Re: bug in autoconf-2.64

[Jim Meyering]

Ralf Wildenhues wrote:

> [ this is http://thread.gmane.org/gmane.comp.sysutils.autoconf.bugs/7834
>   from http://gcc.gnu.org/ml/gcc-patches/2011-02/msg01480.html
>   adding bug-gnulib; followups can elide bug-autoconf ]
>
> * Ralf Wildenhues wrote on Thu, Feb 24, 2011 at 07:24:35AM CET:
>> IOW, it looks like the replacement code in strstr.c and str-two-way.h
>> has a bug (or glibc strchr, which seems rather unlikely).  Besides
>> copyright year bumps, these two files have not been updated since in
>> gnulib.
>
> Here's a reproducer.  Link with gnulib's strstr.c and it will fail.

Wow.  Thanks for that, guys.

Here's a fix that passes this test, which includes Ralf's test case:

    ./gnulib-tool --create-testdir --with-tests --test strstr

I haven't finished testing, and will add a comment attributing
the test case.  Oh, and I'll make the test assertion stronger
(to include the precise offset).

diff --git a/lib/str-two-way.h b/lib/str-two-way.h
index dd80976..8e92c8b 100644
--- a/lib/str-two-way.h
+++ b/lib/str-two-way.h
@@ -284,7 +284,7 @@ two_way_short_needle (const unsigned char *haystack, size_t 
haystack_len,
     {
       /* The two halves of needle are distinct; no extra memory is
          required, and any mismatch results in a maximal shift.  */
-      period = MAX (suffix, needle_len - suffix) + 1;
+      period = MAX (suffix, needle_len - suffix);
       j = 0;
       while (AVAILABLE (haystack, haystack_len, j, needle_len))
         {
diff --git a/tests/test-strstr.c b/tests/test-strstr.c
index f63cb33..a9b2f02 100644
--- a/tests/test-strstr.c
+++ b/tests/test-strstr.c
@@ -181,6 +181,50 @@ main (int argc, char *argv[])
     free (haystack);
   }

+  {
+    const char *haystack =
+      "\n"
+      "with_build_libsubdir\n"
+      "with_local_prefix\n"
+      "with_gxx_include_dir\n"
+      "with_cpp_install_dir\n"
+      "enable_generated_files_in_srcdir\n"
+      "with_gnu_ld\n"
+      "with_ld\n"
+      "with_demangler_in_ld\n"
+      "with_gnu_as\n"
+      "with_as\n"
+      "enable_largefile\n"
+      "enable_werror_always\n"
+      "enable_checking\n"
+      "enable_coverage\n"
+      "enable_gather_detailed_mem_stats\n"
+      "enable_build_with_cxx\n"
+      "with_stabs\n"
+      "enable_multilib\n"
+      "enable___cxa_atexit\n"
+      "enable_decimal_float\n"
+      "enable_fixed_point\n"
+      "enable_threads\n"
+      "enable_tls\n"
+      "enable_objc_gc\n"
+      "with_dwarf2\n"
+      "enable_shared\n"
+      "with_build_sysroot\n"
+      "with_sysroot\n"
+      "with_specs\n"
+      "with_pkgversion\n"
+      "with_bugurl\n"
+      "enable_languages\n"
+      "with_multilib_list\n";
+    const char *needle = "\n"
+      "with_gnu_ld\n";
+    const char* p = strstr (haystack, needle);
+    printf ("searching for %s in %s\n", needle, haystack);
+    printf ("found at %d\n", p ?  p - haystack : -1);
+    ASSERT (p);
+  }
+
   /* Sublinear speed is only possible in memmem; strstr must examine
      every character of haystack to find its length.  */