X-Git-Url: http://erislabs.net/gitweb/?a=blobdiff_plain;f=lib%2Fsafe-read.c;h=b7bf1d5cd60ef2cf12de123820a17d147af6a7c2;hb=3667f8e75409ce7df7bc3f561ddd8d03d5be39f2;hp=5d2cd9dded91145d9a65d5330d73d96333ac92a2;hpb=3336e16fb39ca0fafa5185797f0f0b9431c2330d;p=gnulib.git

diff --git a/lib/safe-read.c b/lib/safe-read.c
index 5d2cd9dde..b7bf1d5cd 100644
--- a/lib/safe-read.c
+++ b/lib/safe-read.c
@@ -1,5 +1,7 @@
-/* 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.
+
+   Copyright (C) 1993, 1994, 1998, 2002, 2003, 2004, 2005, 2006 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
@@ -13,25 +15,22 @@
 
    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
-# 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
 
 #ifdef EINTR
 # define IS_EINTR(x) ((x) == EINTR)
@@ -41,49 +40,39 @@ extern int errno;
 
 #include <limits.h>
 
-#ifndef CHAR_BIT
-# define CHAR_BIT 8
-#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)))
-
-#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 nbytes_to_read = count;
-  ssize_t result;
-
-  /* Limit the number of bytes to read, to avoid running into unspecified
-     behaviour.  But keep the file pointer block aligned when doing so.
-     Note that in this case we don't need to call read() multiple times here,
-     because the caller is prepared to partial results.  */
-  if (nbytes_to_read > MAX_BYTES_TO_READ)
-    nbytes_to_read = MAX_BYTES_TO_READ & ~8191;
+  /* 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 };
 
-  do
+  for (;;)
     {
-      result = read (fd, buf, nbytes_to_read);
+      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;
     }
-  while (result < 0 && IS_EINTR (errno));
-
-  return (size_t) result;
 }