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5197 | serge | 1 | /* BFD library -- caching of file descriptors. |
2 | |||
3 | Copyright 1990, 1991, 1992, 1993, 1994, 1996, 2000, 2001, 2002, |
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4 | 2003, 2004, 2005, 2007, 2008, 2009 Free Software Foundation, Inc. |
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5 | |||
6 | Hacked by Steve Chamberlain of Cygnus Support (steve@cygnus.com). |
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7 | |||
8 | This file is part of BFD, the Binary File Descriptor library. |
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9 | |||
10 | This program is free software; you can redistribute it and/or modify |
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11 | it under the terms of the GNU General Public License as published by |
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12 | the Free Software Foundation; either version 3 of the License, or |
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13 | (at your option) any later version. |
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14 | |||
15 | This program is distributed in the hope that it will be useful, |
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16 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
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17 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
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18 | GNU General Public License for more details. |
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19 | |||
20 | You should have received a copy of the GNU General Public License |
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21 | along with this program; if not, write to the Free Software |
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22 | Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston, |
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23 | MA 02110-1301, USA. */ |
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24 | |||
25 | /* |
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26 | SECTION |
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27 | File caching |
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28 | |||
29 | The file caching mechanism is embedded within BFD and allows |
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30 | the application to open as many BFDs as it wants without |
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31 | regard to the underlying operating system's file descriptor |
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32 | limit (often as low as 20 open files). The module in |
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33 | < |
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34 | < |
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35 | < |
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36 | the required BFD is open. If not, then it chooses a file to |
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37 | close, closes it and opens the one wanted, returning its file |
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38 | handle. |
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39 | |||
40 | SUBSECTION |
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41 | Caching functions |
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42 | */ |
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43 | |||
44 | #include "sysdep.h" |
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45 | #include "bfd.h" |
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46 | #include "libbfd.h" |
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47 | #include "libiberty.h" |
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48 | #include "bfd_stdint.h" |
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49 | |||
50 | #ifdef HAVE_MMAP |
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51 | #include |
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52 | #endif |
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53 | |||
54 | /* In some cases we can optimize cache operation when reopening files. |
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55 | For instance, a flush is entirely unnecessary if the file is already |
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56 | closed, so a flush would use CACHE_NO_OPEN. Similarly, a seek using |
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57 | SEEK_SET or SEEK_END need not first seek to the current position. |
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58 | For stat we ignore seek errors, just in case the file has changed |
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59 | while we weren't looking. If it has, then it's possible that the |
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60 | file is shorter and we don't want a seek error to prevent us doing |
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61 | the stat. */ |
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62 | enum cache_flag { |
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63 | CACHE_NORMAL = 0, |
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64 | CACHE_NO_OPEN = 1, |
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65 | CACHE_NO_SEEK = 2, |
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66 | CACHE_NO_SEEK_ERROR = 4 |
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67 | }; |
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68 | |||
69 | /* The maximum number of files which the cache will keep open at |
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70 | one time. When needed call bfd_cache_max_open to initialize. */ |
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71 | |||
72 | static int max_open_files = 0; |
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73 | |||
74 | /* Set max_open_files, if not already set, to 12.5% of the allowed open |
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75 | file descriptors, but at least 10, and return the value. */ |
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76 | static int |
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77 | bfd_cache_max_open (void) |
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78 | { |
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79 | |||
5199 | serge | 80 | max_open_files = 16; |
81 | |||
5197 | serge | 82 | return max_open_files; |
83 | } |
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84 | |||
85 | /* The number of BFD files we have open. */ |
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86 | |||
87 | static int open_files; |
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88 | |||
89 | /* Zero, or a pointer to the topmost BFD on the chain. This is |
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90 | used by the < |
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91 | determine when it can avoid a function call. */ |
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92 | |||
93 | static bfd *bfd_last_cache = NULL; |
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94 | |||
95 | /* Insert a BFD into the cache. */ |
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96 | |||
97 | static void |
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98 | insert (bfd *abfd) |
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99 | { |
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100 | if (bfd_last_cache == NULL) |
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101 | { |
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102 | abfd->lru_next = abfd; |
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103 | abfd->lru_prev = abfd; |
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104 | } |
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105 | else |
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106 | { |
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107 | abfd->lru_next = bfd_last_cache; |
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108 | abfd->lru_prev = bfd_last_cache->lru_prev; |
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109 | abfd->lru_prev->lru_next = abfd; |
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110 | abfd->lru_next->lru_prev = abfd; |
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111 | } |
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112 | bfd_last_cache = abfd; |
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113 | } |
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114 | |||
115 | /* Remove a BFD from the cache. */ |
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116 | |||
117 | static void |
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118 | snip (bfd *abfd) |
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119 | { |
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120 | abfd->lru_prev->lru_next = abfd->lru_next; |
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121 | abfd->lru_next->lru_prev = abfd->lru_prev; |
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122 | if (abfd == bfd_last_cache) |
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123 | { |
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124 | bfd_last_cache = abfd->lru_next; |
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125 | if (abfd == bfd_last_cache) |
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126 | bfd_last_cache = NULL; |
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127 | } |
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128 | } |
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129 | |||
130 | /* Close a BFD and remove it from the cache. */ |
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131 | |||
132 | static bfd_boolean |
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133 | bfd_cache_delete (bfd *abfd) |
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134 | { |
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135 | bfd_boolean ret; |
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136 | |||
137 | if (fclose ((FILE *) abfd->iostream) == 0) |
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138 | ret = TRUE; |
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139 | else |
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140 | { |
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141 | ret = FALSE; |
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142 | bfd_set_error (bfd_error_system_call); |
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143 | } |
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144 | |||
145 | snip (abfd); |
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146 | |||
147 | abfd->iostream = NULL; |
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148 | --open_files; |
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149 | |||
150 | return ret; |
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151 | } |
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152 | |||
153 | /* We need to open a new file, and the cache is full. Find the least |
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154 | recently used cacheable BFD and close it. */ |
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155 | |||
156 | static bfd_boolean |
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157 | close_one (void) |
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158 | { |
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159 | register bfd *to_kill; |
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160 | |||
161 | if (bfd_last_cache == NULL) |
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162 | to_kill = NULL; |
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163 | else |
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164 | { |
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165 | for (to_kill = bfd_last_cache->lru_prev; |
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166 | ! to_kill->cacheable; |
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167 | to_kill = to_kill->lru_prev) |
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168 | { |
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169 | if (to_kill == bfd_last_cache) |
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170 | { |
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171 | to_kill = NULL; |
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172 | break; |
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173 | } |
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174 | } |
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175 | } |
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176 | |||
177 | if (to_kill == NULL) |
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178 | { |
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179 | /* There are no open cacheable BFD's. */ |
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180 | return TRUE; |
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181 | } |
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182 | |||
183 | to_kill->where = real_ftell ((FILE *) to_kill->iostream); |
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184 | |||
185 | return bfd_cache_delete (to_kill); |
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186 | } |
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187 | |||
188 | /* Check to see if the required BFD is the same as the last one |
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189 | looked up. If so, then it can use the stream in the BFD with |
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190 | impunity, since it can't have changed since the last lookup; |
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191 | otherwise, it has to perform the complicated lookup function. */ |
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192 | |||
193 | #define bfd_cache_lookup(x, flag) \ |
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194 | ((x) == bfd_last_cache \ |
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195 | ? (FILE *) (bfd_last_cache->iostream) \ |
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196 | : bfd_cache_lookup_worker (x, flag)) |
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197 | |||
198 | /* Called when the macro < |
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199 | quick answer. Find a file descriptor for @var{abfd}. If |
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200 | necessary, it open it. If there are already more than |
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201 | < |
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202 | avoid running out of file descriptors. It will return NULL |
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203 | if it is unable to (re)open the @var{abfd}. */ |
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204 | |||
205 | static FILE * |
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206 | bfd_cache_lookup_worker (bfd *abfd, enum cache_flag flag) |
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207 | { |
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208 | bfd *orig_bfd = abfd; |
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209 | if ((abfd->flags & BFD_IN_MEMORY) != 0) |
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210 | abort (); |
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211 | |||
212 | while (abfd->my_archive) |
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213 | abfd = abfd->my_archive; |
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214 | |||
215 | if (abfd->iostream != NULL) |
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216 | { |
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217 | /* Move the file to the start of the cache. */ |
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218 | if (abfd != bfd_last_cache) |
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219 | { |
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220 | snip (abfd); |
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221 | insert (abfd); |
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222 | } |
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223 | return (FILE *) abfd->iostream; |
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224 | } |
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225 | |||
226 | if (flag & CACHE_NO_OPEN) |
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227 | return NULL; |
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228 | |||
229 | if (bfd_open_file (abfd) == NULL) |
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230 | ; |
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231 | else if (!(flag & CACHE_NO_SEEK) |
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232 | && real_fseek ((FILE *) abfd->iostream, abfd->where, SEEK_SET) != 0 |
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233 | && !(flag & CACHE_NO_SEEK_ERROR)) |
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234 | bfd_set_error (bfd_error_system_call); |
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235 | else |
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236 | return (FILE *) abfd->iostream; |
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237 | |||
238 | (*_bfd_error_handler) (_("reopening %B: %s\n"), |
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239 | orig_bfd, bfd_errmsg (bfd_get_error ())); |
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240 | return NULL; |
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241 | } |
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242 | |||
243 | static file_ptr |
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244 | cache_btell (struct bfd *abfd) |
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245 | { |
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246 | FILE *f = bfd_cache_lookup (abfd, CACHE_NO_OPEN); |
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247 | if (f == NULL) |
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248 | return abfd->where; |
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249 | return real_ftell (f); |
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250 | } |
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251 | |||
252 | static int |
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253 | cache_bseek (struct bfd *abfd, file_ptr offset, int whence) |
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254 | { |
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255 | FILE *f = bfd_cache_lookup (abfd, whence != SEEK_CUR ? CACHE_NO_SEEK : CACHE_NORMAL); |
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256 | if (f == NULL) |
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257 | return -1; |
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258 | return real_fseek (f, offset, whence); |
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259 | } |
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260 | |||
261 | /* Note that archive entries don't have streams; they share their parent's. |
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262 | This allows someone to play with the iostream behind BFD's back. |
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263 | |||
264 | Also, note that the origin pointer points to the beginning of a file's |
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265 | contents (0 for non-archive elements). For archive entries this is the |
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266 | first octet in the file, NOT the beginning of the archive header. */ |
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267 | |||
268 | static file_ptr |
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269 | cache_bread_1 (struct bfd *abfd, void *buf, file_ptr nbytes) |
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270 | { |
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271 | FILE *f; |
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272 | file_ptr nread; |
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273 | /* FIXME - this looks like an optimization, but it's really to cover |
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274 | up for a feature of some OSs (not solaris - sigh) that |
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275 | ld/pe-dll.c takes advantage of (apparently) when it creates BFDs |
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276 | internally and tries to link against them. BFD seems to be smart |
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277 | enough to realize there are no symbol records in the "file" that |
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278 | doesn't exist but attempts to read them anyway. On Solaris, |
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279 | attempting to read zero bytes from a NULL file results in a core |
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280 | dump, but on other platforms it just returns zero bytes read. |
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281 | This makes it to something reasonable. - DJ */ |
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282 | if (nbytes == 0) |
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283 | return 0; |
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284 | |||
285 | f = bfd_cache_lookup (abfd, CACHE_NORMAL); |
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286 | if (f == NULL) |
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287 | return 0; |
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288 | |||
289 | #if defined (__VAX) && defined (VMS) |
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290 | /* Apparently fread on Vax VMS does not keep the record length |
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291 | information. */ |
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292 | nread = read (fileno (f), buf, nbytes); |
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293 | /* Set bfd_error if we did not read as much data as we expected. If |
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294 | the read failed due to an error set the bfd_error_system_call, |
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295 | else set bfd_error_file_truncated. */ |
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296 | if (nread == (file_ptr)-1) |
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297 | { |
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298 | bfd_set_error (bfd_error_system_call); |
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299 | return -1; |
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300 | } |
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301 | #else |
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302 | nread = fread (buf, 1, nbytes, f); |
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303 | /* Set bfd_error if we did not read as much data as we expected. If |
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304 | the read failed due to an error set the bfd_error_system_call, |
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305 | else set bfd_error_file_truncated. */ |
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306 | if (nread < nbytes && ferror (f)) |
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307 | { |
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308 | bfd_set_error (bfd_error_system_call); |
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309 | return -1; |
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310 | } |
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311 | #endif |
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312 | if (nread < nbytes) |
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313 | /* This may or may not be an error, but in case the calling code |
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314 | bails out because of it, set the right error code. */ |
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315 | bfd_set_error (bfd_error_file_truncated); |
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316 | return nread; |
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317 | } |
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318 | |||
319 | static file_ptr |
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320 | cache_bread (struct bfd *abfd, void *buf, file_ptr nbytes) |
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321 | { |
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322 | file_ptr nread = 0; |
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323 | |||
324 | /* Some filesystems are unable to handle reads that are too large |
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325 | (for instance, NetApp shares with oplocks turned off). To avoid |
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326 | hitting this limitation, we read the buffer in chunks of 8MB max. */ |
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327 | while (nread < nbytes) |
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328 | { |
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329 | const file_ptr max_chunk_size = 0x800000; |
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330 | file_ptr chunk_size = nbytes - nread; |
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331 | file_ptr chunk_nread; |
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332 | |||
333 | if (chunk_size > max_chunk_size) |
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334 | chunk_size = max_chunk_size; |
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335 | |||
336 | chunk_nread = cache_bread_1 (abfd, (char *) buf + nread, chunk_size); |
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337 | |||
338 | /* Update the nread count. |
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339 | |||
340 | We just have to be careful of the case when cache_bread_1 returns |
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341 | a negative count: If this is our first read, then set nread to |
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342 | that negative count in order to return that negative value to the |
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343 | caller. Otherwise, don't add it to our total count, or we would |
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344 | end up returning a smaller number of bytes read than we actually |
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345 | did. */ |
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346 | if (nread == 0 || chunk_nread > 0) |
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347 | nread += chunk_nread; |
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348 | |||
349 | if (chunk_nread < chunk_size) |
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350 | break; |
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351 | } |
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352 | |||
353 | return nread; |
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354 | } |
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355 | |||
356 | static file_ptr |
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357 | cache_bwrite (struct bfd *abfd, const void *where, file_ptr nbytes) |
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358 | { |
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359 | file_ptr nwrite; |
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360 | FILE *f = bfd_cache_lookup (abfd, CACHE_NORMAL); |
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361 | |||
362 | if (f == NULL) |
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363 | return 0; |
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364 | nwrite = fwrite (where, 1, nbytes, f); |
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365 | if (nwrite < nbytes && ferror (f)) |
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366 | { |
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367 | bfd_set_error (bfd_error_system_call); |
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368 | return -1; |
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369 | } |
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370 | return nwrite; |
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371 | } |
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372 | |||
373 | static int |
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374 | cache_bclose (struct bfd *abfd) |
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375 | { |
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376 | return bfd_cache_close (abfd) - 1; |
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377 | } |
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378 | |||
379 | static int |
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380 | cache_bflush (struct bfd *abfd) |
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381 | { |
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382 | int sts; |
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383 | FILE *f = bfd_cache_lookup (abfd, CACHE_NO_OPEN); |
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384 | |||
385 | if (f == NULL) |
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386 | return 0; |
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387 | sts = fflush (f); |
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388 | if (sts < 0) |
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389 | bfd_set_error (bfd_error_system_call); |
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390 | return sts; |
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391 | } |
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392 | |||
393 | static int |
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394 | cache_bstat (struct bfd *abfd, struct stat *sb) |
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395 | { |
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396 | int sts; |
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397 | FILE *f = bfd_cache_lookup (abfd, CACHE_NO_SEEK_ERROR); |
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398 | |||
399 | if (f == NULL) |
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400 | return -1; |
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401 | sts = fstat (fileno (f), sb); |
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402 | if (sts < 0) |
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403 | bfd_set_error (bfd_error_system_call); |
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404 | return sts; |
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405 | } |
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406 | |||
407 | static void * |
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408 | cache_bmmap (struct bfd *abfd ATTRIBUTE_UNUSED, |
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409 | void *addr ATTRIBUTE_UNUSED, |
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410 | bfd_size_type len ATTRIBUTE_UNUSED, |
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411 | int prot ATTRIBUTE_UNUSED, |
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412 | int flags ATTRIBUTE_UNUSED, |
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413 | file_ptr offset ATTRIBUTE_UNUSED, |
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414 | void **map_addr ATTRIBUTE_UNUSED, |
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415 | bfd_size_type *map_len ATTRIBUTE_UNUSED) |
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416 | { |
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417 | void *ret = (void *) -1; |
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418 | |||
419 | if ((abfd->flags & BFD_IN_MEMORY) != 0) |
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420 | abort (); |
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421 | #ifdef HAVE_MMAP |
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422 | else |
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423 | { |
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424 | static uintptr_t pagesize_m1; |
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425 | FILE *f; |
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426 | file_ptr pg_offset; |
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427 | bfd_size_type pg_len; |
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428 | |||
429 | f = bfd_cache_lookup (abfd, CACHE_NO_SEEK_ERROR); |
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430 | if (f == NULL) |
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431 | return ret; |
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432 | |||
433 | if (pagesize_m1 == 0) |
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434 | pagesize_m1 = getpagesize () - 1; |
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435 | |||
436 | /* Handle archive members. */ |
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437 | if (abfd->my_archive != NULL) |
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438 | offset += abfd->origin; |
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439 | |||
440 | /* Align. */ |
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441 | pg_offset = offset & ~pagesize_m1; |
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442 | pg_len = (len + (offset - pg_offset) + pagesize_m1) & ~pagesize_m1; |
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443 | |||
444 | ret = mmap (addr, pg_len, prot, flags, fileno (f), pg_offset); |
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445 | if (ret == (void *) -1) |
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446 | bfd_set_error (bfd_error_system_call); |
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447 | else |
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448 | { |
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449 | *map_addr = ret; |
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450 | *map_len = pg_len; |
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451 | ret = (char *) ret + (offset & pagesize_m1); |
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452 | } |
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453 | } |
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454 | #endif |
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455 | |||
456 | return ret; |
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457 | } |
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458 | |||
459 | static const struct bfd_iovec cache_iovec = |
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460 | { |
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461 | &cache_bread, &cache_bwrite, &cache_btell, &cache_bseek, |
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462 | &cache_bclose, &cache_bflush, &cache_bstat, &cache_bmmap |
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463 | }; |
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464 | |||
465 | /* |
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466 | INTERNAL_FUNCTION |
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467 | bfd_cache_init |
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468 | |||
469 | SYNOPSIS |
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470 | bfd_boolean bfd_cache_init (bfd *abfd); |
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471 | |||
472 | DESCRIPTION |
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473 | Add a newly opened BFD to the cache. |
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474 | */ |
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475 | |||
476 | bfd_boolean |
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477 | bfd_cache_init (bfd *abfd) |
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478 | { |
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479 | BFD_ASSERT (abfd->iostream != NULL); |
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480 | if (open_files >= bfd_cache_max_open ()) |
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481 | { |
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482 | if (! close_one ()) |
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483 | return FALSE; |
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484 | } |
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485 | abfd->iovec = &cache_iovec; |
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486 | insert (abfd); |
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487 | ++open_files; |
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488 | return TRUE; |
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489 | } |
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490 | |||
491 | /* |
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492 | INTERNAL_FUNCTION |
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493 | bfd_cache_close |
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494 | |||
495 | SYNOPSIS |
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496 | bfd_boolean bfd_cache_close (bfd *abfd); |
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497 | |||
498 | DESCRIPTION |
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499 | Remove the BFD @var{abfd} from the cache. If the attached file is open, |
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500 | then close it too. |
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501 | |||
502 | RETURNS |
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503 | < |
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504 | returned if all is well. |
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505 | */ |
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506 | |||
507 | bfd_boolean |
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508 | bfd_cache_close (bfd *abfd) |
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509 | { |
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510 | if (abfd->iovec != &cache_iovec) |
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511 | return TRUE; |
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512 | |||
513 | if (abfd->iostream == NULL) |
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514 | /* Previously closed. */ |
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515 | return TRUE; |
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516 | |||
517 | return bfd_cache_delete (abfd); |
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518 | } |
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519 | |||
520 | /* |
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521 | FUNCTION |
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522 | bfd_cache_close_all |
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523 | |||
524 | SYNOPSIS |
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525 | bfd_boolean bfd_cache_close_all (void); |
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526 | |||
527 | DESCRIPTION |
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528 | Remove all BFDs from the cache. If the attached file is open, |
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529 | then close it too. |
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530 | |||
531 | RETURNS |
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532 | < |
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533 | returned if all is well. |
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534 | */ |
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535 | |||
536 | bfd_boolean |
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537 | bfd_cache_close_all () |
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538 | { |
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539 | bfd_boolean ret = TRUE; |
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540 | |||
541 | while (bfd_last_cache != NULL) |
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542 | ret &= bfd_cache_close (bfd_last_cache); |
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543 | |||
544 | return ret; |
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545 | } |
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546 | |||
547 | /* |
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548 | INTERNAL_FUNCTION |
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549 | bfd_open_file |
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550 | |||
551 | SYNOPSIS |
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552 | FILE* bfd_open_file (bfd *abfd); |
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553 | |||
554 | DESCRIPTION |
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555 | Call the OS to open a file for @var{abfd}. Return the < |
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556 | (possibly < |
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557 | BFD so that future accesses know the file is open. If the < |
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558 | returned is < |
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559 | cache, so it won't have to be removed from it. |
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560 | */ |
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561 | |||
562 | FILE * |
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563 | bfd_open_file (bfd *abfd) |
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564 | { |
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565 | abfd->cacheable = TRUE; /* Allow it to be closed later. */ |
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566 | |||
567 | if (open_files >= bfd_cache_max_open ()) |
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568 | { |
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569 | if (! close_one ()) |
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570 | return NULL; |
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571 | } |
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572 | |||
573 | switch (abfd->direction) |
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574 | { |
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575 | case read_direction: |
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576 | case no_direction: |
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577 | abfd->iostream = real_fopen (abfd->filename, FOPEN_RB); |
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578 | break; |
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579 | case both_direction: |
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580 | case write_direction: |
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581 | if (abfd->opened_once) |
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582 | { |
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583 | abfd->iostream = real_fopen (abfd->filename, FOPEN_RUB); |
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584 | if (abfd->iostream == NULL) |
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585 | abfd->iostream = real_fopen (abfd->filename, FOPEN_WUB); |
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586 | } |
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587 | else |
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588 | { |
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589 | /* Create the file. |
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590 | |||
591 | Some operating systems won't let us overwrite a running |
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592 | binary. For them, we want to unlink the file first. |
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593 | |||
594 | However, gcc 2.95 will create temporary files using |
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595 | O_EXCL and tight permissions to prevent other users from |
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596 | substituting other .o files during the compilation. gcc |
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597 | will then tell the assembler to use the newly created |
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598 | file as an output file. If we unlink the file here, we |
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599 | open a brief window when another user could still |
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600 | substitute a file. |
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601 | |||
602 | So we unlink the output file if and only if it has |
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603 | non-zero size. */ |
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604 | #ifndef __MSDOS__ |
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605 | /* Don't do this for MSDOS: it doesn't care about overwriting |
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606 | a running binary, but if this file is already open by |
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607 | another BFD, we will be in deep trouble if we delete an |
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608 | open file. In fact, objdump does just that if invoked with |
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609 | the --info option. */ |
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610 | struct stat s; |
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611 | |||
612 | if (stat (abfd->filename, &s) == 0 && s.st_size != 0) |
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613 | unlink_if_ordinary (abfd->filename); |
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614 | #endif |
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615 | abfd->iostream = real_fopen (abfd->filename, FOPEN_WUB); |
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616 | abfd->opened_once = TRUE; |
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617 | } |
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618 | break; |
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619 | } |
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620 | |||
621 | if (abfd->iostream == NULL) |
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622 | bfd_set_error (bfd_error_system_call); |
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623 | else |
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624 | { |
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625 | if (! bfd_cache_init (abfd)) |
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626 | return NULL; |
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627 | } |
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628 | |||
629 | return (FILE *) abfd->iostream; |
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630 | } |