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BUG/MINOR: tools: improve parse_line()'s robustness against empty args

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The fix in 10e6d0bd57 ("BUG/MINOR: tools: only fill first empty arg when
not out of range") was not that good. It focused on protecting against
<arg> becoming out of range to detect we haven't emitted anything, but
it's not the right way to detect this. We're always maintaining arg_start
as a copy of outpos, and that later one is incremented when emitting a
char, so instead of testing args[arg] against out+arg_start, we should
instead check outpos against arg_start, thereby eliminating the <out>
offset and the need to access args[]. This way we now always know if
we've emitted an empty arg without dereferencing args[].

There's no need to backport this unless the fix above is also backported.
This commit is contained in:
Willy Tarreau 2025-05-12 16:01:27 +02:00
parent 7d057e56af
commit 2b60e54fb1
1 changed files with 5 additions and 3 deletions
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8
src/tools.c
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@ -6439,7 +6439,7 @@ uint32_t parse_line(char *in, char *out, size_t *outlen, char **args, int *nbarg
err |= PARSE_ERR_TOOMANY; err |= PARSE_ERR_TOOMANY;
} }
if (prev_in_arg && !in_arg) { if (prev_in_arg && !in_arg) {
if (!empty_arg_ptr && arg < argsmax && args[arg] == out + arg_start) if (!empty_arg_ptr && outpos == arg_start)
empty_arg_ptr = begin_new_arg; empty_arg_ptr = begin_new_arg;
EMIT_CHAR(0); EMIT_CHAR(0);
arg++; arg++;
@ -6481,19 +6481,21 @@ uint32_t parse_line(char *in, char *out, size_t *outlen, char **args, int *nbarg
} }
if (prev_in_arg && !in_arg) { if (prev_in_arg && !in_arg) {
if (!empty_arg_ptr && arg < argsmax && args[arg] == out + arg_start) if (!empty_arg_ptr && outpos == arg_start)
empty_arg_ptr = begin_new_arg; empty_arg_ptr = begin_new_arg;
EMIT_CHAR(0); EMIT_CHAR(0);
arg++; arg++;
arg_start = outpos;
} }
} }
/* end of output string */ /* end of output string */
if (in_arg) { if (in_arg) {
if (!empty_arg_ptr && arg < argsmax && args[arg] == out + arg_start) if (!empty_arg_ptr && outpos == arg_start)
empty_arg_ptr = begin_new_arg; empty_arg_ptr = begin_new_arg;
EMIT_CHAR(0); EMIT_CHAR(0);
arg++; arg++;
arg_start = outpos;
} }
if (quote) { if (quote) {