rm -f: ignore EROFS when it's really ENOENT

rm -f must not print a diagnostic for a nonexistent file.  However,
most linux-based kernel unlinkat functions set errno to EROFS when
the named file (regardless of whether it exists) would lie on a
read-only file system.  remove.c now performs an extra fstatat call
in that case, to determine whether the file exists.
* src/remove.c (excise): Map EROFS to ENOENT, if a file is nonexistent.
Reported by Steven Drake in <http://savannah.gnu.org/bugs/?27923>.
* NEWS (Changes in behavior): Mention it.

1 files changed, 12 insertions, 0 deletions

diff --git a/src/remove.c b/src/remove.c
index 87fb32bf9..c4b93fe7e 100644
--- a/src/remove.c
+++ b/src/remove.c
@@ -437,6 +437,18 @@ excise (FTS *fts, FTSENT *ent, struct rm_options const *x, bool is_dir)
       return RM_OK;
     }
 
+  /* The unlinkat from kernels like linux-2.6.32 reports EROFS even for
+     nonexistent files.  When the file is indeed missing, map that to ENOENT,
+     so that rm -f ignores it, as required.  Even without -f, this is useful
+     because it makes rm print the more precise diagnostic.  */
+  if (errno == EROFS)
+    {
+      struct stat st;
+      if ( ! (lstatat (fts->fts_cwd_fd, ent->fts_accpath, &st)
+                       && errno == ENOENT))
+        errno = EROFS;
+    }
+
   if (ignorable_missing (x, errno))
     return RM_OK;