[Emacs-diffs] trunk r113443: * lread.c: Fix file descriptor leaks and errno issues.

[Paul Eggert]

------------------------------------------------------------
revno: 113443
revision-id: address@hidden
parent: address@hidden
committer: Paul Eggert <address@hidden>
branch nick: trunk
timestamp: Wed 2013-07-17 10:24:54 -0700
message:
  * lread.c: Fix file descriptor leaks and errno issues.
  
  (Fload): Close some races that leaked fds or streams when 'load'
  was interrupted.
  (Fload, openp): Report error number of last nontrivial failure to open.
  ENOENT counts as trivial.
  * eval.c (do_nothing, clear_unwind_protect, set_unwind_protect_ptr):
  New functions.
  * fileio.c (close_file_unwind): No need to test whether FD is nonnegative,
  now that the function is always called with a nonnegative arg.
  * lisp.h (set_unwind_protect_ptr, set_unwind_protect_int): Remove.
  All uses replaced with ...
  (clear_unwind_protect, set_unwind_protect_ptr): New decls.
modified:
  src/ChangeLog                  changelog-20091113204419-o5vbwnq5f7feedwu-1438
  src/editfns.c                  editfns.c-20091113204419-o5vbwnq5f7feedwu-255
  src/eval.c                     eval.c-20091113204419-o5vbwnq5f7feedwu-237
  src/fileio.c                   fileio.c-20091113204419-o5vbwnq5f7feedwu-210
  src/lisp.h                     lisp.h-20091113204419-o5vbwnq5f7feedwu-253
  src/lread.c                    lread.c-20091113204419-o5vbwnq5f7feedwu-266

=== modified file 'src/ChangeLog'
--- a/src/ChangeLog     2013-07-17 04:37:27 +0000
+++ b/src/ChangeLog     2013-07-17 17:24:54 +0000
@@ -1,5 +1,18 @@
 2013-07-17  Paul Eggert  <address@hidden>
 
+       * lread.c: Fix file descriptor leaks and errno issues.
+       (Fload): Close some races that leaked fds or streams when 'load'
+       was interrupted.
+       (Fload, openp): Report error number of last nontrivial failure to open.
+       ENOENT counts as trivial.
+       * eval.c (do_nothing, clear_unwind_protect, set_unwind_protect_ptr):
+       New functions.
+       * fileio.c (close_file_unwind): No need to test whether FD is 
nonnegative,
+       now that the function is always called with a nonnegative arg.
+       * lisp.h (set_unwind_protect_ptr, set_unwind_protect_int): Remove.
+       All uses replaced with ...
+       (clear_unwind_protect, set_unwind_protect_ptr): New decls.
+
        A few more minor file errno-reporting bugs.
        * callproc.c (Fcall_process):
        * doc.c (Fsnarf_documentation):

=== modified file 'src/editfns.c'
--- a/src/editfns.c     2013-07-16 21:35:45 +0000
+++ b/src/editfns.c     2013-07-17 17:24:54 +0000
@@ -4238,7 +4238,7 @@
        else
          {
            buf = xrealloc (buf, bufsize);
-           set_unwind_protect_ptr (buf_save_value_index, buf);
+           set_unwind_protect_ptr (buf_save_value_index, xfree, buf);
          }
 
        p = buf + used;

=== modified file 'src/eval.c'
--- a/src/eval.c        2013-07-16 21:35:45 +0000
+++ b/src/eval.c        2013-07-17 17:24:54 +0000
@@ -3225,6 +3225,27 @@
   grow_specpdl ();
 }
 
+static void
+do_nothing (void)
+{}
+
+void
+clear_unwind_protect (ptrdiff_t count)
+{
+  union specbinding *p = specpdl + count;
+  p->unwind_void.kind = SPECPDL_UNWIND_VOID;
+  p->unwind_void.func = do_nothing;
+}
+
+void
+set_unwind_protect_ptr (ptrdiff_t count, void (*func) (void *), void *arg)
+{
+  union specbinding *p = specpdl + count;
+  p->unwind_ptr.kind = SPECPDL_UNWIND_PTR;
+  p->unwind_ptr.func = func;
+  p->unwind_ptr.arg = arg;
+}
+
 Lisp_Object
 unbind_to (ptrdiff_t count, Lisp_Object value)
 {

=== modified file 'src/fileio.c'
--- a/src/fileio.c      2013-07-17 04:37:27 +0000
+++ b/src/fileio.c      2013-07-17 17:24:54 +0000
@@ -217,8 +217,7 @@
 void
 close_file_unwind (int fd)
 {
-  if (0 <= fd)
-    emacs_close (fd);
+  emacs_close (fd);
 }
 
 /* Restore point, having saved it as a marker.  */
@@ -4029,7 +4028,7 @@
       if (this < 0)
        report_file_error ("Read error", orig_filename);
       emacs_close (fd);
-      set_unwind_protect_int (fd_index, -1);
+      clear_unwind_protect (fd_index);
 
       if (unprocessed > 0)
        {
@@ -4270,7 +4269,7 @@
     Vdeactivate_mark = Qt;
 
   emacs_close (fd);
-  set_unwind_protect_int (fd_index, -1);
+  clear_unwind_protect (fd_index);
 
   if (how_much < 0)
     report_file_error ("Read error", orig_filename);

=== modified file 'src/lisp.h'
--- a/src/lisp.h        2013-07-16 21:49:32 +0000
+++ b/src/lisp.h        2013-07-17 17:24:54 +0000
@@ -2744,18 +2744,6 @@
   return specpdl_ptr - specpdl;
 }
 
-LISP_INLINE void
-set_unwind_protect_ptr (ptrdiff_t count, void *arg)
-{
-  specpdl[count].unwind_ptr.arg = arg;
-}
-
-LISP_INLINE void
-set_unwind_protect_int (ptrdiff_t count, int arg)
-{
-  specpdl[count].unwind_int.arg = arg;
-}
-
 /* Everything needed to describe an active condition case.
 
    Members are volatile if their values need to survive _longjmp when
@@ -3755,6 +3743,8 @@
 extern void record_unwind_protect_int (void (*) (int), int);
 extern void record_unwind_protect_ptr (void (*) (void *), void *);
 extern void record_unwind_protect_void (void (*) (void));
+extern void clear_unwind_protect (ptrdiff_t);
+extern void set_unwind_protect_ptr (ptrdiff_t, void (*) (void *), void *);
 extern Lisp_Object unbind_to (ptrdiff_t, Lisp_Object);
 extern _Noreturn void error (const char *, ...) ATTRIBUTE_FORMAT_PRINTF (1, 2);
 extern _Noreturn void verror (const char *, va_list)

=== modified file 'src/lread.c'
--- a/src/lread.c       2013-07-16 21:35:45 +0000
+++ b/src/lread.c       2013-07-17 17:24:54 +0000
@@ -1040,10 +1040,12 @@
 is bound to the file's name.
 
 Return t if the file exists and loads successfully.  */)
-  (Lisp_Object file, Lisp_Object noerror, Lisp_Object nomessage, Lisp_Object 
nosuffix, Lisp_Object must_suffix)
+  (Lisp_Object file, Lisp_Object noerror, Lisp_Object nomessage,
+   Lisp_Object nosuffix, Lisp_Object must_suffix)
 {
-  register FILE *stream;
-  register int fd = -1;
+  FILE *stream;
+  int fd;
+  int fd_index;
   ptrdiff_t count = SPECPDL_INDEX ();
   struct gcpro gcpro1, gcpro2, gcpro3;
   Lisp_Object found, efound, hist_file_name;
@@ -1054,7 +1056,6 @@
   Lisp_Object handler;
   bool safe_p = 1;
   const char *fmode = "r";
-  Lisp_Object tmp[2];
   int version;
 
 #ifdef DOS_NT
@@ -1087,19 +1088,23 @@
   else
     file = Fsubstitute_in_file_name (file);
 
-
   /* Avoid weird lossage with null string as arg,
      since it would try to load a directory as a Lisp file.  */
-  if (SBYTES (file) > 0)
-    {
-      ptrdiff_t size = SBYTES (file);
-
+  if (SCHARS (file) == 0)
+    {
+      fd = -1;
+      errno = ENOENT;
+    }
+  else
+    {
+      Lisp_Object suffixes;
       found = Qnil;
       GCPRO2 (file, found);
 
       if (! NILP (must_suffix))
        {
          /* Don't insist on adding a suffix if FILE already ends with one.  */
+         ptrdiff_t size = SBYTES (file);
          if (size > 3
              && !strcmp (SSDATA (file) + size - 3, ".el"))
            must_suffix = Qnil;
@@ -1112,20 +1117,28 @@
            must_suffix = Qnil;
        }
 
-      fd = openp (Vload_path, file,
-                 (!NILP (nosuffix) ? Qnil
-                  : !NILP (must_suffix) ? Fget_load_suffixes ()
-                  : Fappend (2, (tmp[0] = Fget_load_suffixes (),
-                                 tmp[1] = Vload_file_rep_suffixes,
-                                 tmp))),
-                 &found, Qnil);
+      if (!NILP (nosuffix))
+       suffixes = Qnil;
+      else
+       {
+         suffixes = Fget_load_suffixes ();
+         if (NILP (must_suffix))
+           {
+             Lisp_Object arg[2];
+             arg[0] = suffixes;
+             arg[1] = Vload_file_rep_suffixes;
+             suffixes = Fappend (2, arg);
+           }
+       }
+
+      fd = openp (Vload_path, file, suffixes, &found, Qnil);
       UNGCPRO;
     }
 
   if (fd == -1)
     {
       if (NILP (noerror))
-       xsignal2 (Qfile_error, build_string ("Cannot open load file"), file);
+       report_file_error ("Cannot open load file", file);
       return Qnil;
     }
 
@@ -1163,6 +1176,12 @@
 #endif
     }
 
+  if (0 <= fd)
+    {
+      fd_index = SPECPDL_INDEX ();
+      record_unwind_protect_int (close_file_unwind, fd);
+    }
+
   /* Check if we're stuck in a recursive load cycle.
 
      2000-09-21: It's not possible to just check for the file loaded
@@ -1178,11 +1197,7 @@
     Lisp_Object tem;
     for (tem = Vloads_in_progress; CONSP (tem); tem = XCDR (tem))
       if (!NILP (Fequal (found, XCAR (tem))) && (++load_count > 3))
-       {
-         if (fd >= 0)
-           emacs_close (fd);
-         signal_error ("Recursive load", Fcons (found, Vloads_in_progress));
-       }
+       signal_error ("Recursive load", Fcons (found, Vloads_in_progress));
     record_unwind_protect (record_load_unwind, Vloads_in_progress);
     Vloads_in_progress = Fcons (found, Vloads_in_progress);
   }
@@ -1195,9 +1210,8 @@
 
   /* Get the name for load-history.  */
   hist_file_name = (! NILP (Vpurify_flag)
-                    ? Fconcat (2, (tmp[0] = Ffile_name_directory (file),
-                                   tmp[1] = Ffile_name_nondirectory (found),
-                                   tmp))
+                    ? concat2 (Ffile_name_directory (file),
+                               Ffile_name_nondirectory (found))
                     : found) ;
 
   version = -1;
@@ -1223,12 +1237,7 @@
            {
              safe_p = 0;
              if (!load_dangerous_libraries)
-               {
-                 if (fd >= 0)
-                   emacs_close (fd);
-                 error ("File `%s' was not compiled in Emacs",
-                        SDATA (found));
-               }
+               error ("File `%s' was not compiled in Emacs", SDATA (found));
              else if (!NILP (nomessage) && !force_load_messages)
                message_with_string ("File `%s' not compiled in Emacs", found, 
1);
            }
@@ -1274,7 +1283,10 @@
          Lisp_Object val;
 
          if (fd >= 0)
-           emacs_close (fd);
+           {
+             emacs_close (fd);
+             clear_unwind_protect (fd_index);
+           }
          val = call4 (Vload_source_file_function, found, hist_file_name,
                       NILP (noerror) ? Qnil : Qt,
                       (NILP (nomessage) || force_load_messages) ? Qnil : Qt);
@@ -1284,26 +1296,28 @@
 
   GCPRO3 (file, found, hist_file_name);
 
+  if (fd < 0)
+    {
+      /* We somehow got here with fd == -2, meaning the file is deemed
+        to be remote.  Don't even try to reopen the file locally;
+        just force a failure.  */
+      stream = NULL;
+      errno = EINVAL;
+    }
+  else
+    {
 #ifdef WINDOWSNT
-  efound = ENCODE_FILE (found);
-  /* If we somehow got here with fd == -2, meaning the file is deemed
-     to be remote, don't even try to reopen the file locally; just
-     force a failure instead.  */
-  if (fd >= 0)
-    {
       emacs_close (fd);
+      clear_unwind_protect (fd_index);
+      efound = ENCODE_FILE (found);
       stream = emacs_fopen (SSDATA (efound), fmode);
-    }
-  else
-    stream = NULL;
-#else  /* not WINDOWSNT */
-  stream = fdopen (fd, fmode);
-#endif /* not WINDOWSNT */
-  if (stream == 0)
-    {
-      emacs_close (fd);
-      error ("Failure to create stdio stream for %s", SDATA (file));
-    }
+#else
+      stream = fdopen (fd, fmode);
+#endif
+    }
+  if (! stream)
+    report_file_error ("Opening stdio stream", file);
+  set_unwind_protect_ptr (fd_index, load_unwind, stream);
 
   if (! NILP (Vpurify_flag))
     Vpreloaded_file_list = Fcons (Fpurecopy (file), Vpreloaded_file_list);
@@ -1322,7 +1336,6 @@
        message_with_string ("Loading %s...", file, 1);
     }
 
-  record_unwind_protect_ptr (load_unwind, stream);
   specbind (Qload_file_name, found);
   specbind (Qinhibit_file_name_operation, Qnil);
   specbind (Qload_in_progress, Qt);
@@ -1521,7 +1534,6 @@
          if ((!NILP (handler) || !NILP (predicate)) && !NATNUMP (predicate))
             {
              bool exists;
-             last_errno = ENOENT;
              if (NILP (predicate))
                exists = !NILP (Ffile_readable_p (string));
              else
@@ -1576,7 +1588,10 @@
                {
                  fd = emacs_open (pfn, O_RDONLY, 0);
                  if (fd < 0)
-                   last_errno = errno;
+                   {
+                     if (errno != ENOENT)
+                       last_errno = errno;
+                   }
                  else
                    {
                      struct stat st;