From: Bruno Haible <bruno@clisp.org>
Date: Tue, 5 Nov 2024 20:10:20 +0000 (+0100)
Subject: strndup: Guarantee N3322 functionality.
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=bf799ba1fb48d9706aa7aa6138604a07577d8a61;p=thirdparty%2Fgnulib.git

strndup: Guarantee N3322 functionality.

* m4/strndup.m4 (gl_FUNC_STRNDUP): Check against the AIX bug.
* doc/posix-functions/strndup.texi: Mention the AIX bug.
---

diff --git a/ChangeLog b/ChangeLog
index d0514e69b0..06ccb74f9a 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+2024-11-05  Bruno Haible  <bruno@clisp.org>
+
+	strndup: Guarantee N3322 functionality.
+	* m4/strndup.m4 (gl_FUNC_STRNDUP): Check against the AIX bug.
+	* doc/posix-functions/strndup.texi: Mention the AIX bug.
+
 2024-11-05  Bruno Haible  <bruno@clisp.org>
 
 	strncpy tests: Verify N3322 functionality.
diff --git a/doc/posix-functions/strndup.texi b/doc/posix-functions/strndup.texi
index 556e0602f1..4baabe2f5b 100644
--- a/doc/posix-functions/strndup.texi
+++ b/doc/posix-functions/strndup.texi
@@ -15,6 +15,10 @@ Mac OS X 10.5, FreeBSD 6.0, NetBSD 3.0, OpenBSD 3.8, Minix 3.1.8, HP-UX 11, Sola
 @item
 This function does not NUL-terminate the result on some platforms:
 AIX 5.1.
+@item
+This function does not support zero-length operations on NULL pointers
+on some platforms:
+AIX 7.3.
 @end itemize
 
 Portability problems not fixed by Gnulib:
diff --git a/m4/strndup.m4 b/m4/strndup.m4
index 7e5aa08698..9c8b212fdd 100644
--- a/m4/strndup.m4
+++ b/m4/strndup.m4
@@ -1,5 +1,5 @@
 # strndup.m4
-# serial 23
+# serial 24
 dnl Copyright (C) 2002-2003, 2005-2024 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -21,7 +21,8 @@ AC_DEFUN([gl_FUNC_STRNDUP],
 
   if test $ac_cv_func_strndup = yes; then
     HAVE_STRNDUP=1
-    # AIX 4.3.3, AIX 5.1 have a function that fails to add the terminating '\0'.
+    dnl AIX 5.1 has a function that fails to add the terminating '\0'.
+    dnl AIX 7.3 has a function that does not support a zero length.
     AC_CACHE_CHECK([for working strndup], [gl_cv_func_strndup_works],
       [AC_RUN_IFELSE([
          AC_LANG_PROGRAM([[#include <string.h>
@@ -33,23 +34,24 @@ AC_DEFUN([gl_FUNC_STRNDUP],
   #endif
   char *strndup (const char *, size_t);
 #endif
-  int result;
-  char *s;
-  s = strndup ("some longer string", 15);
-  free (s);
-  s = strndup ("shorter string", 13);
-  result = s[13] != '\0';
-  free (s);
+  int result = 0;
+  {
+    char *s = strndup ("some longer string", 15);
+    free (s);
+    s = strndup ("shorter string", 13);
+    if (s[13] != '\0')
+      result |= 1;
+    free (s);
+  }
+  if (strndup (NULL, 0) == NULL)
+    result |= 2;
   return result;]])],
          [gl_cv_func_strndup_works=yes],
          [gl_cv_func_strndup_works=no],
-         [
-changequote(,)dnl
-          case $host_os in
-            aix | aix[3-6]*) gl_cv_func_strndup_works="guessing no";;
-            *)               gl_cv_func_strndup_works="guessing yes";;
+         [case $host_os in
+            aix*) gl_cv_func_strndup_works="guessing no";;
+            *)    gl_cv_func_strndup_works="guessing yes";;
           esac
-changequote([,])dnl
          ])])
     case $gl_cv_func_strndup_works in
       *no) REPLACE_STRNDUP=1 ;;