Ramsay JonesSome systems experience failures in t4205-*.sh (tests 18-20, 27) which all relate to the use of truncation with the %< padding placeholder. This capability was added in the commit a7f01c6b ("pretty: support truncating in %>, %< and %><", 19-04-2013).
The truncation support was implemented with the assistance of a new strbuf function (strbuf_utf8_replace). This function contains the following code:
strbuf_attach(sb_src, strbuf_detach(&sb_dst, NULL),
sb_dst.len, sb_dst.alloc);Unfortunately, this code is subject to unspecified behaviour. In particular, the order of evaluation of the argument expressions (along with the associated side effects) is not specified by the C standard. Note that the second argument expression is a call to strbuf_detach() which, as a side effect, sets the 'len' and 'alloc' fields of the sb_dst argument to zero. Depending on the order of evaluation of the argument expressions to the strbuf_attach call, this can lead to assigning an empty string to 'sb_src'.
In order to remove the undesired behaviour, we replace the above line of code with:
strbuf_swap(sb_src, &sb_dst);
strbuf_release(&sb_dst);which achieves the desired effect without provoking unspecified behaviour.
Signed-off-by: Ramsay Jones <ramsay@ramsay1.demon.co.uk> --- utf8.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
Show changes to utf8.c +2 −2
diff --git a/utf8.c b/utf8.c index b1e1303..0d20e0a 100644 --- a/utf8.c +++ b/utf8.c @@ -463,8 +463,8 @@ void strbuf_utf8_replace(struct strbuf *sb_src, int pos, int width, w += n; } strbuf_setlen(&sb_dst, dst - sb_dst.buf); - strbuf_attach(sb_src, strbuf_detach(&sb_dst, NULL), - sb_dst.len, sb_dst.alloc); + strbuf_swap(sb_src, &sb_dst); + strbuf_release(&sb_dst); } int is_encoding_utf8(const char *name)
-- 1.8.2
