diff options
Diffstat (limited to 'libdwfl/find-debuginfo.c')
-rw-r--r-- | libdwfl/find-debuginfo.c | 292 |
1 files changed, 292 insertions, 0 deletions
diff --git a/libdwfl/find-debuginfo.c b/libdwfl/find-debuginfo.c new file mode 100644 index 0000000..f6f802e --- /dev/null +++ b/libdwfl/find-debuginfo.c @@ -0,0 +1,292 @@ +/* Standard find_debuginfo callback for libdwfl. + Copyright (C) 2005-2010 Red Hat, Inc. + This file is part of Red Hat elfutils. + + Red Hat elfutils is free software; you can redistribute it and/or modify + it under the terms of the GNU General Public License as published by the + Free Software Foundation; version 2 of the License. + + Red Hat elfutils is distributed in the hope that it will be useful, but + WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + General Public License for more details. + + You should have received a copy of the GNU General Public License along + with Red Hat elfutils; if not, write to the Free Software Foundation, + Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301 USA. + + In addition, as a special exception, Red Hat, Inc. gives You the + additional right to link the code of Red Hat elfutils with code licensed + under any Open Source Initiative certified open source license + (http://www.opensource.org/licenses/index.php) which requires the + distribution of source code with any binary distribution and to + distribute linked combinations of the two. Non-GPL Code permitted under + this exception must only link to the code of Red Hat elfutils through + those well defined interfaces identified in the file named EXCEPTION + found in the source code files (the "Approved Interfaces"). The files + of Non-GPL Code may instantiate templates or use macros or inline + functions from the Approved Interfaces without causing the resulting + work to be covered by the GNU General Public License. Only Red Hat, + Inc. may make changes or additions to the list of Approved Interfaces. + Red Hat's grant of this exception is conditioned upon your not adding + any new exceptions. If you wish to add a new Approved Interface or + exception, please contact Red Hat. You must obey the GNU General Public + License in all respects for all of the Red Hat elfutils code and other + code used in conjunction with Red Hat elfutils except the Non-GPL Code + covered by this exception. If you modify this file, you may extend this + exception to your version of the file, but you are not obligated to do + so. If you do not wish to provide this exception without modification, + you must delete this exception statement from your version and license + this file solely under the GPL without exception. + + Red Hat elfutils is an included package of the Open Invention Network. + An included package of the Open Invention Network is a package for which + Open Invention Network licensees cross-license their patents. No patent + license is granted, either expressly or impliedly, by designation as an + included package. Should you wish to participate in the Open Invention + Network licensing program, please visit www.openinventionnetwork.com + <http://www.openinventionnetwork.com>. */ + +#include "libdwflP.h" +#include <stdio.h> +#include <fcntl.h> +#include <unistd.h> +#include <sys/stat.h> +#include "system.h" + + +/* Try to open64 [DIR/][SUBDIR/]DEBUGLINK, return file descriptor or -1. + On success, *DEBUGINFO_FILE_NAME has the malloc'd name of the open file. */ +static int +try_open (const struct stat64 *main_stat, + const char *dir, const char *subdir, const char *debuglink, + char **debuginfo_file_name) +{ + char *fname; + if (dir == NULL && subdir == NULL) + { + fname = strdup (debuglink); + if (fname == NULL) + return -1; + } + else if ((subdir == NULL ? asprintf (&fname, "%s/%s", dir, debuglink) + : dir == NULL ? asprintf (&fname, "%s/%s", subdir, debuglink) + : asprintf (&fname, "%s/%s/%s", dir, subdir, debuglink)) < 0) + return -1; + + struct stat64 st; + int fd = TEMP_FAILURE_RETRY (open64 (fname, O_RDONLY)); + if (fd < 0) + free (fname); + else if (fstat64 (fd, &st) == 0 + && st.st_ino == main_stat->st_ino + && st.st_dev == main_stat->st_dev) + { + /* This is the main file by another name. Don't look at it again. */ + close (fd); + errno = ENOENT; + fd = -1; + } + else + *debuginfo_file_name = fname; + + return fd; +} + +/* Return true iff the FD's contents CRC matches DEBUGLINK_CRC. */ +static inline bool +check_crc (int fd, GElf_Word debuglink_crc) +{ + uint32_t file_crc; + return (__libdwfl_crc32_file (fd, &file_crc) == 0 + && file_crc == debuglink_crc); +} + +static bool +validate (Dwfl_Module *mod, int fd, bool check, GElf_Word debuglink_crc) +{ + /* If we have a build ID, check only that. */ + if (mod->build_id_len > 0) + { + /* We need to open an Elf handle on the file so we can check its + build ID note for validation. Backdoor the handle into the + module data structure since we had to open it early anyway. */ + + mod->debug.valid = false; + Dwfl_Error error = __libdw_open_file (&fd, &mod->debug.elf, false, false); + if (error != DWFL_E_NOERROR) + __libdwfl_seterrno (error); + else if (likely (__libdwfl_find_build_id (mod, false, + mod->debug.elf) == 2)) + /* Also backdoor the gratuitous flag. */ + mod->debug.valid = true; + else + { + /* A mismatch! */ + elf_end (mod->debug.elf); + mod->debug.elf = NULL; + close (fd); + fd = -1; + } + + return mod->debug.valid; + } + + return !check || check_crc (fd, debuglink_crc); +} + +static int +find_debuginfo_in_path (Dwfl_Module *mod, const char *file_name, + const char *debuglink_file, GElf_Word debuglink_crc, + char **debuginfo_file_name) +{ + bool cancheck = debuglink_crc != (GElf_Word) 0; + + const char *file_basename = file_name == NULL ? NULL : basename (file_name); + if (debuglink_file == NULL) + { + if (file_basename == NULL) + { + errno = 0; + return -1; + } + + size_t len = strlen (file_basename); + char *localname = alloca (len + sizeof ".debug"); + memcpy (localname, file_basename, len); + memcpy (&localname[len], ".debug", sizeof ".debug"); + debuglink_file = localname; + cancheck = false; + } + + /* Look for a file named DEBUGLINK_FILE in the directories + indicated by the debug directory path setting. */ + + const Dwfl_Callbacks *const cb = mod->dwfl->callbacks; + char *path = strdupa ((cb->debuginfo_path ? *cb->debuginfo_path : NULL) + ?: DEFAULT_DEBUGINFO_PATH); + + /* A leading - or + in the whole path sets whether to check file CRCs. */ + bool defcheck = true; + if (path[0] == '-' || path[0] == '+') + { + defcheck = path[0] == '+'; + ++path; + } + + /* XXX dev/ino should be cached in struct dwfl_file. */ + struct stat64 main_stat; + if (unlikely ((mod->main.fd != -1 ? fstat64 (mod->main.fd, &main_stat) + : file_name != NULL ? stat64 (file_name, &main_stat) + : -1) < 0)) + { + main_stat.st_dev = 0; + main_stat.st_ino = 0; + } + + char *file_dirname = (file_basename == file_name ? NULL + : strndupa (file_name, file_basename - 1 - file_name)); + char *p; + while ((p = strsep (&path, ":")) != NULL) + { + /* A leading - or + says whether to check file CRCs for this element. */ + bool check = defcheck; + if (*p == '+' || *p == '-') + check = *p++ == '+'; + check = check && cancheck; + + const char *dir, *subdir; + switch (p[0]) + { + case '\0': + /* An empty entry says to try the main file's directory. */ + dir = file_dirname; + subdir = NULL; + break; + case '/': + /* An absolute path says to look there for a subdirectory + named by the main file's absolute directory. + This cannot be applied to a relative file name. */ + if (file_dirname == NULL || file_dirname[0] != '/') + continue; + dir = p; + subdir = file_dirname + 1; + break; + default: + /* A relative path says to try a subdirectory of that name + in the main file's directory. */ + dir = file_dirname; + subdir = p; + break; + } + + char *fname = NULL; + int fd = try_open (&main_stat, dir, subdir, debuglink_file, &fname); + if (fd < 0) + switch (errno) + { + case ENOENT: + case ENOTDIR: + continue; + default: + return -1; + } + if (validate (mod, fd, check, debuglink_crc)) + { + *debuginfo_file_name = fname; + return fd; + } + free (fname); + close (fd); + } + + /* No dice. */ + errno = 0; + return -1; +} + +int +dwfl_standard_find_debuginfo (Dwfl_Module *mod, + void **userdata __attribute__ ((unused)), + const char *modname __attribute__ ((unused)), + GElf_Addr base __attribute__ ((unused)), + const char *file_name, + const char *debuglink_file, + GElf_Word debuglink_crc, + char **debuginfo_file_name) +{ + /* First try by build ID if we have one. If that succeeds or fails + other than just by finding nothing, that's all we do. */ + const unsigned char *bits; + GElf_Addr vaddr; + if (INTUSE(dwfl_module_build_id) (mod, &bits, &vaddr) > 0) + { + int fd = INTUSE(dwfl_build_id_find_debuginfo) (mod, + NULL, NULL, 0, + NULL, NULL, 0, + debuginfo_file_name); + if (fd >= 0 || mod->debug.elf != NULL || errno != 0) + return fd; + } + + /* Failing that, search the path by name. */ + int fd = find_debuginfo_in_path (mod, file_name, + debuglink_file, debuglink_crc, + debuginfo_file_name); + + if (fd < 0 && errno == 0) + { + /* If FILE_NAME is a symlink, the debug file might be associated + with the symlink target name instead. */ + + char *canon = canonicalize_file_name (file_name); + if (canon != NULL && strcmp (file_name, canon)) + fd = find_debuginfo_in_path (mod, canon, + debuglink_file, debuglink_crc, + debuginfo_file_name); + free (canon); + } + + return fd; +} +INTDEF (dwfl_standard_find_debuginfo) |