/*-
 * SPDX-License-Identifier: BSD-3-Clause
 *
 * Copyright (c) 1992, 1993
 *      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 <sys/time.h>

#include <err.h>
#include <errno.h>
#include <fcntl.h>
#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#include "zopen.h"

static void     compress(const char *, const char *, int);
static void     cwarn(const char *, ...) __printflike(1, 2);
static void     cwarnx(const char *, ...) __printflike(1, 2);
static void     decompress(const char *, const char *, int);
static int      permission(const char *);
static void     setfile(const char *, struct stat *);
static void     usage(int);

static int eval, force, verbose;

int
main(int argc, char *argv[])
{
        enum {COMPRESS, DECOMPRESS} style;
        size_t len;
        int bits, cat, ch;
        char *p, newname[MAXPATHLEN];

        cat = 0;
        if ((p = strrchr(argv[0], '/')) == NULL)
                p = argv[0];
        else
                ++p;
        if (!strcmp(p, "uncompress"))
                style = DECOMPRESS;
        else if (!strcmp(p, "compress"))
                style = COMPRESS;
        else if (!strcmp(p, "zcat")) {
                cat = 1;
                style = DECOMPRESS;
        } else
                errx(1, "unknown program name");

        bits = 0;
        while ((ch = getopt(argc, argv, "b:cdfv")) != -1)
                switch(ch) {
                case 'b':
                        bits = strtol(optarg, &p, 10);
                        if (*p)
                                errx(1, "illegal bit count -- %s", optarg);
                        break;
                case 'c':
                        cat = 1;
                        break;
                case 'd':               /* Backward compatible. */
                        style = DECOMPRESS;
                        break;
                case 'f':
                        force = 1;
                        break;
                case 'v':
                        verbose = 1;
                        break;
                case '?':
                default:
                        usage(style == COMPRESS);
                }
        argc -= optind;
        argv += optind;

        if (argc == 0) {
                switch(style) {
                case COMPRESS:
                        (void)compress("/dev/stdin", "/dev/stdout", bits);
                        break;
                case DECOMPRESS:
                        (void)decompress("/dev/stdin", "/dev/stdout", bits);
                        break;
                }
                exit (eval);
        }

        if (cat == 1 && style == COMPRESS && argc > 1)
                errx(1, "the -c option permits only a single file argument");

        for (; *argv; ++argv)
                switch(style) {
                case COMPRESS:
                        if (strcmp(*argv, "-") == 0) {
                                compress("/dev/stdin", "/dev/stdout", bits);
                                break;
                        } else if (cat) {
                                compress(*argv, "/dev/stdout", bits);
                                break;
                        }
                        if ((p = strrchr(*argv, '.')) != NULL &&
                            !strcmp(p, ".Z")) {
                                cwarnx("%s: name already has trailing .Z",
                                    *argv);
                                break;
                        }
                        len = strlen(*argv);
                        if (len > sizeof(newname) - 3) {
                                cwarnx("%s: name too long", *argv);
                                break;
                        }
                        memmove(newname, *argv, len);
                        newname[len] = '.';
                        newname[len + 1] = 'Z';
                        newname[len + 2] = '\0';
                        compress(*argv, newname, bits);
                        break;
                case DECOMPRESS:
                        if (strcmp(*argv, "-") == 0) {
                                decompress("/dev/stdin", "/dev/stdout", bits);
                                break;
                        }
                        len = strlen(*argv);
                        if ((p = strrchr(*argv, '.')) == NULL ||
                            strcmp(p, ".Z")) {
                                if (len > sizeof(newname) - 3) {
                                        cwarnx("%s: name too long", *argv);
                                        break;
                                }
                                memmove(newname, *argv, len);
                                newname[len] = '.';
                                newname[len + 1] = 'Z';
                                newname[len + 2] = '\0';
                                decompress(newname,
                                    cat ? "/dev/stdout" : *argv, bits);
                        } else {
                                if (len - 2 > sizeof(newname) - 1) {
                                        cwarnx("%s: name too long", *argv);
                                        break;
                                }
                                memmove(newname, *argv, len - 2);
                                newname[len - 2] = '\0';
                                decompress(*argv,
                                    cat ? "/dev/stdout" : newname, bits);
                        }
                        break;
                }
        exit (eval);
}

static void
compress(const char *in, const char *out, int bits)
{
        size_t nr;
        struct stat isb, sb;
        FILE *ifp, *ofp;
        int exists, isreg, oreg;
        u_char buf[1024];

        exists = !stat(out, &sb);
        if (!force && exists && S_ISREG(sb.st_mode) && !permission(out))
                return;
        isreg = oreg = !exists || S_ISREG(sb.st_mode);

        ifp = ofp = NULL;
        if ((ifp = fopen(in, "r")) == NULL) {
                cwarn("%s", in);
                return;
        }
        if (stat(in, &isb)) {           /* DON'T FSTAT! */
                cwarn("%s", in);
                goto err;
        }
        if (!S_ISREG(isb.st_mode))
                isreg = 0;

        if ((ofp = zopen(out, "w", bits)) == NULL) {
                cwarn("%s", out);
                goto err;
        }
        while ((nr = fread(buf, 1, sizeof(buf), ifp)) != 0)
                if (fwrite(buf, 1, nr, ofp) != nr) {
                        cwarn("%s", out);
                        goto err;
                }

        if (ferror(ifp) || fclose(ifp)) {
                cwarn("%s", in);
                goto err;
        }
        ifp = NULL;

        if (fclose(ofp)) {
                cwarn("%s", out);
                goto err;
        }
        ofp = NULL;

        if (isreg) {
                if (stat(out, &sb)) {
                        cwarn("%s", out);
                        goto err;
                }

                if (!force && sb.st_size >= isb.st_size) {
                        if (verbose)
                (void)fprintf(stderr, "%s: file would grow; left unmodified\n",
                    in);
                        eval = 2;
                        if (unlink(out))
                                cwarn("%s", out);
                        goto err;
                }

                setfile(out, &isb);

                if (unlink(in))
                        cwarn("%s", in);

                if (verbose) {
                        (void)fprintf(stderr, "%s: ", out);
                        if (isb.st_size > sb.st_size)
                                (void)fprintf(stderr, "%.0f%% compression\n",
                                    ((float)sb.st_size / isb.st_size) * 100.0);
                        else
                                (void)fprintf(stderr, "%.0f%% expansion\n",
                                    ((float)isb.st_size / sb.st_size) * 100.0);
                }
        }
        return;

err:    if (ofp) {
                if (oreg)
                        (void)unlink(out);
                (void)fclose(ofp);
        }
        if (ifp)
                (void)fclose(ifp);
}

static void
decompress(const char *in, const char *out, int bits)
{
        size_t nr;
        struct stat sb;
        FILE *ifp, *ofp;
        int exists, isreg, oreg;
        u_char buf[1024];

        exists = !stat(out, &sb);
        if (!force && exists && S_ISREG(sb.st_mode) && !permission(out))
                return;
        isreg = oreg = !exists || S_ISREG(sb.st_mode);

        ifp = ofp = NULL;
        if ((ifp = zopen(in, "r", bits)) == NULL) {
                cwarn("%s", in);
                return;
        }
        if (stat(in, &sb)) {
                cwarn("%s", in);
                goto err;
        }
        if (!S_ISREG(sb.st_mode))
                isreg = 0;

        /*
         * Try to read the first few uncompressed bytes from the input file
         * before blindly truncating the output file.
         */
        if ((nr = fread(buf, 1, sizeof(buf), ifp)) == 0) {
                cwarn("%s", in);
                (void)fclose(ifp);
                return;
        }
        if ((ofp = fopen(out, "w")) == NULL ||
            (nr != 0 && fwrite(buf, 1, nr, ofp) != nr)) {
                cwarn("%s", out);
                if (ofp)
                        (void)fclose(ofp);
                (void)fclose(ifp);
                return;
        }

        while ((nr = fread(buf, 1, sizeof(buf), ifp)) != 0)
                if (fwrite(buf, 1, nr, ofp) != nr) {
                        cwarn("%s", out);
                        goto err;
                }

        if (ferror(ifp) || fclose(ifp)) {
                cwarn("%s", in);
                goto err;
        }
        ifp = NULL;

        if (fclose(ofp)) {
                cwarn("%s", out);
                goto err;
        }

        if (isreg) {
                setfile(out, &sb);

                if (unlink(in))
                        cwarn("%s", in);
        }
        return;

err:    if (ofp) {
                if (oreg)
                        (void)unlink(out);
                (void)fclose(ofp);
        }
        if (ifp)
                (void)fclose(ifp);
}

static void
setfile(const char *name, struct stat *fs)
{
        static struct timespec tspec[2];

        fs->st_mode &= S_ISUID|S_ISGID|S_IRWXU|S_IRWXG|S_IRWXO;

        tspec[0] = fs->st_atim;
        tspec[1] = fs->st_mtim;
        if (utimensat(AT_FDCWD, name, tspec, 0))
                cwarn("utimensat: %s", name);

        /*
         * Changing the ownership probably won't succeed, unless we're root
         * or POSIX_CHOWN_RESTRICTED is not set.  Set uid/gid before setting
         * the mode; current BSD behavior is to remove all setuid bits on
         * chown.  If chown fails, lose setuid/setgid bits.
         */
        if (chown(name, fs->st_uid, fs->st_gid)) {
                if (errno != EPERM)
                        cwarn("chown: %s", name);
                fs->st_mode &= ~(S_ISUID|S_ISGID);
        }
        if (chmod(name, fs->st_mode) && errno != EOPNOTSUPP)
                cwarn("chmod: %s", name);

        if (chflags(name, fs->st_flags) && errno != EOPNOTSUPP)
                cwarn("chflags: %s", name);
}

static int
permission(const char *fname)
{
        int ch, first;

        if (!isatty(fileno(stderr)))
                return (0);
        (void)fprintf(stderr, "overwrite %s? ", fname);
        first = ch = getchar();
        while (ch != '\n' && ch != EOF)
                ch = getchar();
        return (first == 'y');
}

static void
usage(int iscompress)
{
        if (iscompress)
                (void)fprintf(stderr,
                    "usage: compress [-cfv] [-b bits] [file ...]\n");
        else
                (void)fprintf(stderr,
                    "usage: uncompress [-c] [-b bits] [file ...]\n");
        exit(1);
}

static void
cwarnx(const char *fmt, ...)
{
        va_list ap;

        va_start(ap, fmt);
        vwarnx(fmt, ap);
        va_end(ap);
        eval = 1;
}

static void
cwarn(const char *fmt, ...)
{
        va_list ap;

        va_start(ap, fmt);
        vwarn(fmt, ap);
        va_end(ap);
        eval = 1;
}