On 10/14/25 14:23, Peter Krempa wrote: > On Tue, Oct 14, 2025 at 08:31:46 +0200, Michal Privoznik via Devel wrote: >> From: Michal Privoznik <[email protected]> >> >> One of the problems of using val_to_str() is that it may return a >> const string from given table ('vs'), OR return an allocated one. >> Since the caller has no idea which case it is, it resides to safe >> option and don't free returned string. But that might lead to a >> memleak. This behaviour is fixed with wireshark-4.6.0 and support >> for it will be introduced soon. But first, make vir_val_to_str() >> behave like fixed val_to_str() from newer wireshark: just always >> allocate the string. >> >> Now, if val_to_str() needs to allocate new memory it obtains >> allocator by calling wmem_packet_scope() which is what we may do >> too. >> >> Hand in hand with that, we need to free the memory using the >> correct allocator, hence wmem_free(). But let's put it into a >> wrapper vir_wmem_free() because just like val_to_str(), it'll >> need additional argument when adapting to new wireshark. >> >> Oh, and freeing the memory right after col_add_fstr() is safe as >> it uses vsnprintf() under the hood to format passed args. >> >> One last thing, the wmem.h file used to live under epan/wmem/ but >> then in v3.5.0~240 [1] was moved to wsutil/wmem/. >> >> 1: >> https://gitlab.com/wireshark/wireshark/-/commit/7f9c1f5f92c131354fc8b2b88d473706786064c0 >> Signed-off-by: Michal Privoznik <[email protected]> >> --- >> meson.build | 20 ++++++++++++++++ >> tools/wireshark/src/meson.build | 1 + >> tools/wireshark/src/packet-libvirt.c | 35 ++++++++++++++++++++++------ >> 3 files changed, 49 insertions(+), 7 deletions(-) > > [...] > >> @@ -140,13 +145,19 @@ static const value_string status_strings[] = { >> { -1, NULL } >> }; >> >> -static const char * >> +static char * >> G_GNUC_PRINTF(3, 0) >> vir_val_to_str(const uint32_t val, >> const value_string *vs, >> const char *fmt) >> { >> - return val_to_str(val, vs, fmt); >> + return val_to_str_wmem(wmem_packet_scope(), val, vs, fmt); > > I didn't try building this but grepping in the wireshark code base shows > only: > > wsutil/value_string.h:rval_to_str_wmem(wmem_allocator_t* scope, const > uint32_t val, const range_string *rs, const char *fmt) > wsutil/value_string.h:bytesval_to_str_wmem(wmem_allocator_t* scope, const > uint8_t *val, const size_t val_len, const bytes_string *bs, const char *fmt) >
Mind you, val_to_str_wmem() is available only in pre-4.6.0 era. https://gitlab.com/wireshark/wireshark/-/commit/84799be215313e61b83a3eaf074f89d6ee349b8c wireshark.git $ git describe --contains 84799be215313e61b83a3eaf074f89d6ee349b8c v4.6.0rc0~120 In this commit val_to_str_wmem() was renamed to val_to_str(). The whole point of these patches up to this one is to prepare for this change. Michal
