libbb: add xfstat function

function                                             old     new   delta
xfstat                                                 -      25     +25
mkfs_ext2_main                                      2421    2423      +2
mkfs_reiser_main                                    1197    1194      -3
next                                                 312     307      -5
ar_main                                              533     522     -11
mkfs_minix_main                                     2938    2924     -14
mkfs_vfat_main                                      1511    1495     -16
writeTarFile                                         272     255     -17
------------------------------------------------------------------------------
(add/remove: 1/0 grow/shrink: 1/6 up/down: 27/-66)            Total: -39 bytes

Signed-off-by: Denys Vlasenko <dvlasenk@redhat.com>

3 files changed, 12 insertions, 4 deletions

diff --git a/libbb/dump.c b/libbb/dump.c
index a739ff61e..4db3f06f0 100644
--- a/libbb/dump.c
+++ b/libbb/dump.c
@@ -323,9 +323,7 @@ static void do_skip(priv_dumper_t *dumper, const char *fname, int statok)
         struct stat sbuf;
 
         if (statok) {
-                if (fstat(STDIN_FILENO, &sbuf)) {
-                        bb_simple_perror_msg_and_die(fname);
-                }
+                xfstat(STDIN_FILENO, &sbuf, fname);
                 if (!(S_ISCHR(sbuf.st_mode) || S_ISBLK(sbuf.st_mode) || S_ISFIFO(sbuf.st_mode))
                  && dumper->pub.dump_skip >= sbuf.st_size
                 ) {
diff --git a/libbb/update_passwd.c b/libbb/update_passwd.c
index e050dfc0e..a2be0f155 100644
--- a/libbb/update_passwd.c
+++ b/libbb/update_passwd.c
@@ -133,7 +133,7 @@ int FAST_FUNC update_passwd(const char *filename,
         goto close_old_fp;
 
  created:
-        if (!fstat(old_fd, &sb)) {
+        if (fstat(old_fd, &sb) == 0) {
                 fchmod(new_fd, sb.st_mode & 0777); /* ignore errors */
                 fchown(new_fd, sb.st_uid, sb.st_gid);
         }
diff --git a/libbb/xfuncs_printf.c b/libbb/xfuncs_printf.c
index b99f906df..c6db38d33 100644
--- a/libbb/xfuncs_printf.c
+++ b/libbb/xfuncs_printf.c
@@ -436,6 +436,16 @@ void FAST_FUNC xstat(const char *name, struct stat *stat_buf)
                 bb_perror_msg_and_die("can't stat '%s'", name);
 }
 
+void FAST_FUNC xfstat(int fd, struct stat *stat_buf, const char *errmsg)
+{
+        /* errmsg is usually a file name, but not always:
+         * xfstat may be called in a spot where file name is no longer
+         * available, and caller may give e.g. "can't stat input file" string.
+         */
+        if (fstat(fd, stat_buf))
+                bb_simple_perror_msg_and_die(errmsg);
+}
+
 // selinux_or_die() - die if SELinux is disabled.
 void FAST_FUNC selinux_or_die(void)
 {