X-Git-Url: http://erislabs.net/gitweb/?a=blobdiff_plain;f=lib%2Fsafe-read.c;h=6a48c0cca85e2ac19a5de4c954ff7f2e996c3da3;hb=5191b3546cfb6c163228c23f214e325ddf60d46f;hp=75ac7bf311c8f9ef9b44da5826e8b32ee04d5423;hpb=e325242e999c1ff6ebd01f59e978741b73391730;p=gnulib.git

diff --git a/lib/safe-read.c b/lib/safe-read.c
index 75ac7bf31..6a48c0cca 100644
--- a/lib/safe-read.c
+++ b/lib/safe-read.c
@@ -1,10 +1,12 @@
-/* An interface to read that retries after interrupts.
-   Copyright (C) 1993, 1994, 1998, 2002 Free Software Foundation, Inc.
+/* An interface to read and write that retries after interrupts.
 
-   This program is free software; you can redistribute it and/or modify
+   Copyright (C) 1993-1994, 1998, 2002-2006, 2009-2013 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.
+   the Free Software Foundation; either version 3 of the License, 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
@@ -12,86 +14,64 @@
    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.  */
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
 
-#if HAVE_CONFIG_H
-# include <config.h>
-#endif
+#include <config.h>
 
 /* Specification.  */
-#include "safe-read.h"
+#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 <unistd.h>
 
 #include <errno.h>
-#ifndef errno
-extern int errno;
-#endif
-
-#include <limits.h>
 
-#ifndef CHAR_BIT
-# define CHAR_BIT 8
+#ifdef EINTR
+# define IS_EINTR(x) ((x) == EINTR)
+#else
+# define IS_EINTR(x) 0
 #endif
 
-/* The extra casts work around common compiler bugs.  */
-#define TYPE_SIGNED(t) (! ((t) 0 < (t) -1))
-/* The outer cast is needed to work around a bug in Cray C 5.0.3.0.
-   It is necessary at least when t == time_t.  */
-#define TYPE_MINIMUM(t) ((t) (TYPE_SIGNED (t) \
-			      ? ~ (t) 0 << (sizeof (t) * CHAR_BIT - 1) : (t) 0))
-#define TYPE_MAXIMUM(t) ((t) (~ (t) 0 - TYPE_MINIMUM (t)))
+#include <limits.h>
 
-#ifndef INT_MAX
-# define INT_MAX TYPE_MAXIMUM (int)
+#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
 
-/* We don't pass an nbytes count > SSIZE_MAX to read() - POSIX says the
-   effect would be implementation-defined.  Also we don't pass an nbytes
-   count > INT_MAX but <= SSIZE_MAX to read() - this triggers a bug in
-   Tru64 5.1.  */
-#define MAX_BYTES_TO_READ INT_MAX
-
-/* Read up to COUNT bytes at BUF from descriptor FD, retrying if interrupted.
-   Return the actual number of bytes read, zero for EOF, or SAFE_READ_ERROR
-   upon error.  */
+/* 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_read (int fd, void *buf, size_t count)
+safe_rw (int fd, void const *buf, size_t count)
 {
-  size_t total_read = 0;
-  char *ptr = buf;
+  /* 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 };
 
-  while (count > 0)
+  for (;;)
     {
-      size_t nbytes_to_read = count;
-      ssize_t result;
-
-      /* Limit the number of bytes to read in one round, to avoid running
-	 into unspecified behaviour.  But keep the file pointer block
-	 aligned when doing so.  */
-      if (nbytes_to_read > MAX_BYTES_TO_READ)
-	nbytes_to_read = MAX_BYTES_TO_READ & ~8191;
-
-      result = read (fd, ptr, nbytes_to_read);
-      if (result == 0)
-	break;
-      if (result < 0)
-	{
-#ifdef EINTR
-	  if (errno == EINTR)
-	    continue;
-#endif
-	  return SAFE_READ_ERROR;
-	}
-      total_read += result;
-      ptr += result;
-      count -= result;
+      ssize_t result = rw (fd, buf, count);
+
+      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;
     }
-
-  return total_read;
 }