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Rev | Author | Line No. | Line |
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5197 | serge | 1 | /* Generic BFD support for file formats. |
6324 | serge | 2 | Copyright (C) 1990-2015 Free Software Foundation, Inc. |
5197 | serge | 3 | Written by Cygnus Support. |
4 | |||
5 | This file is part of BFD, the Binary File Descriptor library. |
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6 | |||
7 | This program is free software; you can redistribute it and/or modify |
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8 | it under the terms of the GNU General Public License as published by |
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9 | the Free Software Foundation; either version 3 of the License, or |
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10 | (at your option) any later version. |
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11 | |||
12 | This program is distributed in the hope that it will be useful, |
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13 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
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14 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
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15 | GNU General Public License for more details. |
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16 | |||
17 | You should have received a copy of the GNU General Public License |
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18 | along with this program; if not, write to the Free Software |
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19 | Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston, |
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20 | MA 02110-1301, USA. */ |
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21 | |||
22 | |||
23 | /* |
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24 | SECTION |
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25 | File formats |
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26 | |||
27 | A format is a BFD concept of high level file contents type. The |
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28 | formats supported by BFD are: |
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29 | |||
30 | o < |
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31 | |||
32 | The BFD may contain data, symbols, relocations and debug info. |
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33 | |||
34 | o < |
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35 | |||
36 | The BFD contains other BFDs and an optional index. |
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37 | |||
38 | o < |
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39 | |||
40 | The BFD contains the result of an executable core dump. |
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41 | |||
42 | SUBSECTION |
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43 | File format functions |
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44 | */ |
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45 | |||
46 | #include "sysdep.h" |
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47 | #include "bfd.h" |
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48 | #include "libbfd.h" |
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49 | |||
50 | /* IMPORT from targets.c. */ |
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51 | extern const size_t _bfd_target_vector_entries; |
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52 | |||
53 | /* |
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54 | FUNCTION |
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55 | bfd_check_format |
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56 | |||
57 | SYNOPSIS |
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58 | bfd_boolean bfd_check_format (bfd *abfd, bfd_format format); |
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59 | |||
60 | DESCRIPTION |
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61 | Verify if the file attached to the BFD @var{abfd} is compatible |
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62 | with the format @var{format} (i.e., one of < |
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63 | < |
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64 | |||
65 | If the BFD has been set to a specific target before the |
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66 | call, only the named target and format combination is |
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67 | checked. If the target has not been set, or has been set to |
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68 | < |
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69 | interrogated to determine a match. If the default target |
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70 | matches, it is used. If not, exactly one target must recognize |
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71 | the file, or an error results. |
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72 | |||
73 | The function returns < |
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74 | with one of the following error codes: |
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75 | |||
76 | o < |
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77 | if < |
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78 | < |
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79 | |||
80 | o < |
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81 | if an error occured during a read - even some file mismatches |
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82 | can cause bfd_error_system_calls. |
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83 | |||
84 | o < |
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85 | none of the backends recognised the file format. |
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86 | |||
87 | o < |
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88 | more than one backend recognised the file format. |
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89 | */ |
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90 | |||
91 | bfd_boolean |
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92 | bfd_check_format (bfd *abfd, bfd_format format) |
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93 | { |
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94 | return bfd_check_format_matches (abfd, format, NULL); |
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95 | } |
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96 | |||
97 | struct bfd_preserve |
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98 | { |
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99 | void *marker; |
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100 | void *tdata; |
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101 | flagword flags; |
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102 | const struct bfd_arch_info *arch_info; |
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103 | struct bfd_section *sections; |
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104 | struct bfd_section *section_last; |
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105 | unsigned int section_count; |
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106 | struct bfd_hash_table section_htab; |
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107 | }; |
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108 | |||
109 | /* When testing an object for compatibility with a particular target |
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110 | back-end, the back-end object_p function needs to set up certain |
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111 | fields in the bfd on successfully recognizing the object. This |
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112 | typically happens in a piecemeal fashion, with failures possible at |
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113 | many points. On failure, the bfd is supposed to be restored to its |
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114 | initial state, which is virtually impossible. However, restoring a |
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115 | subset of the bfd state works in practice. This function stores |
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116 | the subset. */ |
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117 | |||
118 | static bfd_boolean |
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119 | bfd_preserve_save (bfd *abfd, struct bfd_preserve *preserve) |
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120 | { |
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121 | preserve->tdata = abfd->tdata.any; |
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122 | preserve->arch_info = abfd->arch_info; |
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123 | preserve->flags = abfd->flags; |
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124 | preserve->sections = abfd->sections; |
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125 | preserve->section_last = abfd->section_last; |
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126 | preserve->section_count = abfd->section_count; |
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127 | preserve->section_htab = abfd->section_htab; |
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128 | preserve->marker = bfd_alloc (abfd, 1); |
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129 | if (preserve->marker == NULL) |
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130 | return FALSE; |
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131 | |||
132 | return bfd_hash_table_init (&abfd->section_htab, bfd_section_hash_newfunc, |
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133 | sizeof (struct section_hash_entry)); |
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134 | } |
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135 | |||
136 | /* Clear out a subset of BFD state. */ |
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137 | |||
138 | static void |
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139 | bfd_reinit (bfd *abfd) |
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140 | { |
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141 | abfd->tdata.any = NULL; |
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142 | abfd->arch_info = &bfd_default_arch_struct; |
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143 | abfd->flags &= BFD_FLAGS_SAVED; |
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144 | bfd_section_list_clear (abfd); |
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145 | } |
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146 | |||
147 | /* Restores bfd state saved by bfd_preserve_save. */ |
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148 | |||
149 | static void |
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150 | bfd_preserve_restore (bfd *abfd, struct bfd_preserve *preserve) |
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151 | { |
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152 | bfd_hash_table_free (&abfd->section_htab); |
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153 | |||
154 | abfd->tdata.any = preserve->tdata; |
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155 | abfd->arch_info = preserve->arch_info; |
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156 | abfd->flags = preserve->flags; |
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157 | abfd->section_htab = preserve->section_htab; |
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158 | abfd->sections = preserve->sections; |
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159 | abfd->section_last = preserve->section_last; |
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160 | abfd->section_count = preserve->section_count; |
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161 | |||
162 | /* bfd_release frees all memory more recently bfd_alloc'd than |
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163 | its arg, as well as its arg. */ |
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164 | bfd_release (abfd, preserve->marker); |
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165 | preserve->marker = NULL; |
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166 | } |
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167 | |||
168 | /* Called when the bfd state saved by bfd_preserve_save is no longer |
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169 | needed. */ |
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170 | |||
171 | static void |
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172 | bfd_preserve_finish (bfd *abfd ATTRIBUTE_UNUSED, struct bfd_preserve *preserve) |
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173 | { |
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174 | /* It would be nice to be able to free more memory here, eg. old |
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175 | tdata, but that's not possible since these blocks are sitting |
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176 | inside bfd_alloc'd memory. The section hash is on a separate |
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177 | objalloc. */ |
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178 | bfd_hash_table_free (&preserve->section_htab); |
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179 | preserve->marker = NULL; |
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180 | } |
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181 | |||
182 | /* |
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183 | FUNCTION |
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184 | bfd_check_format_matches |
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185 | |||
186 | SYNOPSIS |
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187 | bfd_boolean bfd_check_format_matches |
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188 | (bfd *abfd, bfd_format format, char ***matching); |
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189 | |||
190 | DESCRIPTION |
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191 | Like < |
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192 | < |
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193 | case, if @var{matching} is not NULL, it will be filled in with |
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194 | a NULL-terminated list of the names of the formats that matched, |
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195 | allocated with < |
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196 | Then the user may choose a format and try again. |
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197 | |||
198 | When done with the list that @var{matching} points to, the caller |
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199 | should free it. |
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200 | */ |
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201 | |||
202 | bfd_boolean |
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203 | bfd_check_format_matches (bfd *abfd, bfd_format format, char ***matching) |
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204 | { |
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205 | extern const bfd_target binary_vec; |
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206 | const bfd_target * const *target; |
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207 | const bfd_target **matching_vector = NULL; |
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208 | const bfd_target *save_targ, *right_targ, *ar_right_targ, *match_targ; |
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209 | int match_count, best_count, best_match; |
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210 | int ar_match_index; |
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211 | struct bfd_preserve preserve; |
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212 | |||
213 | if (matching != NULL) |
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214 | *matching = NULL; |
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215 | |||
216 | if (!bfd_read_p (abfd) |
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217 | || (unsigned int) abfd->format >= (unsigned int) bfd_type_end) |
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218 | { |
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219 | bfd_set_error (bfd_error_invalid_operation); |
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220 | return FALSE; |
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221 | } |
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222 | |||
223 | if (abfd->format != bfd_unknown) |
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224 | return abfd->format == format; |
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225 | |||
226 | if (matching != NULL || *bfd_associated_vector != NULL) |
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227 | { |
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228 | bfd_size_type amt; |
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229 | |||
230 | amt = sizeof (*matching_vector) * 2 * _bfd_target_vector_entries; |
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231 | matching_vector = (const bfd_target **) bfd_malloc (amt); |
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232 | if (!matching_vector) |
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233 | return FALSE; |
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234 | } |
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235 | |||
236 | /* Presume the answer is yes. */ |
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237 | abfd->format = format; |
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238 | save_targ = abfd->xvec; |
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239 | preserve.marker = NULL; |
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240 | |||
241 | /* If the target type was explicitly specified, just check that target. */ |
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242 | if (!abfd->target_defaulted) |
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243 | { |
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244 | if (bfd_seek (abfd, (file_ptr) 0, SEEK_SET) != 0) /* rewind! */ |
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245 | goto err_ret; |
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246 | |||
247 | right_targ = BFD_SEND_FMT (abfd, _bfd_check_format, (abfd)); |
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248 | |||
249 | if (right_targ) |
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250 | goto ok_ret; |
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251 | |||
252 | /* For a long time the code has dropped through to check all |
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253 | targets if the specified target was wrong. I don't know why, |
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254 | and I'm reluctant to change it. However, in the case of an |
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255 | archive, it can cause problems. If the specified target does |
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256 | not permit archives (e.g., the binary target), then we should |
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257 | not allow some other target to recognize it as an archive, but |
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258 | should instead allow the specified target to recognize it as an |
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259 | object. When I first made this change, it broke the PE target, |
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260 | because the specified pei-i386 target did not recognize the |
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261 | actual pe-i386 archive. Since there may be other problems of |
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262 | this sort, I changed this test to check only for the binary |
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263 | target. */ |
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264 | if (format == bfd_archive && save_targ == &binary_vec) |
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265 | goto err_unrecog; |
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266 | } |
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267 | |||
268 | /* Since the target type was defaulted, check them all in the hope |
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269 | that one will be uniquely recognized. */ |
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270 | right_targ = NULL; |
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271 | ar_right_targ = NULL; |
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272 | match_targ = NULL; |
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273 | best_match = 256; |
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274 | best_count = 0; |
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275 | match_count = 0; |
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276 | ar_match_index = _bfd_target_vector_entries; |
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277 | |||
278 | for (target = bfd_target_vector; *target != NULL; target++) |
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279 | { |
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280 | const bfd_target *temp; |
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281 | |||
282 | /* Don't check the default target twice. */ |
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283 | if (*target == &binary_vec |
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284 | || (!abfd->target_defaulted && *target == save_targ) |
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285 | || (*target)->match_priority > best_match) |
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286 | continue; |
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287 | |||
288 | /* If we already tried a match, the bfd is modified and may |
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289 | have sections attached, which will confuse the next |
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290 | _bfd_check_format call. */ |
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291 | bfd_reinit (abfd); |
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292 | |||
293 | /* Change BFD's target temporarily. */ |
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294 | abfd->xvec = *target; |
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295 | |||
296 | if (bfd_seek (abfd, (file_ptr) 0, SEEK_SET) != 0) |
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297 | goto err_ret; |
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298 | |||
299 | /* If _bfd_check_format neglects to set bfd_error, assume |
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300 | bfd_error_wrong_format. We didn't used to even pay any |
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301 | attention to bfd_error, so I suspect that some |
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302 | _bfd_check_format might have this problem. */ |
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303 | bfd_set_error (bfd_error_wrong_format); |
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304 | |||
305 | temp = BFD_SEND_FMT (abfd, _bfd_check_format, (abfd)); |
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306 | if (temp) |
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307 | { |
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308 | match_targ = temp; |
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309 | if (preserve.marker != NULL) |
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310 | bfd_preserve_finish (abfd, &preserve); |
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311 | |||
312 | if (abfd->format != bfd_archive |
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313 | || (bfd_has_map (abfd) |
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314 | && bfd_get_error () != bfd_error_wrong_object_format)) |
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315 | { |
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316 | /* This format checks out as ok! */ |
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317 | right_targ = temp; |
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318 | |||
319 | /* If this is the default target, accept it, even if |
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320 | other targets might match. People who want those |
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321 | other targets have to set the GNUTARGET variable. */ |
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322 | if (temp == bfd_default_vector[0]) |
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323 | goto ok_ret; |
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324 | |||
325 | if (matching_vector) |
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326 | matching_vector[match_count] = temp; |
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327 | match_count++; |
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328 | |||
329 | if (temp->match_priority < best_match) |
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330 | { |
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331 | best_match = temp->match_priority; |
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332 | best_count = 0; |
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333 | } |
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334 | best_count++; |
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335 | } |
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336 | else |
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337 | { |
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338 | /* An archive with no armap or objects of the wrong |
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339 | type. We want this target to match if we get no |
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340 | better matches. */ |
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341 | if (ar_right_targ != bfd_default_vector[0]) |
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342 | ar_right_targ = *target; |
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343 | if (matching_vector) |
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344 | matching_vector[ar_match_index] = *target; |
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345 | ar_match_index++; |
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346 | } |
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347 | |||
348 | if (!bfd_preserve_save (abfd, &preserve)) |
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349 | goto err_ret; |
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350 | } |
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351 | else if (bfd_get_error () != bfd_error_wrong_format) |
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352 | goto err_ret; |
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353 | } |
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354 | |||
355 | if (best_count == 1) |
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356 | match_count = 1; |
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357 | |||
358 | if (match_count == 0) |
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359 | { |
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360 | /* Try partial matches. */ |
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361 | right_targ = ar_right_targ; |
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362 | |||
363 | if (right_targ == bfd_default_vector[0]) |
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364 | { |
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365 | match_count = 1; |
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366 | } |
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367 | else |
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368 | { |
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369 | match_count = ar_match_index - _bfd_target_vector_entries; |
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370 | |||
371 | if (matching_vector && match_count > 1) |
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372 | memcpy (matching_vector, |
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373 | matching_vector + _bfd_target_vector_entries, |
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374 | sizeof (*matching_vector) * match_count); |
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375 | } |
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376 | } |
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377 | |||
378 | /* We have more than one equally good match. If any of the best |
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379 | matches is a target in config.bfd targ_defvec or targ_selvecs, |
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380 | choose it. */ |
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381 | if (match_count > 1) |
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382 | { |
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383 | const bfd_target * const *assoc = bfd_associated_vector; |
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384 | |||
385 | while ((right_targ = *assoc++) != NULL) |
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386 | { |
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387 | int i = match_count; |
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388 | |||
389 | while (--i >= 0) |
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390 | if (matching_vector[i] == right_targ |
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391 | && right_targ->match_priority <= best_match) |
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392 | break; |
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393 | |||
394 | if (i >= 0) |
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395 | { |
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396 | match_count = 1; |
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397 | break; |
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398 | } |
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399 | } |
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400 | } |
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401 | |||
402 | /* We still have more than one equally good match, and at least some |
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403 | of the targets support match priority. Choose the first of the |
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404 | best matches. */ |
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6324 | serge | 405 | if (matching_vector && match_count > 1 && best_count != match_count) |
5197 | serge | 406 | { |
407 | int i; |
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408 | |||
409 | for (i = 0; i < match_count; i++) |
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410 | { |
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411 | right_targ = matching_vector[i]; |
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412 | if (right_targ->match_priority <= best_match) |
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413 | break; |
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414 | } |
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415 | match_count = 1; |
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416 | } |
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417 | |||
418 | /* There is way too much undoing of half-known state here. We |
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419 | really shouldn't iterate on live bfd's. Note that saving the |
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420 | whole bfd and restoring it would be even worse; the first thing |
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421 | you notice is that the cached bfd file position gets out of sync. */ |
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422 | if (preserve.marker != NULL) |
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423 | bfd_preserve_restore (abfd, &preserve); |
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424 | |||
425 | if (match_count == 1) |
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426 | { |
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427 | abfd->xvec = right_targ; |
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428 | /* If we come out of the loop knowing that the last target that |
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429 | matched is the one we want, then ABFD should still be in a usable |
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430 | state (except possibly for XVEC). */ |
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431 | if (match_targ != right_targ) |
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432 | { |
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433 | bfd_reinit (abfd); |
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434 | if (bfd_seek (abfd, (file_ptr) 0, SEEK_SET) != 0) |
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435 | goto err_ret; |
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436 | match_targ = BFD_SEND_FMT (abfd, _bfd_check_format, (abfd)); |
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437 | BFD_ASSERT (match_targ != NULL); |
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438 | } |
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439 | |||
440 | ok_ret: |
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441 | /* If the file was opened for update, then `output_has_begun' |
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442 | some time ago when the file was created. Do not recompute |
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443 | sections sizes or alignments in _bfd_set_section_contents. |
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444 | We can not set this flag until after checking the format, |
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445 | because it will interfere with creation of BFD sections. */ |
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446 | if (abfd->direction == both_direction) |
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447 | abfd->output_has_begun = TRUE; |
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448 | |||
449 | if (matching_vector) |
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450 | free (matching_vector); |
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451 | |||
452 | /* File position has moved, BTW. */ |
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453 | return TRUE; |
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454 | } |
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455 | |||
456 | if (match_count == 0) |
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457 | { |
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458 | err_unrecog: |
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459 | bfd_set_error (bfd_error_file_not_recognized); |
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460 | err_ret: |
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461 | abfd->xvec = save_targ; |
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462 | abfd->format = bfd_unknown; |
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463 | if (matching_vector) |
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464 | free (matching_vector); |
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465 | if (preserve.marker != NULL) |
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466 | bfd_preserve_restore (abfd, &preserve); |
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467 | return FALSE; |
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468 | } |
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469 | |||
470 | /* Restore original target type and format. */ |
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471 | abfd->xvec = save_targ; |
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472 | abfd->format = bfd_unknown; |
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473 | bfd_set_error (bfd_error_file_ambiguously_recognized); |
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474 | |||
475 | if (matching) |
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476 | { |
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477 | *matching = (char **) matching_vector; |
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478 | matching_vector[match_count] = NULL; |
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479 | /* Return target names. This is a little nasty. Maybe we |
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480 | should do another bfd_malloc? */ |
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481 | while (--match_count >= 0) |
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482 | { |
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483 | const char *name = matching_vector[match_count]->name; |
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484 | *(const char **) &matching_vector[match_count] = name; |
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485 | } |
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486 | } |
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487 | return FALSE; |
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488 | } |
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489 | |||
490 | /* |
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491 | FUNCTION |
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492 | bfd_set_format |
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493 | |||
494 | SYNOPSIS |
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495 | bfd_boolean bfd_set_format (bfd *abfd, bfd_format format); |
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496 | |||
497 | DESCRIPTION |
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498 | This function sets the file format of the BFD @var{abfd} to the |
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499 | format @var{format}. If the target set in the BFD does not |
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500 | support the format requested, the format is invalid, or the BFD |
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501 | is not open for writing, then an error occurs. |
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502 | */ |
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503 | |||
504 | bfd_boolean |
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505 | bfd_set_format (bfd *abfd, bfd_format format) |
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506 | { |
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507 | if (bfd_read_p (abfd) |
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508 | || (unsigned int) abfd->format >= (unsigned int) bfd_type_end) |
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509 | { |
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510 | bfd_set_error (bfd_error_invalid_operation); |
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511 | return FALSE; |
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512 | } |
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513 | |||
514 | if (abfd->format != bfd_unknown) |
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515 | return abfd->format == format; |
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516 | |||
517 | /* Presume the answer is yes. */ |
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518 | abfd->format = format; |
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519 | |||
520 | if (!BFD_SEND_FMT (abfd, _bfd_set_format, (abfd))) |
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521 | { |
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522 | abfd->format = bfd_unknown; |
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523 | return FALSE; |
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524 | } |
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525 | |||
526 | return TRUE; |
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527 | } |
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528 | |||
529 | /* |
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530 | FUNCTION |
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531 | bfd_format_string |
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532 | |||
533 | SYNOPSIS |
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534 | const char *bfd_format_string (bfd_format format); |
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535 | |||
536 | DESCRIPTION |
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537 | Return a pointer to a const string |
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538 | < |
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539 | depending upon the value of @var{format}. |
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540 | */ |
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541 | |||
542 | const char * |
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543 | bfd_format_string (bfd_format format) |
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544 | { |
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545 | if (((int) format < (int) bfd_unknown) |
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546 | || ((int) format >= (int) bfd_type_end)) |
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547 | return "invalid"; |
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548 | |||
549 | switch (format) |
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550 | { |
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551 | case bfd_object: |
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552 | return "object"; /* Linker/assembler/compiler output. */ |
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553 | case bfd_archive: |
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554 | return "archive"; /* Object archive file. */ |
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555 | case bfd_core: |
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556 | return "core"; /* Core dump. */ |
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557 | default: |
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558 | return "unknown"; |
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559 | } |
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560 | }> |