwarf_Debug |
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128 | reference on a successful call these functions. |
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129 | .Pp |
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130 | Argument |
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131 | .Ar err |
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132 | references a memory location that would hold a |
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133 | .Vt Dwarf_Error |
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134 | descriptor in case of an error. |
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135 | .Ss Memory Management |
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136 | The |
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137 | .Vt Dwarf_Debug |
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138 | instance returned by these functions should be freed using |
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139 | .Fn dwarf_finish . |
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140 | .Sh RETURN VALUES |
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141 | These functions return the following values: |
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142 | .Bl -tag -width ".Bq Er DW_DLV_NO_ENTRY" |
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143 | .It Bq Er DW_DLV_OK |
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144 | This return value indicates a successful return. |
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145 | .It Bq Er DW_DLV_ERROR |
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146 | The operation failed. |
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147 | .It Bq Er DW_DLV_NO_ENTRY |
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148 | The object specified by arguments |
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149 | .Ar "fd" |
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150 | or |
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151 | .Ar "elf" |
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152 | did not contain debug information. |
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153 | .El |
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154 | .Sh IMPLEMENTATION NOTES |
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155 | The current implementation does not support access modes |
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156 | .Dv DW_DLC_RDWR |
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157 | and |
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158 | .Dv DW_DLC_WRITE . |
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159 | .Sh EXAMPLES |
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160 | To initialize a |
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161 | .Vt Dwarf_Debug |
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162 | instance from a open file descriptor referencing an ELF object, and |
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163 | with the default error handler, use: |
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164 | .Bd -literal -offset indent |
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165 | Dwarf_Error err; |
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166 | Dwarf_Debug dbg; |
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167 | |
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168 | if (dwarf_init(fd, DW_DLC_READ, NULL, NULL, &dbg, &err) != |
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169 | DW_DLV_OK) |
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170 | errx(EXIT_FAILURE, "dwarf_init: %s", dwarf_errmsg(err)); |
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171 | .Ed |
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172 | .Sh SEE ALSO |
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173 | .Xr dwarf 3 , |
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174 | .Xr dwarf_errmsg 3 , |
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175 | .Xr dwarf_finish 3 , |
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176 | .Xr dwarf_get_elf 3 , |
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177 | .Xr elf_begin 3 , |
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178 | .Xr elf_memory 3 |
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