Handle errno and exit status a bit more carefully.

* lib/ignore-value.h: Remove this gnulib-imported file.
* lib/gnulib.mk, m4/gnulib-comp.m4: Regenerate.
* admin/merge-gnulib (GNULIB_MODULES): Remove ignore-value.
* src/callproc.c (child_setup) [!DOS_NT]: Don't try to stuff an error
number into an exit status.  Instead, use EXIT_CANCELED.
(child_setup) [!MSDOS]: Avoid possible deadlock with vfork.
* src/callproc.c (relocate_fd):
* src/emacs.c (close_output_streams, main):
* src/process.c (create_process):
* src/sysdep.c (sys_subshell) [!DOS_NT || !WINDOWSNT]:
Use emacs_perror for simplicity.
* src/callproc.c (relocate_fd, main):
* src/sysdep.c (sys_subshell):
Exit with EXIT_CANCELED etc., not 1, when exec setup fails.
(shut_down_emacs): Use emacs_write, not write.
* src/emacs.c, src/sysdep.c: Don't include <ignore-value.h>.
* src/fileio.c (Fcopy_file, e_write):
* src/nsterm.m (ns_select):
* src/process.c (send_process):
* src/sound.c (vox_write):
Use emacs_write_sig, not emacs_write.
* src/lisp.h (emacs_write_sig, emacs_perror): New decls.
* src/process.h (EXIT_CANCELED), EXIT_CANNOT_INVOKE, EXIT_ENOENT):
New constants.
* src/sysdep.c (emacs_backtrace): Use emacs_write, not ignore_value
of write.
(emacs_full_write): New function.
(emacs_write): Rewrite to use it.
(emacswrite_sig, emacs_perror): New functions.
* src/xrdb.c (fatal): Don't invoke perror, since errno might be garbage.

1 files changed, 64 insertions, 21 deletions

diff --git a/src/sysdep.c b/src/sysdep.c
index faca7fae461..6346b0bbfcd 100644
--- a/src/sysdep.c
+++ b/src/sysdep.c
@@ -31,7 +31,6 @@ along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.  */
 #include <unistd.h>
 
 #include <c-ctype.h>
-#include <ignore-value.h>
 #include <utimens.h>
 
 #include "lisp.h"
@@ -538,8 +537,8 @@ sys_subshell (void)
       if (str && chdir ((char *) str) != 0)
         {
 #ifndef DOS_NT
-          ignore_value (write (1, "Can't chdir\n", 12));
-          _exit (1);
+          emacs_perror ((char *) str);
+          _exit (EXIT_CANCELED);
 #endif
         }
 
@@ -570,8 +569,8 @@ sys_subshell (void)
         write (1, "Can't execute subshell", 22);
 #else   /* not WINDOWSNT */
       execlp (sh, sh, (char *) 0);
-      ignore_value (write (1, "Can't execute subshell", 22));
-      _exit (1);
+      emacs_perror (sh);
+      _exit (errno == ENOENT ? EXIT_ENOENT : EXIT_CANNOT_INVOKE);
 #endif  /* not WINDOWSNT */
 #endif /* not MSDOS */
     }
@@ -2134,10 +2133,10 @@ emacs_backtrace (int backtrace_limit)
 
   if (npointers)
     {
-      ignore_value (write (STDERR_FILENO, "\nBacktrace:\n", 12));
+      emacs_write (STDERR_FILENO, "\nBacktrace:\n", 12);
       backtrace_symbols_fd (buffer, npointers, STDERR_FILENO);
       if (bounded_limit < npointers)
-        ignore_value (write (STDERR_FILENO, "...\n", 4));
+        emacs_write (STDERR_FILENO, "...\n", 4);
     }
 }
 
@@ -2246,27 +2245,26 @@ emacs_read (int fildes, char *buf, ptrdiff_t nbyte)
 }
 
 /* Write to FILEDES from a buffer BUF with size NBYTE, retrying if interrupted
-   or if a partial write occurs.  Return the number of bytes written, setting
+   or if a partial write occurs.  If interrupted, process pending
+   signals if PROCESS SIGNALS.  Return the number of bytes written, setting
    errno if this is less than NBYTE.  */
-ptrdiff_t
-emacs_write (int fildes, const char *buf, ptrdiff_t nbyte)
+static ptrdiff_t
+emacs_full_write (int fildes, char const *buf, ptrdiff_t nbyte,
+                  bool process_signals)
 {
-  ssize_t rtnval;
-  ptrdiff_t bytes_written;
-
-  bytes_written = 0;
+  ptrdiff_t bytes_written = 0;
 
   while (nbyte > 0)
     {
-      rtnval = write (fildes, buf, min (nbyte, MAX_RW_COUNT));
+      ssize_t n = write (fildes, buf, min (nbyte, MAX_RW_COUNT));
 
-      if (rtnval < 0)
+      if (n < 0)
         {
           if (errno == EINTR)
             {
               /* I originally used `QUIT' but that might causes files to
                  be truncated if you hit C-g in the middle of it.  --Stef  */
-              if (pending_signals)
+              if (process_signals && pending_signals)
                 process_pending_signals ();
               continue;
             }
@@ -2274,12 +2272,57 @@ emacs_write (int fildes, const char *buf, ptrdiff_t nbyte)
             break;
         }
 
-      buf += rtnval;
-      nbyte -= rtnval;
-      bytes_written += rtnval;
+      buf += n;
+      nbyte -= n;
+      bytes_written += n;
     }
 
-  return (bytes_written);
+  return bytes_written;
+}
+
+/* Write to FILEDES from a buffer BUF with size NBYTE, retrying if
+   interrupted or if a partial write occurs.  Return the number of
+   bytes written, setting errno if this is less than NBYTE.  */
+ptrdiff_t
+emacs_write (int fildes, char const *buf, ptrdiff_t nbyte)
+{
+  return emacs_full_write (fildes, buf, nbyte, 0);
+}
+
+/* Like emacs_write, but also process pending signals if interrupted.  */
+ptrdiff_t
+emacs_write_sig (int fildes, char const *buf, ptrdiff_t nbyte)
+{
+  return emacs_full_write (fildes, buf, nbyte, 1);
+}
+
+/* Write a diagnostic to standard error that contains MESSAGE and a
+   string derived from errno.  Preserve errno.  Do not buffer stderr.
+   Do not process pending signals if interrupted.  */
+void
+emacs_perror (char const *message)
+{
+  int err = errno;
+  char const *error_string = strerror (err);
+  char const *command = (initial_argv && initial_argv[0]
+                         ? initial_argv[0] : "emacs");
+  /* Write it out all at once, if it's short; this is less likely to
+     be interleaved with other output.  */
+  char buf[BUFSIZ];
+  int nbytes = snprintf (buf, sizeof buf, "%s: %s: %s\n",
+                         command, message, error_string);
+  if (0 <= nbytes && nbytes < BUFSIZ)
+    emacs_write (STDERR_FILENO, buf, nbytes);
+  else
+    {
+      emacs_write (STDERR_FILENO, command, strlen (command));
+      emacs_write (STDERR_FILENO, ": ", 2);
+      emacs_write (STDERR_FILENO, message, strlen (message));
+      emacs_write (STDERR_FILENO, ": ", 2);
+      emacs_write (STDERR_FILENO, error_string, strlen (error_string));
+      emacs_write (STDERR_FILENO, "\n", 1);
+    }
+  errno = err;
 }
 
 /* Return a struct timeval that is roughly equivalent to T.