/*      $OpenBSD: rm.c,v 1.45 2025/04/20 13:47:54 kn Exp $      */
/*      $NetBSD: rm.c,v 1.19 1995/09/07 06:48:50 jtc Exp $      */

/*-
 * 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/types.h>
#include <sys/stat.h>
#include <sys/mount.h>

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

#define MAXIMUM(a, b)   (((a) > (b)) ? (a) : (b))

extern char *__progname;

int dflag, eval, fflag, iflag, Pflag, vflag, stdin_ok;

int     check(char *, char *, struct stat *);
void    checkdot(char **);
void    rm_file(char **);
int     rm_overwrite(char *, struct stat *);
int     pass(int, off_t, char *, size_t);
void    rm_tree(char **);
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, rflag;

        Pflag = rflag = 0;
        while ((ch = getopt(argc, argv, "dfiPRrv")) != -1)
                switch(ch) {
                case 'd':
                        dflag = 1;
                        break;
                case 'f':
                        fflag = 1;
                        iflag = 0;
                        break;
                case 'i':
                        fflag = 0;
                        iflag = 1;
                        break;
                case 'P':
                        Pflag = 1;
                        break;
                case 'R':
                case 'r':                       /* Compatibility. */
                        rflag = 1;
                        break;
                case 'v':
                        vflag = 1;
                        break;
                default:
                        usage();
                }
        argc -= optind;
        argv += optind;

        if (Pflag) {
                if (pledge("stdio rpath wpath cpath getpw", NULL) == -1)
                        err(1, "pledge");
        } else {
                if (pledge("stdio rpath cpath getpw", NULL) == -1)
                        err(1, "pledge");
        }

        if (argc < 1 && fflag == 0)
                usage();

        checkdot(argv);

        if (*argv) {
                stdin_ok = isatty(STDIN_FILENO);

                if (rflag)
                        rm_tree(argv);
                else
                        rm_file(argv);
        }

        return (eval);
}

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

        /*
         * Remove a file hierarchy.  If forcing removal (-f), or interactive
         * (-i) or can't ask anyway (stdin_ok), don't stat the file.
         */
        needstat = !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 (!(fts = fts_open(argv, flags, NULL)))
                err(1, NULL);
        while ((p = fts_read(fts)) != NULL) {
                switch (p->fts_info) {
                case FTS_DNR:
                        if (!fflag || p->fts_errno != ENOENT) {
                                warnc(p->fts_errno, "%s", p->fts_path);
                                eval = 1;
                        }
                        continue;
                case FTS_ERR:
                        errc(1, p->fts_errno, "%s", p->fts_path);
                case FTS_NS:
                        /*
                         * FTS_NS: assume that if can't stat the file, it
                         * can't be unlinked.
                         */
                        if (!needstat)
                                break;
                        if (!fflag || p->fts_errno != ENOENT) {
                                warnc(p->fts_errno, "%s", p->fts_path);
                                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;
                        }
                        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;
                }

                /*
                 * 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:
                        if (!rmdir(p->fts_accpath)) {
                                if (vflag)
                                        fprintf(stdout, "%s\n", p->fts_path);
                                continue;
                        }
                        if (fflag && errno == ENOENT)
                                continue;
                        break;

                case FTS_F:
                case FTS_NSOK:
                        if (Pflag)
                                rm_overwrite(p->fts_accpath, p->fts_info ==
                                    FTS_NSOK ? NULL : p->fts_statp);
                        /* FALLTHROUGH */
                default:
                        if (!unlink(p->fts_accpath)) {
                                if (vflag)
                                        fprintf(stdout, "%s\n", p->fts_path);
                                continue;
                        }
                        if (fflag && errno == ENOENT)
                                continue;
                }
                warn("%s", p->fts_path);
                eval = 1;
        }
        if (errno)
                err(1, "fts_read");
        fts_close(fts);
}

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 (!fflag || errno != ENOENT) {
                                warn("%s", f);
                                eval = 1;
                        }
                        continue;
                }

                if (S_ISDIR(sb.st_mode) && !dflag) {
                        warnx("%s: is a directory", f);
                        eval = 1;
                        continue;
                }
                if (!fflag && !check(f, f, &sb))
                        continue;
                else if (S_ISDIR(sb.st_mode))
                        rval = rmdir(f);
                else {
                        if (Pflag)
                                rm_overwrite(f, &sb);
                        rval = unlink(f);
                }
                if (rval && (!fflag || errno != ENOENT)) {
                        warn("%s", f);
                        eval = 1;
                } else if (rval == 0 && vflag)
                        (void)fprintf(stdout, "%s\n", f);
        }
}

/*
 * rm_overwrite --
 *      Overwrite the file with varying bit patterns.
 *
 * XXX
 * This is a cheap way to *really* delete files.  Note that only regular
 * files are deleted, directories (and therefore names) will remain.
 * Also, this assumes a fixed-block file system (like FFS, or a V7 or a
 * System V file system).  In a logging file system, you'll have to have
 * kernel support.
 * Returns 1 for success.
 */
int
rm_overwrite(char *file, struct stat *sbp)
{
        struct stat sb, sb2;
        struct statfs fsb;
        size_t bsize;
        int fd;
        char *buf = NULL;

        fd = -1;
        if (sbp == NULL) {
                if (lstat(file, &sb))
                        goto err;
                sbp = &sb;
        }
        if (!S_ISREG(sbp->st_mode))
                return (1);
        if (sbp->st_nlink > 1) {
                warnx("%s (inode %llu): not overwritten due to multiple links",
                    file, (unsigned long long)sbp->st_ino);
                return (0);
        }
        if ((fd = open(file, O_WRONLY|O_NONBLOCK|O_NOFOLLOW)) == -1)
                goto err;
        if (fstat(fd, &sb2))
                goto err;
        if (sb2.st_dev != sbp->st_dev || sb2.st_ino != sbp->st_ino ||
            !S_ISREG(sb2.st_mode)) {
                errno = EPERM;
                goto err;
        }
        if (fstatfs(fd, &fsb) == -1)
                goto err;
        bsize = MAXIMUM(fsb.f_iosize, 1024U);
        if ((buf = malloc(bsize)) == NULL)
                err(1, "%s: malloc", file);

        if (!pass(fd, sbp->st_size, buf, bsize))
                goto err;
        if (fsync(fd))
                goto err;
        close(fd);
        free(buf);
        return (1);

err:
        warn("%s", file);
        close(fd);
        eval = 1;
        free(buf);
        return (0);
}

int
pass(int fd, off_t len, char *buf, size_t bsize)
{
        size_t wlen;

        for (; len > 0; len -= wlen) {
                wlen = len < bsize ? len : bsize;
                arc4random_buf(buf, wlen);
                if (write(fd, buf, wlen) != wlen)
                        return (0);
        }
        return (1);
}

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

        /* 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) ||
                    errno != EACCES)
                        return (1);
                strmode(sp->st_mode, modep);
                (void)fprintf(stderr, "override %s%s%s/%s for %s? ",
                    modep + 1, modep[9] == ' ' ? "" : " ",
                    user_from_uid(sp->st_uid, 0),
                    group_from_gid(sp->st_gid, 0), path);
        }
        (void)fflush(stderr);

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

/*
 * POSIX.2 requires that if "." or ".." are specified as the basename
 * portion of an operand, a diagnostic message be written to standard
 * error and nothing more be done with such operands.
 *
 * Since POSIX.2 defines basename as the final portion of a path after
 * trailing slashes have been removed, we'll remove them here.
 */
#define ISDOT(a) ((a)[0] == '.' && (!(a)[1] || ((a)[1] == '.' && !(a)[2])))
void
checkdot(char **argv)
{
        char *p, **save, **t;
        int complained;
        struct stat sb, root;

        stat("/", &root);
        complained = 0;
        for (t = argv; *t;) {
                if (lstat(*t, &sb) == 0 &&
                    root.st_ino == sb.st_ino && root.st_dev == sb.st_dev) {
                        if (!complained++)
                                warnx("\"/\" may not be removed");
                        goto skip;
                }
                /* strip trailing slashes */
                p = strrchr(*t, '\0');
                while (--p > *t && *p == '/')
                        *p = '\0';

                /* extract basename */
                if ((p = strrchr(*t, '/')) != NULL)
                        ++p;
                else
                        p = *t;

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

void
usage(void)
{
        (void)fprintf(stderr, "usage: %s [-dfiPRrv] file ...\n", __progname);
        exit(1);
}