[gcc r12-5234] fixincludes: simplify handling for access() failure [PR21283, PR80047]

[gcc r12-5234] fixincludes: simplify handling for access() failure [PR21283, PR80047]

[Xi Ruoyao]

https://gcc.gnu.org/g:04c5a91d068c4ca2f09c2bc206fce00db9d1790b

commit r12-5234-g04c5a91d068c4ca2f09c2bc206fce00db9d1790b
Author: Xi Ruoyao <xry111@mengyan1223.wang>
Date:   Tue Nov 9 21:40:04 2021 +0800

    fixincludes: simplify handling for access() failure [PR21283, PR80047]
    
    POSIX says:
    
        On some implementations, if buf is a null pointer, getcwd() may obtain
        size bytes of memory using malloc(). In this case, the pointer returned
        by getcwd() may be used as the argument in a subsequent call to free().
        Invoking getcwd() with buf as a null pointer is not recommended in
        conforming applications.
    
    This produces an error building GCC with --enable-werror-always:
    
        ../../../fixincludes/fixincl.c: In function ‘process’:
        ../../../fixincludes/fixincl.c:1356:7: error: argument 1 is null but
        the corresponding size argument 2 value is 4096 [-Werror=nonnull]
    
    It's suggested by POSIX to call getcwd() with progressively larger
    buffers until it does not give an [ERANGE] error. However, it's highly
    unlikely that this error-handling route is ever used.
    
    So we can simplify it instead of writting too much code.  We give up to
    use getcwd(), because `make` will output a `Leaving directory ...` message
    containing the path to cwd when we call abort().
    
    fixincludes/ChangeLog:
    
            PR other/21823
            PR bootstrap/80047
            * fixincl.c (process): Simplify the handling for highly
              unlikely access() failure, to avoid using non-standard
              extensions.

Diff:
---
 fixincludes/fixincl.c | 9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

diff --git a/fixincludes/fixincl.c b/fixincludes/fixincl.c
index 6dba2f6e830..a17b65866c3 100644
--- a/fixincludes/fixincl.c
+++ b/fixincludes/fixincl.c
@@ -1352,11 +1352,10 @@ process (void)
 
   if (access (pz_curr_file, R_OK) != 0)
     {
-      int erno = errno;
-      fprintf (stderr, "Cannot access %s from %s\n\terror %d (%s)\n",
-               pz_curr_file, getcwd ((char *) NULL, MAXPATHLEN),
-               erno, xstrerror (erno));
-      return;
+      /* Some really strange error happened.  */
+      fprintf (stderr, "Cannot access %s: %s\n", pz_curr_file,
+	       xstrerror (errno));
+      abort ();
     }
 
   pz_curr_data = load_file (pz_curr_file);