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Fix mishandling of $Id$ expanded in the repository copy in convert.c

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If the repository contained an expanded ident keyword (i.e. $Id:XXXX$),
then the wrong bytes were discarded, and the Id keyword was not
expanded.  The fault was in convert.c:ident_to_worktree().

Previously, when a "$Id:" was found in the repository version,
ident_to_worktree() would search for the next "$" after this, and
discarded everything it found until then.  That was done with the loop:

    do {
        ch = *cp++;
        if (ch == '$')
            break;
        rem--;
    } while (rem);

The above loop left cp pointing one character _after_ the final "$"
(because of ch = *cp++).  This was different from the non-expanded case,
were cp is left pointing at the "$", and was different from the comment
which stated "discard up to but not including the closing $".  This
patch fixes that by making the loop:

    do {
        ch = *cp;
        if (ch == '$')
            break;
        cp++;
        rem--;
    } while (rem);

That is, cp is tested _then_ incremented.

This loop exits if it finds a "$" or if it runs out of bytes in the
source.  After this loop, if there was no closing "$" the expansion is
skipped, and the outer loop is allowed to continue leaving this
non-keyword as it was.  However, when the "$" is found, size is
corrected, before running the expansion:

    size -= (cp - src);

This is wrong; size is going to be corrected anyway after the expansion,
so there is no need to do it here.  This patch removes that redundant
correction.

To help find this bug, I heavily commented the routine; those comments
are included here as a bonus.

Signed-off-by: Andy Parkins <andyparkins@gmail.com>
Signed-off-by: Junio C Hamano <junkio@cox.net>
This commit is contained in:
Andy Parkins 2007-05-25 11:50:08 +01:00 committed by Junio C Hamano
parent 6d9d26d826
commit c23290d528
1 changed files with 37 additions and 2 deletions
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39
convert.c
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@ -509,36 +509,71 @@ static char *ident_to_worktree(const char *path, const char *src, unsigned long
for (dst = buf; size; size--) {
const char *cp;
/* Fetch next source character, move the pointer on */
char ch = *src++;
/* Copy the current character to the destination */
*dst++ = ch;
/* If the current character is "$" or there are less than three
* remaining bytes or the two bytes following this one are not
* "Id", then simply read the next character */
if ((ch != '$') || (size < 3) || memcmp("Id", src, 2))
continue;
/*
* Here when
* - There are more than 2 bytes remaining
* - The current three bytes are "$Id"
* with
* - ch == "$"
* - src[0] == "I"
*/
/*
* It's possible that an expanded Id has crept its way into the
* repository, we cope with that by stripping the expansion out
*/
if (src[2] == ':') {
/* Expanded keywords have "$Id:" at the front */
/* discard up to but not including the closing $ */
unsigned long rem = size - 3;
/* Point at first byte after the ":" */
cp = src + 3;
/*
* Throw away characters until either
* - we reach a "$"
* - we run out of bytes (rem == 0)
*/
do {
ch = *cp++;
ch = *cp;
if (ch == '$')
break;
cp++;
rem--;
} while (rem);
/* If the above finished because it ran out of characters, then
* this is an incomplete keyword, so don't run the expansion */
if (!rem)
continue;
size -= (cp - src);
} else if (src[2] == '$')
cp = src + 2;
else
/* Anything other than "$Id:XXX$" or $Id$ and we skip the
* expansion */
continue;
/* cp is now pointing at the last $ of the keyword */
memcpy(dst, "Id: ", 4);
dst += 4;
memcpy(dst, sha1_to_hex(sha1), 40);
dst += 40;
*dst++ = ' ';
/* Adjust for the characters we've discarded */
size -= (cp - src);
src = cp;
/* Copy the final "$" */
*dst++ = *src++;
size--;
}