X-Git-Url: http://erislabs.net/gitweb/?a=blobdiff_plain;f=lib%2Fsafe-read.c;h=6f8bd780ed01a25da8452bb0b77a95eb302fbbc6;hb=12797e006016ec69a5c0760999d5cd7c2a372b54;hp=c36f6e8243237b066eeae1dbca478312ed277ec7;hpb=b56555472c813684bbe2eddf3a54744a9a822406;p=gnulib.git

diff --git a/lib/safe-read.c b/lib/safe-read.c
index c36f6e824..6f8bd780e 100644
--- 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 Free Software Foundation, Inc.
+
+   Copyright (C) 1993, 1994, 1998, 2002, 2003, 2004 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
@@ -19,6 +21,13 @@
 # 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
@@ -26,9 +35,6 @@
 #endif
 
 #include <errno.h>
-#ifndef errno
-extern int errno;
-#endif
 
 #ifdef EINTR
 # define IS_EINTR(x) ((x) == EINTR)
@@ -38,28 +44,10 @@ 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)
-#endif
-
 #ifdef SAFE_WRITE
-# include "safe-write.h"
 # define safe_rw safe_write
 # define rw write
 #else
-# include "safe-read.h"
 # define safe_rw safe_read
 # define rw read
 # undef const
@@ -72,22 +60,23 @@ 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);
+      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;
 }