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* configure.ac: tar: close some race conditions when extracting

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* configure.ac: Check for fchmod and fchown.  Don't check for utimes.
* src/extract.c (fdchmod, fdchown, fdstat): New functions.
(set_mode, set_stat): New arg FD.  All callers changed.
This avoids some race conditions between closing a regular file
and setting its metadata, and it's a bit faster.
This commit is contained in:
Paul Eggert
2010-09-14 13:33:21 -07:00
parent 0fb3020da0
commit 59146768ef
2 changed files with 55 additions and 20 deletions
Download Patch File Download Diff File Expand all files Collapse all files

2
configure.ac
View File

@@ -90,7 +90,7 @@ gl_INIT
# paxutils modules
tar_PAXUTILS
AC_CHECK_FUNCS(fsync getdtablesize lstat mkfifo readlink symlink setlocale utimes)
AC_CHECK_FUNCS(fchmod fchown fsync getdtablesize lstat mkfifo readlink symlink setlocale)
AC_CHECK_DECLS([getgrgid],,, [#include <grp.h>])
AC_CHECK_DECLS([getpwuid],,, [#include <pwd.h>])
AC_CHECK_DECLS([time],,, [#include <time.h>])

73
src/extract.c
View File

@@ -136,8 +136,40 @@ extr_init (void)
}
}
/* Use fchmod if possible, chmod otherwise. */
static int
fdchmod (char const *file, int fd, mode_t mode)
{
#if HAVE_FCHMOD
if (0 <= fd)
return fchmod (fd, mode);
#endif
return chmod (file, mode);
}
/* Use fchown if possible, chown otherwise. */
static int
fdchown (char const *file, int fd, uid_t uid, gid_t gid)
{
#if HAVE_FCHOWN
if (0 <= fd)
return fchown (fd, uid, gid);
#endif
return chown (file, uid, gid);
}
/* Use fstat if possible, stat otherwise. */
static int
fdstat (char const *file, int fd, struct stat *st)
{
if (0 <= fd)
return fstat (fd, st);
return stat (file, st);
}
/* If restoring permissions, restore the mode for FILE_NAME from
information given in *STAT_INFO (where *CUR_INFO gives
information given in *STAT_INFO (where FD is a file descriptor
for the file if FD is nonnegative, and where *CUR_INFO gives
the current status if CUR_INFO is nonzero); otherwise invert the
INVERT_PERMISSIONS bits from the file's current permissions.
PERMSTATUS specifies the status of the file's permissions.
@@ -145,7 +177,7 @@ extr_init (void)
static void
set_mode (char const *file_name,
struct stat const *stat_info,
struct stat const *cur_info,
int fd, struct stat const *cur_info,
mode_t invert_permissions, enum permstatus permstatus,
char typeflag)
{
@@ -183,7 +215,7 @@ set_mode (char const *file_name,
struct stat st;
if (! cur_info)
{
if (stat (file_name, &st) != 0)
if (fdstat (file_name, fd, &st) != 0)
{
stat_error (file_name);
return;
@@ -193,7 +225,7 @@ set_mode (char const *file_name,
mode = cur_info->st_mode ^ invert_permissions;
}
chmod_errno = chmod (file_name, mode) == 0 ? 0 : errno;
chmod_errno = fdchmod (file_name, fd, mode) == 0 ? 0 : errno;
if (chmod_errno == EPERM && (mode & S_ISUID) != 0)
{
/* On Solaris, chmod may fail if we don't have PRIV_ALL, because
@@ -202,7 +234,7 @@ set_mode (char const *file_name,
(2009-09-03). */
if (priv_set_restore_linkdir () == 0)
{
chmod_errno = chmod (file_name, mode) == 0 ? 0 : errno;
chmod_errno = fdchmod (file_name, fd, mode) == 0 ? 0 : errno;
priv_set_remove_linkdir ();
}
}
@@ -245,6 +277,7 @@ check_time (char const *file_name, struct timespec t)
/* Restore stat attributes (owner, group, mode and times) for
FILE_NAME, using information given in *ST.
If FD is nonnegative, it is a file descriptor for the file.
If CUR_INFO is nonzero, *CUR_INFO is the
file's current status.
If not restoring permissions, invert the
@@ -260,7 +293,7 @@ check_time (char const *file_name, struct timespec t)
static void
set_stat (char const *file_name,
struct tar_stat_info const *st,
struct stat const *cur_info,
int fd, struct stat const *cur_info,
mode_t invert_permissions, enum permstatus permstatus,
char typeflag)
{
@@ -284,7 +317,7 @@ set_stat (char const *file_name,
ts[0] = start_time;
ts[1] = st->mtime;
if (utimens (file_name, ts) != 0)
if (fdutimens (file_name, fd, ts) != 0)
utime_error (file_name);
else
{
@@ -317,7 +350,8 @@ set_stat (char const *file_name,
}
else
{
chown_result = chown (file_name, st->stat.st_uid, st->stat.st_gid);
chown_result = fdchown (file_name, fd,
st->stat.st_uid, st->stat.st_gid);
}
if (chown_result == 0)
@@ -335,7 +369,7 @@ set_stat (char const *file_name,
}
if (typeflag != SYMTYPE)
set_mode (file_name, &st->stat, cur_info,
set_mode (file_name, &st->stat, fd, cur_info,
invert_permissions, permstatus, typeflag);
}
@@ -638,7 +672,7 @@ apply_nonancestor_delayed_set_stat (char const *file_name, bool after_links)
sb.stat.st_gid = data->gid;
sb.atime = data->atime;
sb.mtime = data->mtime;
set_stat (data->file_name, &sb, cur_info,
set_stat (data->file_name, &sb, -1, cur_info,
data->invert_permissions, data->permstatus, DIRTYPE);
}
@@ -872,17 +906,18 @@ extract_file (char *file_name, int typeflag)
if (to_stdout_option)
return 0;
if (! to_command_option)
set_stat (file_name, &current_stat_info, fd, NULL, invert_permissions,
(old_files_option == OVERWRITE_OLD_FILES
? UNKNOWN_PERMSTATUS : ARCHIVED_PERMSTATUS),
typeflag);
status = close (fd);
if (status < 0)
close_error (file_name);
if (to_command_option)
sys_wait_command ();
else
set_stat (file_name, &current_stat_info, NULL, invert_permissions,
(old_files_option == OVERWRITE_OLD_FILES ?
UNKNOWN_PERMSTATUS : ARCHIVED_PERMSTATUS),
typeflag);
return status;
}
@@ -1058,7 +1093,7 @@ extract_symlink (char *file_name, int typeflag)
return -1;
}
set_stat (file_name, &current_stat_info, NULL, 0, 0, SYMTYPE);
set_stat (file_name, &current_stat_info, -1, NULL, 0, 0, SYMTYPE);
return 0;
#else
@@ -1099,7 +1134,7 @@ extract_node (char *file_name, int typeflag)
return -1;
}
set_stat (file_name, &current_stat_info, NULL, invert_permissions,
set_stat (file_name, &current_stat_info, -1, NULL, invert_permissions,
ARCHIVED_PERMSTATUS, typeflag);
return 0;
}
@@ -1129,7 +1164,7 @@ extract_fifo (char *file_name, int typeflag)
return -1;
}
set_stat (file_name, &current_stat_info, NULL, invert_permissions,
set_stat (file_name, &current_stat_info, -1, NULL, invert_permissions,
ARCHIVED_PERMSTATUS, typeflag);
return 0;
}
@@ -1384,7 +1419,7 @@ apply_delayed_links (void)
struct tar_stat_info st1;
st1.stat.st_uid = ds->uid;
st1.stat.st_gid = ds->gid;
set_stat (source, &st1, NULL, 0, 0, SYMTYPE);
set_stat (source, &st1, -1, NULL, 0, 0, SYMTYPE);
valid_source = source;
}
}