1 /* Standard find_debuginfo callback for libdwfl. 2 Copyright (C) 2005-2010 Red Hat, Inc. 3 This file is part of Red Hat elfutils. 4 5 Red Hat elfutils is free software; you can redistribute it and/or modify 6 it under the terms of the GNU General Public License as published by the 7 Free Software Foundation; version 2 of the License. 8 9 Red Hat elfutils is distributed in the hope that it will be useful, but 10 WITHOUT ANY WARRANTY; without even the implied warranty of 11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 12 General Public License for more details. 13 14 You should have received a copy of the GNU General Public License along 15 with Red Hat elfutils; if not, write to the Free Software Foundation, 16 Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301 USA. 17 18 In addition, as a special exception, Red Hat, Inc. gives You the 19 additional right to link the code of Red Hat elfutils with code licensed 20 under any Open Source Initiative certified open source license 21 (http://www.opensource.org/licenses/index.php) which requires the 22 distribution of source code with any binary distribution and to 23 distribute linked combinations of the two. Non-GPL Code permitted under 24 this exception must only link to the code of Red Hat elfutils through 25 those well defined interfaces identified in the file named EXCEPTION 26 found in the source code files (the "Approved Interfaces"). The files 27 of Non-GPL Code may instantiate templates or use macros or inline 28 functions from the Approved Interfaces without causing the resulting 29 work to be covered by the GNU General Public License. Only Red Hat, 30 Inc. may make changes or additions to the list of Approved Interfaces. 31 Red Hat's grant of this exception is conditioned upon your not adding 32 any new exceptions. If you wish to add a new Approved Interface or 33 exception, please contact Red Hat. You must obey the GNU General Public 34 License in all respects for all of the Red Hat elfutils code and other 35 code used in conjunction with Red Hat elfutils except the Non-GPL Code 36 covered by this exception. If you modify this file, you may extend this 37 exception to your version of the file, but you are not obligated to do 38 so. If you do not wish to provide this exception without modification, 39 you must delete this exception statement from your version and license 40 this file solely under the GPL without exception. 41 42 Red Hat elfutils is an included package of the Open Invention Network. 43 An included package of the Open Invention Network is a package for which 44 Open Invention Network licensees cross-license their patents. No patent 45 license is granted, either expressly or impliedly, by designation as an 46 included package. Should you wish to participate in the Open Invention 47 Network licensing program, please visit www.openinventionnetwork.com 48 <http://www.openinventionnetwork.com>. */ 49 50 #include "libdwflP.h" 51 #include <stdio.h> 52 #include <fcntl.h> 53 #include <unistd.h> 54 #include <sys/stat.h> 55 #include "system.h" 56 57 58 /* Try to open64 [DIR/][SUBDIR/]DEBUGLINK, return file descriptor or -1. 59 On success, *DEBUGINFO_FILE_NAME has the malloc'd name of the open file. */ 60 static int 61 try_open (const struct stat64 *main_stat, 62 const char *dir, const char *subdir, const char *debuglink, 63 char **debuginfo_file_name) 64 { 65 char *fname; 66 if (dir == NULL && subdir == NULL) 67 { 68 fname = strdup (debuglink); 69 if (fname == NULL) 70 return -1; 71 } 72 else if ((subdir == NULL ? asprintf (&fname, "%s/%s", dir, debuglink) 73 : dir == NULL ? asprintf (&fname, "%s/%s", subdir, debuglink) 74 : asprintf (&fname, "%s/%s/%s", dir, subdir, debuglink)) < 0) 75 return -1; 76 77 struct stat64 st; 78 int fd = TEMP_FAILURE_RETRY (open64 (fname, O_RDONLY)); 79 if (fd < 0) 80 free (fname); 81 else if (fstat64 (fd, &st) == 0 82 && st.st_ino == main_stat->st_ino 83 && st.st_dev == main_stat->st_dev) 84 { 85 /* This is the main file by another name. Don't look at it again. */ 86 close (fd); 87 errno = ENOENT; 88 fd = -1; 89 } 90 else 91 *debuginfo_file_name = fname; 92 93 return fd; 94 } 95 96 /* Return true iff the FD's contents CRC matches DEBUGLINK_CRC. */ 97 static inline bool 98 check_crc (int fd, GElf_Word debuglink_crc) 99 { 100 uint32_t file_crc; 101 return (__libdwfl_crc32_file (fd, &file_crc) == 0 102 && file_crc == debuglink_crc); 103 } 104 105 static bool 106 validate (Dwfl_Module *mod, int fd, bool check, GElf_Word debuglink_crc) 107 { 108 /* If we have a build ID, check only that. */ 109 if (mod->build_id_len > 0) 110 { 111 /* We need to open an Elf handle on the file so we can check its 112 build ID note for validation. Backdoor the handle into the 113 module data structure since we had to open it early anyway. */ 114 115 mod->debug.valid = false; 116 Dwfl_Error error = __libdw_open_file (&fd, &mod->debug.elf, false, false); 117 if (error != DWFL_E_NOERROR) 118 __libdwfl_seterrno (error); 119 else if (likely (__libdwfl_find_build_id (mod, false, 120 mod->debug.elf) == 2)) 121 /* Also backdoor the gratuitous flag. */ 122 mod->debug.valid = true; 123 else 124 { 125 /* A mismatch! */ 126 elf_end (mod->debug.elf); 127 mod->debug.elf = NULL; 128 close (fd); 129 fd = -1; 130 } 131 132 return mod->debug.valid; 133 } 134 135 return !check || check_crc (fd, debuglink_crc); 136 } 137 138 static int 139 find_debuginfo_in_path (Dwfl_Module *mod, const char *file_name, 140 const char *debuglink_file, GElf_Word debuglink_crc, 141 char **debuginfo_file_name) 142 { 143 bool cancheck = debuglink_crc != (GElf_Word) 0; 144 145 const char *file_basename = file_name == NULL ? NULL : basename (file_name); 146 if (debuglink_file == NULL) 147 { 148 if (file_basename == NULL) 149 { 150 errno = 0; 151 return -1; 152 } 153 154 size_t len = strlen (file_basename); 155 char *localname = alloca (len + sizeof ".debug"); 156 memcpy (localname, file_basename, len); 157 memcpy (&localname[len], ".debug", sizeof ".debug"); 158 debuglink_file = localname; 159 cancheck = false; 160 } 161 162 /* Look for a file named DEBUGLINK_FILE in the directories 163 indicated by the debug directory path setting. */ 164 165 const Dwfl_Callbacks *const cb = mod->dwfl->callbacks; 166 #if defined(__BIONIC__) || defined(__APPLE__) 167 char *path = strdup ((cb->debuginfo_path ? *cb->debuginfo_path : NULL) 168 ?: DEFAULT_DEBUGINFO_PATH); 169 #else 170 char *path = strdupa ((cb->debuginfo_path ? *cb->debuginfo_path : NULL) 171 ?: DEFAULT_DEBUGINFO_PATH); 172 #endif 173 174 /* A leading - or + in the whole path sets whether to check file CRCs. */ 175 bool defcheck = true; 176 if (path[0] == '-' || path[0] == '+') 177 { 178 defcheck = path[0] == '+'; 179 ++path; 180 } 181 182 /* XXX dev/ino should be cached in struct dwfl_file. */ 183 struct stat64 main_stat; 184 if (unlikely ((mod->main.fd != -1 ? fstat64 (mod->main.fd, &main_stat) 185 : file_name != NULL ? stat64 (file_name, &main_stat) 186 : -1) < 0)) 187 { 188 main_stat.st_dev = 0; 189 main_stat.st_ino = 0; 190 } 191 192 #if defined(__BIONIC__) || defined(__APPLE__) 193 char *file_dirname = (file_basename == file_name ? NULL 194 : strndup (file_name, file_basename - 1 - file_name)); 195 #else 196 char *file_dirname = (file_basename == file_name ? NULL 197 : strndupa (file_name, file_basename - 1 - file_name)); 198 #endif 199 200 char *p; 201 while ((p = strsep (&path, ":")) != NULL) 202 { 203 /* A leading - or + says whether to check file CRCs for this element. */ 204 bool check = defcheck; 205 if (*p == '+' || *p == '-') 206 check = *p++ == '+'; 207 check = check && cancheck; 208 209 const char *dir, *subdir; 210 switch (p[0]) 211 { 212 case '\0': 213 /* An empty entry says to try the main file's directory. */ 214 dir = file_dirname; 215 subdir = NULL; 216 break; 217 case '/': 218 /* An absolute path says to look there for a subdirectory 219 named by the main file's absolute directory. 220 This cannot be applied to a relative file name. */ 221 if (file_dirname == NULL || file_dirname[0] != '/') 222 continue; 223 dir = p; 224 subdir = file_dirname + 1; 225 break; 226 default: 227 /* A relative path says to try a subdirectory of that name 228 in the main file's directory. */ 229 dir = file_dirname; 230 subdir = p; 231 break; 232 } 233 234 char *fname = NULL; 235 int fd = try_open (&main_stat, dir, subdir, debuglink_file, &fname); 236 if (fd < 0) 237 switch (errno) 238 { 239 case ENOENT: 240 case ENOTDIR: 241 continue; 242 default: 243 #if defined(__BIONIC__) || defined(__APPLE__) 244 free(path); 245 free(file_dirname); 246 #endif 247 return -1; 248 } 249 if (validate (mod, fd, check, debuglink_crc)) 250 { 251 *debuginfo_file_name = fname; 252 #if defined(__BIONIC__) || defined(__APPLE__) 253 free(path); 254 free(file_dirname); 255 #endif 256 return fd; 257 } 258 free (fname); 259 close (fd); 260 } 261 262 /* No dice. */ 263 errno = 0; 264 #if defined(__BIONIC__) || defined(__APPLE__) 265 free(path); 266 free(file_dirname); 267 #endif 268 return -1; 269 } 270 271 int 272 dwfl_standard_find_debuginfo (Dwfl_Module *mod, 273 void **userdata __attribute__ ((unused)), 274 const char *modname __attribute__ ((unused)), 275 GElf_Addr base __attribute__ ((unused)), 276 const char *file_name, 277 const char *debuglink_file, 278 GElf_Word debuglink_crc, 279 char **debuginfo_file_name) 280 { 281 /* First try by build ID if we have one. If that succeeds or fails 282 other than just by finding nothing, that's all we do. */ 283 const unsigned char *bits; 284 GElf_Addr vaddr; 285 if (INTUSE(dwfl_module_build_id) (mod, &bits, &vaddr) > 0) 286 { 287 int fd = INTUSE(dwfl_build_id_find_debuginfo) (mod, 288 NULL, NULL, 0, 289 NULL, NULL, 0, 290 debuginfo_file_name); 291 if (fd >= 0 || mod->debug.elf != NULL || errno != 0) 292 return fd; 293 } 294 295 /* Failing that, search the path by name. */ 296 int fd = find_debuginfo_in_path (mod, file_name, 297 debuglink_file, debuglink_crc, 298 debuginfo_file_name); 299 300 if (fd < 0 && errno == 0) 301 { 302 /* If FILE_NAME is a symlink, the debug file might be associated 303 with the symlink target name instead. */ 304 305 char *canon = canonicalize_file_name (file_name); 306 if (canon != NULL && strcmp (file_name, canon)) 307 fd = find_debuginfo_in_path (mod, canon, 308 debuglink_file, debuglink_crc, 309 debuginfo_file_name); 310 free (canon); 311 } 312 313 return fd; 314 } 315 INTDEF (dwfl_standard_find_debuginfo) 316
