/* vi: set sw=4 ts=4: */
/*
 * tiny fuser implementation
 *
 * Copyright 2004 Tony J. White
 *
 * May be distributed under the conditions of the
 * GNU Library General Public License
 */

#include "busybox.h"

#define FUSER_PROC_DIR "/proc"
#define FUSER_MAX_LINE 255

#define FUSER_OPT_MOUNT  1
#define FUSER_OPT_KILL   2
#define FUSER_OPT_SILENT 4
#define FUSER_OPT_IP6    8
#define FUSER_OPT_IP4    16

typedef struct inode_list {
	ino_t inode;
	dev_t dev;
	struct inode_list *next;
} inode_list;

typedef struct pid_list {
	pid_t pid;
	struct pid_list *next;
} pid_list;

static int fuser_option(char *option)
{
	int opt = 0;

	if (!option[0])
		return 0;
	if (option[0] != '-')
		return 0;
	++option;
	while (*option != '\0') {
		if (*option == 'm') opt |= FUSER_OPT_MOUNT;
		else if (*option == 'k') opt |= FUSER_OPT_KILL;
		else if (*option == 's') opt |= FUSER_OPT_SILENT;
		else if (*option == '6') opt |= FUSER_OPT_IP6;
		else if (*option == '4') opt |= FUSER_OPT_IP4;
		else
			bb_error_msg_and_die("unsupported option '%c'", *option);
		++option;
	}
	return opt;
}

static int fuser_file_to_dev_inode(const char *filename,
	 dev_t *dev, ino_t *inode)
{
	struct stat f_stat;
	if ((stat(filename, &f_stat)) < 0)
		return 0;
	*inode = f_stat.st_ino;
	*dev = f_stat.st_dev;
	return 1;
}

static int fuser_find_socket_dev(dev_t *dev)
{
	int fd = socket(PF_INET, SOCK_DGRAM,0);
	struct stat buf;

	if (fd >= 0 && (fstat(fd, &buf)) == 0) {
		*dev = buf.st_dev;
		close(fd);
		return 1;
	}
	return 0;
}

static int fuser_parse_net_arg(const char *filename,
	const char **proto, int *port)
{
	char path[sizeof(FUSER_PROC_DIR)+12], tproto[5];

	if ((sscanf(filename, "%d/%4s", port, tproto)) != 2)
		return 0;
	sprintf(path, FUSER_PROC_DIR "/net/%s", tproto);
	if ((access(path, R_OK)) != 0)
		return 0;
	*proto = xstrdup(tproto);
	return 1;
}

static int fuser_add_pid(pid_list *plist, pid_t pid)
{
	pid_list *curr = NULL, *last = NULL;

	if (plist->pid == 0)
		plist->pid = pid;
	curr = plist;
	while (curr != NULL) {
		if (curr->pid == pid)
			return 1;
		last = curr;
		curr = curr->next;
	}
	curr = xzalloc(sizeof(pid_list));
	last->next = curr;
	curr->pid = pid;
	/*curr->next = NULL;*/
	return 1;
}

static int fuser_add_inode(inode_list *ilist, dev_t dev, ino_t inode)
{
	inode_list *curr = NULL, *last = NULL;

	if (!ilist->inode && !ilist->dev) {
		ilist->dev = dev;
		ilist->inode = inode;
	}
	curr = ilist;
	while (curr != NULL) {
		if (curr->inode == inode && curr->dev == dev)
			return 1;
		last = curr;
		curr = curr->next;
	}
	curr = xzalloc(sizeof(inode_list));
	last->next = curr;
	curr->dev = dev;
	curr->inode = inode;
	/*curr->next = NULL;*/
	return 1;
}

static int fuser_scan_proc_net(int opts, const char *proto,
	int port, inode_list *ilist)
{
	char path[sizeof(FUSER_PROC_DIR)+12], line[FUSER_MAX_LINE+1];
	char addr[128];
	ino_t tmp_inode;
	dev_t tmp_dev;
	long long uint64_inode;
	int tmp_port;
	FILE *f;

	if (!fuser_find_socket_dev(&tmp_dev))
		tmp_dev = 0;
	sprintf(path, FUSER_PROC_DIR "/net/%s", proto);

	f = fopen(path, "r");
	if (!f)
		return 0;
	while (fgets(line, FUSER_MAX_LINE, f)) {
		if (sscanf(line, "%*d: %64[0-9A-Fa-f]:%x %*x:%*x %*x %*x:%*x "
				"%*x:%*x %*x %*d %*d %llu",
				addr, &tmp_port, &uint64_inode) == 3
		) {
			if (strlen(addr) == 8 && (opts & FUSER_OPT_IP6))
				continue;
			if (strlen(addr) > 8 && (opts & FUSER_OPT_IP4))
				continue;
			if (tmp_port == port) {
				tmp_inode = uint64_inode;
				fuser_add_inode(ilist, tmp_dev, tmp_inode);
			}
		}
	}
	fclose(f);
	return 1;
}

static int fuser_search_dev_inode(int opts, inode_list *ilist,
	dev_t dev, ino_t inode)
{
	inode_list *curr;
	curr = ilist;

	while (curr) {
		if ((opts & FUSER_OPT_MOUNT) && curr->dev == dev)
			return 1;
		if (curr->inode == inode && curr->dev == dev)
			return 1;
		curr = curr->next;
	}
	return 0;
}

static int fuser_scan_pid_maps(int opts, const char *fname, pid_t pid,
	inode_list *ilist, pid_list *plist)
{
	FILE *file;
	char line[FUSER_MAX_LINE + 1];
	int major, minor;
	ino_t inode;
	long long uint64_inode;
	dev_t dev;

	file = fopen(fname, "r");
	if (!file)
		return 0;
	while (fgets(line, FUSER_MAX_LINE, file)) {
		if (sscanf(line, "%*s %*s %*s %x:%x %llu", &major, &minor, &uint64_inode) != 3)
			continue;
		inode = uint64_inode;
		if (major == 0 && minor == 0 && inode == 0)
			continue;
		dev = makedev(major, minor);
		if (fuser_search_dev_inode(opts, ilist, dev, inode)) {
			fuser_add_pid(plist, pid);
		}
	}
	fclose(file);
	return 1;
}

static int fuser_scan_link(int opts, const char *lname, pid_t pid,
	inode_list *ilist, pid_list *plist)
{
	ino_t inode;
	dev_t dev;

	if (!fuser_file_to_dev_inode(lname, &dev, &inode))
		return 0;
	if (fuser_search_dev_inode(opts, ilist, dev, inode))
		fuser_add_pid(plist, pid);
	return 1;
}

static int fuser_scan_dir_links(int opts, const char *dname, pid_t pid,
	inode_list *ilist, pid_list *plist)
{
	DIR *d;
	struct dirent *de;
	char *lname;

	d = opendir(dname);
	if (!d)
		return 0;
	while ((de = readdir(d)) != NULL) {
		lname = concat_subpath_file(dname, de->d_name);
		if (lname == NULL)
			continue;
		fuser_scan_link(opts, lname, pid, ilist, plist);
		free(lname);
	}
	closedir(d);
	return 1;
}

static int fuser_scan_proc_pids(int opts, inode_list *ilist, pid_list *plist)
{
	DIR *d;
	struct dirent *de;
	pid_t pid;
	char *dname;

	d = opendir(FUSER_PROC_DIR);
	if (!d)
		return 0;
	while ((de = readdir(d)) != NULL) {
		pid = (pid_t)atoi(de->d_name);
		if (!pid)
			continue;
		dname = concat_subpath_file(FUSER_PROC_DIR, de->d_name);
		if (chdir(dname) < 0) {
			free(dname);
			continue;
		}
		free(dname);
		fuser_scan_link(opts, "cwd", pid, ilist, plist);
		fuser_scan_link(opts, "exe", pid, ilist, plist);
		fuser_scan_link(opts, "root", pid, ilist, plist);
		fuser_scan_dir_links(opts, "fd", pid, ilist, plist);
		fuser_scan_dir_links(opts, "lib", pid, ilist, plist);
		fuser_scan_dir_links(opts, "mmap", pid, ilist, plist);
		fuser_scan_pid_maps(opts, "maps", pid, ilist, plist);
		chdir("..");
	}
	closedir(d);
	return 1;
}

static int fuser_print_pid_list(pid_list *plist)
{
	pid_list *curr = plist;

	if (plist == NULL)
		return 0;
	while (curr != NULL) {
		if (curr->pid > 0)
			printf("%d ", curr->pid);
		curr = curr->next;
	}
	puts("");
	return 1;
}

static int fuser_kill_pid_list(pid_list *plist, int sig)
{
	pid_list *curr = plist;
	pid_t mypid = getpid();
	int success = 1;

	if (plist == NULL)
		return 0;
	while (curr != NULL) {
		if (curr->pid > 0 && curr->pid != mypid) {
			if (kill(curr->pid, sig) != 0) {
				bb_perror_msg("kill pid '%d'", curr->pid);
				success = 0;
			}
		}
		curr = curr->next;
	}
	return success;
}

int fuser_main(int argc, char **argv);
int fuser_main(int argc, char **argv)
{
	/*static -- huh???*/ int opt = 0; /* FUSER_OPT_ */

	int port, i, optn;
	int* fni; /* file name indexes of argv */
	int fnic = 0;  /* file name index count */
	const char *proto;
	dev_t dev;
	ino_t inode;
	pid_list *pids;
	inode_list *inodes;
	int killsig = SIGTERM;
	int success = 1;

	if (argc < 2)
		bb_show_usage();

	fni = xmalloc(sizeof(int));
	for (i = 1; i < argc; i++) {
		optn = fuser_option(argv[i]);
		if (optn)
			opt |= optn;
		else if (argv[i][0] == '-') {
			killsig = get_signum(argv[i]+1);
			if (killsig < 0)
				killsig = SIGTERM;
		} else {
			fni = xrealloc(fni, sizeof(int) * (fnic+2));
			fni[fnic++] = i;
		}
	}

	if (!fnic)
		return 1;

	inodes = xmalloc(sizeof(inode_list));
	for (i = 0; i < fnic; i++) {
		if (fuser_parse_net_arg(argv[fni[i]], &proto, &port)) {
			fuser_scan_proc_net(opt, proto, port, inodes);
		} else {
			if (!fuser_file_to_dev_inode(argv[fni[i]], &dev, &inode)) {
				if (ENABLE_FEATURE_CLEAN_UP)
					free(inodes);
				bb_perror_msg_and_die("cannot open '%s'", argv[fni[i]]);
			}
			fuser_add_inode(inodes, dev, inode);
		}
	}
	pids = xmalloc(sizeof(pid_list));
	success = fuser_scan_proc_pids(opt, inodes, pids);
	/* if the first pid in the list is 0, none have been found */
	if (pids->pid == 0)
		success = 0;
	if (success) {
		if (opt & FUSER_OPT_KILL) {
			success = fuser_kill_pid_list(pids, killsig);
		} else if (!(opt & FUSER_OPT_SILENT)) {
			success = fuser_print_pid_list(pids);
		}
	}
	if (ENABLE_FEATURE_CLEAN_UP) {
		free(pids);
		free(inodes);
	}
	/* return 0 on (success == 1) 1 otherwise */
	return (success != 1);
}