* m4/stat-time.m4 (STATE_TIMESPEC, STAT_TIMESPEC_NS): Add check for

[gnulib.git] / lib / safe-read.c

diff --git a/lib/safe-read.c b/lib/safe-read.c
index c21d1cf..9caf846 100644 (file)
--- a/lib/safe-read.c
+++ b/lib/safe-read.c
@@ -1,5 +1,7 @@
 /* An interface to read and write that retries after interrupts.
-   Copyright (C) 1993, 1994, 1998, 2002-2003 Free Software Foundation, Inc.
+
+   Copyright (C) 1993, 1994, 1998, 2002, 2003, 2004, 2005 Free Software
+   Foundation, Inc.
 
    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
@@ -13,9 +15,9 @@
 
    You should have received a copy of the GNU General Public License
    along with this program; if not, write to the Free Software Foundation,
-   Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */
+   Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.  */
 
-#if HAVE_CONFIG_H
+#ifdef HAVE_CONFIG_H
 # include <config.h>
 #endif
 
@@ -28,14 +30,9 @@
 
 /* Get ssize_t.  */
 #include <sys/types.h>
-#if HAVE_UNISTD_H
-# include <unistd.h>
-#endif
+#include <unistd.h>
 
 #include <errno.h>
-#ifndef errno
-extern int errno;
-#endif
 
 #ifdef EINTR
 # define IS_EINTR(x) ((x) == EINTR)
@@ -61,22 +58,23 @@ extern int errno;
 size_t
 safe_rw (int fd, void const *buf, size_t count)
 {
-  ssize_t result;
+  /* Work around a bug in Tru64 5.1.  Attempting to read more than
+     INT_MAX bytes fails with errno == EINVAL.  See
+     <http://lists.gnu.org/archive/html/bug-gnu-utils/2002-04/msg00010.html>.
+     When decreasing COUNT, keep it block-aligned.  */
+  enum { BUGGY_READ_MAXIMUM = INT_MAX & ~8191 };
 
-  /* POSIX limits COUNT to SSIZE_MAX, but we limit it further, requiring
-     that COUNT <= INT_MAX, to avoid triggering a bug in Tru64 5.1.
-     When decreasing COUNT, keep the file pointer block-aligned.
-     Note that in any case, read(write) may succeed, yet read(write)
-     fewer than COUNT bytes, so the caller must be prepared to handle
-     partial results.  */
-  if (count > INT_MAX)
-    count = INT_MAX & ~8191;
-
-  do
+  for (;;)
     {
-      result = rw (fd, buf, count);
-    }
-  while (result < 0 && IS_EINTR (errno));
+      ssize_t result = rw (fd, buf, count);
 
-  return (size_t) result;
+      if (0 <= result)
+       return result;
+      else if (IS_EINTR (errno))
+       continue;
+      else if (errno == EINVAL && BUGGY_READ_MAXIMUM < count)
+       count = BUGGY_READ_MAXIMUM;
+      else
+       return result;
+    }
 }