root/usr.bin/diff/diff.c
/*      $OpenBSD: diff.c,v 1.67 2019/06/28 13:35:00 deraadt Exp $       */

/*
 * Copyright (c) 2003 Todd C. Miller <Todd.Miller@courtesan.com>
 *
 * 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 <limits.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

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

static const char diff_version[] = "FreeBSD diff 20260206";
bool     lflag, Nflag, Pflag, rflag, sflag, Tflag, cflag;
bool     ignore_file_case, suppress_common, color, noderef;
static bool help = false;
int      diff_format, diff_context, diff_algorithm, status;
bool     diff_algorithm_set;
int      tabsize = 8, width = 130;
static int      colorflag = COLORFLAG_NEVER;
char    *start, *ifdefname, *diffargs, *label[2];
char    *ignore_pats, *most_recent_pat;
char    *group_format = NULL;
const char      *add_code, *del_code;
struct stat stb1, stb2;
struct excludes *excludes_list;
regex_t  ignore_re, most_recent_re;

static struct algorithm {
        const char *name;
        int id;
} algorithms[] = {
        {"stone", D_DIFFSTONE},
        {"myers", D_DIFFMYERS},
        {"patience", D_DIFFPATIENCE},
        {NULL, D_DIFFNONE}
};

#define OPTIONS "0123456789A:aBbC:cdD:efF:HhI:iL:lnNPpqrS:sTtU:uwW:X:x:y"
enum {
        OPT_TSIZE = CHAR_MAX + 1,
        OPT_STRIPCR,
        OPT_IGN_FN_CASE,
        OPT_NO_IGN_FN_CASE,
        OPT_NORMAL,
        OPT_HELP,
        OPT_HORIZON_LINES,
        OPT_CHANGED_GROUP_FORMAT,
        OPT_SUPPRESS_COMMON,
        OPT_COLOR,
        OPT_NO_DEREFERENCE,
        OPT_VERSION,
};

static struct option longopts[] = {
        { "algorithm",                  required_argument,      0,      'A' },
        { "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' },
        { "show-function-line",         required_argument,      0,      'F' },
        { "speed-large-files",          no_argument,            NULL,   'H' },
        { "ignore-blank-lines",         no_argument,            0,      'B' },
        { "ignore-matching-lines",      required_argument,      0,      'I' },
        { "ignore-case",                no_argument,            0,      'i' },
        { "paginate",                   no_argument,            NULL,   'l' },
        { "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' },
        { "width",                      required_argument,      0,      'W' },
        { "exclude",                    required_argument,      0,      'x' },
        { "exclude-from",               required_argument,      0,      'X' },
        { "side-by-side",               no_argument,            NULL,   'y' },
        { "ignore-file-name-case",      no_argument,            NULL,   OPT_IGN_FN_CASE },
        { "help",                       no_argument,            NULL,   OPT_HELP},
        { "horizon-lines",              required_argument,      NULL,   OPT_HORIZON_LINES },
        { "no-dereference",             no_argument,            NULL,   OPT_NO_DEREFERENCE},
        { "no-ignore-file-name-case",   no_argument,            NULL,   OPT_NO_IGN_FN_CASE },
        { "normal",                     no_argument,            NULL,   OPT_NORMAL },
        { "strip-trailing-cr",          no_argument,            NULL,   OPT_STRIPCR },
        { "tabsize",                    required_argument,      NULL,   OPT_TSIZE },
        { "changed-group-format",       required_argument,      NULL,   OPT_CHANGED_GROUP_FORMAT},
        { "suppress-common-lines",      no_argument,            NULL,   OPT_SUPPRESS_COMMON },
        { "color",                      optional_argument,      NULL,   OPT_COLOR },
        { "version",                    no_argument,            NULL,   OPT_VERSION},
        { NULL,                         0,                      0,      '\0'}
};

static void checked_regcomp(char const *, regex_t *);
static void usage(void) __dead2;
static void conflicting_format(void) __dead2;
static void push_excludes(char *);
static void push_ignore_pats(char *);
static void read_excludes_file(char *file);
static void set_argstr(char **, char **);
static char *splice(char *, char *);
static bool do_color(void);

int
main(int argc, char **argv)
{
        const char *errstr;
        char **oargv;
        int ch, dflags, lastch, gotstdin, prevoptind, newarg;

        oargv = argv;
        gotstdin = 0;
        dflags = 0;
        lastch = '\0';
        prevoptind = 1;
        newarg = 1;
        diff_context = 3;
        diff_format = D_UNSET;
        diff_algorithm = D_DIFFMYERS;
        diff_algorithm_set = false;
#define FORMAT_MISMATCHED(type) \
        (diff_format != D_UNSET && diff_format != (type))
        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':
                        diff_algorithm = D_DIFFNONE;
                        for (struct algorithm *a = algorithms; a->name;a++) {
                                if(strcasecmp(optarg, a->name) == 0) {
                                        diff_algorithm = a->id;
                                        diff_algorithm_set = true;
                                        break;
                                }
                        }

                        if (diff_algorithm == D_DIFFNONE) {
                                warnx("unknown algorithm: %s", optarg);
                                usage();
                        }
                        break;
                case 'a':
                        dflags |= D_FORCEASCII;
                        break;
                case 'b':
                        dflags |= D_FOLDBLANKS;
                        break;
                case 'C':
                case 'c':
                        if (FORMAT_MISMATCHED(D_CONTEXT))
                                conflicting_format();
                        cflag = true;
                        diff_format = D_CONTEXT;
                        if (optarg != NULL) {
                                diff_context = (int) strtonum(optarg,
                                    1, INT_MAX, &errstr);
                                if (errstr != NULL) {
                                        warnx("context size is %s: %s",
                                            errstr, optarg);
                                        usage();
                                }
                        }
                        break;
                case 'd':
                        dflags |= D_MINIMAL;
                        break;
                case 'D':
                        if (FORMAT_MISMATCHED(D_IFDEF))
                                conflicting_format();
                        diff_format = D_IFDEF;
                        ifdefname = optarg;
                        break;
                case 'e':
                        if (FORMAT_MISMATCHED(D_EDIT))
                                conflicting_format();
                        diff_format = D_EDIT;
                        break;
                case 'f':
                        if (FORMAT_MISMATCHED(D_REVERSE))
                                conflicting_format();
                        diff_format = D_REVERSE;
                        break;
                case 'H':
                        /* ignore but needed for compatibility with GNU diff */
                        break;
                case 'h':
                        /* silently ignore for backwards compatibility */
                        break;
                case 'B':
                        dflags |= D_SKIPBLANKLINES;
                        break;
                case 'F':
                        if (dflags & D_PROTOTYPE)
                                conflicting_format();
                        dflags |= D_MATCHLAST;
                        most_recent_pat = xstrdup(optarg);
                        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 'l':
                        dflags |= D_PAGINATION;
                        lflag = true;
                        break;
                case 'N':
                        Nflag = true;
                        break;
                case 'n':
                        if (FORMAT_MISMATCHED(D_NREVERSE))
                                conflicting_format();
                        diff_format = D_NREVERSE;
                        break;
                case 'p':
                        if (dflags & D_MATCHLAST)
                                conflicting_format();
                        dflags |= D_PROTOTYPE;
                        break;
                case 'P':
                        Pflag = true;
                        break;
                case 'r':
                        rflag = true;
                        break;
                case 'q':
                        if (FORMAT_MISMATCHED(D_BRIEF))
                                conflicting_format();
                        diff_format = D_BRIEF;
                        break;
                case 'S':
                        start = optarg;
                        break;
                case 's':
                        sflag = true;
                        break;
                case 'T':
                        Tflag = true;
                        break;
                case 't':
                        dflags |= D_EXPANDTABS;
                        break;
                case 'U':
                case 'u':
                        if (FORMAT_MISMATCHED(D_UNIFIED))
                                conflicting_format();
                        diff_format = D_UNIFIED;
                        if (optarg != NULL) {
                                diff_context = (int) strtonum(optarg,
                                    0, INT_MAX, &errstr);
                                if (errstr != NULL) {
                                        warnx("context size is %s: %s",
                                            errstr, optarg);
                                        usage();
                                }
                        }
                        break;
                case 'w':
                        dflags |= D_IGNOREBLANKS;
                        break;
                case 'W':
                        width = (int) strtonum(optarg, 1, INT_MAX, &errstr);
                        if (errstr != NULL) {
                                warnx("width is %s: %s", errstr, optarg);
                                usage();
                        }
                        break;
                case 'X':
                        read_excludes_file(optarg);
                        break;
                case 'x':
                        push_excludes(optarg);
                        break;
                case 'y':
                        if (FORMAT_MISMATCHED(D_SIDEBYSIDE))
                                conflicting_format();
                        diff_format = D_SIDEBYSIDE;
                        break;
                case OPT_CHANGED_GROUP_FORMAT:
                        if (FORMAT_MISMATCHED(D_GFORMAT))
                                conflicting_format();
                        diff_format = D_GFORMAT;
                        group_format = optarg;
                        break;
                case OPT_HELP:
                        help = true;
                        usage();
                        break;
                case OPT_HORIZON_LINES:
                        break; /* XXX TODO for compatibility with GNU diff3 */
                case OPT_IGN_FN_CASE:
                        ignore_file_case = true;
                        break;
                case OPT_NO_IGN_FN_CASE:
                        ignore_file_case = false;
                        break;
                case OPT_NORMAL:
                        if (FORMAT_MISMATCHED(D_NORMAL))
                                conflicting_format();
                        diff_format = D_NORMAL;
                        break;
                case OPT_TSIZE:
                        tabsize = (int) strtonum(optarg, 1, INT_MAX, &errstr);
                        if (errstr != NULL) {
                                warnx("tabsize is %s: %s", errstr, optarg);
                                usage();
                        }
                        break;
                case OPT_STRIPCR:
                        dflags |= D_STRIPCR;
                        break;
                case OPT_SUPPRESS_COMMON:
                        suppress_common = 1;
                        break;
                case OPT_COLOR:
                        if (optarg == NULL || strncmp(optarg, "auto", 4) == 0)
                                colorflag = COLORFLAG_AUTO;
                        else if (strncmp(optarg, "always", 6) == 0)
                                colorflag = COLORFLAG_ALWAYS;
                        else if (strncmp(optarg, "never", 5) == 0)
                                colorflag = COLORFLAG_NEVER;
                        else {
                                warnx("unsupported --color value "
                                    "(must be always, auto, or never): "
                                    "%s", optarg);
                                usage();
                        }
                        break;
                case OPT_NO_DEREFERENCE:
                        noderef = true;
                        break;
                case OPT_VERSION:
                        printf("%s\n", diff_version);
                        exit(0);
                default:
                        usage();
                        break;
                }
                lastch = ch;
                newarg = optind != prevoptind;
                prevoptind = optind;
        }
        if (diff_format == D_UNSET && (dflags & D_PROTOTYPE) != 0)
                diff_format = D_CONTEXT;
        if (diff_format == D_UNSET)
                diff_format = D_NORMAL;
        argc -= optind;
        argv += optind;

        if (do_color()) {
                char *p;
                const char *env;

                color = true;
                add_code = "32";
                del_code = "31";
                env = getenv("DIFFCOLORS");
                if (env != NULL && *env != '\0' && (p = strdup(env))) {
                        add_code = p;
                        strsep(&p, ":");
                        if (p != NULL)
                                del_code = p;
                }
        }

#ifdef __OpenBSD__
        if (pledge("stdio rpath tmppath", NULL) == -1)
                err(2, "pledge");
#endif

        /*
         * 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();
        checked_regcomp(ignore_pats, &ignore_re);
        checked_regcomp(most_recent_pat, &most_recent_re);
        if (strcmp(argv[0], "-") == 0) {
                fstat(STDIN_FILENO, &stb1);
                gotstdin = 1;
        } else if (stat(argv[0], &stb1) != 0) {
                if (!Nflag || errno != ENOENT)
                        err(2, "%s", argv[0]);
                dflags |= D_EMPTY1;
                memset(&stb1, 0, sizeof(struct stat));
        }

        if (strcmp(argv[1], "-") == 0) {
                fstat(STDIN_FILENO, &stb2);
                gotstdin = 1;
        } else if (stat(argv[1], &stb2) != 0) {
                if (!Nflag || errno != ENOENT)
                        err(2, "%s", argv[1]);
                dflags |= D_EMPTY2;
                memset(&stb2, 0, sizeof(stb2));
                stb2.st_mode = stb1.st_mode;
        }

        if (dflags & D_EMPTY1 && dflags & D_EMPTY2){
                warn("%s", argv[0]);
                warn("%s", argv[1]);
                exit(2);
        }

        if (stb1.st_mode == 0)
                stb1.st_mode = stb2.st_mode;

        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, 1), argv[0],
                    argv[1], "");
        }
        if (fflush(stdout) != 0)
                err(2, "stdout");
        exit(status);
}

static void
checked_regcomp(char const *pattern, regex_t *comp)
{
        char buf[BUFSIZ];
        int error;

        if (pattern == NULL)
                return;

        error = regcomp(comp, pattern, REG_NEWLINE | REG_EXTENDED);
        if (error != 0) {
                regerror(error, comp, buf, sizeof(buf));
                if (*pattern != '\0')
                        errx(2, "%s: %s", pattern, buf);
                else
                        errx(2, "%s", buf);
        }
}

static 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.
 */
static void
read_excludes_file(char *file)
{
        FILE *fp;
        char *pattern = NULL;
        size_t blen = 0;
        ssize_t len;

        if (strcmp(file, "-") == 0)
                fp = stdin;
        else if ((fp = fopen(file, "r")) == NULL)
                err(2, "%s", file);
        while ((len = getline(&pattern, &blen, fp)) >= 0) {
                if ((len > 0) && (pattern[len - 1] == '\n'))
                        pattern[len - 1] = '\0';
                push_excludes(pattern);
                /* we allocate a new string per line */
                pattern = NULL;
                blen = 0;
        }
        free(pattern);
        if (strcmp(file, "-") != 0)
                fclose(fp);
}

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

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

static 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_status(int val, char *path1, char *path2, const char *entry)
{
        if (label[0] != NULL)
                path1 = label[0];
        if (label[1] != NULL)
                path2 = label[1];

        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;
        case D_ERROR:
                break;
        }
}

static void
usage(void)
{
        (void)fprintf(help ? stdout : stderr,
            "usage: diff [-aBbdilpTtw] [-c | -e | -f | -n | -q | -u] [--ignore-case]\n"
            "            [--no-ignore-case] [--normal] [--strip-trailing-cr] [--tabsize]\n"
            "            [-I pattern] [-F pattern] [-L label] file1 file2\n"
            "       diff [-aBbdilpTtw] [-I pattern] [-L label] [--ignore-case]\n"
            "            [--no-ignore-case] [--normal] [--strip-trailing-cr] [--tabsize]\n"
            "            [-F pattern] -C number file1 file2\n"
            "       diff [-aBbdiltw] [-I pattern] [--ignore-case] [--no-ignore-case]\n"
            "            [--normal] [--strip-trailing-cr] [--tabsize] -D string file1 file2\n"
            "       diff [-aBbdilpTtw] [-I pattern] [-L label] [--ignore-case]\n"
            "            [--no-ignore-case] [--normal] [--tabsize] [--strip-trailing-cr]\n"
            "            [-F pattern] -U number file1 file2\n"
            "       diff [-aBbdilNPprsTtw] [-c | -e | -f | -n | -q | -u] [--ignore-case]\n"
            "            [--no-ignore-case] [--normal] [--tabsize] [-I pattern] [-L label]\n"
            "            [-F pattern] [-S name] [-X file] [-x pattern] dir1 dir2\n"
            "       diff [-aBbditwW] [--expand-tabs] [--ignore-all-space]\n"
            "            [--ignore-blank-lines] [--ignore-case] [--minimal]\n"
            "            [--no-ignore-file-name-case] [--strip-trailing-cr]\n"
            "            [--suppress-common-lines] [--tabsize] [--text] [--width]\n"
            "            -y | --side-by-side file1 file2\n"
            "       diff [--help] [--version]\n");

        if (help)
                exit(0);
        else
                exit(2);
}

static void
conflicting_format(void)
{

        fprintf(stderr, "error: conflicting output format options.\n");
        usage();
}

static bool
do_color(void)
{
        const char *p, *p2;

        switch (colorflag) {
        case COLORFLAG_AUTO:
                p = getenv("CLICOLOR");
                p2 = getenv("COLORTERM");
                if ((p != NULL && *p != '\0') || (p2 != NULL && *p2 != '\0'))
                        return isatty(STDOUT_FILENO);
                break;
        case COLORFLAG_ALWAYS:
                return (true);
        case COLORFLAG_NEVER:
                return (false);
        }

        return (false);
}

static char *
splice(char *dir, char *path)
{
        char *tail, *buf;
        size_t dirlen;

        dirlen = strlen(dir);
        while (dirlen != 0 && dir[dirlen - 1] == '/')
            dirlen--;
        if ((tail = strrchr(path, '/')) == NULL)
                tail = path;
        else
                tail++;
        xasprintf(&buf, "%.*s/%s", (int)dirlen, dir, tail);
        return (buf);
}