grep: do input==output check more like dir loop check

* src/main.c (grepfile): Just use SAME_INODE; don't bother
with SAME_REGULAR_FILE.  This works better on properly-working
POSIX hosts, since it handles the case where the file is changing
as we grep it.  It works worse on hosts that don't support st_ino
properly, but in practice this isn't that much of a problem here.
* src/system.h (same_file_attributes, SAME_REGULAR_FILE):
Remove; no longer needed.

2 files changed, 2 insertions, 41 deletions

diff --git a/src/main.c b/src/main.c
index ca6f85f7..3fff5b75 100644
--- a/src/main.c
+++ b/src/main.c
@@ -1423,8 +1423,8 @@ grepfile (char const *file, struct stats *stats)
          input==output, while there is no risk of infloop, there is a race
          condition that could result in "alternate" output.  */
       if (!out_quiet && list_files == 0 && 1 < max_count
-          && S_ISREG (stats->stat.st_mode) && out_stat.st_ino
-          && SAME_REGULAR_FILE (stats->stat, out_stat))
+          && S_ISREG (out_stat.st_mode) && out_stat.st_ino
+          && SAME_INODE (stats->stat, out_stat))
         {
           error (0, 0, _("input file %s is also the output"), quote (file));
           errseen = 1;
diff --git a/src/system.h b/src/system.h
index db2fea3f..f356c086 100644
--- a/src/system.h
+++ b/src/system.h
@@ -51,44 +51,5 @@ enum { EXIT_TROUBLE = 2 };
 # define initialize_main(argcp, argvp)
 #endif
 
-/* Do struct stat *S, *T have the same file attributes?
-
-   POSIX says that two files are identical if st_ino and st_dev are
-   the same, but many file systems incorrectly assign the same (device,
-   inode) pair to two distinct files, including:
-
-   - GNU/Linux NFS servers that export all local file systems as a
-     single NFS file system, if a local device number (st_dev) exceeds
-     255, or if a local inode number (st_ino) exceeds 16777215.
-
-   - Network Appliance NFS servers in snapshot directories; see
-     Network Appliance bug #195.
-
-   - ClearCase MVFS; see bug id ATRia04618.
-
-   Check whether two files that purport to be the same have the same
-   attributes, to work around instances of this common bug.  Do not
-   inspect all attributes, only attributes useful in checking for this
-   bug.
-
-   It's possible for two distinct files on a buggy file system to have
-   the same attributes, but it's not worth slowing down all
-   implementations (or complicating the configuration) to cater to
-   these rare cases in buggy implementations.  */
-
-#ifndef same_file_attributes
-# define same_file_attributes(s, t) \
-   ((s)->st_mode == (t)->st_mode \
-    && (s)->st_nlink == (t)->st_nlink \
-    && (s)->st_uid == (t)->st_uid \
-    && (s)->st_gid == (t)->st_gid \
-    && (s)->st_size == (t)->st_size \
-    && (s)->st_mtime == (t)->st_mtime \
-    && (s)->st_ctime == (t)->st_ctime)
-#endif
-
-#define SAME_REGULAR_FILE(s, t) \
-  (SAME_INODE (s, t) && same_file_attributes (&s, &t))
-
 #include "unlocked-io.h"
 #endif