root/usr.bin/diff/diff.c
/*      $OpenBSD: diff.c,v 1.69 2026/02/18 15:25:01 deraadt Exp $       */

/*
 * Copyright (c) 2003 Todd C. Miller <millert@openbsd.org>
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 *
 * Sponsored in part by the Defense Advanced Research Projects
 * Agency (DARPA) and Air Force Research Laboratory, Air Force
 * Materiel Command, USAF, under agreement number F39502-99-1-0512.
 */

#include <sys/stat.h>

#include <ctype.h>
#include <err.h>
#include <errno.h>
#include <getopt.h>
#include <stdlib.h>
#include <stdio.h>
#include <stdarg.h>
#include <string.h>
#include <unistd.h>
#include <limits.h>

#include "diff.h"
#include "xmalloc.h"

int      Nflag, Pflag, rflag, sflag, Tflag;
int      diff_format, diff_context, status;
char    *start, *ifdefname, *diffargs, *label[2], *ignore_pats;
struct stat stb1, stb2;
struct excludes *excludes_list;
regex_t  ignore_re;

#define OPTIONS "0123456789abC:cdD:efhI:iL:nNPpqrS:sTtU:uwX:x:"
static struct option longopts[] = {
        { "text",                       no_argument,            0,      'a' },
        { "ignore-space-change",        no_argument,            0,      'b' },
        { "context",                    optional_argument,      0,      'C' },
        { "ifdef",                      required_argument,      0,      'D' },
        { "minimal",                    no_argument,            0,      'd' },
        { "ed",                         no_argument,            0,      'e' },
        { "forward-ed",                 no_argument,            0,      'f' },
        { "ignore-matching-lines",      required_argument,      0,      'I' },
        { "ignore-case",                no_argument,            0,      'i' },
        { "label",                      required_argument,      0,      'L' },
        { "new-file",                   no_argument,            0,      'N' },
        { "rcs",                        no_argument,            0,      'n' },
        { "unidirectional-new-file",    no_argument,            0,      'P' },
        { "show-c-function",            no_argument,            0,      'p' },
        { "brief",                      no_argument,            0,      'q' },
        { "recursive",                  no_argument,            0,      'r' },
        { "report-identical-files",     no_argument,            0,      's' },
        { "starting-file",              required_argument,      0,      'S' },
        { "expand-tabs",                no_argument,            0,      't' },
        { "initial-tab",                no_argument,            0,      'T' },
        { "unified",                    optional_argument,      0,      'U' },
        { "ignore-all-space",           no_argument,            0,      'w' },
        { "exclude",                    required_argument,      0,      'x' },
        { "exclude-from",               required_argument,      0,      'X' },
        { NULL,                         0,                      0,      '\0'}
};

__dead void usage(void);
void push_excludes(char *);
void push_ignore_pats(char *);
void read_excludes_file(char *file);
void set_argstr(char **, char **);

int
main(int argc, char **argv)
{
        char *ep, **oargv;
        long  l;
        int   ch, dflags, lastch, gotstdin, prevoptind, newarg;

        oargv = argv;
        gotstdin = 0;
        dflags = 0;
        lastch = '\0';
        prevoptind = 1;
        newarg = 1;
        while ((ch = getopt_long(argc, argv, OPTIONS, longopts, NULL)) != -1) {
                switch (ch) {
                case '0': case '1': case '2': case '3': case '4':
                case '5': case '6': case '7': case '8': case '9':
                        if (newarg)
                                usage();        /* disallow -[0-9]+ */
                        else if (lastch == 'c' || lastch == 'u')
                                diff_context = 0;
                        else if (!isdigit(lastch) || diff_context > INT_MAX / 10)
                                usage();
                        diff_context = (diff_context * 10) + (ch - '0');
                        break;
                case 'a':
                        dflags |= D_FORCEASCII;
                        break;
                case 'b':
                        dflags |= D_FOLDBLANKS;
                        break;
                case 'C':
                case 'c':
                        diff_format = D_CONTEXT;
                        if (optarg != NULL) {
                                l = strtol(optarg, &ep, 10);
                                if (*ep != '\0' || l < 0 || l >= INT_MAX)
                                        usage();
                                diff_context = (int)l;
                        } else
                                diff_context = 3;
                        break;
                case 'd':
                        dflags |= D_MINIMAL;
                        break;
                case 'D':
                        diff_format = D_IFDEF;
                        ifdefname = optarg;
                        break;
                case 'e':
                        diff_format = D_EDIT;
                        break;
                case 'f':
                        diff_format = D_REVERSE;
                        break;
                case 'h':
                        /* silently ignore for backwards compatibility */
                        break;
                case 'I':
                        push_ignore_pats(optarg);
                        break;
                case 'i':
                        dflags |= D_IGNORECASE;
                        break;
                case 'L':
                        if (label[0] == NULL)
                                label[0] = optarg;
                        else if (label[1] == NULL)
                                label[1] = optarg;
                        else
                                usage();
                        break;
                case 'N':
                        Nflag = 1;
                        break;
                case 'n':
                        diff_format = D_NREVERSE;
                        break;
                case 'p':
                        dflags |= D_PROTOTYPE;
                        break;
                case 'P':
                        Pflag = 1;
                        break;
                case 'r':
                        rflag = 1;
                        break;
                case 'q':
                        diff_format = D_BRIEF;
                        break;
                case 'S':
                        start = optarg;
                        break;
                case 's':
                        sflag = 1;
                        break;
                case 'T':
                        Tflag = 1;
                        break;
                case 't':
                        dflags |= D_EXPANDTABS;
                        break;
                case 'U':
                case 'u':
                        diff_format = D_UNIFIED;
                        if (optarg != NULL) {
                                l = strtol(optarg, &ep, 10);
                                if (*ep != '\0' || l < 0 || l >= INT_MAX)
                                        usage();
                                diff_context = (int)l;
                        } else
                                diff_context = 3;
                        break;
                case 'w':
                        dflags |= D_IGNOREBLANKS;
                        break;
                case 'X':
                        read_excludes_file(optarg);
                        break;
                case 'x':
                        push_excludes(optarg);
                        break;
                default:
                        usage();
                        break;
                }
                lastch = ch;
                newarg = optind != prevoptind;
                prevoptind = optind;
        }
        argc -= optind;
        argv += optind;

        if (unveil("/tmp", "rwc") == -1)
                err(2, "unveil /tmp");
        if (unveil("/", "r") == -1)
                err(2, "unveil /");
        if (pledge("stdio rpath wpath cpath", NULL) == -1)
                err(2, "pledge");

        /*
         * Do sanity checks, fill in stb1 and stb2 and call the appropriate
         * driver routine.  Both drivers use the contents of stb1 and stb2.
         */
        if (argc != 2)
                usage();
        if (ignore_pats != NULL) {
                char buf[BUFSIZ];
                int error;

                if ((error = regcomp(&ignore_re, ignore_pats,
                                     REG_NEWLINE | REG_EXTENDED)) != 0) {
                        regerror(error, &ignore_re, buf, sizeof(buf));
                        if (*ignore_pats != '\0')
                                errx(2, "%s: %s", ignore_pats, buf);
                        else
                                errx(2, "%s", buf);
                }
        }
        if (strcmp(argv[0], "-") == 0) {
                fstat(STDIN_FILENO, &stb1);
                gotstdin = 1;
        } else if (stat(argv[0], &stb1) != 0)
                err(2, "%s", argv[0]);
        if (strcmp(argv[1], "-") == 0) {
                fstat(STDIN_FILENO, &stb2);
                gotstdin = 1;
        } else if (stat(argv[1], &stb2) != 0)
                err(2, "%s", argv[1]);
        if (gotstdin && (S_ISDIR(stb1.st_mode) || S_ISDIR(stb2.st_mode)))
                errx(2, "can't compare - to a directory");
        set_argstr(oargv, argv);
        if (S_ISDIR(stb1.st_mode) && S_ISDIR(stb2.st_mode)) {
                if (diff_format == D_IFDEF)
                        errx(2, "-D option not supported with directories");
                diffdir(argv[0], argv[1], dflags);
        } else {
                if (S_ISDIR(stb1.st_mode)) {
                        argv[0] = splice(argv[0], argv[1]);
                        if (stat(argv[0], &stb1) == -1)
                                err(2, "%s", argv[0]);
                }
                if (S_ISDIR(stb2.st_mode)) {
                        argv[1] = splice(argv[1], argv[0]);
                        if (stat(argv[1], &stb2) == -1)
                                err(2, "%s", argv[1]);
                }
                print_status(diffreg(argv[0], argv[1], dflags), argv[0], argv[1],
                    "");
        }
        exit(status);
}

void
set_argstr(char **av, char **ave)
{
        size_t argsize;
        char **ap;

        argsize = 4 + *ave - *av + 1;
        diffargs = xmalloc(argsize);
        strlcpy(diffargs, "diff", argsize);
        for (ap = av + 1; ap < ave; ap++) {
                if (strcmp(*ap, "--") != 0) {
                        strlcat(diffargs, " ", argsize);
                        strlcat(diffargs, *ap, argsize);
                }
        }
}

/*
 * Read in an excludes file and push each line.
 */
void
read_excludes_file(char *file)
{
        FILE *fp;
        char *buf, *pattern;
        size_t len;

        if (strcmp(file, "-") == 0)
                fp = stdin;
        else if ((fp = fopen(file, "r")) == NULL)
                err(2, "%s", file);
        while ((buf = fgetln(fp, &len)) != NULL) {
                if (buf[len - 1] == '\n')
                        len--;
                pattern = xmalloc(len + 1);
                memcpy(pattern, buf, len);
                pattern[len] = '\0';
                push_excludes(pattern);
        }
        if (strcmp(file, "-") != 0)
                fclose(fp);
}

/*
 * Push a pattern onto the excludes list.
 */
void
push_excludes(char *pattern)
{
        struct excludes *entry;

        entry = xmalloc(sizeof(*entry));
        entry->pattern = pattern;
        entry->next = excludes_list;
        excludes_list = entry;
}

void
push_ignore_pats(char *pattern)
{
        size_t len;

        if (ignore_pats == NULL)
                ignore_pats = xstrdup(pattern);
        else {
                /* old + "|" + new + NUL */
                len = strlen(ignore_pats) + strlen(pattern) + 2;
                ignore_pats = xreallocarray(ignore_pats, 1, len);
                strlcat(ignore_pats, "|", len);
                strlcat(ignore_pats, pattern, len);
        }
}

void
print_only(const char *path, size_t dirlen, const char *entry)
{
        if (dirlen > 1)
                dirlen--;
        printf("Only in %.*s: %s\n", (int)dirlen, path, entry);
}

void
print_status(int val, char *path1, char *path2, char *entry)
{
        switch (val) {
        case D_BINARY:
                printf("Binary files %s%s and %s%s differ\n",
                    path1, entry, path2, entry);
                break;
        case D_DIFFER:
                if (diff_format == D_BRIEF)
                        printf("Files %s%s and %s%s differ\n",
                            path1, entry, path2, entry);
                break;
        case D_SAME:
                if (sflag)
                        printf("Files %s%s and %s%s are identical\n",
                            path1, entry, path2, entry);
                break;
        case D_MISMATCH1:
                printf("File %s%s is a directory while file %s%s is a regular file\n",
                    path1, entry, path2, entry);
                break;
        case D_MISMATCH2:
                printf("File %s%s is a regular file while file %s%s is a directory\n",
                    path1, entry, path2, entry);
                break;
        case D_SKIPPED1:
                printf("File %s%s is not a regular file or directory and was skipped\n",
                    path1, entry);
                break;
        case D_SKIPPED2:
                printf("File %s%s is not a regular file or directory and was skipped\n",
                    path2, entry);
                break;
        }
}

__dead void
usage(void)
{
        (void)fprintf(stderr,
            "usage: diff [-abdipTtw] [-c | -e | -f | -n | -q | -u] [-I pattern] [-L label]\n"
            "            file1 file2\n"
            "       diff [-abdipTtw] [-I pattern] [-L label] -C number file1 file2\n"
            "       diff [-abditw] [-I pattern] -D string file1 file2\n"
            "       diff [-abdipTtw] [-I pattern] [-L label] -U number file1 file2\n"
            "       diff [-abdiNPprsTtw] [-c | -e | -f | -n | -q | -u] [-I pattern]\n"
            "            [-L label] [-S name] [-X file] [-x pattern] dir1 dir2\n");

        exit(2);
}