svn commit: r313480 - in stable/10: contrib/netbsd-tests/lib/libc/string lib/libc/string

[Ngie Cooper]

Author: ngie
Date: Thu Feb  9 21:23:41 2017
New Revision: 313480
URL: https://svnweb.freebsd.org/changeset/base/313480

Log:
  MFC r283584:
  
  Relnotes:	yes
  
  r283584 (by emaste):
  
  memmem(3): empty little string matches the beginning of the big string
  
  This function originated in glibc, and this matches their behaviour
  (and NetBSD, OpenBSD, and musl).
  
  An empty big string (arg "l") is handled by the existing
  l_len < s_len test.

Modified:
  stable/10/contrib/netbsd-tests/lib/libc/string/t_memmem.c
  stable/10/lib/libc/string/memmem.3
  stable/10/lib/libc/string/memmem.c
Directory Properties:
  stable/10/   (props changed)

Modified: stable/10/contrib/netbsd-tests/lib/libc/string/t_memmem.c
==============================================================================
--- stable/10/contrib/netbsd-tests/lib/libc/string/t_memmem.c	Thu Feb  9 21:19:24 2017	(r313479)
+++ stable/10/contrib/netbsd-tests/lib/libc/string/t_memmem.c	Thu Feb  9 21:23:41 2017	(r313480)
@@ -75,7 +75,7 @@ ATF_TC_HEAD(memmem_basic, tc)
 ATF_TC_BODY(memmem_basic, tc)
 {
 
-#if defined(__darwin__) || defined(__FreeBSD__)
+#if defined(__darwin__)
 	expect(memmem(b2, lb2, p0, lp0) == NULL);
 	expect(memmem(b0, lb0, p0, lp0) == NULL);
 #else

Modified: stable/10/lib/libc/string/memmem.3
==============================================================================
--- stable/10/lib/libc/string/memmem.3	Thu Feb  9 21:19:24 2017	(r313479)
+++ stable/10/lib/libc/string/memmem.3	Thu Feb  9 21:23:41 2017	(r313480)
@@ -26,7 +26,7 @@
 .\"
 .\" $FreeBSD$
 .\"
-.Dd August 24, 2005
+.Dd May 26, 2015
 .Dt MEMMEM 3
 .Os
 .Sh NAME
@@ -51,14 +51,12 @@ in the byte string
 .Fa big .
 .Sh RETURN VALUES
 If
-.Fa big_len
-is smaller than
-.Fa little_len ,
-if
 .Fa little_len
-is 0, if
-.Fa big_len
-is 0 or if
+is zero
+.Fa big
+is returned (that is, an empty little is deemed to match at the beginning of
+big);
+if
 .Fa little
 occurs nowhere in
 .Fa big ,
@@ -84,3 +82,11 @@ function first appeared in
 .Sh BUGS
 This function was broken in Linux libc up to and including version 5.0.9
 and in GNU libc prior to version 2.1.
+Prior to
+.Fx 11.0
+.Nm
+returned
+.Dv NULL
+when
+.Fa little_len
+equals 0.

Modified: stable/10/lib/libc/string/memmem.c
==============================================================================
--- stable/10/lib/libc/string/memmem.c	Thu Feb  9 21:19:24 2017	(r313479)
+++ stable/10/lib/libc/string/memmem.c	Thu Feb  9 21:23:41 2017	(r313480)
@@ -42,9 +42,9 @@ memmem(const void *l, size_t l_len, cons
 	const char *cl = (const char *)l;
 	const char *cs = (const char *)s;
 
-	/* we need something to compare */
-	if (l_len == 0 || s_len == 0)
-		return NULL;
+	/* empty "s" matches the beginning of "l" */
+	if (s_len == 0)
+		return (void *)cl;
 
 	/* "s" must be smaller or equal to "l" */
 	if (l_len < s_len)