Function runcmd

GPRS/pinghttp.c:169–232

Run the command. This is not ip specific, but used to call linux "ip" and "route" commands. If commands starts with '|', capture stdout and return the file descriptor to read it.

// This is not ip specific, but used to call linux "ip" and "route" commands.
// If commands starts with '|', capture stdout and return the file descriptor to read it.
int runcmd(const char *path, ...)
{
	int pipefd[2];
	int dopipe = 0;
	if (*path == '|') {
		path++;
		dopipe = 1;
		if (pipe(pipefd) == -1) {
			MGERROR("could not create pipe: %s",strerror(errno));
			return -1;
		}
	}
	int pid = fork();
	if (pid == -1) {
		MGERROR("could not fork: %s",strerror(errno));
		return -1;
	}
	if (pid) {	// This is the parent; wait for child to exit, then return childs status.
		int status;
		if (dopipe) {
			close(pipefd[1]); // Close unused write end of pipe.
		}
		waitpid(pid,&status,0);
		return dopipe ? pipefd[0] : status;	// Return read end of pipe, if piped.
	}
	// This is the child process.
	if (dopipe) {
		close(pipefd[0]); // Close unused read end of pipe.
		dup2(pipefd[1],1);	// Capture stdout to pipe.
		close(pipefd[1]);	// Close now redundant fd.
	}

	// Gather args into argc,argv;
	int argc = 0; char *argv[100];
	va_list ap;
	va_start(ap, path);
	do {
		argv[argc] = va_arg(ap,char*);
	} while (argv[argc++]);
	argv[argc] = NULL;
	va_end(ap);

	// Print them out.
	// But dont print if piped, because it goes into the pipe!
	if (! dopipe) {
		char buf[208], *bp = buf, *ep = &buf[200];
		int i;
		for (i = 0; argv[i]; i++) {
			int len = strlen(argv[i]);
			if (bp + len > ep) { strcpy(bp,"..."); break; }
			strcpy(bp,argv[i]);
			bp += len;
			*bp++ = ' ';
			*bp = 0;
		}
		buf[200] = 0;
		MGINFO("%s",buf);
	}