Re: [PATCH] (x)memcoll: minor tweaks

[Bruno Haible]

Paul Eggert fixed the memcoll0 description on 2010-07-12:
>  
> -/* Compare S1 (with length S1LEN) and S2 (with length S2LEN) according
> -   to the LC_COLLATE locale.  S1 and S2 must both end in a null byte.
> +/* Compare S1 (with size S1SIZE) and S2 (with length S2SIZE) according
> +   to the LC_COLLATE locale.  S1 and S2 are both blocks of memory with
> +   nonzero sizes, and the last byte in each block must be a null byte.
>     Set errno to an error number if there is an error, and to zero
>     otherwise.  */

While writing a unit test for the memcoll module, I noticed that this
description was still ambiguous (it talks about "length S2SIZE") and
hard to understand because it explains what S1 is in two sentences
that each provide a partial understanding. Additionally, the xmemcoll0
function confuses the concepts of size (includes the trailing NUL) and
length (does not include the trailing NUL).

I'm applying the obvious fix:


2010-09-22  Bruno Haible  <address@hidden>

        memcoll, xmemcoll: Clarify size vs. length.
        * modules/memcoll.c (memcoll0): Clarify specification.
        * modules/xmemcoll.c (xmemcoll0): Likewise. Reduce by 1 the lengths
        passed to collate_error.

--- lib/memcoll.c.orig  Wed Sep 22 12:33:39 2010
+++ lib/memcoll.c       Wed Sep 22 12:16:19 2010
@@ -93,9 +93,9 @@
   return diff;
 }
 
-/* Compare S1 (with size S1SIZE) and S2 (with length S2SIZE) according
-   to the LC_COLLATE locale.  S1 and S2 are both blocks of memory with
-   nonzero sizes, and the last byte in each block must be a null byte.
+/* Compare S1 (a memory block of size S1SIZE, with a NUL as last byte)
+   and S2 (a memory block of size S2SIZE, with a NUL as last byte)
+   according to the LC_COLLATE locale.  S1SIZE and S2SIZE must be > 0.
    Set errno to an error number if there is an error, and to zero
    otherwise.  */
 int
--- lib/xmemcoll.c.orig Wed Sep 22 12:33:39 2010
+++ lib/xmemcoll.c      Wed Sep 22 12:32:33 2010
@@ -60,17 +60,17 @@
   return diff;
 }
 
-/* Compare S1 (with size S1SIZE) and S2 (with length S2SIZE) according
-   to the LC_COLLATE locale.  S1 and S2 are both blocks of memory with
-   nonzero sizes, and the last byte in each block must be a null byte.
+/* Compare S1 (a memory block of size S1SIZE, with a NUL as last byte)
+   and S2 (a memory block of size S2SIZE, with a NUL as last byte)
+   according to the LC_COLLATE locale.  S1SIZE and S2SIZE must be > 0.
    Report an error and exit if there is an error.  */
 
 int
-xmemcoll0 (char const *s1, size_t s1len, char const *s2, size_t s2len)
+xmemcoll0 (char const *s1, size_t s1size, char const *s2, size_t s2size)
 {
-  int diff = memcoll0 (s1, s1len, s2, s2len);
+  int diff = memcoll0 (s1, s1size, s2, s2size);
   int collation_errno = errno;
   if (collation_errno)
-    collate_error (collation_errno, s1, s1len, s2, s2len);
+    collate_error (collation_errno, s1, s1size - 1, s2, s2size - 1);
   return diff;
 }