[PATCH 02/18] bootchartd: convert execl calls to BB_EXECVP

[Nadav Tasher]

I'm casting to (char *) because BB_EXECVP expects "char *const argv[]".

This is because BB_EXECVP mimics the signature of execvp, which is:
int execvp(const char *file, char *const argv[]);

On Wed, Jan 22, 2025 at 09:39:46AM +0100, Csókás Bence wrote:
> Hi,
> 
> On 2025. 01. 20. 0:10, Nadav Tasher wrote:
> > Signed-off-by: Nadav Tasher <tashernadav at gmail.com>
> > ---
> >   init/bootchartd.c | 19 +++++++++++++++----
> >   1 file changed, 15 insertions(+), 4 deletions(-)
> > 
> > diff --git a/init/bootchartd.c b/init/bootchartd.c
> > index 0929890a3..0833e0fe4 100644
> > --- a/init/bootchartd.c
> > +++ b/init/bootchartd.c
> > @@ -355,6 +355,7 @@ int bootchartd_main(int argc UNUSED_PARAM, char **argv)
> >   		CMD_INIT,
> >   		CMD_PID1, /* used to mark pid 1 case */
> >   	};
> > +	char* exec_argv[2];
> >   	INIT_G();
> > @@ -446,10 +447,20 @@ int bootchartd_main(int argc UNUSED_PARAM, char **argv)
> >   	if (cmd == CMD_PID1) {
> >   		char *bootchart_init = getenv("bootchart_init");
> > -		if (bootchart_init)
> > -			execl(bootchart_init, bootchart_init, NULL);
> > -		execl("/init", "init", NULL);
> > -		execl("/sbin/init", "init", NULL);
> > +
> > +		/* make second arg always NULL */
> > +		exec_argv[1] = NULL;
> > +
> > +		if (bootchart_init) {
> > +			exec_argv[0] = bootchart_init;
> > +			BB_EXECVP(bootchart_init, exec_argv);
> > +		}
> > +		
> > +		/* fallback, we are calling different init binaries */
> > +		exec_argv[0] = (char *) "init";
> 
> Why are you casting to (char *) ?
> 
> > +		BB_EXECVP("/init", exec_argv);
> > +		BB_EXECVP("/sbin/init", exec_argv);
> >   		bb_perror_msg_and_die("can't execute '%s'", "/sbin/init");
> >   	}
> 
> Bence
>