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changeset 15452:9086fb6c1ded

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ftell: do not assume wraparound signed arithmetic * lib/ftell.c: Include <limits.h>. (ftell): Don't assume wraparound signed arithmetic.
author Paul Eggert <eggert@cs.ucla.edu>
date Sun, 24 Jul 2011 09:42:14 -0700
parents 276662233d21
children 173d1d491540
files ChangeLog lib/ftell.c
diffstat 2 files changed, 6 insertions(+), 1 deletions(-) [+]
line wrap: on
line diff
--- a/ChangeLog
+++ b/ChangeLog
@@ -23,6 +23,10 @@
 
 2011-07-24  Paul Eggert  <eggert@cs.ucla.edu>
 
+	ftell: do not assume wraparound signed arithmetic
+	* lib/ftell.c: Include <limits.h>.
+	(ftell): Don't assume wraparound signed arithmetic.
+
 	* README: Modernize discussion of signed integers.
 	Assuming overflow wraparound is no longer safe.
 	Mention ones' complement and signed magnitude.
--- a/lib/ftell.c
+++ b/lib/ftell.c
@@ -20,6 +20,7 @@
 #include <stdio.h>
 
 #include <errno.h>
+#include <limits.h>
 /* Get off_t.  */
 #include <unistd.h>
 
@@ -28,7 +29,7 @@
 {
   /* Use the replacement ftello function with all its workarounds.  */
   off_t offset = ftello (fp);
-  if (offset == (long)offset)
+  if (LONG_MIN <= offset && offset <= LONG_MAX)
     return (long)offset;
   else
     {