/*-
 * SPDX-License-Identifier: BSD-3-Clause
 *
 * Copyright (c) 1990, 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/stat.h>
#include <sys/param.h>
#include <sys/mount.h>

#include <err.h>
#include <errno.h>
#include <fcntl.h>
#include <fts.h>
#include <grp.h>
#include <locale.h>
#include <pwd.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sysexits.h>
#include <unistd.h>

static int dflag, eval, fflag, iflag, vflag, Wflag, stdin_ok;
static int rflag, Iflag, xflag;
static uid_t uid;
static volatile sig_atomic_t info;

static int      check(const char *, const char *, struct stat *);
static int      check2(char **);
static void     checkdot(char **);
static void     checkslash(char **);
static void     rm_file(char **);
static void     rm_tree(char **);
static void siginfo(int __unused);
static void     usage(void);

/*
 * rm --
 *      This rm is different from historic rm's, but is expected to match
 *      POSIX 1003.2 behavior.  The most visible difference is that -f
 *      has two specific effects now, ignore non-existent files and force
 *      file removal.
 */
int
main(int argc, char *argv[])
{
        int ch;
        char *p;

        (void)setlocale(LC_ALL, "");

        /*
         * Test for the special case where the utility is called as
         * "unlink", for which the functionality provided is greatly
         * simplified.
         */
        if ((p = strrchr(argv[0], '/')) == NULL)
                p = argv[0];
        else
                ++p;
        if (strcmp(p, "unlink") == 0) {
                if (argc == 2)
                        rm_file(&argv[1]);
                else if (argc == 3 && strcmp(argv[1], "--") == 0)
                        rm_file(&argv[2]);
                else
                        usage();
                exit(eval);
        }

        rflag = xflag = 0;
        while ((ch = getopt(argc, argv, "dfiIPRrvWx")) != -1)
                switch(ch) {
                case 'd':
                        dflag = 1;
                        break;
                case 'f':
                        fflag = 1;
                        iflag = 0;
                        break;
                case 'i':
                        fflag = 0;
                        iflag = 1;
                        break;
                case 'I':
                        Iflag = 1;
                        break;
                case 'P':
                        /* Compatibility no-op. */
                        break;
                case 'R':
                case 'r':                       /* Compatibility. */
                        rflag = 1;
                        break;
                case 'v':
                        vflag = 1;
                        break;
                case 'W':
                        Wflag = 1;
                        break;
                case 'x':
                        xflag = 1;
                        break;
                default:
                        usage();
                }
        argc -= optind;
        argv += optind;

        if (argc < 1) {
                if (fflag)
                        return (0);
                usage();
        }

        checkdot(argv);
        checkslash(argv);
        uid = geteuid();

        (void)signal(SIGINFO, siginfo);
        if (*argv) {
                stdin_ok = isatty(STDIN_FILENO);

                if (Iflag) {
                        if (check2(argv) == 0)
                                exit (1);
                }
                if (rflag)
                        rm_tree(argv);
                else
                        rm_file(argv);
        }

        exit (eval);
}

static void
rm_tree(char **argv)
{
        FTS *fts;
        FTSENT *p;
        int needstat;
        int flags;
        int rval;

        /*
         * Remove a file hierarchy.  If forcing removal (-f), or interactive
         * (-i) or can't ask anyway (stdin_ok), don't stat the file.
         */
        needstat = !uid || (!fflag && !iflag && stdin_ok);

        /*
         * If the -i option is specified, the user can skip on the pre-order
         * visit.  The fts_number field flags skipped directories.
         */
#define SKIPPED 1

        flags = FTS_PHYSICAL;
        if (!needstat)
                flags |= FTS_NOSTAT;
        if (Wflag || fflag)
                flags |= FTS_WHITEOUT;
        if (xflag)
                flags |= FTS_XDEV;
        if (!(fts = fts_open(argv, flags, NULL))) {
                if (fflag && errno == ENOENT)
                        return;
                err(1, "fts_open");
        }
        while (errno = 0, (p = fts_read(fts)) != NULL) {
                switch (p->fts_info) {
                case FTS_DNR:
                        if (!fflag || p->fts_errno != ENOENT) {
                                warnx("%s: %s",
                                    p->fts_path, strerror(p->fts_errno));
                                eval = 1;
                        }
                        continue;
                case FTS_ERR:
                        errx(1, "%s: %s", p->fts_path, strerror(p->fts_errno));
                case FTS_NS:
                        /*
                         * Assume that since fts_read() couldn't stat the
                         * file, it can't be unlinked.
                         */
                        if (!needstat)
                                break;
                        if (!fflag || p->fts_errno != ENOENT) {
                                warnx("%s: %s",
                                    p->fts_path, strerror(p->fts_errno));
                                eval = 1;
                        }
                        continue;
                case FTS_D:
                        /* Pre-order: give user chance to skip. */
                        if (!fflag && !check(p->fts_path, p->fts_accpath,
                            p->fts_statp)) {
                                (void)fts_set(fts, p, FTS_SKIP);
                                p->fts_number = SKIPPED;
                        }
                        else if (!uid &&
                                 (p->fts_statp->st_flags & (UF_APPEND|UF_IMMUTABLE)) &&
                                 !(p->fts_statp->st_flags & (SF_APPEND|SF_IMMUTABLE)) &&
                                 lchflags(p->fts_accpath,
                                         p->fts_statp->st_flags &= ~(UF_APPEND|UF_IMMUTABLE)) < 0)
                                goto err;
                        continue;
                case FTS_DP:
                        /* Post-order: see if user skipped. */
                        if (p->fts_number == SKIPPED)
                                continue;
                        break;
                default:
                        if (!fflag &&
                            !check(p->fts_path, p->fts_accpath, p->fts_statp))
                                continue;
                }

                rval = 0;
                if (!uid &&
                    (p->fts_statp->st_flags & (UF_APPEND|UF_IMMUTABLE)) &&
                    !(p->fts_statp->st_flags & (SF_APPEND|SF_IMMUTABLE)))
                        rval = lchflags(p->fts_accpath,
                                       p->fts_statp->st_flags &= ~(UF_APPEND|UF_IMMUTABLE));
                if (rval == 0) {
                        /*
                         * If we can't read or search the directory, may still be
                         * able to remove it.  Don't print out the un{read,search}able
                         * message unless the remove fails.
                         */
                        switch (p->fts_info) {
                        case FTS_DP:
                        case FTS_DNR:
                                rval = rmdir(p->fts_accpath);
                                if (rval == 0 || (fflag && errno == ENOENT)) {
                                        if (rval == 0 && vflag)
                                                (void)printf("%s\n",
                                                    p->fts_path);
                                        if (rval == 0 && info) {
                                                info = 0;
                                                (void)printf("%s\n",
                                                    p->fts_path);
                                        }
                                        continue;
                                }
                                break;

                        case FTS_W:
                                rval = undelete(p->fts_accpath);
                                if (rval == 0 || (fflag && errno == ENOENT)) {
                                        if (vflag)
                                                (void)printf("%s\n",
                                                    p->fts_path);
                                        if (info) {
                                                info = 0;
                                                (void)printf("%s\n",
                                                    p->fts_path);
                                        }
                                        continue;
                                }
                                break;

                        case FTS_NS:
                                /*
                                 * Assume that since fts_read() couldn't stat
                                 * the file, it can't be unlinked.
                                 */
                                if (fflag)
                                        continue;
                                /* FALLTHROUGH */

                        case FTS_F:
                        case FTS_NSOK:
                        default:
                                rval = unlink(p->fts_accpath);
                                if (rval == 0 || (fflag && errno == ENOENT)) {
                                        if (rval == 0 && vflag)
                                                (void)printf("%s\n",
                                                    p->fts_path);
                                        if (rval == 0 && info) {
                                                info = 0;
                                                (void)printf("%s\n",
                                                    p->fts_path);
                                        }
                                        continue;
                                }
                        }
                }
err:
                warn("%s", p->fts_path);
                eval = 1;
        }
        if (!fflag && errno)
                err(1, "fts_read");
        fts_close(fts);
}

static void
rm_file(char **argv)
{
        struct stat sb;
        int rval;
        char *f;

        /*
         * Remove a file.  POSIX 1003.2 states that, by default, attempting
         * to remove a directory is an error, so must always stat the file.
         */
        while ((f = *argv++) != NULL) {
                /* Assume if can't stat the file, can't unlink it. */
                if (lstat(f, &sb)) {
                        if (Wflag) {
                                sb.st_mode = S_IFWHT|S_IWUSR|S_IRUSR;
                        } else {
                                if (!fflag || errno != ENOENT) {
                                        warn("%s", f);
                                        eval = 1;
                                }
                                continue;
                        }
                } else if (Wflag) {
                        warnx("%s: %s", f, strerror(EEXIST));
                        eval = 1;
                        continue;
                }

                if (S_ISDIR(sb.st_mode) && !dflag) {
                        warnx("%s: is a directory", f);
                        eval = 1;
                        continue;
                }
                if (!fflag && !S_ISWHT(sb.st_mode) && !check(f, f, &sb))
                        continue;
                rval = 0;
                if (!uid && !S_ISWHT(sb.st_mode) &&
                    (sb.st_flags & (UF_APPEND|UF_IMMUTABLE)) &&
                    !(sb.st_flags & (SF_APPEND|SF_IMMUTABLE)))
                        rval = lchflags(f, sb.st_flags & ~(UF_APPEND|UF_IMMUTABLE));
                if (rval == 0) {
                        if (S_ISWHT(sb.st_mode))
                                rval = undelete(f);
                        else if (S_ISDIR(sb.st_mode))
                                rval = rmdir(f);
                        else
                                rval = unlink(f);
                }
                if (rval && (!fflag || errno != ENOENT)) {
                        warn("%s", f);
                        eval = 1;
                }
                if (vflag && rval == 0)
                        (void)printf("%s\n", f);
                if (info && rval == 0) {
                        info = 0;
                        (void)printf("%s\n", f);
                }
        }
}

static int
check(const char *path, const char *name, struct stat *sp)
{
        int ch, first;
        char modep[15], *flagsp;

        /* Check -i first. */
        if (iflag)
                (void)fprintf(stderr, "remove %s? ", path);
        else {
                /*
                 * If it's not a symbolic link and it's unwritable and we're
                 * talking to a terminal, ask.  Symbolic links are excluded
                 * because their permissions are meaningless.  Check stdin_ok
                 * first because we may not have stat'ed the file.
                 */
                if (!stdin_ok || S_ISLNK(sp->st_mode) ||
                    (!access(name, W_OK) &&
                    !(sp->st_flags & (SF_APPEND|SF_IMMUTABLE)) &&
                    (!(sp->st_flags & (UF_APPEND|UF_IMMUTABLE)) || !uid)))
                        return (1);
                strmode(sp->st_mode, modep);
                if ((flagsp = fflagstostr(sp->st_flags)) == NULL)
                        err(1, "fflagstostr");
                (void)fprintf(stderr, "override %s%s%s/%s %s%sfor %s? ",
                    modep + 1, modep[10] == ' ' ? "" : " ",
                    user_from_uid(sp->st_uid, 0),
                    group_from_gid(sp->st_gid, 0),
                    *flagsp ? flagsp : "", *flagsp ? " " : "",
                    path);
                free(flagsp);
        }
        (void)fflush(stderr);

        first = ch = getchar();
        while (ch != '\n' && ch != EOF)
                ch = getchar();
        return (first == 'y' || first == 'Y');
}

#define ISSLASH(a)      ((a)[0] == '/' && (a)[1] == '\0')
static void
checkslash(char **argv)
{
        char **t, **u;
        int complained;

        complained = 0;
        for (t = argv; *t;) {
                if (ISSLASH(*t)) {
                        if (!complained++)
                                warnx("\"/\" may not be removed");
                        eval = 1;
                        for (u = t; u[0] != NULL; ++u)
                                u[0] = u[1];
                } else {
                        ++t;
                }
        }
}

static int
check2(char **argv)
{
        struct stat st;
        int first;
        int ch;
        int fcount = 0;
        int dcount = 0;
        int i;
        const char *dname = NULL;

        for (i = 0; argv[i]; ++i) {
                if (lstat(argv[i], &st) == 0) {
                        if (S_ISDIR(st.st_mode)) {
                                ++dcount;
                                dname = argv[i];    /* only used if 1 dir */
                        } else {
                                ++fcount;
                        }
                }
        }
        first = 0;
        while (first != 'n' && first != 'N' && first != 'y' && first != 'Y') {
                if (dcount && rflag) {
                        fprintf(stderr, "recursively remove");
                        if (dcount == 1)
                                fprintf(stderr, " %s", dname);
                        else
                                fprintf(stderr, " %d dirs", dcount);
                        if (fcount == 1)
                                fprintf(stderr, " and 1 file");
                        else if (fcount > 1)
                                fprintf(stderr, " and %d files", fcount);
                } else if (dcount + fcount > 3) {
                        fprintf(stderr, "remove %d files", dcount + fcount);
                } else {
                        return(1);
                }
                fprintf(stderr, "? ");
                fflush(stderr);

                first = ch = getchar();
                while (ch != '\n' && ch != EOF)
                        ch = getchar();
                if (ch == EOF)
                        break;
        }
        return (first == 'y' || first == 'Y');
}

#define ISDOT(a)        ((a)[0] == '.' && (!(a)[1] || ((a)[1] == '.' && !(a)[2])))
static void
checkdot(char **argv)
{
        char *p, **save, **t;
        int complained;

        complained = 0;
        for (t = argv; *t;) {
                if ((p = strrchr(*t, '/')) != NULL)
                        ++p;
                else
                        p = *t;
                if (ISDOT(p)) {
                        if (!complained++)
                                warnx("\".\" and \"..\" may not be removed");
                        eval = 1;
                        for (save = t; (t[0] = t[1]) != NULL; ++t)
                                continue;
                        t = save;
                } else
                        ++t;
        }
}

static void
usage(void)
{

        (void)fprintf(stderr, "%s\n%s\n",
            "usage: rm [-f | -i] [-dIPRrvWx] file ...",
            "       unlink [--] file");
        exit(EX_USAGE);
}

static void
siginfo(int sig __unused)
{

        info = 1;
}