[src/trunk]: src/lib/libc/stdio Check for EOF before erroring fgets() with le...

[dsl <dsl%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/e90c52eacbd9
branches:  trunk
changeset: 748460:e90c52eacbd9
user:      dsl <dsl%NetBSD.org@localhost>
date:      Sat Oct 24 14:50:48 2009 +0000

description:
Check for EOF before erroring fgets() with length <= 0.
If length is invalid, set errno = EINVAL and __SERR as well returning NULL.
Should let me close PR/41992.

diffstat:

 lib/libc/stdio/fgets.c |  27 ++++++++++++++++++++-------
 1 files changed, 20 insertions(+), 7 deletions(-)

diffs (68 lines):

diff -r cd2796c92b81 -r e90c52eacbd9 lib/libc/stdio/fgets.c
--- a/lib/libc/stdio/fgets.c    Sat Oct 24 14:41:57 2009 +0000
+++ b/lib/libc/stdio/fgets.c    Sat Oct 24 14:50:48 2009 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: fgets.c,v 1.23 2009/10/14 21:25:52 dsl Exp $   */
+/*     $NetBSD: fgets.c,v 1.24 2009/10/24 14:50:48 dsl Exp $   */
 
 /*-
  * Copyright (c) 1990, 1993
@@ -37,12 +37,13 @@
 #if 0
 static char sccsid[] = "@(#)fgets.c    8.2 (Berkeley) 12/22/93";
 #else
-__RCSID("$NetBSD: fgets.c,v 1.23 2009/10/14 21:25:52 dsl Exp $");
+__RCSID("$NetBSD: fgets.c,v 1.24 2009/10/24 14:50:48 dsl Exp $");
 #endif
 #endif /* LIBC_SCCS and not lint */
 
 #include <assert.h>
 #include <stdio.h>
+#include <errno.h>
 #include <string.h>
 #include "reentrant.h"
 #include "local.h"
@@ -61,14 +62,12 @@
        int n;
        FILE *fp;
 {
-       size_t len;
+       int len;
        char *s;
        unsigned char *p, *t;
 
        _DIAGASSERT(buf != NULL);
        _DIAGASSERT(fp != NULL);
-       if (n <= 0)                                     /* sanity check */
-               return (NULL);
 
        FLOCKFILE(fp);
        _SET_ORIENTATION(fp, -1);
@@ -97,11 +96,25 @@
                 * newline, and stop.  Otherwise, copy entire chunk
                 * and loop.
                 */
-               if (len > (size_t)n)
+               if (len > n) {
+                       if (n < 0) {
+                               /*
+                                * Caller's length <= 0
+                                * We can't write into the buffer, so cannot
+                                * return a string, so must return NULL.
+                                * Set errno and __SERR so it is consistent.
+                                * TOG gives no indication of what to do here!
+                                */
+                               errno = EINVAL;
+                               fp->_flags |= __SERR;
+                               FUNLOCKFILE(fp);
+                               return NULL;
+                       }
                        len = n;
+               }
                t = memchr((void *)p, '\n', len);
                if (t != NULL) {
-                       len = ++t - p;
+                       len = (int)(++t - p);
                        fp->_r -= len;
                        fp->_p = t;
                        (void)memcpy((void *)s, (void *)p, len);