[PATCH] fast-import: Reinitialize command_buf rather than detach it.
- From
Mike Hommey <mh@glandium.org>
- Date
- Aug 25, 2019, 04:13 UTC
- Message-ID
- <20190825041348.31835-1-mh@glandium.org>
command_buf.buf is also stored in cmd_hist, so instead of strbuf_release, the current code uses strbuf_detach in order to "leak" the buffer as far as the strbuf is concerned.
However, strbuf_detach does more than "leak" the strbuf buffer: it possibly reallocates it to ensure a terminating nul character. And when that happens, what is already stored in cmd_hist may now be a free()d buffer.
In practice, though, command_buf.buf is most of the time a nul terminated string, meaning command_buf.len < command_buf.alloc, and strbuf_detach is a no-op. BUT, when it's not (e.g. on the first call), command_buf.buf is &strbuf_slopbuf. In that case, strbuf_detach does allocate a 1 byte buffer to store a nul character in it, which is then leaked.
Since the code using strbuf_detach is assuming it does nothing to command_buf.buf, it's overall safer to use strbuf_init, which has the same practical effect in the usual case, and works appropriately when command_buf is empty. --- fast-import.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-)
diff --git a/fast-import.c b/fast-import.c index b44d6a467e..b1d07efe8c 100644 --- a/fast-import.c +++ b/fast-import.c @@ -1763,7 +1763,9 @@ static int read_next_command(void) } else { struct recent_command *rc; - strbuf_detach(&command_buf, NULL); + // command_buf is enther empty or also stored in cmd_hist, + // reinitialize it. + strbuf_init(&command_buf, 0); stdin_eof = strbuf_getline_lf(&command_buf, stdin); if (stdin_eof) return EOF; @@ -1833,7 +1835,9 @@ static int parse_data(struct strbuf *sb, uintmax_t limit, uintmax_t *len_res) char *term = xstrdup(data); size_t term_len = command_buf.len - (data - command_buf.buf); - strbuf_detach(&command_buf, NULL); + // command_buf is enther empty or also stored in cmd_hist, + // reinitialize it. + strbuf_init(&command_buf, 0); for (;;) { if (strbuf_getline_lf(&command_buf, stdin) == EOF) die("EOF in data (terminator '%s' not found)", term);
-- 2.23.0