ps.c

/* vi: set sw=4 ts=4: */
/*
 * Mini ps implementation for busybox
 *
 *
 * Copyright (C) 1999 by Lineo, inc.
 * Written by Erik Andersen <andersen@lineo.com>, <andersee@debian.org>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 *
 */

#include "internal.h"
#include <unistd.h>
#include <dirent.h>
#include <stdio.h>
#include <fcntl.h>
#include <ctype.h>

#if ! defined BB_FEATURE_USE_PROCFS
#error Sorry, I depend on the /proc filesystem right now.
#endif

typedef struct proc_s {
	char
	 cmd[16];					/* basename of executable file in call to exec(2) */
	int
	 ruid, rgid,				/* real only (sorry) */
	 pid,						/* process id */
	 ppid;						/* pid of parent process */
	char
	 state;						/* single-char code for process state (S=sleeping) */
} proc_t;



static int file2str(char *filename, char *ret, int cap)
{
	int fd, num_read;

	if ((fd = open(filename, O_RDONLY, 0)) == -1)
		return -1;
	if ((num_read = read(fd, ret, cap - 1)) <= 0)
		return -1;
	ret[num_read] = 0;
	close(fd);
	return num_read;
}


static void parse_proc_status(char *S, proc_t * P)
{
	char *tmp;

	memset(P->cmd, 0, sizeof P->cmd);
	sscanf(S, "Name:\t%15c", P->cmd);
	tmp = strchr(P->cmd, '\n');
	if (tmp)
		*tmp = '\0';
	tmp = strstr(S, "State");
	sscanf(tmp, "State:\t%c", &P->state);

	tmp = strstr(S, "Pid:");
	if (tmp)
		sscanf(tmp, "Pid:\t%d\n" "PPid:\t%d\n", &P->pid, &P->ppid);
	else
		fprintf(stderr, "Internal error!\n");

	/* For busybox, ignoring effective, saved, etc */
	tmp = strstr(S, "Uid:");
	if (tmp)
		sscanf(tmp, "Uid:\t%d", &P->ruid);
	else
		fprintf(stderr, "Internal error!\n");

	tmp = strstr(S, "Gid:");
	if (tmp)
		sscanf(tmp, "Gid:\t%d", &P->rgid);
	else
		fprintf(stderr, "Internal error!\n");

}


extern int ps_main(int argc, char **argv)
{
	proc_t p;
	DIR *dir;
	FILE *file;
	struct dirent *entry;
	char path[32], sbuf[512];
	char uidName[10] = "";
	char groupName[10] = "";
	int i, c;

	if (argc > 1 && **(argv + 1) == '-') {
		usage
			("ps\n\nReport process status\n\nThis version of ps accepts no options.\n");
	}

	dir = opendir("/proc");
	if (!dir) {
		perror("Can't open /proc");
		exit(FALSE);
	}

	fprintf(stdout, "%5s  %-8s %-3s %5s %s\n", "PID", "Uid", "Gid",
			"State", "Command");
	while ((entry = readdir(dir)) != NULL) {
		uidName[0] = '\0';
		groupName[0] = '\0';

		if (!isdigit(*entry->d_name))
			continue;
		sprintf(path, "/proc/%s/status", entry->d_name);
		if ((file2str(path, sbuf, sizeof sbuf)) != -1) {
			parse_proc_status(sbuf, &p);
		}

		/* Make some adjustments as needed */
		my_getpwuid(uidName, p.ruid);
		my_getgrgid(groupName, p.rgid);
		if (*uidName == '\0')
			sprintf(uidName, "%d", p.ruid);
		if (*groupName == '\0')
			sprintf(groupName, "%d", p.rgid);

		fprintf(stdout, "%5d %-8s %-8s %c ", p.pid, uidName, groupName,
				p.state);
		sprintf(path, "/proc/%s/cmdline", entry->d_name);
		file = fopen(path, "r");
		if (file == NULL) {
			perror(path);
			exit(FALSE);
		}
		i = 0;
		while (((c = getc(file)) != EOF) && (i < 53)) {
			i++;
			if (c == '\0')
				c = ' ';
			putc(c, stdout);
		}
		if (i == 0)
			fprintf(stdout, "%s", p.cmd);
		fprintf(stdout, "\n");
	}
	closedir(dir);
	exit(TRUE);
}