Merge frem coreutils.

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

diff --git a/lib/safe-read.c b/lib/safe-read.c
index d915d4e..c21d1cf 100644 (file)
--- a/lib/safe-read.c
+++ b/lib/safe-read.c
@@ -1,31 +1,82 @@
-/* Read LEN bytes at PTR from descriptor DESC, retrying if necessary.
-   Return the actual number of bytes read, zero for EOF, or negative
-   for an error.  */
-
-int
-safe_read (desc, ptr, len)
-     int desc;
-     char *ptr;
-     int len;
-{
-  int n_remaining;
+/* An interface to read and write that retries after interrupts.
+   Copyright (C) 1993, 1994, 1998, 2002-2003 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
+   the Free Software Foundation; either version 2, or (at your option)
+   any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   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.  */
+
+#if HAVE_CONFIG_H
+# include <config.h>
+#endif
+
+/* Specification.  */
+#ifdef SAFE_WRITE
+# include "safe-write.h"
+#else
+# include "safe-read.h"
+#endif
+
+/* Get ssize_t.  */
+#include <sys/types.h>
+#if HAVE_UNISTD_H
+# include <unistd.h>
+#endif
+
+#include <errno.h>
+#ifndef errno
+extern int errno;
+#endif
 
-  n_remaining = len;
-  while (n_remaining > 0)
-    {
-      int n_chars = read (desc, ptr, n_remaining);
-      if (n_chars < 0)
-       {
 #ifdef EINTR
-         if (errno == EINTR)
-           continue;
+# define IS_EINTR(x) ((x) == EINTR)
+#else
+# define IS_EINTR(x) 0
+#endif
+
+#include <limits.h>
+
+#ifdef SAFE_WRITE
+# define safe_rw safe_write
+# define rw write
+#else
+# define safe_rw safe_read
+# define rw read
+# undef const
+# define const /* empty */
 #endif
-         return n_chars;
-       }
-      if (n_chars == 0)
-       break;
-      ptr += n_chars;
-      n_remaining -= n_chars;
+
+/* Read(write) up to COUNT bytes at BUF from(to) descriptor FD, retrying if
+   interrupted.  Return the actual number of bytes read(written), zero for EOF,
+   or SAFE_READ_ERROR(SAFE_WRITE_ERROR) upon error.  */
+size_t
+safe_rw (int fd, void const *buf, size_t count)
+{
+  ssize_t result;
+
+  /* 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
+    {
+      result = rw (fd, buf, count);
     }
-  return len - n_remaining;
+  while (result < 0 && IS_EINTR (errno));
+
+  return (size_t) result;
 }