Re: [PATCH] maintenance: compare output of pthread functions for inequality with 0

> 
> On Fri, Dec 02 2022, Rose via GitGitGadget wrote:
> 
>> From: Seija <doremylover123@gmail.com>
>>
>> The documentation for pthread_create and pthread_sigmask state that:
>>
>> "On success, pthread_create() returns 0;
>> on error, it returns an error number"
>>
>> As such, we ought to check for an error
>> by seeing if the output is not 0.
>>
>> Checking for "less than" is a mistake
>> as the error code numbers can be greater than 0.
>>
>> Signed-off-by: Seija <doremylover123@gmail.com>
>> ---
>>      maintenance: compare output of pthread functions for inequality with 0
>>      
>>      The documentation for pthread_create and pthread_sigmask state that "On
>>      success, pthread_create() returns 0; on error, it returns an error
>>      number, and the contents of *thread are undefined."
>>      
>>      As such, we ought to check for an error by seeing if the output is not
>>      0, rather than being less than 0, since nothing stops these functions
>>      from returning a positive number.
>>      
>>      Signed-off by: Seija doremylover123@gmail.com
>>
>> Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-git-1389%2FAtariDreams%2Faddress-v1
>> Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-git-1389/AtariDreams/address-v1
>> Pull-Request: https://github.com/git/git/pull/1389
>>
>>   builtin/fsmonitor--daemon.c | 4 ++--
>>   run-command.c               | 2 +-
>>   2 files changed, 3 insertions(+), 3 deletions(-)
>>
>> diff --git a/builtin/fsmonitor--daemon.c b/builtin/fsmonitor--daemon.c
>> index 6f30a4f93a7..52a08bb3b57 100644
>> --- a/builtin/fsmonitor--daemon.c
>> +++ b/builtin/fsmonitor--daemon.c
>> @@ -1209,7 +1209,7 @@ static int fsmonitor_run_daemon_1(struct fsmonitor_daemon_state *state)
>>   	 * events.
>>   	 */
>>   	if (pthread_create(&state->listener_thread, NULL,
>> -			   fsm_listen__thread_proc, state) < 0) {
>> +			   fsm_listen__thread_proc, state)) {
>>   		ipc_server_stop_async(state->ipc_server_data);
>>   		err = error(_("could not start fsmonitor listener thread"));
>>   		goto cleanup;
>> @@ -1220,7 +1220,7 @@ static int fsmonitor_run_daemon_1(struct fsmonitor_daemon_state *state)
>>   	 * Start the health thread to watch over our process.
>>   	 */
>>   	if (pthread_create(&state->health_thread, NULL,
>> -			   fsm_health__thread_proc, state) < 0) {
>> +			   fsm_health__thread_proc, state)) {
>>   		ipc_server_stop_async(state->ipc_server_data);
>>   		err = error(_("could not start fsmonitor health thread"));
>>   		goto cleanup;
>> diff --git a/run-command.c b/run-command.c
>> index 48b9ba6d6f0..756f1839aab 100644
>> --- a/run-command.c
>> +++ b/run-command.c
>> @@ -1019,7 +1019,7 @@ static void *run_thread(void *data)
>>   		sigset_t mask;
>>   		sigemptyset(&mask);
>>   		sigaddset(&mask, SIGPIPE);
>> -		if (pthread_sigmask(SIG_BLOCK, &mask, NULL) < 0) {
>> +		if (pthread_sigmask(SIG_BLOCK, &mask, NULL)) {
>>   			ret = error("unable to block SIGPIPE in async thread");
>>   			return (void *)ret;
>>   		}
>>
>> base-commit: 805265fcf7a737664a8321aaf4a0587b78435184
> 
> This looks good to me, and skimming through the rest of the
> pthread_create() it seems the rest of the code in-tree is correct.
> 
> But (and especially if you're interested) we really should follow-up
> here and fix the "error()" etc. part of this. After this we have cases
> in-tree where we on failure:

> 
>   * Call die_errno() (good)
>   * Call die(), error() etc., but with a manual strerror() argument,
>     these should just use the *_errno() helper.
>   * Don't report on the errno at all, e.g. in this case shown here.
> 
> It seems to me that all of these should be using die_errno(),
> error_errno() etc.
> 
> Or maybe it's the other way around, and we should not rely on the global
> "errno", but always capture the return value, and give that to
> strerror() (or set "errno = ret", and call {die,error,warning}_errno()).
> 
> In any case, some low-hanging #leftoverbits there...
>