Re: [bug-gnulib] Re: nit in strftime.c

[Paul Eggert]

Eric Blake <address@hidden> writes:

> Why not prime the buffer?

Thanks.  (I thought of exactly the same thing while driving home last night.)
I installed this patch in both gnulib and coreutils.  Similar fixes
would be useful in coreutils date.c and pr.c; I'll look at those separately.


Come to think of it, perhas the "return 0" below should be an abort()?


2005-03-15  Paul Eggert  <address@hidden>

        * strftime.c (my_strftime): Prepend space to format so that we can
        reliably distinguish strftime failure from empty output on POSIX
        hosts.

--- strftime.c  14 Mar 2005 23:23:25 -0000      1.81
+++ strftime.c  16 Mar 2005 01:01:23 -0000      1.82
@@ -386,7 +386,7 @@ static CHAR_T const month_name[][10] =
    (including the terminating '\0') and returning number of
    characters written.  If S is NULL, nothing will be written
    anywhere, so to determine how many characters would be
-   written, use NULL for S and (size_t) UINT_MAX for MAXSIZE.  */
+   written, use NULL for S and (size_t) -1 for MAXSIZE.  */
 size_t
 my_strftime (CHAR_T *s, size_t maxsize, const CHAR_T *format,
             const struct tm *tp extra_args_spec LOCALE_PARAM_PROTO)
@@ -759,7 +759,7 @@ my_strftime (CHAR_T *s, size_t maxsize, 
          {
            /* The relevant information is available only via the
               underlying strftime implementation, so use that.  */
-           char ufmt[4];
+           char ufmt[5];
            char *u = ufmt;
            char ubuf[1024]; /* enough for any single format in practice */
            size_t len;
@@ -771,16 +771,18 @@ my_strftime (CHAR_T *s, size_t maxsize, 
            size_t strftime ();
 # endif
 
+           /* The space helps distinguish strftime failure from empty
+              output.  */
+           *u++ = ' ';
            *u++ = '%';
            if (modifier != 0)
              *u++ = modifier;
            *u++ = format_char;
            *u = '\0';
-           ubuf[0] = '\1';
            len = strftime (ubuf, sizeof ubuf, ufmt, tp);
-           if (len == 0 && ubuf[0] != '\0')
+           if (len == 0)
              return 0;
-           cpy (len, ubuf);
+           cpy (len - 1, ubuf + 1);
          }
          break;
 #endif