[PATCH v1 13/30] lib/process: Add process_get_stdout

[Geoff Levand]

Hi Sam,

On 07/29/2018 08:25 PM, Samuel Mendoza-Jonas wrote:
> On Tue, 2018-07-24 at 22:15 +0000, Geoff Levand wrote:
>> +int process_get_stdout_argv(void *ctx, struct process_stdout **stdout,
>> +	const char *argv[])
>>  {
>> -	struct process *process;
>> +	struct process *p;
>>  	int rc;
>>  
>> -	process = process_create(ctx);
>> +	p = process_create(NULL);
>> +	p->path = argv[0];
>> +	p->argv = argv;
>>  
>> -	process->path = argv[0];
>> -	process->argv = argv;
>> +	if (stdout) {
>> +		p->keep_stdout = true;
>> +		*stdout = NULL;
>> +	}
>>  
>> -	rc = process_run_sync(process);
>> +	rc = process_run_sync(p);
>>  
>>  	if (!rc)
>> -		rc = process->exit_status;
>> +		rc = p->exit_status;
>> +	else {
>> +		pb_debug("%s: process_run_sync failed: %s.\n", __func__,
>> +			p->path);
>> +		if (*stdout)
>> +			pb_debug("%s: stdout: %s\n\n", __func__, p->stdout_buf);
>> +		goto exit;
> 
> Clang catches this check here:
> 12:01:55 lib/process/process.c:477:7: warning: Dereference of null pointer (loaded from variable 'stdout')
> 12:01:55                 if (*stdout)
> 12:01:55                     ^~~~~~~
> 
> For example if this is called via process_run_simple_argv() then stdout
> is NULL which is not caught earlier.
> Since this is guarding using p->stdout_buf can I fix this up by just changing
> it to `if (stdout)` instead?

Yes, that's what I had intended, to print only if a stdout was passed.

-Geoff