maint: update copyright

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

diff --git a/lib/safe-read.c b/lib/safe-read.c
index 93d35e4..c9b8828 100644 (file)
--- a/lib/safe-read.c
+++ b/lib/safe-read.c
@@ -1,10 +1,12 @@
-/* safe-read.c -- an interface to read that retries after interrupts
-   Copyright (C) 1993, 1994 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, 2009-2014 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
@@ -12,49 +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., 675 Mass Ave, Cambridge, MA 02139, USA.
-   */
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
 
-#ifdef HAVE_CONFIG_H
 #include <config.h>
+
+/* Specification.  */
+#ifdef SAFE_WRITE
+# include "safe-write.h"
+#else
+# include "safe-read.h"
 #endif
 
+/* Get ssize_t.  */
 #include <sys/types.h>
-
-#ifdef HAVE_UNISTD_H
 #include <unistd.h>
-#endif
 
 #include <errno.h>
-#ifndef errno
-extern int errno;
+
+#ifdef EINTR
+# define IS_EINTR(x) ((x) == EINTR)
+#else
+# define IS_EINTR(x) 0
 #endif
 
-/* Read LEN bytes at PTR from descriptor DESC, retrying if interrupted.
-   Return the actual number of bytes read, zero for EOF, or negative
-   for an error.  */
+#include <limits.h>
 
-int
-safe_read (desc, ptr, len)
-     int desc;
-     char *ptr;
-     int len;
-{
-  int n_chars;
+#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
 
-  if (len <= 0)
-    return len;
+/* 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)
+{
+  /* 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 };
 
-#ifdef EINTR
-  do
+  for (;;)
     {
-      n_chars = read (desc, ptr, len);
-    }
-  while (n_chars < 0 && errno == EINTR);
-#else
-  n_chars = read (desc, ptr, len);
-#endif
+      ssize_t result = rw (fd, buf, count);
 
-  return n_chars;
+      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;
+    }
 }