ftell: two minor proposed patches

[Paul Eggert]

>From 66b4bf9e4933f708a5729f28df5b594c731f9431 Mon Sep 17 00:00:00 2001
From: Paul Eggert <address@hidden>
Date: Sun, 24 Jul 2011 01:44:03 -0700
Subject: [PATCH 1/2] ftell: do not assume wraparound signed arithmetic

* lib/ftell.c: Include <limits.h>.
(ftell): Don't assume wraparound signed arithmetic.
---
 ChangeLog   |    4 ++++
 lib/ftell.c |    5 +++--
 2 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index 4571ed4..196a76a 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,9 @@
 2011-07-24  Paul Eggert  <address@hidden>
 
+       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.
diff --git a/lib/ftell.c b/lib/ftell.c
index 79083fb..1e8e3a2 100644
--- 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>
 
@@ -28,8 +29,8 @@ ftell (FILE *fp)
 {
   /* Use the replacement ftello function with all its workarounds.  */
   off_t offset = ftello (fp);
-  if (offset == (long)offset)
-    return (long)offset;
+  if (LONG_MIN <= offset && offset <= LONG_MAX)
+    return offset;
   else
     {
       errno = EOVERFLOW;
-- 
1.7.4.4


>From cdacbab7b59b72db82b9cac404c7b884d8cdd682 Mon Sep 17 00:00:00 2001
From: Paul Eggert <address@hidden>
Date: Sun, 24 Jul 2011 01:47:12 -0700
Subject: [PATCH 2/2] ftell: don't include <unistd.h>

* lib/ftell.c: Don't include <unistd.h>.  <stdio.h> is now
guaranteed to define off_t, since the ftell module depends on the
stdio module.
---
 ChangeLog   |    5 +++++
 lib/ftell.c |    2 --
 2 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index 196a76a..24ae09e 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,10 @@
 2011-07-24  Paul Eggert  <address@hidden>
 
+       ftell: don't include <unistd.h>
+       * lib/ftell.c: Don't include <unistd.h>.  <stdio.h> is now
+       guaranteed to define off_t, since the ftell module depends on the
+       stdio module.
+
        ftell: do not assume wraparound signed arithmetic
        * lib/ftell.c: Include <limits.h>.
        (ftell): Don't assume wraparound signed arithmetic.
diff --git a/lib/ftell.c b/lib/ftell.c
index 1e8e3a2..bd72a2f 100644
--- a/lib/ftell.c
+++ b/lib/ftell.c
@@ -21,8 +21,6 @@
 
 #include <errno.h>
 #include <limits.h>
-/* Get off_t.  */
-#include <unistd.h>
 
 long
 ftell (FILE *fp)
-- 
1.7.4.4