/* Standard find_debuginfo callback for libdwfl.
Copyright (C) 2005-2010, 2014 Red Hat, Inc.
This file is part of elfutils.
This file is free software; you can redistribute it and/or modify
it under the terms of either
* the GNU Lesser General Public License as published by the Free
Software Foundation; either version 3 of the License, or (at
your option) any later version
or
* the GNU General Public License as published by the Free
Software Foundation; either version 2 of the License, or (at
your option) any later version
or both in parallel, as here.
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 copies of the GNU General Public License and
the GNU Lesser General Public License along with this program. If
not, see <http://www.gnu.org/licenses/>. */
#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)
{
/* For alt debug files always check the build-id from the Dwarf and alt. */
if (mod->dw != NULL)
{
bool valid = false;
const void *build_id;
const char *altname;
ssize_t build_id_len = INTUSE(dwelf_dwarf_gnu_debugaltlink) (mod->dw,
&altname,
&build_id);
if (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. */
Dwfl_Error error = __libdw_open_file (&fd, &mod->alt_elf,
false, false);
if (error != DWFL_E_NOERROR)
__libdwfl_seterrno (error);
else
{
const void *alt_build_id;
ssize_t alt_len = INTUSE(dwelf_elf_gnu_build_id) (mod->alt_elf,
&alt_build_id);
if (alt_len > 0 && alt_len == build_id_len
&& memcmp (build_id, alt_build_id, alt_len) == 0)
valid = true;
else
{
/* A mismatch! */
elf_end (mod->alt_elf);
mod->alt_elf = NULL;
close (fd);
fd = -1;
}
}
}
return valid;
}
/* 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)
{
/* For a alt debug multi file we need a name, for a separate debug
name we may be able to fall back on file_basename.debug. */
if (file_basename == NULL || mod->dw != 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, *file;
switch (p[0])
{
case '\0':
/* An empty entry says to try the main file's directory. */
dir = file_dirname;
subdir = NULL;
file = debuglink_file;
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. For alt debug files
it means to look for the basename file in that dir or the
.dwz subdir (see below). */
if (mod->dw == NULL
&& (file_dirname == NULL || file_dirname[0] != '/'))
continue;
dir = p;
if (mod->dw == NULL)
{
subdir = file_dirname + 1;
file = debuglink_file;
}
else
{
subdir = NULL;
file = basename (debuglink_file);
}
break;
default:
/* A relative path says to try a subdirectory of that name
in the main file's directory. */
dir = file_dirname;
subdir = p;
file = debuglink_file;
break;
}
char *fname = NULL;
int fd = try_open (&main_stat, dir, subdir, file, &fname);
if (fd < 0)
switch (errno)
{
case ENOENT:
case ENOTDIR:
/* If we are looking for the alt file also try the .dwz subdir.
But only if this is the empty or absolute path. */
if (mod->dw != NULL && (p[0] == '\0' || p[0] == '/'))
{
fd = try_open (&main_stat, dir, ".dwz",
basename (file), &fname);
if (fd < 0)
{
if (errno != ENOENT && errno != ENOTDIR)
return -1;
else
continue;
}
break;
}
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)
{
/* Dropping most arguments means we cannot rely on them in
dwfl_build_id_find_debuginfo. But leave it that way since
some user code out there also does this, so we'll have to
handle it anyway. */
int fd = INTUSE(dwfl_build_id_find_debuginfo) (mod,
NULL, NULL, 0,
NULL, NULL, 0,
debuginfo_file_name);
/* Did the build_id callback find something or report an error?
Then we are done. Otherwise fallback on path based search. */
if (fd >= 0
|| (mod->dw == NULL && mod->debug.elf != NULL)
|| (mod->dw != NULL && mod->alt_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)