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.rheinha...@outlook.com>
---
libavutil/opt.c | 10 +++++++---
1 file changed, 7 insertions(+), 3 deletions(-)
diff --git a/libavutil/opt.c b/libavutil/opt.c
index 76080f87e8..3130606337 100644
--- a/libavutil/opt.c
+++ b/libavutil/opt.c
@@ -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);
- *dst8 = av_strdup(*src8);
- if (*src8 && !*dst8)
- return AVERROR(ENOMEM);
+ if (*src8) {
+ *dst8 = av_strdup(*src8);
+ if (!*dst8)
+ return AVERROR(ENOMEM);
+ }
} else if (type == AV_OPT_TYPE_BINARY) {
int len = *(const int *)(src8 + 1);
if (*dst8 != *src8)
--
2.40.1
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