+2020-12-07 Siddhesh Poyarekar <siddhesh@sourceware.org>
+
+ PR 26945
+ * ar.c
+ (write_archive) [!defined (_WIN32) || defined (__CYGWIN32__)]:
+ Initialize TARGET_STAT and OFD to pass to SMART_RENAME.
+ * arsup.c
+ (ar_save) [defined (_WIN32) || defined (__CYGWIN32__)]:
+ Likewise.
+ * bucomm.h (smart_rename): Add new arguments to declaration.
+ * objcopy.c
+ (strip_main)[defined (_WIN32) || defined (__CYGWIN32__)]:
+ Initialize COPYFD and pass to SMART_RENAME.
+ (copy_main) [defined (_WIN32) || defined (__CYGWIN32__)]:
+ Likewise.
+ * rename.c (try_preserve_permissions): New function.
+ (smart_rename): Use it and add new arguments.
+
2020-12-07 Siddhesh Poyarekar <siddhesh@sourceware.org>
PR 26945
char *old_name, *new_name;
bfd *contents_head = iarch->archive_next;
int ofd = -1;
+ struct stat target_stat;
+ bfd_boolean skip_stat = FALSE;
old_name = (char *) xmalloc (strlen (bfd_get_filename (iarch)) + 1);
strcpy (old_name, bfd_get_filename (iarch));
if (!bfd_set_archive_head (obfd, contents_head))
bfd_fatal (old_name);
+#if !defined (_WIN32) || defined (__CYGWIN32__)
+ ofd = dup (ofd);
+ if (iarch == NULL || iarch->iostream == NULL)
+ skip_stat = TRUE;
+ else if (ofd == -1 || fstat (fileno (iarch->iostream), &target_stat) != 0)
+ bfd_fatal (old_name);
+#endif
+
if (!bfd_close (obfd))
bfd_fatal (old_name);
/* We don't care if this fails; we might be creating the archive. */
bfd_close (iarch);
- if (smart_rename (new_name, old_name, 0) != 0)
+ if (smart_rename (new_name, old_name, ofd, skip_stat ? NULL : &target_stat, 0) != 0)
xexit (1);
free (old_name);
free (new_name);
else
{
char *ofilename = xstrdup (bfd_get_filename (obfd));
+ bfd_boolean skip_stat = FALSE;
+ struct stat target_stat;
+ int ofd = -1;
if (deterministic > 0)
obfd->flags |= BFD_DETERMINISTIC_OUTPUT;
+#if !defined (_WIN32) || defined (__CYGWIN32__)
+ /* It's OK to fail; at worst it will result in SMART_RENAME using a slow
+ copy fallback to write the output. */
+ ofd = dup (fileno (obfd->iostream));
+ if (lstat (real_name, &target_stat) != 0)
+ skip_stat = TRUE;
+#endif
+
bfd_close (obfd);
- smart_rename (ofilename, real_name, 0);
+ smart_rename (ofilename, real_name, ofd,
+ skip_stat ? NULL : &target_stat, 0);
obfd = 0;
free (ofilename);
}
/* In rename.c. */
extern void set_times (const char *, const struct stat *);
-extern int smart_rename (const char *, const char *, int);
+extern int smart_rename (const char *, const char *, int, struct stat *, int);
+
/* In libiberty. */
void *xmalloc (size_t);
struct stat statbuf;
char *tmpname;
int tmpfd = -1;
+ int copyfd = -1;
if (get_file_size (argv[i]) < 1)
{
else
tmpname = output_file;
- if (tmpname == NULL)
+ if (tmpname == NULL
+#if !defined (_WIN32) || defined (__CYGWIN32__)
+ /* Retain a copy of TMPFD since we will need it for SMART_RENAME. */
+ || (tmpfd >= 0 && (copyfd = dup (tmpfd)) == -1)
+#endif
+ )
{
bfd_nonfatal_message (argv[i], NULL, NULL,
_("could not create temporary file to hold stripped copy"));
if (output_file != tmpname)
status = (smart_rename (tmpname,
output_file ? output_file : argv[i],
- preserve_dates) != 0);
+ copyfd, &statbuf, preserve_dates) != 0);
if (status == 0)
status = hold_status;
}
else
- unlink_if_ordinary (tmpname);
+ {
+#if !defined (_WIN32) || defined (__CYGWIN32__)
+ if (copyfd >= 0)
+ close (copyfd);
+#endif
+ unlink_if_ordinary (tmpname);
+ }
if (output_file != tmpname)
free (tmpname);
}
bfd_boolean use_globalize = FALSE;
bfd_boolean use_keep_global = FALSE;
int c, tmpfd = -1;
+ int copyfd = -1;
struct stat statbuf;
const bfd_arch_info_type *input_arch = NULL;
else
tmpname = output_filename;
- if (tmpname == NULL)
- fatal (_("warning: could not create temporary file whilst copying '%s', (error: %s)"),
- input_filename, strerror (errno));
+ if (tmpname == NULL
+#if !defined (_WIN32) || defined (__CYGWIN32__)
+ /* Retain a copy of TMPFD since we will need it for SMART_RENAME. */
+ || (tmpfd >= 0 && (copyfd = dup (tmpfd)) == -1)
+#endif
+ )
+ {
+ fatal (_("warning: could not create temporary file whilst copying '%s', (error: %s)"),
+ input_filename, strerror (errno));
+ }
copy_file (input_filename, tmpname, tmpfd, &statbuf, input_target,
output_target, input_arch);
if (preserve_dates)
set_times (tmpname, &statbuf);
if (tmpname != output_filename)
- status = (smart_rename (tmpname, input_filename,
+ status = (smart_rename (tmpname, input_filename, copyfd, &statbuf,
preserve_dates) != 0);
}
else
- unlink_if_ordinary (tmpname);
+ {
+#if !defined (_WIN32) || defined (__CYGWIN32__)
+ if (copyfd >= 0)
+ close (copyfd);
+#endif
+ unlink_if_ordinary (tmpname);
+ }
if (tmpname != output_filename)
free (tmpname);
#endif
#endif
-/* Rename FROM to TO, copying if TO is a link.
- Return 0 if ok, -1 if error. */
+#if !defined (_WIN32) || defined (__CYGWIN32__)
+/* Try to preserve the permission bits and ownership of an existing file when
+ rename overwrites it. FD is the file being renamed and TARGET_STAT has the
+ status of the file that was overwritten. */
+static void
+try_preserve_permissions (int fd, struct stat *target_stat)
+{
+ struct stat from_stat;
+ int ret = 0;
+
+ if (fstat (fd, &from_stat) != 0)
+ return;
+
+ int from_mode = from_stat.st_mode & 0777;
+ int to_mode = target_stat->st_mode & 0777;
+
+ /* Fix up permissions before we potentially lose ownership with fchown.
+ Clear the setxid bits because in case the fchown below fails then we don't
+ want to end up with a sxid file owned by the invoking user. If the user
+ hasn't changed or if fchown succeeded, we add back the sxid bits at the
+ end. */
+ if (from_mode != to_mode)
+ fchmod (fd, to_mode);
+
+ /* Fix up ownership, this will clear the setxid bits. */
+ if (from_stat.st_uid != target_stat->st_uid
+ || from_stat.st_gid != target_stat->st_gid)
+ ret = fchown (fd, target_stat->st_uid, target_stat->st_gid);
+
+ /* Fix up the sxid bits if either the fchown wasn't needed or it
+ succeeded. */
+ if (ret == 0)
+ fchmod (fd, target_stat->st_mode & 07777);
+}
+#endif
+
+/* Rename FROM to TO, copying if TO is either a link or is not a regular file.
+ FD is an open file descriptor pointing to FROM that we can use to safely fix
+ up permissions of the file after renaming. TARGET_STAT has the file status
+ that is used to fix up permissions and timestamps after rename. Return 0 if
+ ok, -1 if error and FD is closed before returning. */
int
-smart_rename (const char *from, const char *to, int preserve_dates ATTRIBUTE_UNUSED)
+smart_rename (const char *from, const char *to, int fd ATTRIBUTE_UNUSED,
+ struct stat *target_stat ATTRIBUTE_UNUSED,
+ int preserve_dates ATTRIBUTE_UNUSED)
{
- bfd_boolean exists;
- struct stat s;
int ret = 0;
-
- exists = lstat (to, &s) == 0;
+ bfd_boolean exists = target_stat != NULL;
#if defined (_WIN32) && !defined (__CYGWIN32__)
/* Win32, unlike unix, will not erase `to' in `rename(from, to)' but
unlink (from);
}
#else
- /* Use rename only if TO is not a symbolic link and has
- only one hard link, and we have permission to write to it. */
+ /* Avoid a full copy and use rename if we can fix up permissions of the
+ file after renaming, i.e.:
+
+ - TO is not a symbolic link
+ - TO is a regular file with only one hard link
+ - We have permission to write to TO
+ - FD is available to safely fix up permissions to be the same as the file
+ we overwrote with the rename.
+
+ Note though that the actual file on disk that TARGET_STAT describes may
+ have changed and we're only trying to preserve the status we know about.
+ At no point do we try to interact with the new file changes, so there can
+ only be two outcomes, i.e. either the external file change survives
+ without knowledge of our change (if it happens after the rename syscall)
+ or our rename and permissions fixup survive without any knowledge of the
+ external change. */
if (! exists
- || (!S_ISLNK (s.st_mode)
- && S_ISREG (s.st_mode)
- && (s.st_mode & S_IWUSR)
- && s.st_nlink == 1)
+ || (fd >= 0
+ && !S_ISLNK (target_stat->st_mode)
+ && S_ISREG (target_stat->st_mode)
+ && (target_stat->st_mode & S_IWUSR)
+ && target_stat->st_nlink == 1)
)
{
ret = rename (from, to);
if (ret == 0)
{
if (exists)
- {
- /* Try to preserve the permission bits and ownership of
- TO. First get the mode right except for the setuid
- bit. Then change the ownership. Then fix the setuid
- bit. We do the chmod before the chown because if the
- chown succeeds, and we are a normal user, we won't be
- able to do the chmod afterward. We don't bother to
- fix the setuid bit first because that might introduce
- a fleeting security problem, and because the chown
- will clear the setuid bit anyhow. We only fix the
- setuid bit if the chown succeeds, because we don't
- want to introduce an unexpected setuid file owned by
- the user running objcopy. */
- chmod (to, s.st_mode & 0777);
- if (chown (to, s.st_uid, s.st_gid) >= 0)
- chmod (to, s.st_mode & 07777);
- }
+ try_preserve_permissions (fd, target_stat);
}
else
{
non_fatal (_("unable to copy file '%s'; reason: %s"), to, strerror (errno));
if (preserve_dates)
- set_times (to, &s);
+ set_times (to, target_stat);
unlink (from);
}
+ if (fd >= 0)
+ close (fd);
#endif /* _WIN32 && !__CYGWIN32__ */
return ret;
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