#include <u.h>
#include <libc.h>
#include <bio.h>

char *makeline(void);

#define NUMARGS 470
#define MAXSIZE 5000

void run(char **cmd);
Biobuf stdin;
int main(int argc, char **argv)
{
	char **cmd;
	int i, n, m, size;
	if (argc < 2) {
		fprint(2, "Usage: xargs [cmd args...]\n");
		exits("bad usage");
	}
	if (Binit(&stdin, 0, OREAD) == -1) {
		fprint(2, "couldn't init stdin\n");
		exits("error");
	}
	cmd = malloc((argc - 1 + NUMARGS + 1) * sizeof(char *));
	n = 0;
	for (i = 1; i < argc; i++) {
		cmd[n++] = argv[i];
	}

	for (;;) {
		int eof = 0;;
		size = 0;
		for (m = 0; m < NUMARGS && size < MAXSIZE; m++) {
			if ((cmd[n + m] = makeline()) == 0) {
				eof = 1;
				break;
			}
			size += strlen(cmd[n + m]);
		}
		cmd[n + m] = 0;
		if (m > 0)
			run(cmd);
		for (i = 0; i < m; i++) {
			free(cmd[n+i]);
		}
		if (eof)
			break;
	}
	return 0;
}

int pwait(void)
{
	Waitmsg msg;
	if (wait(&msg) == -1)
		return -1;
	return atoi(msg.pid);
}

void run(char **cmd)
{
	char buf[256];
	int npid, pid = fork();
	if (pid == -1) {
		perror("couldn't fork");
		exits("no forkage");
	}
	if (pid == 0) {
		if (cmd[0][0] != '/' && strncmp(cmd[0], "./", 2)) {
			sprint(buf, "/bin/%s", cmd[0]);
			exec(buf, cmd);
		} else {
			exec(cmd[0], cmd);
		}
		perror(cmd[0]);
		exits("no exec");
	}
	while ((npid = pwait()) != pid && npid != -1)
		;
}

char *makeline(void)
{
	char *ln, *ret;
	int len;
	if ((ln = Brdline(&stdin, '\n')) == 0) {
		return 0;
	}
	len = Blinelen(&stdin);
	ret = malloc(len + 1);
	memcpy(ret, ln, len);
	ret[len-1] = '\0';
	return ret;
}