Some 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@xxxxxxxxxxxxxxxxxxx>
---
utf8.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
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
--
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