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avutil/opt: Avoid av_strdup(NULL)

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It is not documented to be safe and in any case it is nonsense:
Currently av_strdup(NULL) returns NULL and in order to distinguish
this from a genuine allocation failure, opt_copy_elem()
checked afterwards whether src was actually NULL. But then one
can simply check in advance whether one should call av_strdup()
at all.
set_string() was even worse and returned ENOMEM in case the value
to be duplicated is NULL; this only worked because
av_opt_set_defaults2() does not check the return value at all
(given that it can't propagate it).

These two places account for 389114 of 390356 av_strdup(NULL)
calls during one FATE run.

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
This commit is contained in:
Andreas Rheinhardt 2024-03-25 13:34:42 +01:00
parent 686d33a6b0
commit aa7d6520e6
1 changed files with 7 additions and 3 deletions
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6
libavutil/opt.c
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@ -309,6 +309,8 @@ static int set_string_binary(void *obj, const AVOption *o, const char *val, uint
static int set_string(void *obj, const AVOption *o, const char *val, uint8_t **dst)
{
av_freep(dst);
if (!val)
return 0;
*dst = av_strdup(val);
return *dst ? 0 : AVERROR(ENOMEM);
}
@ -2032,9 +2034,11 @@ static int opt_copy_elem(void *logctx, enum AVOptionType type,
if (type == AV_OPT_TYPE_STRING) {
if (*dst8 != *src8)
av_freep(dst8);
if (*src8) {
*dst8 = av_strdup(*src8);
if (*src8 && !*dst8)
if (!*dst8)
return AVERROR(ENOMEM);
}
} else if (type == AV_OPT_TYPE_BINARY) {
int len = *(const int *)(src8 + 1);
if (*dst8 != *src8)