On Wed, 2023-07-26 at 13:54 +0200, AngeloGioacchino Del Regno wrote: ..snip.. > > > > > > > > > > > > @@ -306,6 +312,18 @@ static int > > > > > > mt8188_mt6359_mtkaif_calibration(struct snd_soc_pcm_runtime > > > > > > *rtd) > > > > > > return 0; > > > > > > } > > > > > > > > > > > > + for_each_card_widgets(rtd->card, w) { > > > > > > + if (!strcmp(w->name, "MTKAIF_PIN")) { > > > > > > > > > > if (strncmp(w->name, "MTKAIF_PIN", strlen(w->name) == 0) { > > > > > pin_w = w; > > > > > break; > > > > > } > > > > > > > > > > That's safer. > > > > > > > > > > > > > If w->name is MTKAIF, the strncmp expression will return 0. > > > > However, > > > > the result is not expected. I prefer to keep strcmp here. > > > > > > > > > > You could also do, instead > > > > > > if (strncmp(w->name, "MTKAIF_PIN", strlen("MTKAIF_PIN") == 0)) > > > > > > ...solving your concern. > > > > > > > > > > From my understanding, strncmp is utilized to determine a string > > begins > > with a particular prefix while strcmp is used to compare a whole > > string. In this scenario, I wish to verify if the widget name is > > exactly 'MTKAIF_PIN', so I believe using strcmp would be more > > appropriate. > > > > Using either strlen(w->name) or strlen("MTKAIF_PIN") may lead to > > incorrect results when w->name is either MTKAIF or MTKAIF_PIN1. > > > > Thanks, > > Trevor > > strcmp() and strncmp() are the same; except strncmp() compares *at > most* `n` bytes, > where `n` is my `strlen("MTKAIF_PIN")`. > > From Linux man pages.... > https://urldefense.com/v3/__https://www.man7.org/linux/man-pages/man3/strcmp.3.html__;!!CTRNKA9wMg0ARbw!n-X-ckbkVYv4cbrhpwb2f7NH6sQkxx1czmCU2-q5BtSOhQU0C68wj9JNcu47YfbYeTpVEzjYQVXGuQb5ulpeWwKjnVMdZpg$ ; > > > Hi Angelo, My concern is that strncmp() compares at most `n` bytes, where `n` is the length of the string 'MTKAIF_PIN'. For instance, if both 'MTKAIF_PIN' and 'MTKAIF_PINMUX' exist in the widget list, they will both enter execute_something() function below when executing this code: if (strncmp(w->name, "MTKAIF_PIN", strlen("MTKAIF_PIN")) == 0) { execute_something(); }. This is not my expected scenario. To prevent this problem, we can use strcmp() instead of strncmp(). strcmp() compares two strings until it finds a difference or reaches the end of one of them. Therefore, it will compare the entire string 'MTKAIF_PIN' with w->name and make sure that only do execute_something() when w->names is the same as 'MTKAIF_PIN'. Thanks, Trevor