/*-
 * SPDX-License-Identifier: BSD-3-Clause
 *
 * Copyright (c) 1989, 1993, 1994
 *      The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Chris Newcomb.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <sys/param.h>
#include <sys/queue.h>
#include <sys/stat.h>
#include <err.h>
#include <errno.h>
#include <fnmatch.h>
#include <fts.h>
#include <getopt.h>
#include <libutil.h>
#include <locale.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>
#include <string.h>
#include <sysexits.h>
#include <unistd.h>
#include <libxo/xo.h>

#define SI_OPT  (CHAR_MAX + 1)

#define UNITS_2         1
#define UNITS_SI        2

#define DU_XO_VERSION "1"

static SLIST_HEAD(ignhead, ignentry) ignores;
struct ignentry {
        char                    *mask;
        SLIST_ENTRY(ignentry)   next;
};

static bool     check_threshold(FTSENT *);
static void     ignoreadd(const char *);
static void     ignoreclean(void);
static int      ignorep(FTSENT *);
static int      linkchk(FTSENT *);
static void     print_file_size(FTSENT *);
static void     prthumanval(const char *, int64_t);
static void     record_file_size(FTSENT *);
static void     siginfo(int __unused);
static void     usage(void);

static int      nodumpflag = 0;
static int      Aflag, hflag;
static long     blocksize, cblocksize;
static volatile sig_atomic_t info;
static off_t    threshold, threshold_sign;

static const struct option long_options[] = {
        { "si", no_argument, NULL, SI_OPT },
        { NULL, no_argument, NULL, 0 },
};

int
main(int argc, char *argv[])
{
        FTS             *fts;
        FTSENT          *p;
        off_t           savednumber;
        int             ftsoptions;
        int             depth;
        int             Hflag, Lflag, aflag, sflag, dflag, cflag;
        int             lflag, ch, notused, rval;
        char            **save;
        static char     dot[] = ".";

        setlocale(LC_ALL, "");

        Hflag = Lflag = aflag = sflag = dflag = cflag = lflag = Aflag = 0;

        save = argv;
        ftsoptions = FTS_PHYSICAL;
        savednumber = 0;
        threshold = 0;
        threshold_sign = 1;
        cblocksize = DEV_BSIZE;
        blocksize = 0;
        depth = INT_MAX;
        SLIST_INIT(&ignores);

        argc = xo_parse_args(argc, argv);
        if (argc < 0)
                exit(EX_USAGE);

        while ((ch = getopt_long(argc, argv, "+AB:HI:LPasd:cghklmnrt:x",
            long_options, NULL)) != -1)
                switch (ch) {
                case 'A':
                        Aflag = 1;
                        break;
                case 'B':
                        errno = 0;
                        cblocksize = atoi(optarg);
                        if (errno == ERANGE || cblocksize <= 0) {
                                xo_warnx("invalid argument to option B: %s",
                                    optarg);
                                usage();
                        }
                        break;
                case 'H':
                        Hflag = 1;
                        Lflag = 0;
                        break;
                case 'I':
                        ignoreadd(optarg);
                        break;
                case 'L':
                        Lflag = 1;
                        Hflag = 0;
                        break;
                case 'P':
                        Hflag = Lflag = 0;
                        break;
                case 'a':
                        aflag = 1;
                        break;
                case 's':
                        sflag = 1;
                        break;
                case 'd':
                        dflag = 1;
                        errno = 0;
                        depth = atoi(optarg);
                        if (errno == ERANGE || depth < 0) {
                                xo_warnx("invalid argument to option d: %s",
                                    optarg);
                                usage();
                        }
                        break;
                case 'c':
                        cflag = 1;
                        break;
                case 'g':
                        hflag = 0;
                        blocksize = 1073741824;
                        break;
                case 'h':
                        hflag = UNITS_2;
                        break;
                case 'k':
                        hflag = 0;
                        blocksize = 1024;
                        break;
                case 'l':
                        lflag = 1;
                        break;
                case 'm':
                        hflag = 0;
                        blocksize = 1048576;
                        break;
                case 'n':
                        nodumpflag = 1;
                        break;
                case 'r':                /* Compatibility. */
                        break;
                case 't':
                        if (expand_number(optarg, &threshold) != 0 ||
                            threshold == 0) {
                                xo_warnx("invalid threshold: %s", optarg);
                                usage();
                        } else if (threshold < 0)
                                threshold_sign = -1;
                        break;
                case 'x':
                        ftsoptions |= FTS_XDEV;
                        break;
                case SI_OPT:
                        hflag = UNITS_SI;
                        break;
                case '?':
                default:
                        usage();
                        /* NOTREACHED */
                }

        argc -= optind;
        argv += optind;

        /*
         * XXX
         * Because of the way that fts(3) works, logical walks will not count
         * the blocks actually used by symbolic links.  We rationalize this by
         * noting that users computing logical sizes are likely to do logical
         * copies, so not counting the links is correct.  The real reason is
         * that we'd have to re-implement the kernel's symbolic link traversing
         * algorithm to get this right.  If, for example, you have relative
         * symbolic links referencing other relative symbolic links, it gets
         * very nasty, very fast.  The bottom line is that it's documented in
         * the man page, so it's a feature.
         */

        if (Hflag)
                ftsoptions |= FTS_COMFOLLOW;
        if (Lflag) {
                ftsoptions &= ~FTS_PHYSICAL;
                ftsoptions |= FTS_LOGICAL;
        }

        if (!Aflag && (cblocksize % DEV_BSIZE) != 0)
                cblocksize = howmany(cblocksize, DEV_BSIZE) * DEV_BSIZE;

        if (aflag + dflag + sflag > 1)
                usage();
        if (sflag)
                depth = 0;

        if (!*argv) {
                argv = save;
                argv[0] = dot;
                argv[1] = NULL;
        }

        if (blocksize == 0)
                (void)getbsize(&notused, &blocksize);

        if (!Aflag) {
                cblocksize /= DEV_BSIZE;
                blocksize /= DEV_BSIZE;
        }

        if (threshold != 0)
                threshold = howmany(threshold / DEV_BSIZE * cblocksize,
                    blocksize);

        rval = 0;

        (void)signal(SIGINFO, siginfo);

        if ((fts = fts_open(argv, ftsoptions, NULL)) == NULL)
                err(1, "fts_open");


        xo_set_version(DU_XO_VERSION);
        xo_open_container("disk-usage-information");
        xo_open_list("paths");
        while (errno = 0, (p = fts_read(fts)) != NULL) {
                switch (p->fts_info) {
                case FTS_D:                     /* Ignore. */
                        if (ignorep(p))
                                fts_set(fts, p, FTS_SKIP);
                        break;
                case FTS_DP:                    /* Directory files */
                        if (ignorep(p))
                                break;

                        record_file_size(p);

                        if (p->fts_level <= depth && check_threshold(p))
                                print_file_size(p);

                        if (info) {
                                info = 0;
                                (void)printf("\t%s\n", p->fts_path);
                        }
                        break;
                case FTS_DC:                    /* Ignore. */
                        break;
                case FTS_DNR:                   /* Warn, continue. */
                case FTS_ERR:
                case FTS_NS:
                        xo_warnx("%s: %s", p->fts_path, strerror(p->fts_errno));
                        rval = 1;
                        break;
                default:                        /* All other files */
                        if (ignorep(p))
                                break;

                        if (lflag == 0 && p->fts_statp->st_nlink > 1 &&
                            linkchk(p))
                                break;

                        record_file_size(p);

                        if ((aflag || p->fts_level == 0) && check_threshold(p))
                                print_file_size(p);
                }
                savednumber = p->fts_parent->fts_number;
        }
        xo_close_list("paths");

        if (errno)
                xo_err(1, "fts_read");

        if (cflag) {
                if (hflag > 0) {
                        prthumanval("{:total-blocks/%4s}\ttotal\n",
                            savednumber);
                } else {
                        xo_emit("{:total-blocks/%jd}\ttotal\n",
                            (intmax_t)howmany(
                            savednumber * cblocksize, blocksize));
                }
        }

        ignoreclean();
        xo_close_container("disk-usage-information");
        if (xo_finish() < 0)
                xo_err(1, "stdout");
        exit(rval);
}

static int
linkchk(FTSENT *p)
{
        struct links_entry {
                struct links_entry *next;
                struct links_entry *previous;
                int      links;
                dev_t    dev;
                ino_t    ino;
        };
        static const size_t links_hash_initial_size = 8192;
        static struct links_entry **buckets;
        static struct links_entry *free_list;
        static size_t number_buckets;
        static unsigned long number_entries;
        static char stop_allocating;
        struct links_entry *le, **new_buckets;
        struct stat *st;
        size_t i, new_size;
        int hash;

        st = p->fts_statp;

        /* If necessary, initialize the hash table. */
        if (buckets == NULL) {
                number_buckets = links_hash_initial_size;
                buckets = malloc(number_buckets * sizeof(buckets[0]));
                if (buckets == NULL)
                        errx(1, "No memory for hardlink detection");
                for (i = 0; i < number_buckets; i++)
                        buckets[i] = NULL;
        }

        /* If the hash table is getting too full, enlarge it. */
        if (number_entries > number_buckets * 10 && !stop_allocating) {
                new_size = number_buckets * 2;
                new_buckets = calloc(new_size, sizeof(struct links_entry *));

                /* Try releasing the free list to see if that helps. */
                if (new_buckets == NULL && free_list != NULL) {
                        while (free_list != NULL) {
                                le = free_list;
                                free_list = le->next;
                                free(le);
                        }
                        new_buckets = calloc(new_size, sizeof(new_buckets[0]));
                }

                if (new_buckets == NULL) {
                        stop_allocating = 1;
                        xo_warnx("No more memory for tracking hard links");
                } else {
                        for (i = 0; i < number_buckets; i++) {
                                while (buckets[i] != NULL) {
                                        /* Remove entry from old bucket. */
                                        le = buckets[i];
                                        buckets[i] = le->next;

                                        /* Add entry to new bucket. */
                                        hash = (le->dev ^ le->ino) % new_size;

                                        if (new_buckets[hash] != NULL)
                                                new_buckets[hash]->previous =
                                                    le;
                                        le->next = new_buckets[hash];
                                        le->previous = NULL;
                                        new_buckets[hash] = le;
                                }
                        }
                        free(buckets);
                        buckets = new_buckets;
                        number_buckets = new_size;
                }
        }

        /* Try to locate this entry in the hash table. */
        hash = (st->st_dev ^ st->st_ino) % number_buckets;
        for (le = buckets[hash]; le != NULL; le = le->next) {
                if (le->dev == st->st_dev && le->ino == st->st_ino) {
                        /*
                         * Save memory by releasing an entry when we've seen
                         * all of its links.
                         */
                        if (--le->links <= 0) {
                                if (le->previous != NULL)
                                        le->previous->next = le->next;
                                if (le->next != NULL)
                                        le->next->previous = le->previous;
                                if (buckets[hash] == le)
                                        buckets[hash] = le->next;
                                number_entries--;
                                /* Recycle this node through the free list */
                                if (stop_allocating) {
                                        free(le);
                                } else {
                                        le->next = free_list;
                                        free_list = le;
                                }
                        }
                        return (1);
                }
        }

        if (stop_allocating)
                return (0);

        /* Add this entry to the links cache. */
        if (free_list != NULL) {
                /* Pull a node from the free list if we can. */
                le = free_list;
                free_list = le->next;
        } else
                /* Malloc one if we have to. */
                le = malloc(sizeof(struct links_entry));
        if (le == NULL) {
                stop_allocating = 1;
                xo_warnx("No more memory for tracking hard links");
                return (0);
        }
        le->dev = st->st_dev;
        le->ino = st->st_ino;
        le->links = st->st_nlink - 1;
        number_entries++;
        le->next = buckets[hash];
        le->previous = NULL;
        if (buckets[hash] != NULL)
                buckets[hash]->previous = le;
        buckets[hash] = le;
        return (0);
}

static void
prthumanval(const char *fmt, int64_t bytes)
{
        char buf[5];
        int flags;

        bytes *= cblocksize;
        flags = HN_B | HN_NOSPACE | HN_DECIMAL;
        if (!Aflag)
                bytes *= DEV_BSIZE;
        if (hflag == UNITS_SI)
                flags |= HN_DIVISOR_1000;

        humanize_number(buf, sizeof(buf), bytes, "", HN_AUTOSCALE, flags);

        xo_emit(fmt, buf);
}

static void
usage(void)
{
        xo_error("%s\n%s\n%s\n",
            "usage: du [--libxo] [-Aclnx] [-H | -L | -P] [-g | -h | -k | -m]",
            "          [-a | -s | -d depth] [-B blocksize] [-I mask] [-t threshold]",
            "          [file ...]");
        exit(EX_USAGE);
}

static void
ignoreadd(const char *mask)
{
        struct ignentry *ign;

        ign = calloc(1, sizeof(*ign));
        if (ign == NULL)
                errx(1, "cannot allocate memory");
        ign->mask = strdup(mask);
        if (ign->mask == NULL)
                errx(1, "cannot allocate memory");
        SLIST_INSERT_HEAD(&ignores, ign, next);
}

static void
ignoreclean(void)
{
        struct ignentry *ign;

        while (!SLIST_EMPTY(&ignores)) {
                ign = SLIST_FIRST(&ignores);
                SLIST_REMOVE_HEAD(&ignores, next);
                free(ign->mask);
                free(ign);
        }
}

static int
ignorep(FTSENT *ent)
{
        struct ignentry *ign;

        if (nodumpflag && (ent->fts_statp->st_flags & UF_NODUMP))
                return (1);
        SLIST_FOREACH(ign, &ignores, next)
                if (fnmatch(ign->mask, ent->fts_name, 0) != FNM_NOMATCH)
                        return (1);
        return (0);
}

static void
siginfo(int sig __unused)
{
        info = 1;
}

/*
 * Record the total disk/block size of the file or directory. The fts_number
 * variable provided in FTSENT is used for keeping track of the total size.
 * See FTS(3).
 */
static void
record_file_size(FTSENT *p)
{
        p->fts_number += Aflag ?
            howmany(p->fts_statp->st_size, cblocksize) :
            howmany(p->fts_statp->st_blocks, cblocksize);

        p->fts_parent->fts_number += p->fts_number;
}

static bool
check_threshold(FTSENT *p)
{
        return (threshold <= threshold_sign *
            howmany(p->fts_number * cblocksize, blocksize));
}

static void
print_file_size(FTSENT *p)
{
        xo_open_instance("paths");
        if (hflag > 0) {
                prthumanval("{:blocks/%4s}", p->fts_number);
                xo_emit("\t{:path/%s}\n", p->fts_path);
        } else {
                xo_emit("{:blocks/%jd}\t{:path/%s}\n",
                    (intmax_t)howmany(p->fts_number * cblocksize, blocksize),
                p->fts_path);
        }
        xo_close_instance("paths");
}