/*
 * lslocks(8) - list local system locks
 *
 * Copyright (C) 2012 Davidlohr Bueso <dave@gnu.org>
 *
 * Very generally based on lslk(8) by Victor A. Abell <abe@purdue.edu>
 * Since it stopped being maintained over a decade ago, this
 * program should be considered its replacement.
 *
 * 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 would 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 <stdio.h>
#include <string.h>
#include <getopt.h>
#include <stdlib.h>
#include <assert.h>
#include <dirent.h>
#include <unistd.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <stdbool.h>
#include <search.h>

#include <libmount.h>
#include <libsmartcols.h>

#include "pathnames.h"
#include "canonicalize.h"
#include "nls.h"
#include "xalloc.h"
#include "strutils.h"
#include "c.h"
#include "cctype.h"
#include "list.h"
#include "closestream.h"
#include "optutils.h"
#include "procfs.h"
#include "column-list-table.h"
#include "fileutils.h"

/* column IDs */
enum {
	COL_SRC = 0,
	COL_PID,
	COL_TYPE,
	COL_SIZE,
	COL_INODE,
	COL_MAJMIN,
	COL_MODE,
	COL_M,
	COL_START,
	COL_END,
	COL_PATH,
	COL_BLOCKER,
	COL_HOLDERS,
};

/* column names */
struct colinfo {
	const char * const	name; /* header */
	double			whint; /* width hint (N < 1 is in percent of termwidth) */
	int			flags; /* SCOLS_FL_* */
	const char		*help;
};

/* columns descriptions */
static struct colinfo infos[] = {
	[COL_SRC]  = { "COMMAND",15, 0, N_("command of the process holding the lock") },
	[COL_PID]  = { "PID",     5, SCOLS_FL_RIGHT, N_("PID of the process holding the lock") },
	[COL_TYPE] = { "TYPE",    5, SCOLS_FL_RIGHT, N_("kind of lock") },
	[COL_SIZE] = { "SIZE",    4, SCOLS_FL_RIGHT, N_("size of the lock, use <number> if --bytes is given") },
	[COL_INODE] = { "INODE",  5, SCOLS_FL_RIGHT, N_("inode number") },
	[COL_MAJMIN] = { "MAJ:MIN", 6, 0, N_("major:minor device number") },
	[COL_MODE] = { "MODE",    5, 0, N_("lock access mode") },
	[COL_M]    = { "M",       1, 0, N_("mandatory state of the lock: 0 (none), 1 (set)")},
	[COL_START] = { "START", 10, SCOLS_FL_RIGHT, N_("relative byte offset of the lock")},
	[COL_END]  = { "END",    10, SCOLS_FL_RIGHT, N_("ending offset of the lock")},
	[COL_PATH] = { "PATH",    0, SCOLS_FL_TRUNC, N_("path of the locked file")},
	[COL_BLOCKER] = { "BLOCKER", 0, SCOLS_FL_RIGHT, N_("PID of the process blocking the lock") },
	[COL_HOLDERS] = { "HOLDERS", 0, SCOLS_FL_WRAP, N_("holders of the lock") },
};

static int columns[ARRAY_SIZE(infos) * 2];
static size_t ncolumns;

static inline void add_column(int id)
{
	if (ncolumns >= ARRAY_SIZE(columns))
		errx(EXIT_FAILURE, _("too many columns specified, "
				     "the limit is %zu columns"),
				ARRAY_SIZE(columns) - 1);
	columns[ncolumns++] = id;
}

struct lock {
	struct list_head locks;

	char *cmdname;
	pid_t pid;
	char *path;
	char *type;
	char *mode;
	off_t start;
	off_t end;
	ino_t inode;
	dev_t dev;
	bool  mandatory,
	      blocked;
	uint64_t size;
	int fd;
	int id;
};

struct lock_tnode {
	dev_t dev;
	ino_t inode;

	struct list_head chain;
};

struct lslocks {
	/* basic output flags */
	int no_headings;
	int no_inaccessible;
	int raw;
	int json;
	int bytes;

	pid_t target_pid;

	struct list_head proc_locks;
	void *pid_locks;
	struct libmnt_table *tab;		/* /proc/self/mountinfo */
};

static int lock_tnode_compare(const void *a, const void *b)
{
	struct lock_tnode *anode = ((struct lock_tnode *)a);
	struct lock_tnode *bnode = ((struct lock_tnode *)b);

	if (anode->dev > bnode->dev)
		return 1;
	else if (anode->dev < bnode->dev)
		return -1;

	if (anode->inode > bnode->inode)
		return 1;
	else if (anode->inode < bnode->inode)
		return -1;

	return 0;
}

static void add_to_tree(void *troot, struct lock *l)
{
	struct lock_tnode tmp = { .dev = l->dev, .inode = l->inode, };
	struct lock_tnode **head = tfind(&tmp, troot, lock_tnode_compare);
	struct lock_tnode *new_head;

	if (head) {
		list_add_tail(&l->locks, &(*head)->chain);
		return;
	}

	new_head = xmalloc(sizeof(*new_head));
	new_head->dev = l->dev;
	new_head->inode = l->inode;
	INIT_LIST_HEAD(&new_head->chain);
	if (tsearch(new_head, troot, lock_tnode_compare) == NULL)
		errx(EXIT_FAILURE, _("failed to allocate memory"));

	list_add_tail(&l->locks, &new_head->chain);
}

static void rem_lock(struct lock *lock)
{
	if (!lock)
		return;

	free(lock->path);
	free(lock->mode);
	free(lock->cmdname);
	free(lock->type);
	list_del(&lock->locks);
	free(lock);
}

static void disable_columns_truncate(void)
{
	for (size_t i = 0; i < ARRAY_SIZE(infos); i++)
		infos[i].flags &= ~SCOLS_FL_TRUNC;
}

/*
 * Associate the device's mountpoint for a filename
 */
static char *get_fallback_filename(struct libmnt_table *tab, dev_t dev)
{
	struct libmnt_fs *fs;
	char *res = NULL;

	fs = mnt_table_find_devno(tab, dev, MNT_ITER_BACKWARD);
	if (!fs)
		return NULL;

	xasprintf(&res, "%s...", mnt_fs_get_target(fs));
	return res;
}

/*
 * Return the absolute path of a file from
 * a given inode number (and its size)
 */
static char *get_filename_sz(ino_t inode, pid_t lock_pid, size_t *size)
{
	struct stat sb;
	struct dirent *dp;
	DIR *dirp;
	int fd;
	char path[PATH_MAX] = { 0 },
	     sym[PATH_MAX] = { 0 }, *ret = NULL;

	*size = 0;

	if (lock_pid < 0)
		/* pid could be -1 for OFD locks */
		return NULL;

	/*
	 * We know the pid so we don't have to
	 * iterate the *entire* filesystem searching
	 * for the damn file.
	 */
	snprintf(path, sizeof(path), "/proc/%d/fd/", lock_pid);
	if (!(dirp = opendir(path)))
		return NULL;

	if (strlen(path) >= (sizeof(path) - 2))
		goto out;

	if ((fd = dirfd(dirp)) < 0 )
		goto out;

	while ((dp = xreaddir(dirp))) {
		ssize_t len;

		errno = 0;

		/* care only for numerical descriptors */
		if (!strtol(dp->d_name, (char **) NULL, 10) || errno)
			continue;

		if (!fstatat(fd, dp->d_name, &sb, 0)
		    && inode != sb.st_ino)
			continue;

		if ((len = readlinkat(fd, dp->d_name, sym, sizeof(sym) - 1)) < 1)
			goto out;

		*size = sb.st_size;
		sym[len] = '\0';

		ret = xstrdup(sym);
		break;
	}
out:
	closedir(dirp);
	return ret;
}

/*
 * Return the inode number from a string
 */
static ino_t get_dev_inode(char *str, dev_t *dev)
{
	unsigned int maj = 0, min = 0;
	ino_t inum = 0;

	if (sscanf(str, "%x:%x:%ju", &maj, &min, &inum) != 3)
		errx(EXIT_FAILURE, _("failed to parse '%s'"), str);

	*dev = (dev_t) makedev(maj, min);
	return inum;
}

struct override_info {
	pid_t pid;
	const char *cmdname;
};

static bool is_holder(struct lock *l, struct lock *m)
{
	return (l->start == m->start &&
		l->end == m->end &&
		l->inode == m->inode &&
		l->dev == m->dev &&
		l->mandatory == m->mandatory &&
		l->blocked == m->blocked &&
		strcmp(l->type, m->type) == 0 &&
		strcmp(l->mode, m->mode) == 0);
}

static void patch_lock(struct lock *l, void *fallback)
{
	struct lock_tnode tmp = { .dev = l->dev, .inode = l->inode, };
	struct lock_tnode **head = tfind(&tmp, fallback, lock_tnode_compare);
	struct list_head *p;

	if (!head)
		return;

	list_for_each(p, &(*head)->chain) {
		struct lock *m = list_entry(p, struct lock, locks);
		if (is_holder(l, m)) {
			/* size and id can be ignored. */
			l->pid = m->pid;
			l->cmdname = xstrdup(m->cmdname);
			break;
		}
	}
}

static void add_to_list(struct list_head *locks, struct lock *l)
{
	list_add(&l->locks, locks);
}

static struct lock *get_lock(char *buf, struct override_info *oinfo, void *fallback)
{
	int i;
	char *tok = NULL;
	size_t sz;
	struct lock *l = xcalloc(1, sizeof(*l));
	INIT_LIST_HEAD(&l->locks);
	l->fd = -1;

	bool cmdname_unknown = false;

	for (tok = strtok(buf, " "), i = 0; tok;
	     tok = strtok(NULL, " "), i++) {

		/*
		 * /proc/locks has *exactly* 8 "blocks" of text
		 * separated by ' ' - check <kernel>/fs/locks.c
		 */
		switch (i) {
		case 0: /* ID: */
			if (oinfo)
				l->id = -1;
			else {
				tok[strlen(tok) - 1] = '\0';
				l->id = strtos32_or_err(tok, _("failed to parse ID"));
			}
			break;
		case 1: /* posix, flock, etc */
			if (strcmp(tok, "->") == 0) {	/* optional field */
				l->blocked = 1;
				i--;
			} else
				l->type = xstrdup(tok);
			break;

		case 2: /* is this a mandatory lock? other values are advisory or noinode */
			l->mandatory = *tok == 'M' ? 1 : 0;
			break;
		case 3: /* lock mode */
			l->mode = xstrdup(tok);
			break;

		case 4: /* PID */
			/*
			 * If user passed a pid we filter it later when adding
			 * to the list, no need to worry now. OFD locks use -1 PID.
			 */
			if (oinfo) {
				l->pid = oinfo->pid;
				l->cmdname = xstrdup(oinfo->cmdname);
			} else {
				/* strtopid_or_err() is not suitable here; tok can be -1.*/
				l->pid = strtos32_or_err(tok, _("invalid PID argument"));
				if (l->pid > 0) {
					l->cmdname = pid_get_cmdname(l->pid);
					if (!l->cmdname)
						cmdname_unknown = true;
				} else
					l->cmdname = NULL;
			}
			break;

		case 5: /* device major:minor and inode number */
			l->inode = get_dev_inode(tok, &l->dev);
			break;

		case 6: /* start */
			l->start = !strcmp(tok, "EOF") ? 0 :
			strtou64_or_err(tok, _("failed to parse start"));
			break;

		case 7: /* end */
			/* replace '\n' character */
			tok[strlen(tok)-1] = '\0';
			l->end = !strcmp(tok, "EOF") ? 0 :
				strtou64_or_err(tok, _("failed to parse end"));
			break;
		default:
			break;
		}
	}

	if ((!l->blocked) && fallback && !l->cmdname)
		patch_lock(l, fallback);
	if (!l->cmdname) {
		if (cmdname_unknown)
			l->cmdname = xstrdup(_("(unknown)"));
		else
			l->cmdname = xstrdup(_("(undefined)"));
	}
	l->path = get_filename_sz(l->inode, l->pid, &sz);
	if (l->path)
		l->size = sz;

	return l;
}

static struct lock *refine_lock(struct lock *lock,
				int no_inaccessible, struct libmnt_table *tab)
{
	/* no permissions -- ignore */
	if (!lock->path && no_inaccessible) {
		rem_lock(lock);
		return NULL;
	}

	if (!lock->path) {
		/* probably no permission to peek into l->pid's path */
		lock->path = tab
			? get_fallback_filename(tab, lock->dev)
			: NULL;
		lock->size = 0;
	}

	return lock;
}

static int get_pid_lock(struct lslocks *lslocks, FILE *fp,
			pid_t pid, const char *cmdname, int fd)
{
	char buf[PATH_MAX];
	struct override_info oinfo = {
		.pid = pid,
		.cmdname = cmdname,
	};

	while (fgets(buf, sizeof(buf), fp)) {
		struct lock *l;
		if (strncmp(buf, "lock:\t", 6))
			continue;
		l = get_lock(buf + 6, &oinfo, NULL);
		if (l)
			l = refine_lock(l, lslocks->no_inaccessible,
					lslocks->tab);
		if (l) {
			add_to_tree(&lslocks->pid_locks, l);
			l->fd = fd;
		}
		/* no break here.
		   Multiple recode locks can be taken via one fd. */
	}

	return 0;
}

static int get_pid_locks(struct lslocks *lslocks,
			 struct path_cxt *pc,
			 pid_t pid, const char *cmdname)
{
	DIR *sub = NULL;
	struct dirent *d = NULL;
	int rc = 0;

	while (ul_path_next_dirent(pc, &sub, "fdinfo", &d) == 0) {
		uint64_t num;
		FILE *fdinfo;

		if (ul_strtou64(d->d_name, &num, 10) != 0)	/* only numbers */
			continue;

		fdinfo = ul_path_fopenf(pc, "r", "fdinfo/%ju", num);
		if (fdinfo == NULL)
			continue;

		get_pid_lock(lslocks, fdinfo, pid, cmdname, (int)num);
		fclose(fdinfo);
	}

	return rc;
}

static void get_pids_locks(struct lslocks *lslocks)
{
	DIR *dir;
	struct dirent *d;
	struct path_cxt *pc = NULL;

	pc = ul_new_path(NULL);
	if (!pc)
		err(EXIT_FAILURE, _("failed to alloc procfs handler"));

	dir = opendir(_PATH_PROC);
	if (!dir)
		err(EXIT_FAILURE, _("failed to open /proc"));

	while ((d = readdir(dir))) {
		pid_t pid;
		char buf[BUFSIZ];
		const char *cmdname = NULL;

		if (procfs_dirent_get_pid(d, &pid) != 0)
			continue;

		if (procfs_process_init_path(pc, pid) != 0)
			continue;

		if (procfs_process_get_cmdname(pc, buf, sizeof(buf)) <= 0)
			continue;
		cmdname = buf;

		get_pid_locks(lslocks, pc, pid, cmdname);
	}

	closedir(dir);
	ul_unref_path(pc);

	return;
}

static int get_proc_locks(struct lslocks *lslocks)
{
	FILE *fp;
	char buf[PATH_MAX];

	if (!(fp = fopen(_PATH_PROC_LOCKS, "r")))
		return -1;

	while (fgets(buf, sizeof(buf), fp)) {
		struct lock *l = get_lock(buf, NULL, &lslocks->pid_locks);
		if (l)
			l = refine_lock(l, lslocks->no_inaccessible,
					lslocks->tab);
		if (l)
			add_to_list(&lslocks->proc_locks, l);
	}

	fclose(fp);
	return 0;
}

static int column_name_to_id(const char *name, size_t namesz)
{
	assert(name);

	for (size_t i = 0; i < ARRAY_SIZE(infos); i++) {
		const char *cn = infos[i].name;

		if (!c_strncasecmp(name, cn, namesz) && !*(cn + namesz))
			return i;
	}
	warnx(_("unknown column: %s"), name);
	return -1;
}

static inline int get_column_id(int num)
{
	assert(num >= 0);
	assert((size_t) num < ncolumns);
	assert(columns[num] < (int) ARRAY_SIZE(infos));

	return columns[num];
}


static inline const struct colinfo *get_column_info(unsigned num)
{
	return &infos[ get_column_id(num) ];
}

static pid_t get_blocker(int id, struct list_head *locks)
{
	struct list_head *p;

	list_for_each(p, locks) {
		struct lock *l = list_entry(p, struct lock, locks);

		if (l->id == id && !l->blocked)
			return l->pid;
	}

	return 0;
}

static void xstrcoholder(char **str, struct lock *l)
{
	xstrfappend(str, "%d,%s,%d",
		    l->pid, l->cmdname, l->fd);
}

static char *get_data(struct lslocks *lslocks, struct lock *l, int num,
		      uint64_t *rawdata)
{
	char *str = NULL;

	/*
	 * Whenever cmdname or filename is NULL it is most
	 * likely  because there's no read permissions
	 * for the specified process.
	 */
	const char *notfnd = "";

	switch (get_column_id(num)) {
	case COL_SRC:
		xasprintf(&str, "%s", l->cmdname ? l->cmdname : notfnd);
		break;
	case COL_PID:
		xasprintf(&str, "%d", l->pid);
		if (l->pid >= 0 && rawdata)
			*rawdata = (uint64_t)l->pid;
		break;
	case COL_TYPE:
		xasprintf(&str, "%s", l->type);
		break;
	case COL_INODE:
		xasprintf(&str, "%ju", (uintmax_t) l->inode);
		break;
	case COL_MAJMIN:
		if (lslocks->json || lslocks->raw)
			xasprintf(&str, "%u:%u", major(l->dev), minor(l->dev));
		else
			xasprintf(&str, "%3u:%-3u", major(l->dev), minor(l->dev));
		break;
	case COL_SIZE:
		if (!l->size)
			break;
		if (lslocks->bytes)
			xasprintf(&str, "%ju", l->size);
		else
			str = size_to_human_string(SIZE_SUFFIX_1LETTER, l->size);
		if (rawdata)
			*rawdata = l->size;
		break;
	case COL_MODE:
		xasprintf(&str, "%s%s", l->mode, l->blocked ? "*" : "");
		break;
	case COL_M:
		xasprintf(&str, "%d", l->mandatory ? 1 : 0);
		break;
	case COL_START:
		xasprintf(&str, "%jd", l->start);
		break;
	case COL_END:
		xasprintf(&str, "%jd", l->end);
		break;
	case COL_PATH:
		xasprintf(&str, "%s", l->path ? l->path : notfnd);
		break;
	case COL_BLOCKER:
	{
		pid_t bl = l->blocked && l->id ?
			get_blocker(l->id, &lslocks->proc_locks) : 0;
		if (bl)
			xasprintf(&str, "%d", (int) bl);
		break;
	}
	case COL_HOLDERS:
	{
		struct lock_tnode tmp = { .dev = l->dev, .inode = l->inode, };
		struct lock_tnode **head = tfind(&tmp, &lslocks->pid_locks, lock_tnode_compare);
		struct list_head *p;

		if (!head)
			break;

		list_for_each(p, &(*head)->chain) {
			struct lock *m = list_entry(p, struct lock, locks);

			if (!is_holder(l, m))
				continue;

			if (str)
				xstrputc(&str, '\n');
			xstrcoholder(&str, m);
		}
		break;
	}
	default:
		break;
	}

	return str;
}

static void set_line_data(struct libscols_line *line, size_t i, char *data)
{
	if (data && scols_line_refer_data(line, i, data))
		err(EXIT_FAILURE, _("failed to add output data"));
}

struct filler_data {
	struct lslocks *lslocks;
	struct lock *l;
	struct libscols_table *table;
};

/* stores data to scols cell userdata (invisible and independent on output)
 * to make the original values accessible for sort functions
 */
static void set_rawdata_u64(struct libscols_line *ln, int col, uint64_t x)
{
	struct libscols_cell *ce = scols_line_get_cell(ln, col);
	uint64_t *data;

	if (!ce)
		return;
	data = xmalloc(sizeof(uint64_t));
	*data = x;
	scols_cell_set_userdata(ce, data);
}

static int filter_filler_cb(struct libscols_filter *filter __attribute__((__unused__)),
			    struct libscols_line *line,
			    size_t column_index,
			    void *userdata)
{
	struct filler_data *fid = (struct filler_data *)userdata;
	struct libscols_column *cl = scols_table_get_column(fid->table, column_index);
	bool needs_rawdata = !!scols_column_has_data_func(cl);
	uint64_t rawdata = (uint64_t) -1;
	char *data = get_data(fid->lslocks, fid->l, column_index,
			      needs_rawdata ? &rawdata : NULL);
	if (data) {
		set_line_data(line, column_index, data);
		if (needs_rawdata && rawdata != (uint64_t) -1)
			set_rawdata_u64(line, column_index, rawdata);
	}
	return 0;
}

static void unref_line_rawdata(struct libscols_line *ln, struct libscols_table *tb)
{
	size_t i;

	for (i = 0; i < ncolumns; i++) {
		struct libscols_column *cl = scols_table_get_column(tb, i);
		struct libscols_cell *ce;
		void *data;

		if (!scols_column_has_data_func(cl))
			continue;

		ce = scols_line_get_column_cell(ln, cl);
		data = scols_cell_get_userdata(ce);
		free(data);
	}
}

static void add_scols_line(struct lslocks *lslocks,
			   struct libscols_table *table, struct libscols_filter *filter,
			   struct lock *l)
{
	struct libscols_line *line;
	struct filler_data fid = {
		.lslocks = lslocks,
		.l = l,
		.table = table,
	};

	assert(l);
	assert(table);

	line = scols_table_new_line(table, NULL);
	if (!line)
		err(EXIT_FAILURE, _("failed to allocate output line"));

	if (filter) {
		int status = 0;
		scols_filter_set_filler_cb(filter,
					   filter_filler_cb, (void *)&fid);

		if (scols_line_apply_filter(line, filter, &status))
			err(EXIT_FAILURE, _("failed to apply filter"));

		if (status == 0) {
			unref_line_rawdata(line, table);
			scols_table_remove_line(table, line);
			return;
		}
	}

	for (size_t i = 0; i < ncolumns; i++) {
		char *str;

		if (scols_line_is_filled(line, i))
			continue;

		str = get_data(lslocks, l,  i, NULL);
		if (str)
			set_line_data(line, i, str);
	}
}

static void rem_locks(struct list_head *locks)
{
	struct list_head *p, *pnext;

	/* destroy the list */
	list_for_each_safe(p, pnext, locks) {
		struct lock *l = list_entry(p, struct lock, locks);
		rem_lock(l);
	}
}

static void rem_tnode(void *node)
{
	struct lock_tnode *tnode = node;

	rem_locks(&tnode->chain);
	free(node);
}

static int get_json_type_for_column(int column_id, int bytes)
{
	switch (column_id) {
	case COL_SIZE:
		if (!bytes)
			return SCOLS_JSON_STRING;
		FALLTHROUGH;
	case COL_PID:
	case COL_START:
	case COL_END:
	case COL_BLOCKER:
	case COL_INODE:
		return SCOLS_JSON_NUMBER;
	case COL_M:
		return SCOLS_JSON_BOOLEAN;
	case COL_HOLDERS:
		return SCOLS_JSON_ARRAY_STRING;
	default:
		return SCOLS_JSON_STRING;
	}
}

static struct libscols_table *init_scols_table(int raw, int json, int no_headings, int bytes,
					       bool use_filter)
{
	struct libscols_table *table;

	table = scols_new_table();
	if (!table)
		err(EXIT_FAILURE, _("failed to allocate output table"));

	scols_table_enable_raw(table, raw);
	scols_table_enable_json(table, json);
	scols_table_enable_noheadings(table, no_headings);

	if (json)
		scols_table_set_name(table, "locks");

	for (size_t i = 0; i < ncolumns; i++) {
		struct libscols_column *cl;
		const struct colinfo *col = get_column_info(i);

		cl = scols_table_new_column(table, col->name, col->whint, col->flags);
		if (!cl)
			err(EXIT_FAILURE, _("failed to allocate output column"));

		if (col->flags & SCOLS_FL_WRAP) {
			scols_column_set_wrapfunc(cl,
						  scols_wrapnl_chunksize,
						  scols_wrapnl_nextchunk,
						  NULL);
			scols_column_set_safechars(cl, "\n");
		}

		if (json || use_filter) {
			int id = get_column_id(i);
			int json_type = get_json_type_for_column(id, bytes);
			scols_column_set_json_type(cl, json_type);
		}

	}
	return table;
}

static int show_locks(struct lslocks *lslocks, struct libscols_table *table,
		      struct libscols_filter *filter)
{
	struct list_head *p;

	/* prepare data for output */
	list_for_each(p, &lslocks->proc_locks) {
		struct lock *l = list_entry(p, struct lock, locks);

		if (lslocks->target_pid && lslocks->target_pid != l->pid)
			continue;


		add_scols_line(lslocks, table, filter, l);
	}

	scols_print_table(table);
	return 0;
}


static void __attribute__((__noreturn__)) usage(void)
{
	FILE *out = stdout;

	fputs(USAGE_HEADER, out);

	fprintf(out,
		_(" %s [options]\n"), program_invocation_short_name);

	fputs(USAGE_SEPARATOR, out);
	fputs(_("List local system locks.\n"), out);

	fputs(USAGE_OPTIONS, out);
	fputs(_(" -b, --bytes            print SIZE in bytes rather than in human readable format\n"), out);
	fputs(_(" -J, --json             use JSON output format\n"), out);
	fputs(_(" -i, --noinaccessible   ignore locks without read permissions\n"), out);
	fputs(_(" -n, --noheadings       don't print headings\n"), out);
	fputs(_(" -o, --output <list>    output columns (see --list-columns)\n"), out);
	fputs(_("     --output-all       output all columns\n"), out);
	fputs(_(" -p, --pid <pid>        display only locks held by this process\n"), out);
	fputs(_(" -Q, --filter <expr>    apply display filter\n"), out);
	fputs(_(" -r, --raw              use the raw output format\n"), out);
	fputs(_(" -u, --notruncate       don't truncate text in columns\n"), out);

	fputs(USAGE_SEPARATOR, out);
	fprintf(out, USAGE_LIST_COLUMNS_OPTION(24));
	fprintf(out, USAGE_HELP_OPTIONS(24));
	fprintf(out, USAGE_MAN_TAIL("lslocks(8)"));

	exit(EXIT_SUCCESS);
}

static void __attribute__((__noreturn__)) list_columns(struct lslocks *lslocks)
{
	struct libscols_table *col_tb = xcolumn_list_table_new(
					"lslocks-columns", stdout, lslocks->raw, lslocks->json);

	for (size_t i = 0; i < ARRAY_SIZE(infos); i++) {
		if (i != COL_SIZE) {
			int json_type = get_json_type_for_column(i, lslocks->bytes);
			xcolumn_list_table_append_line(col_tb, infos[i].name,
						       json_type, NULL,
						       _(infos[i].help));
		} else
			xcolumn_list_table_append_line(col_tb, infos[i].name,
						       -1, "<string|number>",
						       _(infos[i].help));
	}

	scols_print_table(col_tb);
	scols_unref_table(col_tb);

	exit(EXIT_SUCCESS);
}

static struct libscols_filter *new_filter(const char *query)
{
	struct libscols_filter *f;

	f = scols_new_filter(NULL);
	if (!f)
		err(EXIT_FAILURE, _("failed to allocate filter"));
	if (query && scols_filter_parse_string(f, query) != 0)
		errx(EXIT_FAILURE, _("failed to parse \"%s\": %s"), query,
		     scols_filter_get_errmsg(f));
	return f;
}

static void *get_u64_cell(const struct libscols_column *cl __attribute__((__unused__)),
			  struct libscols_cell *ce,
			  void *data __attribute__((__unused__)))
{
	return scols_cell_get_userdata(ce);
}

static void init_scols_filter(struct libscols_table *tb, struct libscols_filter *filter,
			      int bytes)
{
	struct libscols_iter *itr;
	const char *name = NULL;
	int nerrs = 0;

	itr = scols_new_iter(SCOLS_ITER_FORWARD);
	if (!itr)
		err(EXIT_FAILURE, _("failed to allocate iterator"));

	while (scols_filter_next_holder(filter, itr, &name, 0) == 0) {
		struct libscols_column *col = scols_table_get_column_by_name(tb, name);
		int id = column_name_to_id(name, strlen(name));
		const struct colinfo *ci = id >= 0 ? &infos[id] : NULL;

		if (!ci) {
			nerrs++;
			continue;   /* report all unknown columns */
		}
		if (!col) {
			int json_type = get_json_type_for_column(id, bytes);
			add_column(id);
			col = scols_table_new_column(tb, ci->name,
						     ci->whint, SCOLS_FL_HIDDEN);
			if (!col)
				err(EXIT_FAILURE, _("failed to allocate output column"));

			scols_column_set_json_type(col, json_type);
		}

		if ((id == COL_SIZE && !bytes) || id == COL_PID) {
			scols_column_set_data_type(col, SCOLS_DATA_U64);
			scols_column_set_data_func(col, get_u64_cell, NULL);
		}

		scols_filter_assign_column(filter, itr, name, col);
	}

	scols_free_iter(itr);

	if (!nerrs)
		return;

	errx(EXIT_FAILURE, _("failed to initialize filter"));
}

static void unref_table_rawdata(struct libscols_table *tb)
{
	struct libscols_iter *itr;
	struct libscols_line *ln;

	itr = scols_new_iter(SCOLS_ITER_FORWARD);
	if (!itr)
		return;
	while (scols_table_next_line(tb, itr, &ln) == 0)
		unref_line_rawdata(ln, tb);

	scols_free_iter(itr);
}

static void lslocks_init(struct lslocks *lslocks)
{
	memset(lslocks, 0, sizeof(*lslocks));

	INIT_LIST_HEAD(&lslocks->proc_locks);
}

static void lslocks_free(struct lslocks *lslocks)
{
	rem_locks(&lslocks->proc_locks);
	tdestroy(lslocks->pid_locks, rem_tnode);
}

int main(int argc, char *argv[])
{
	struct lslocks lslocks;
	int c, rc = 0, collist = 0;
	struct libscols_table *table;
	struct libscols_filter *filter = NULL;
	char *outarg = NULL;
	enum {
		OPT_OUTPUT_ALL = CHAR_MAX + 1
	};
	static const struct option long_opts[] = {
		{ "bytes",      no_argument,       NULL, 'b' },
		{ "json",       no_argument,       NULL, 'J' },
		{ "pid",	required_argument, NULL, 'p' },
		{ "help",	no_argument,       NULL, 'h' },
		{ "output",     required_argument, NULL, 'o' },
		{ "output-all",	no_argument,       NULL, OPT_OUTPUT_ALL },
		{ "notruncate", no_argument,       NULL, 'u' },
		{ "version",    no_argument,       NULL, 'V' },
		{ "noheadings", no_argument,       NULL, 'n' },
		{ "raw",        no_argument,       NULL, 'r' },
		{ "noinaccessible", no_argument, NULL, 'i' },
		{ "filter",     required_argument, NULL, 'Q' },
		{ "list-columns", no_argument,     NULL, 'H' },
		{ NULL, 0, NULL, 0 }
	};

	static const ul_excl_t excl[] = {	/* rows and cols in ASCII order */
		{ 'J','r' },
		{ 0 }
	};
	int excl_st[ARRAY_SIZE(excl)] = UL_EXCL_STATUS_INIT;

	setlocale(LC_ALL, "");
	bindtextdomain(PACKAGE, LOCALEDIR);
	textdomain(PACKAGE);
	close_stdout_atexit();

	lslocks_init(&lslocks);

	while ((c = getopt_long(argc, argv,
				"biJp:o:nruhVHQ:", long_opts, NULL)) != -1) {

		err_exclusive_options(c, long_opts, excl, excl_st);

		switch(c) {
		case 'b':
			lslocks.bytes = 1;
			break;
		case 'i':
			lslocks.no_inaccessible = 1;
			break;
		case 'J':
			lslocks.json = 1;
			break;
		case 'p':
			lslocks.target_pid = strtopid_or_err(optarg, _("invalid PID argument"));
			break;
		case 'o':
			outarg = optarg;
			break;
		case OPT_OUTPUT_ALL:
			for (ncolumns = 0; ncolumns < ARRAY_SIZE(infos); ncolumns++)
				columns[ncolumns] = ncolumns;
			break;
		case 'n':
			lslocks.no_headings = 1;
			break;
		case 'r':
			lslocks.raw = 1;
			break;
		case 'u':
			disable_columns_truncate();
			break;

		case 'H':
			collist = 1;
			break;
		case 'Q':
			filter = new_filter(optarg);
			break;
		case 'V':
			print_version(EXIT_SUCCESS);
		case 'h':
			usage();
		default:
			errtryhelp(EXIT_FAILURE);
		}
	}

	if (collist)
		list_columns(&lslocks);	/* print end exit */

	if (!ncolumns) {
		/* default columns */
		columns[ncolumns++] = COL_SRC;
		columns[ncolumns++] = COL_PID;
		columns[ncolumns++] = COL_TYPE;
		columns[ncolumns++] = COL_SIZE;
		columns[ncolumns++] = COL_MODE;
		columns[ncolumns++] = COL_M;
		columns[ncolumns++] = COL_START;
		columns[ncolumns++] = COL_END;
		columns[ncolumns++] = COL_PATH;
	}

	if (!outarg)
		outarg = getenv("LSLOCKS_COLUMNS");
	if (outarg && string_add_to_idarray(outarg, columns, ARRAY_SIZE(columns),
					 &ncolumns, column_name_to_id) < 0)
		return EXIT_FAILURE;

	scols_init_debug(0);
	table = init_scols_table(lslocks.raw, lslocks.json, lslocks.no_headings, lslocks.bytes,
				 (bool)filter);
	if (filter)
		init_scols_filter(table, filter, lslocks.bytes);

	/* get_pids_locks() get locks related information from "lock:" fields
	 * of /proc/$pid/fdinfo/$fd as fallback information.
	 * get_proc_locks() used the fallback information if /proc/locks
	 * doesn't provide enough information or provides stale information. */
	lslocks.tab = mnt_new_table_from_file(_PATH_PROC_MOUNTINFO);
	get_pids_locks(&lslocks);
	rc = get_proc_locks(&lslocks);
	mnt_unref_table(lslocks.tab);

	if (!rc && !list_empty(&lslocks.proc_locks))
		rc = show_locks(&lslocks, table, filter);

	scols_unref_filter(filter);
	unref_table_rawdata(table);
	scols_unref_table(table);

	lslocks_free(&lslocks);
	return rc;
}