On Tue, 14 Jul 2026 21:36:37 +0200, Ian Bridges wrote: > > In preparation for removing the strlcat() API[1], replace its two > uses in the generic parser. > > Both call sites append one suffix to a string that the function has > already bounded to the buffer size. A strscpy() anchored at the > current end of the string writes the same bytes, including when the > suffix is truncated. > > Link: https://github.com/KSPP/linux/issues/370 [1] > Signed-off-by: Ian Bridges <[email protected]> > --- > The patch was tested as follows. > > - W=1 build of sound/hda/, zero warnings. > - A userspace differential harness compiled the old and the new > functions side by side. The buffers were byte identical over their > full length, including the bytes after the terminator. > - A QEMU runtime compare. A guest with an emulated HDA codec was > booted on the base and on the patched kernel, and the captured > /proc/asound state was byte identical. That covers the PCM stream > names from fill_pcm_stream_name() live. > > sound/hda/codecs/generic.c | 8 ++++++-- > 1 file changed, 6 insertions(+), 2 deletions(-) > > diff --git a/sound/hda/codecs/generic.c b/sound/hda/codecs/generic.c > index 660a9f2c0ded..5f373cbf4a53 100644 > --- a/sound/hda/codecs/generic.c > +++ b/sound/hda/codecs/generic.c > @@ -2712,10 +2712,12 @@ static void get_jack_mode_name(struct hda_codec > *codec, hda_nid_t pin, > char *name, size_t name_len) > { > struct hda_gen_spec *spec = codec->spec; > + size_t used; > int idx = 0; > > snd_hda_get_pin_label(codec, pin, &spec->autocfg, name, name_len, &idx); > - strlcat(name, " Jack Mode", name_len); > + used = strnlen(name, name_len); > + strscpy(name + used, " Jack Mode", name_len - used); > > for (; find_kctl_name(codec, name, idx); idx++) > ; > @@ -5682,6 +5684,7 @@ static const struct hda_pcm_stream > dyn_adc_pcm_analog_capture = { > static void fill_pcm_stream_name(char *str, size_t len, const char *sfx, > const char *chip_name) > { > + size_t used; > char *p; > > if (*str) > @@ -5695,7 +5698,8 @@ static void fill_pcm_stream_name(char *str, size_t len, > const char *sfx, > break; > } > } > - strlcat(str, sfx, len); > + used = strnlen(str, len); > + strscpy(str + used, sfx, len - used); > } > > /* copy PCM stream info from @default_str, and override non-NULL entries
Hmm... IMHO, those changes are *too ugly*. Is the reason to drop strlcat() is only about the performance, no? If it were some security hardening, I'd find OK, but if not, this kind of change is doubtful: the code path is no hot path, hence the effect is nothing, and yet readability becomes significantly worse. thanks, Takashi
