diffutils-3.5HEADdiffutils-3.5master

1 files changed, 109 insertions, 0 deletions

diff --git a/lib/cmpbuf.c b/lib/cmpbuf.c
new file mode 100644
index 0000000..fd34505
--- /dev/null
+++ b/lib/cmpbuf.c
@@ -0,0 +1,109 @@
+/* Buffer primitives for comparison operations.
+
+   Copyright (C) 1993, 1995, 1998, 2001-2002, 2006, 2009-2013, 2015-2016 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 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
+   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, see <http://www.gnu.org/licenses/>.  */
+
+#include <config.h>
+
+#include <errno.h>
+#include <limits.h>
+#include <signal.h>
+#include <unistd.h>
+#include <stdint.h>
+#include <inttypes.h>
+#include <sys/types.h>
+#include "cmpbuf.h"
+#include "intprops.h"
+
+#ifndef SSIZE_MAX
+# define SSIZE_MAX TYPE_MAXIMUM (ssize_t)
+#endif
+
+#undef MIN
+#define MIN(a, b) ((a) <= (b) ? (a) : (b))
+
+/* Read NBYTES bytes from descriptor FD into BUF.
+   NBYTES must not be SIZE_MAX.
+   Return the number of characters successfully read.
+   On error, return SIZE_MAX, setting errno.
+   The number returned is always NBYTES unless end-of-file or error.  */
+
+size_t
+block_read (int fd, char *buf, size_t nbytes)
+{
+  char *bp = buf;
+  char const *buflim = buf + nbytes;
+  size_t readlim = MIN (SSIZE_MAX, SIZE_MAX);
+
+  do
+    {
+      size_t bytes_remaining = buflim - bp;
+      size_t bytes_to_read = MIN (bytes_remaining, readlim);
+      ssize_t nread = read (fd, bp, bytes_to_read);
+      if (nread <= 0)
+	{
+	  if (nread == 0)
+	    break;
+
+	  /* Accommodate Tru64 5.1, which can't read more than INT_MAX
+	     bytes at a time.  They call that a 64-bit OS?  */
+	  if (errno == EINVAL && INT_MAX < bytes_to_read)
+	    {
+	      readlim = INT_MAX;
+	      continue;
+	    }
+
+	  /* This is needed for programs that have signal handlers on
+	     older hosts without SA_RESTART.  It also accommodates
+	     ancient AIX hosts that set errno to EINTR after uncaught
+	     SIGCONT.  See <news:1r77ojINN85n@ftp.UU.NET>
+	     (1993-04-22).  */
+	  if (! SA_RESTART && errno == EINTR)
+	    continue;
+
+	  return SIZE_MAX;
+	}
+      bp += nread;
+    }
+  while (bp < buflim);
+
+  return bp - buf;
+}
+
+/* Least common multiple of two buffer sizes A and B.  However, if
+   either A or B is zero, or if the multiple is greater than LCM_MAX,
+   return a reasonable buffer size.  */
+
+size_t
+buffer_lcm (size_t a, size_t b, size_t lcm_max)
+{
+  size_t lcm, m, n, q, r;
+
+  /* Yield reasonable values if buffer sizes are zero.  */
+  if (!a)
+    return b ? b : 8 * 1024;
+  if (!b)
+    return a;
+
+  /* n = gcd (a, b) */
+  for (m = a, n = b;  (r = m % n) != 0;  m = n, n = r)
+    continue;
+
+  /* Yield a if there is an overflow.  */
+  q = a / n;
+  lcm = q * b;
+  return lcm <= lcm_max && lcm / b == q ? lcm : a;
+}