/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright © 2002, Jörg Wunsch
 *
 * 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.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR(S) ``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 AUTHOR(S) 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.
 */

/*
 * 4.3BSD UI-compatible whereis(1) utility.  Rewritten from scratch
 * since the original 4.3BSD version suffers legal problems that
 * prevent it from being redistributed, and since the 4.4BSD version
 * was pretty inferior in functionality.
 */

#include <sys/types.h>
#include <sys/stat.h>
#include <sys/sysctl.h>

#include <dirent.h>
#include <err.h>
#include <errno.h>
#include <locale.h>
#include <regex.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sysexits.h>
#include <unistd.h>

#include "pathnames.h"

#define NO_BIN_FOUND    1
#define NO_MAN_FOUND    2
#define NO_SRC_FOUND    4

typedef const char *ccharp;

static int opt_a, opt_b, opt_m, opt_q, opt_s, opt_u, opt_x;
static ccharp *bindirs, *mandirs, *sourcedirs;
static char **query;

static const char *sourcepath = PATH_SOURCES;

static char     *colonify(ccharp *);
static int       contains(ccharp *, const char *);
static void      decolonify(char *, ccharp **, int *);
static void      defaults(void);
static void      scanopts(int, char **);
static void      usage(void);

/*
 * Throughout this program, a number of strings are dynamically
 * allocated but never freed.  Their memory is written to when
 * splitting the strings into string lists which will later be
 * processed.  Since it's important that those string lists remain
 * valid even after the functions allocating the memory returned,
 * those functions cannot free them.  They could be freed only at end
 * of main(), which is pretty pointless anyway.
 *
 * The overall amount of memory to be allocated for processing the
 * strings is not expected to exceed a few kilobytes.  For that
 * reason, allocation can usually always be assumed to succeed (within
 * a virtual memory environment), thus we simply bail out using
 * abort(3) in case of an allocation failure.
 */

static void
usage(void)
{
        (void)fprintf(stderr,
             "usage: whereis [-abmqsux] [-BMS dir ... -f] program ...\n");
        exit(EX_USAGE);
}

/*
 * Scan options passed to program.
 *
 * Note that the -B/-M/-S options expect a list of directory
 * names that must be terminated with -f.
 */
static void
scanopts(int argc, char **argv)
{
        int c, i;
        ccharp **dirlist;

        while ((c = getopt(argc, argv, "BMSabfmqsux")) != -1)
                switch (c) {
                case 'B':
                        dirlist = &bindirs;
                        goto dolist;

                case 'M':
                        dirlist = &mandirs;
                        goto dolist;

                case 'S':
                        dirlist = &sourcedirs;
                  dolist:
                        i = 0;
                        *dirlist = realloc(*dirlist, (i + 1) * sizeof(char *));
                        (*dirlist)[i] = NULL;
                        while (optind < argc &&
                               strcmp(argv[optind], "-f") != 0 &&
                               strcmp(argv[optind], "-B") != 0 &&
                               strcmp(argv[optind], "-M") != 0 &&
                               strcmp(argv[optind], "-S") != 0) {
                                decolonify(argv[optind], dirlist, &i);
                                optind++;
                        }
                        break;

                case 'a':
                        opt_a = 1;
                        break;

                case 'b':
                        opt_b = 1;
                        break;

                case 'f':
                        goto breakout;

                case 'm':
                        opt_m = 1;
                        break;

                case 'q':
                        opt_q = 1;
                        break;

                case 's':
                        opt_s = 1;
                        break;

                case 'u':
                        opt_u = 1;
                        break;

                case 'x':
                        opt_x = 1;
                        break;

                default:
                        usage();
                }
  breakout:
        if (optind == argc)
                usage();
        query = argv + optind;
}

/*
 * Find out whether string `s' is contained in list `cpp'.
 */
static int
contains(ccharp *cpp, const char *s)
{
        ccharp cp;

        if (cpp == NULL)
                return (0);

        while ((cp = *cpp) != NULL) {
                if (strcmp(cp, s) == 0)
                        return (1);
                cpp++;
        }
        return (0);
}

/*
 * Split string `s' at colons, and pass it to the string list pointed
 * to by `cppp' (which has `*ip' elements).  Note that the original
 * string is modified by replacing the colon with a NUL byte.  The
 * partial string is only added if it has a length greater than 0, and
 * if it's not already contained in the string list.
 */
static void
decolonify(char *s, ccharp **cppp, int *ip)
{
        char *cp;

        while ((cp = strchr(s, ':')), *s != '\0') {
                if (cp)
                        *cp = '\0';
                if (strlen(s) && !contains(*cppp, s)) {
                        *cppp = realloc(*cppp, (*ip + 2) * sizeof(char *));
                        if (*cppp == NULL)
                                abort();
                        (*cppp)[*ip] = s;
                        (*cppp)[*ip + 1] = NULL;
                        (*ip)++;
                }
                if (cp)
                        s = cp + 1;
                else
                        break;
        }
}

/*
 * Join string list `cpp' into a colon-separated string.
 */
static char *
colonify(ccharp *cpp)
{
        size_t s;
        char *cp;
        int i;

        if (cpp == NULL)
                return (0);

        for (s = 0, i = 0; cpp[i] != NULL; i++)
                s += strlen(cpp[i]) + 1;
        if ((cp = malloc(s + 1)) == NULL)
                abort();
        for (i = 0, *cp = '\0'; cpp[i] != NULL; i++) {
                strcat(cp, cpp[i]);
                strcat(cp, ":");
        }
        cp[s - 1] = '\0';               /* eliminate last colon */

        return (cp);
}

/*
 * Provide defaults for all options and directory lists.
 */
static void
defaults(void)
{
        size_t s;
        char *b, buf[BUFSIZ], *cp;
        int nele;
        FILE *p;
        DIR *dir;
        struct stat sb;
        struct dirent *dirp;
        const int oid[2] = {CTL_USER, USER_CS_PATH};

        /* default to -bms if none has been specified */
        if (!opt_b && !opt_m && !opt_s)
                opt_b = opt_m = opt_s = 1;

        /* -b defaults to default path + /usr/libexec +
         * user's path */
        if (!bindirs) {
                if (sysctl(oid, 2, NULL, &s, NULL, 0) == -1)
                        err(EX_OSERR, "sysctl(\"user.cs_path\")");
                if ((b = malloc(s + 1)) == NULL)
                        abort();
                if (sysctl(oid, 2, b, &s, NULL, 0) == -1)
                        err(EX_OSERR, "sysctl(\"user.cs_path\")");
                nele = 0;
                decolonify(b, &bindirs, &nele);
                bindirs = realloc(bindirs, (nele + 2) * sizeof(char *));
                if (bindirs == NULL)
                        abort();
                bindirs[nele++] = PATH_LIBEXEC;
                bindirs[nele] = NULL;
                if ((cp = getenv("PATH")) != NULL) {
                        /* don't destroy the original environment... */
                        b = strdup(cp);
                        if (b == NULL)
                                abort();
                        decolonify(b, &bindirs, &nele);
                }
        }

        /* -m defaults to $(manpath) */
        if (!mandirs) {
                if ((p = popen(MANPATHCMD, "r")) == NULL)
                        err(EX_OSERR, "cannot execute manpath command");
                if (fgets(buf, BUFSIZ - 1, p) == NULL ||
                    pclose(p))
                        err(EX_OSERR, "error processing manpath results");
                if ((b = strchr(buf, '\n')) != NULL)
                        *b = '\0';
                b = strdup(buf);
                if (b == NULL)
                        abort();
                nele = 0;
                decolonify(b, &mandirs, &nele);
        }

        /* -s defaults to precompiled list, plus subdirs of /usr/ports */
        if (!sourcedirs) {
                b = strdup(sourcepath);
                if (b == NULL)
                        abort();
                nele = 0;
                decolonify(b, &sourcedirs, &nele);

                if (stat(PATH_PORTS, &sb) == -1) {
                        if (errno == ENOENT)
                                /* no /usr/ports, we are done */
                                return;
                        err(EX_OSERR, "stat(" PATH_PORTS ")");
                }
                if ((sb.st_mode & S_IFMT) != S_IFDIR)
                        /* /usr/ports is not a directory, ignore */
                        return;
                if (access(PATH_PORTS, R_OK | X_OK) != 0)
                        return;
                if ((dir = opendir(PATH_PORTS)) == NULL)
                        err(EX_OSERR, "opendir" PATH_PORTS ")");
                while ((dirp = readdir(dir)) != NULL) {
                        /*
                         * Not everything below PATH_PORTS is of
                         * interest.  First, all dot files and
                         * directories (e. g. .snap) can be ignored.
                         * Also, all subdirectories starting with a
                         * capital letter are not going to be
                         * examined, as they are used for internal
                         * purposes (Mk, Tools, ...).  This also
                         * matches a possible CVS subdirectory.
                         * Finally, the distfiles subdirectory is also
                         * special, and should not be considered to
                         * avoid false matches.
                         */
                        if (dirp->d_name[0] == '.' ||
                            /*
                             * isupper() not used on purpose: the
                             * check is supposed to default to the C
                             * locale instead of the current user's
                             * locale.
                             */
                            (dirp->d_name[0] >= 'A' && dirp->d_name[0] <= 'Z') ||
                            strcmp(dirp->d_name, "distfiles") == 0)
                                continue;
                        if ((b = malloc(sizeof PATH_PORTS + 1 + dirp->d_namlen))
                            == NULL)
                                abort();
                        strcpy(b, PATH_PORTS);
                        strcat(b, "/");
                        strcat(b, dirp->d_name);
                        if (stat(b, &sb) == -1 ||
                            (sb.st_mode & S_IFMT) != S_IFDIR ||
                            access(b, R_OK | X_OK) != 0) {
                                free(b);
                                continue;
                        }
                        sourcedirs = realloc(sourcedirs,
                                             (nele + 2) * sizeof(char *));
                        if (sourcedirs == NULL)
                                abort();
                        sourcedirs[nele++] = b;
                        sourcedirs[nele] = NULL;
                }
                closedir(dir);
        }
}

int
main(int argc, char **argv)
{
        int unusual, i, printed;
        char *bin, buf[BUFSIZ], *cp, *cp2, *man, *name, *src;
        ccharp *dp;
        size_t nlen, olen, s;
        struct stat sb;
        regex_t re, re2;
        regmatch_t matches[2];
        regoff_t rlen;
        FILE *p;

        setlocale(LC_ALL, "");

        scanopts(argc, argv);
        defaults();

        if (mandirs == NULL)
                opt_m = 0;
        if (bindirs == NULL)
                opt_b = 0;
        if (sourcedirs == NULL)
                opt_s = 0;
        if (opt_m + opt_b + opt_s == 0)
                errx(EX_DATAERR, "no directories to search");

        if (opt_m) {
                setenv("MANPATH", colonify(mandirs), 1);
                if ((i = regcomp(&re, MANWHEREISMATCH, REG_EXTENDED)) != 0) {
                        regerror(i, &re, buf, BUFSIZ - 1);
                        errx(EX_UNAVAILABLE, "regcomp(%s) failed: %s",
                             MANWHEREISMATCH, buf);
                }
        }

        for (; (name = *query) != NULL; query++) {
                /* strip leading path name component */
                if ((cp = strrchr(name, '/')) != NULL)
                        name = cp + 1;
                /* strip SCCS or RCS suffix/prefix */
                if (strlen(name) > 2 && strncmp(name, "s.", 2) == 0)
                        name += 2;
                if ((s = strlen(name)) > 2 && strcmp(name + s - 2, ",v") == 0)
                        name[s - 2] = '\0';
                /* compression suffix */
                s = strlen(name);
                if (s > 2 &&
                    (strcmp(name + s - 2, ".z") == 0 ||
                     strcmp(name + s - 2, ".Z") == 0))
                        name[s - 2] = '\0';
                else if (s > 3 &&
                         strcmp(name + s - 3, ".gz") == 0)
                        name[s - 3] = '\0';
                else if (s > 4 &&
                         strcmp(name + s - 4, ".bz2") == 0)
                        name[s - 4] = '\0';

                unusual = 0;
                bin = man = src = NULL;
                s = strlen(name);

                if (opt_b) {
                        /*
                         * Binaries have to match exactly, and must be regular
                         * executable files.
                         */
                        unusual = unusual | NO_BIN_FOUND;
                        for (dp = bindirs; *dp != NULL; dp++) {
                                cp = malloc(strlen(*dp) + 1 + s + 1);
                                if (cp == NULL)
                                        abort();
                                strcpy(cp, *dp);
                                strcat(cp, "/");
                                strcat(cp, name);
                                if (stat(cp, &sb) == 0 &&
                                    (sb.st_mode & S_IFMT) == S_IFREG &&
                                    (sb.st_mode & (S_IXUSR | S_IXGRP | S_IXOTH))
                                    != 0) {
                                        unusual = unusual & ~NO_BIN_FOUND;
                                        if (bin == NULL) {
                                                bin = strdup(cp);
                                        } else {
                                                olen = strlen(bin);
                                                nlen = strlen(cp);
                                                bin = realloc(bin, 
                                                              olen + nlen + 2);
                                                if (bin == NULL)
                                                        abort();
                                                strcat(bin, " ");
                                                strcat(bin, cp);
                                        }
                                        if (!opt_a) {
                                                free(cp);
                                                break;
                                        }
                                }
                                free(cp);
                        }
                }

                if (opt_m) {
                        /*
                         * Ask the man command to perform the search for us.
                         */
                        unusual = unusual | NO_MAN_FOUND;
                        if (opt_a)
                                cp = malloc(sizeof MANWHEREISALLCMD - 2 + s);
                        else
                                cp = malloc(sizeof MANWHEREISCMD - 2 + s);

                        if (cp == NULL)
                                abort();

                        if (opt_a)
                                sprintf(cp, MANWHEREISALLCMD, name);
                        else
                                sprintf(cp, MANWHEREISCMD, name);

                        if ((p = popen(cp, "r")) != NULL) {
                            
                                while (fgets(buf, BUFSIZ - 1, p) != NULL) {
                                        unusual = unusual & ~NO_MAN_FOUND;
                                
                                        if ((cp2 = strchr(buf, '\n')) != NULL)
                                                *cp2 = '\0';
                                        if (regexec(&re, buf, 2, 
                                                    matches, 0) == 0 &&
                                            (rlen = matches[1].rm_eo - 
                                             matches[1].rm_so) > 0) {
                                                /*
                                                 * man -w found formatted
                                                 * page, need to pick up
                                                 * source page name.
                                                 */
                                                cp2 = malloc(rlen + 1);
                                                if (cp2 == NULL)
                                                        abort();
                                                memcpy(cp2, 
                                                       buf + matches[1].rm_so,
                                                       rlen);
                                                cp2[rlen] = '\0';
                                        } else {
                                                /*
                                                 * man -w found plain source
                                                 * page, use it.
                                                 */
                                                cp2 = strdup(buf);
                                                if (cp2 == NULL)
                                                        abort();
                                        }

                                        if (man == NULL) {
                                                man = strdup(cp2);
                                        } else {
                                                olen = strlen(man);
                                                nlen = strlen(cp2);
                                                man = realloc(man, 
                                                              olen + nlen + 2);
                                                if (man == NULL)
                                                        abort();
                                                strcat(man, " ");
                                                strcat(man, cp2);
                                        }

                                        free(cp2);
                                        
                                        if (!opt_a)
                                                break;
                                }
                                pclose(p);
                                free(cp);
                        }
                }

                if (opt_s) {
                        /*
                         * Sources match if a subdir with the exact
                         * name is found.
                         */
                        unusual = unusual | NO_SRC_FOUND;
                        for (dp = sourcedirs; *dp != NULL; dp++) {
                                cp = malloc(strlen(*dp) + 1 + s + 1);
                                if (cp == NULL)
                                        abort();
                                strcpy(cp, *dp);
                                strcat(cp, "/");
                                strcat(cp, name);
                                if (stat(cp, &sb) == 0 &&
                                    (sb.st_mode & S_IFMT) == S_IFDIR) {
                                        unusual = unusual & ~NO_SRC_FOUND;
                                        if (src == NULL) {
                                                src = strdup(cp);
                                        } else {
                                                olen = strlen(src);
                                                nlen = strlen(cp);
                                                src = realloc(src, 
                                                              olen + nlen + 2);
                                                if (src == NULL)
                                                        abort();
                                                strcat(src, " ");
                                                strcat(src, cp);
                                        }
                                        if (!opt_a) {
                                                free(cp);
                                                break;
                                        }
                                }
                                free(cp);
                        }
                        /*
                         * If still not found, ask locate to search it
                         * for us.  This will find sources for things
                         * like lpr that are well hidden in the
                         * /usr/src tree, but takes a lot longer.
                         * Thus, option -x (`expensive') prevents this
                         * search.
                         *
                         * Do only match locate output that starts
                         * with one of our source directories, and at
                         * least one further level of subdirectories.
                         */
                        if (opt_x || (src && !opt_a))
                                goto done_sources;

                        cp = malloc(sizeof LOCATECMD - 2 + s);
                        if (cp == NULL)
                                abort();
                        sprintf(cp, LOCATECMD, name);
                        if ((p = popen(cp, "r")) == NULL)
                                goto done_sources;
                        while ((src == NULL || opt_a) &&
                               (fgets(buf, BUFSIZ - 1, p)) != NULL) {
                                if ((cp2 = strchr(buf, '\n')) != NULL)
                                        *cp2 = '\0';
                                for (dp = sourcedirs;
                                     (src == NULL || opt_a) && *dp != NULL;
                                     dp++) {
                                        cp2 = malloc(strlen(*dp) + 9);
                                        if (cp2 == NULL)
                                                abort();
                                        strcpy(cp2, "^");
                                        strcat(cp2, *dp);
                                        strcat(cp2, "/[^/]+/");
                                        if ((i = regcomp(&re2, cp2,
                                                         REG_EXTENDED|REG_NOSUB))
                                            != 0) {
                                                regerror(i, &re, buf,
                                                         BUFSIZ - 1);
                                                errx(EX_UNAVAILABLE,
                                                     "regcomp(%s) failed: %s",
                                                     cp2, buf);
                                        }
                                        free(cp2);
                                        if (regexec(&re2, buf, 0,
                                                    (regmatch_t *)NULL, 0)
                                            == 0) {
                                                unusual = unusual & 
                                                          ~NO_SRC_FOUND;
                                                if (src == NULL) {
                                                        src = strdup(buf);
                                                } else {
                                                        olen = strlen(src);
                                                        nlen = strlen(buf);
                                                        src = realloc(src, 
                                                                      olen + 
                                                                      nlen + 2);
                                                        if (src == NULL)
                                                                abort();
                                                        strcat(src, " ");
                                                        strcat(src, buf);
                                                }
                                        }
                                        regfree(&re2);
                                }
                        }
                        pclose(p);
                        free(cp);
                }
          done_sources:

                if (opt_u && !unusual)
                        continue;

                printed = 0;
                if (!opt_q) {
                        printf("%s:", name);
                        printed++;
                }
                if (bin) {
                        if (printed++)
                                putchar(' ');
                        fputs(bin, stdout);
                }
                if (man) {
                        if (printed++)
                                putchar(' ');
                        fputs(man, stdout);
                }
                if (src) {
                        if (printed++)
                                putchar(' ');
                        fputs(src, stdout);
                }
                if (printed)
                        putchar('\n');
        }

        if (opt_m)
                regfree(&re);

        return (0);
}