[Emacs-diffs] master 735940f: Be less picky about EACCES in file test predicates

[Paul Eggert]

branch: master
commit 735940f4551a43f3b4381105dc074cd7d494f2f3
Author: Paul Eggert <address@hidden>
Commit: Paul Eggert <address@hidden>

    Be less picky about EACCES in file test predicates
    
    Problem reported by Tino Calancha (Bug#37445) and others.
    * src/fileio.c (PICKY_EACCES): New constant, false by default.
    (file_test_errno): Ignore EACCES if not picky.
    (check_file_access): Investigate EACCES problems further
    if picky.
---
 src/fileio.c | 16 +++++++++++++++-
 1 file changed, 15 insertions(+), 1 deletion(-)

diff --git a/src/fileio.c b/src/fileio.c
index 0977516..58bc6b7 100644
--- a/src/fileio.c
+++ b/src/fileio.c
@@ -253,9 +253,23 @@ file_attribute_errno (Lisp_Object file, int err)
   return file_metadata_errno ("Getting attributes", file, err);
 }
 
+/* In theory, EACCES errors for predicates like file-readable-p should
+   be checked further because they may be problems with an ancestor
+   directory instead of with the file itself, which means that we
+   don't have reliable info about the requested file.  In practice,
+   though, such errors are common enough that signaling them can be
+   annoying even if the errors are real (e.g., Bug#37445).  So return
+   nil for EACCES unless compiling with -DPICKY_EACCES, which is off
+   by default.  */
+#ifndef PICKY_EACCES
+enum { PICKY_EACCES = false };
+#endif
+
 static Lisp_Object
 file_test_errno (Lisp_Object file, int err)
 {
+  if (!PICKY_EACCES && err == EACCES)
+    return Qnil;
   return file_metadata_errno ("Testing file", file, err);
 }
 
@@ -2745,7 +2759,7 @@ check_file_access (Lisp_Object file, Lisp_Object 
operation, int amode)
     return Qt;
   int err = errno;
   if (err == EROFS || err == ETXTBSY
-      || (err == EACCES && amode != F_OK
+      || (PICKY_EACCES && err == EACCES && amode != F_OK
          && file_access_p (encoded_file, F_OK)))
     {
       errno = err;