/*-
 * SPDX-License-Identifier: BSD-3-Clause
 *
 * Copyright (c) 1988, 1993, 1994
 *      The Regents of the University of California.  All rights reserved.
 *
 * 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/stat.h>

#include <err.h>
#include <errno.h>
#include <fcntl.h>
#include <fts.h>
#include <grp.h>
#include <libgen.h>
#include <pwd.h>
#include <signal.h>
#include <stddef.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

static void     a_gid(const char *);
static void     a_uid(const char *);
static void     chownerr(const char *);
static uid_t    id(const char *, const char *);
static void     usage(void);
static void     print_info(const FTSENT *, int);

static uid_t uid;
static gid_t gid;
static int ischown;
static const char *gname;
static volatile sig_atomic_t siginfo;

static void
siginfo_handler(int sig __unused)
{

        siginfo = 1;
}

int
main(int argc, char **argv)
{
        FTS *ftsp;
        FTSENT *p;
        int Hflag, Lflag, Rflag, fflag, hflag, vflag, xflag;
        int ch, fts_options, rval;
        char *cp;

        ischown = (strcmp(basename(argv[0]), "chown") == 0);

        Hflag = Lflag = Rflag = fflag = hflag = vflag = xflag = 0;
        while ((ch = getopt(argc, argv, "HLPRfhvx")) != -1)
                switch (ch) {
                case 'H':
                        Hflag = 1;
                        Lflag = 0;
                        break;
                case 'L':
                        Lflag = 1;
                        Hflag = 0;
                        break;
                case 'P':
                        Hflag = Lflag = 0;
                        break;
                case 'R':
                        Rflag = 1;
                        break;
                case 'f':
                        fflag = 1;
                        break;
                case 'h':
                        hflag = 1;
                        break;
                case 'v':
                        vflag++;
                        break;
                case 'x':
                        xflag = 1;
                        break;
                case '?':
                default:
                        usage();
                }
        argv += optind;
        argc -= optind;

        if (argc < 2)
                usage();

        (void)signal(SIGINFO, siginfo_handler);

        if (Rflag) {
                if (hflag && (Hflag || Lflag))
                        errx(1, "the -R%c and -h options may not be "
                            "specified together", Hflag ? 'H' : 'L');
                if (Lflag) {
                        fts_options = FTS_LOGICAL;
                } else {
                        fts_options = FTS_PHYSICAL;

                        if (Hflag) {
                                fts_options |= FTS_COMFOLLOW;
                        }
                }
        } else if (hflag) {
                fts_options = FTS_PHYSICAL;
        } else {
                fts_options = FTS_LOGICAL;
        }

        if (xflag)
                fts_options |= FTS_XDEV;

        uid = (uid_t)-1;
        gid = (gid_t)-1;
        if (ischown) {
                if ((cp = strchr(*argv, ':')) != NULL) {
                        *cp++ = '\0';
                        a_gid(cp);
                }
#ifdef SUPPORT_DOT
                else if ((cp = strchr(*argv, '.')) != NULL) {
                        warnx("separation of user and group with a period is deprecated");
                        *cp++ = '\0';
                        a_gid(cp);
                }
#endif
                a_uid(*argv);
        } else
                a_gid(*argv);

        if ((ftsp = fts_open(++argv, fts_options, NULL)) == NULL)
                err(1, NULL);

        for (rval = 0; errno = 0, (p = fts_read(ftsp)) != NULL;) {
                int atflag;

                if ((fts_options & FTS_LOGICAL) ||
                    ((fts_options & FTS_COMFOLLOW) &&
                    p->fts_level == FTS_ROOTLEVEL))
                        atflag = 0;
                else
                        atflag = AT_SYMLINK_NOFOLLOW;

                switch (p->fts_info) {
                case FTS_D:                     /* Change it at FTS_DP. */
                        if (!Rflag)
                                fts_set(ftsp, p, FTS_SKIP);
                        continue;
                case FTS_DNR:                   /* Warn, chown. */
                        warnx("%s: %s", p->fts_path, strerror(p->fts_errno));
                        rval = 1;
                        break;
                case FTS_ERR:                   /* Warn, continue. */
                case FTS_NS:
                        warnx("%s: %s", p->fts_path, strerror(p->fts_errno));
                        rval = 1;
                        continue;
                default:
                        break;
                }
                if (siginfo) {
                        print_info(p, 2);
                        siginfo = 0;
                }
                if ((uid == (uid_t)-1 || uid == p->fts_statp->st_uid) &&
                    (gid == (gid_t)-1 || gid == p->fts_statp->st_gid))
                        continue;
                if (fchownat(AT_FDCWD, p->fts_accpath, uid, gid, atflag)
                    == -1 && !fflag) {
                        chownerr(p->fts_path);
                        rval = 1;
                } else if (vflag)
                        print_info(p, vflag);
        }
        if (errno)
                err(1, "fts_read");
        exit(rval);
}

static void
a_gid(const char *s)
{
        struct group *gr;

        if (*s == '\0')                 /* Argument was "uid[:.]". */
                return;
        gname = s;
        gid = ((gr = getgrnam(s)) != NULL) ? gr->gr_gid : id(s, "group");
}

static void
a_uid(const char *s)
{
        struct passwd *pw;

        if (*s == '\0')                 /* Argument was "[:.]gid". */
                return;
        uid = ((pw = getpwnam(s)) != NULL) ? pw->pw_uid : id(s, "user");
}

static uid_t
id(const char *name, const char *type)
{
        unsigned long val;
        char *ep;

        errno = 0;
        val = strtoul(name, &ep, 10);
        _Static_assert(UID_MAX >= GID_MAX, "UID MAX less than GID MAX");
        if (errno || *ep != '\0' || val > UID_MAX)
                errx(1, "%s: illegal %s name", name, type);
        return (val);
}

static void
chownerr(const char *file)
{
        static uid_t euid = -1;
        static int ngroups = -1;
        static long ngroups_max;
        gid_t *groups;

        /* Check for chown without being root. */
        if (errno != EPERM || (uid != (uid_t)-1 &&
            euid == (uid_t)-1 && (euid = geteuid()) != 0)) {
                warn("%s", file);
                return;
        }

        /* Check group membership; kernel just returns EPERM. */
        if (gid != (gid_t)-1 && ngroups == -1 &&
            euid == (uid_t)-1 && (euid = geteuid()) != 0) {
                ngroups_max = sysconf(_SC_NGROUPS_MAX) + 1;
                if ((groups = malloc(sizeof(gid_t) * ngroups_max)) == NULL)
                        err(1, "malloc");
                ngroups = getgroups(ngroups_max, groups);
                while (--ngroups >= 0 && gid != groups[ngroups]);
                free(groups);
                if (ngroups < 0) {
                        warnx("you are not a member of group %s", gname);
                        return;
                }
        }
        warn("%s", file);
}

static void
usage(void)
{

        if (ischown)
                (void)fprintf(stderr, "%s\n%s\n",
                    "usage: chown [-fhvx] [-R [-H | -L | -P]] owner[:group]"
                    " file ...",
                    "       chown [-fhvx] [-R [-H | -L | -P]] :group file ...");
        else
                (void)fprintf(stderr, "%s\n",
                    "usage: chgrp [-fhvx] [-R [-H | -L | -P]] group file ...");
        exit(1);
}

static void
print_info(const FTSENT *p, int vflag)
{

        printf("%s", p->fts_path);
        if (vflag > 1) {
                if (ischown) {
                        printf(": %ju:%ju -> %ju:%ju",
                            (uintmax_t)p->fts_statp->st_uid, 
                            (uintmax_t)p->fts_statp->st_gid,
                            (uid == (uid_t)-1) ? 
                            (uintmax_t)p->fts_statp->st_uid : (uintmax_t)uid,
                            (gid == (gid_t)-1) ? 
                            (uintmax_t)p->fts_statp->st_gid : (uintmax_t)gid);
                } else {
                        printf(": %ju -> %ju", (uintmax_t)p->fts_statp->st_gid,
                            (gid == (gid_t)-1) ? 
                            (uintmax_t)p->fts_statp->st_gid : (uintmax_t)gid);
                }
        }
        printf("\n");
}