execl.c

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#include <stdlib.h>
#include <unistd.h>
#include <stdarg.h>

int execl(__const char *path, __const char *arg, ...)
{
	const char *shortargv[16];
	const char **argv;
	const char *c;
	int i;
	va_list args;

	i = 1;

	va_start(args, arg);

	do {
		c = va_arg(args, const char *);

		i++;
	} while (c);

	va_end(args);

	if (i <= 16)
		argv = shortargv;
	else {
		argv = (const char **) alloca(sizeof(char *) * i);
	}

	argv[0] = arg;
	i = 1;

	va_start(args, arg);

	do {
		argv[i] = va_arg(args, const char *);
	} while (argv[i++]);

	va_end(args);

	i = execve(path, (char *const *) argv, __environ);

	if (argv != shortargv)
		free(argv);

	return i;
}