/* $OpenBSD: mansearch.c,v 1.67 2022/12/26 19:16:02 jmc Exp $ */
/*
 * Copyright (c) 2012 Kristaps Dzonsons <kristaps@bsd.lv>
 * Copyright (c) 2013-2018 Ingo Schwarze <schwarze@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 AUTHORS DISCLAIM ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHORS 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.
 */

#include <sys/mman.h>
#include <sys/types.h>

#include <assert.h>
#include <err.h>
#include <errno.h>
#include <fcntl.h>
#include <glob.h>
#include <limits.h>
#include <regex.h>
#include <stdio.h>
#include <stdint.h>
#include <stddef.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#include "mandoc_aux.h"
#include "mandoc_ohash.h"
#include "manconf.h"
#include "mansearch.h"
#include "dbm.h"

struct  expr {
        /* Used for terms: */
        struct dbm_match match;   /* Match type and expression. */
        uint64_t         bits;    /* Type mask. */
        /* Used for OR and AND groups: */
        struct expr     *next;    /* Next child in the parent group. */
        struct expr     *child;   /* First child in this group. */
        enum { EXPR_TERM, EXPR_OR, EXPR_AND } type;
};

const char *const mansearch_keynames[KEY_MAX] = {
        "arch", "sec",  "Xr",   "Ar",   "Fa",   "Fl",   "Dv",   "Fn",
        "Ic",   "Pa",   "Cm",   "Li",   "Em",   "Cd",   "Va",   "Ft",
        "Tn",   "Er",   "Ev",   "Sy",   "Sh",   "In",   "Ss",   "Ox",
        "An",   "Mt",   "St",   "Bx",   "At",   "Nx",   "Fx",   "Lk",
        "Ms",   "Bsx",  "Dx",   "Rs",   "Vt",   "Lb",   "Nm",   "Nd"
};


static  struct ohash    *manmerge(struct expr *, struct ohash *);
static  struct ohash    *manmerge_term(struct expr *, struct ohash *);
static  struct ohash    *manmerge_or(struct expr *, struct ohash *);
static  struct ohash    *manmerge_and(struct expr *, struct ohash *);
static  char            *buildnames(const struct dbm_page *);
static  char            *buildoutput(size_t, struct dbm_page *);
static  size_t           lstlen(const char *, size_t);
static  void             lstcat(char *, size_t *, const char *, const char *);
static  int              lstmatch(const char *, const char *);
static  struct expr     *exprcomp(const struct mansearch *,
                                int, char *[], int *);
static  struct expr     *expr_and(const struct mansearch *,
                                int, char *[], int *);
static  struct expr     *exprterm(const struct mansearch *,
                                int, char *[], int *);
static  void             exprfree(struct expr *);
static  int              manpage_compare(const void *, const void *);


int
mansearch(const struct mansearch *search,
                const struct manpaths *paths,
                int argc, char *argv[],
                struct manpage **res, size_t *sz)
{
        char             buf[PATH_MAX];
        struct dbm_res  *rp;
        struct expr     *e;
        struct dbm_page *page;
        struct manpage  *mpage;
        struct ohash    *htab;
        size_t           cur, i, maxres, outkey;
        unsigned int     slot;
        int              argi, chdir_status, getcwd_status, im;

        argi = 0;
        if ((e = exprcomp(search, argc, argv, &argi)) == NULL) {
                *sz = 0;
                return 0;
        }

        cur = maxres = 0;
        if (res != NULL)
                *res = NULL;

        outkey = KEY_Nd;
        if (search->outkey != NULL)
                for (im = 0; im < KEY_MAX; im++)
                        if (0 == strcasecmp(search->outkey,
                            mansearch_keynames[im])) {
                                outkey = im;
                                break;
                        }

        /*
         * Remember the original working directory, if possible.
         * This will be needed if the second or a later directory
         * is given as a relative path.
         * Do not error out if the current directory is not
         * searchable: Maybe it won't be needed after all.
         */

        if (getcwd(buf, PATH_MAX) == NULL) {
                getcwd_status = 0;
                (void)strlcpy(buf, strerror(errno), sizeof(buf));
        } else
                getcwd_status = 1;

        /*
         * Loop over the directories (containing databases) for us to
         * search.
         * Don't let missing/bad databases/directories phase us.
         * In each, try to open the resident database and, if it opens,
         * scan it for our match expression.
         */

        chdir_status = 0;
        for (i = 0; i < paths->sz; i++) {
                if (chdir_status && paths->paths[i][0] != '/') {
                        if ( ! getcwd_status) {
                                warnx("%s: getcwd: %s", paths->paths[i], buf);
                                continue;
                        } else if (chdir(buf) == -1) {
                                warn("%s", buf);
                                continue;
                        }
                }
                if (chdir(paths->paths[i]) == -1) {
                        warn("%s", paths->paths[i]);
                        continue;
                }
                chdir_status = 1;

                if (dbm_open(MANDOC_DB) == -1) {
                        if (errno != ENOENT)
                                warn("%s/%s", paths->paths[i], MANDOC_DB);
                        continue;
                }

                if ((htab = manmerge(e, NULL)) == NULL) {
                        dbm_close();
                        continue;
                }

                for (rp = ohash_first(htab, &slot); rp != NULL;
                    rp = ohash_next(htab, &slot)) {
                        page = dbm_page_get(rp->page);

                        if (lstmatch(search->sec, page->sect) == 0 ||
                            lstmatch(search->arch, page->arch) == 0 ||
                            (search->argmode == ARG_NAME &&
                             rp->bits <= (int32_t)(NAME_SYN & NAME_MASK)))
                                continue;

                        if (res == NULL) {
                                cur = 1;
                                break;
                        }
                        if (cur + 1 > maxres) {
                                maxres += 1024;
                                *res = mandoc_reallocarray(*res,
                                    maxres, sizeof(**res));
                        }
                        mpage = *res + cur;
                        mandoc_asprintf(&mpage->file, "%s/%s",
                            paths->paths[i], page->file + 1);
                        if (access(chdir_status ? page->file + 1 :
                            mpage->file, R_OK) == -1) {
                                warn("%s", mpage->file);
                                warnx("outdated mandoc.db contains "
                                    "bogus %s entry, run makewhatis %s",
                                    page->file + 1, paths->paths[i]);
                                free(mpage->file);
                                free(rp);
                                continue;
                        }
                        mpage->names = buildnames(page);
                        mpage->output = buildoutput(outkey, page);
                        mpage->bits = search->firstmatch ? rp->bits : 0;
                        mpage->ipath = i;
                        mpage->sec = *page->sect - '0';
                        if (mpage->sec < 0 || mpage->sec > 9)
                                mpage->sec = 10;
                        mpage->form = *page->file;
                        free(rp);
                        cur++;
                }
                ohash_delete(htab);
                free(htab);
                dbm_close();

                /*
                 * In man(1) mode, prefer matches in earlier trees
                 * over matches in later trees.
                 */

                if (cur && search->firstmatch)
                        break;
        }
        if (res != NULL && cur > 1)
                qsort(*res, cur, sizeof(struct manpage), manpage_compare);
        if (chdir_status && getcwd_status && chdir(buf) == -1)
                warn("%s", buf);
        exprfree(e);
        *sz = cur;
        return res != NULL || cur;
}

/*
 * Merge the results for the expression tree rooted at e
 * into the the result list htab.
 */
static struct ohash *
manmerge(struct expr *e, struct ohash *htab)
{
        switch (e->type) {
        case EXPR_TERM:
                return manmerge_term(e, htab);
        case EXPR_OR:
                return manmerge_or(e->child, htab);
        case EXPR_AND:
                return manmerge_and(e->child, htab);
        default:
                abort();
        }
}

static struct ohash *
manmerge_term(struct expr *e, struct ohash *htab)
{
        struct dbm_res   res, *rp;
        uint64_t         ib;
        unsigned int     slot;
        int              im;

        if (htab == NULL) {
                htab = mandoc_malloc(sizeof(*htab));
                mandoc_ohash_init(htab, 4, offsetof(struct dbm_res, page));
        }

        for (im = 0, ib = 1; im < KEY_MAX; im++, ib <<= 1) {
                if ((e->bits & ib) == 0)
                        continue;

                switch (ib) {
                case TYPE_arch:
                        dbm_page_byarch(&e->match);
                        break;
                case TYPE_sec:
                        dbm_page_bysect(&e->match);
                        break;
                case TYPE_Nm:
                        dbm_page_byname(&e->match);
                        break;
                case TYPE_Nd:
                        dbm_page_bydesc(&e->match);
                        break;
                default:
                        dbm_page_bymacro(im - 2, &e->match);
                        break;
                }

                /*
                 * When hashing for deduplication, use the unique
                 * page ID itself instead of a hash function;
                 * that is quite efficient.
                 */

                for (;;) {
                        res = dbm_page_next();
                        if (res.page == -1)
                                break;
                        slot = ohash_lookup_memory(htab,
                            (char *)&res, sizeof(res.page), res.page);
                        if ((rp = ohash_find(htab, slot)) != NULL) {
                                rp->bits |= res.bits;
                                continue;
                        }
                        rp = mandoc_malloc(sizeof(*rp));
                        *rp = res;
                        ohash_insert(htab, slot, rp);
                }
        }
        return htab;
}

static struct ohash *
manmerge_or(struct expr *e, struct ohash *htab)
{
        while (e != NULL) {
                htab = manmerge(e, htab);
                e = e->next;
        }
        return htab;
}

static struct ohash *
manmerge_and(struct expr *e, struct ohash *htab)
{
        struct ohash    *hand, *h1, *h2;
        struct dbm_res  *res;
        unsigned int     slot1, slot2;

        /* Evaluate the first term of the AND clause. */

        hand = manmerge(e, NULL);

        while ((e = e->next) != NULL) {

                /* Evaluate the next term and prepare for ANDing. */

                h2 = manmerge(e, NULL);
                if (ohash_entries(h2) < ohash_entries(hand)) {
                        h1 = h2;
                        h2 = hand;
                } else
                        h1 = hand;
                hand = mandoc_malloc(sizeof(*hand));
                mandoc_ohash_init(hand, 4, offsetof(struct dbm_res, page));

                /* Keep all pages that are in both result sets. */

                for (res = ohash_first(h1, &slot1); res != NULL;
                    res = ohash_next(h1, &slot1)) {
                        if (ohash_find(h2, ohash_lookup_memory(h2,
                            (char *)res, sizeof(res->page),
                            res->page)) == NULL)
                                free(res);
                        else
                                ohash_insert(hand, ohash_lookup_memory(hand,
                                    (char *)res, sizeof(res->page),
                                    res->page), res);
                }

                /* Discard the merged results. */

                for (res = ohash_first(h2, &slot2); res != NULL;
                    res = ohash_next(h2, &slot2))
                        free(res);
                ohash_delete(h2);
                free(h2);
                ohash_delete(h1);
                free(h1);
        }

        /* Merge the result of the AND into htab. */

        if (htab == NULL)
                return hand;

        for (res = ohash_first(hand, &slot1); res != NULL;
            res = ohash_next(hand, &slot1)) {
                slot2 = ohash_lookup_memory(htab,
                    (char *)res, sizeof(res->page), res->page);
                if (ohash_find(htab, slot2) == NULL)
                        ohash_insert(htab, slot2, res);
                else
                        free(res);
        }

        /* Discard the merged result. */

        ohash_delete(hand);
        free(hand);
        return htab;
}

void
mansearch_free(struct manpage *res, size_t sz)
{
        size_t   i;

        for (i = 0; i < sz; i++) {
                free(res[i].file);
                free(res[i].names);
                free(res[i].output);
        }
        free(res);
}

static int
manpage_compare(const void *vp1, const void *vp2)
{
        const struct manpage    *mp1, *mp2;
        const char              *cp1, *cp2;
        size_t                   sz1, sz2;
        int                      diff;

        mp1 = vp1;
        mp2 = vp2;
        if ((diff = mp2->bits - mp1->bits) ||
            (diff = mp1->sec - mp2->sec))
                return diff;

        /* Fall back to alphabetic ordering of names. */
        sz1 = strcspn(mp1->names, "(");
        sz2 = strcspn(mp2->names, "(");
        if (sz1 < sz2)
                sz1 = sz2;
        if ((diff = strncasecmp(mp1->names, mp2->names, sz1)))
                return diff;

        /* For identical names and sections, prefer arch-dependent. */
        cp1 = strchr(mp1->names + sz1, '/');
        cp2 = strchr(mp2->names + sz2, '/');
        return cp1 != NULL && cp2 != NULL ? strcasecmp(cp1, cp2) :
            cp1 != NULL ? -1 : cp2 != NULL ? 1 : 0;
}

static char *
buildnames(const struct dbm_page *page)
{
        char    *buf;
        size_t   i, sz;

        sz = lstlen(page->name, 2) + 1 + lstlen(page->sect, 2) +
            (page->arch == NULL ? 0 : 1 + lstlen(page->arch, 2)) + 2;
        buf = mandoc_malloc(sz);
        i = 0;
        lstcat(buf, &i, page->name, ", ");
        buf[i++] = '(';
        lstcat(buf, &i, page->sect, ", ");
        if (page->arch != NULL) {
                buf[i++] = '/';
                lstcat(buf, &i, page->arch, ", ");
        }
        buf[i++] = ')';
        buf[i++] = '\0';
        assert(i == sz);
        return buf;
}

/*
 * Count the buffer space needed to print the NUL-terminated
 * list of NUL-terminated strings, when printing sep separator
 * characters between strings.
 */
static size_t
lstlen(const char *cp, size_t sep)
{
        size_t   sz;

        for (sz = 0; *cp != '\0'; cp++) {

                /* Skip names appearing only in the SYNOPSIS. */
                if (*cp <= (char)(NAME_SYN & NAME_MASK)) {
                        while (*cp != '\0')
                                cp++;
                        continue;
                }

                /* Skip name class markers. */
                if (*cp < ' ')
                        cp++;

                /* Print a separator before each but the first string. */
                if (sz)
                        sz += sep;

                /* Copy one string. */
                while (*cp != '\0') {
                        sz++;
                        cp++;
                }
        }
        return sz;
}

/*
 * Print the NUL-terminated list of NUL-terminated strings
 * into the buffer, separating strings with sep.
 */
static void
lstcat(char *buf, size_t *i, const char *cp, const char *sep)
{
        const char      *s;
        size_t           i_start;

        for (i_start = *i; *cp != '\0'; cp++) {

                /* Skip names appearing only in the SYNOPSIS. */
                if (*cp <= (char)(NAME_SYN & NAME_MASK)) {
                        while (*cp != '\0')
                                cp++;
                        continue;
                }

                /* Skip name class markers. */
                if (*cp < ' ')
                        cp++;

                /* Print a separator before each but the first string. */
                if (*i > i_start) {
                        s = sep;
                        while (*s != '\0')
                                buf[(*i)++] = *s++;
                }

                /* Copy one string. */
                while (*cp != '\0')
                        buf[(*i)++] = *cp++;
        }

}

/*
 * Return 1 if the string *want occurs in any of the strings
 * in the NUL-terminated string list *have, or 0 otherwise.
 * If either argument is NULL or empty, assume no filtering
 * is desired and return 1.
 */
static int
lstmatch(const char *want, const char *have)
{
        if (want == NULL || have == NULL || *have == '\0')
                return 1;
        while (*have != '\0') {
                if (strcasestr(have, want) != NULL)
                        return 1;
                have = strchr(have, '\0') + 1;
        }
        return 0;
}

/*
 * Build a list of values taken by the macro im in the manual page.
 */
static char *
buildoutput(size_t im, struct dbm_page *page)
{
        const char      *oldoutput, *sep, *input;
        char            *output, *newoutput, *value;
        size_t           sz, i;

        switch (im) {
        case KEY_Nd:
                return mandoc_strdup(page->desc);
        case KEY_Nm:
                input = page->name;
                break;
        case KEY_sec:
                input = page->sect;
                break;
        case KEY_arch:
                input = page->arch;
                if (input == NULL)
                        input = "all\0";
                break;
        default:
                input = NULL;
                break;
        }

        if (input != NULL) {
                sz = lstlen(input, 3) + 1;
                output = mandoc_malloc(sz);
                i = 0;
                lstcat(output, &i, input, " # ");
                output[i++] = '\0';
                assert(i == sz);
                return output;
        }

        output = NULL;
        dbm_macro_bypage(im - 2, page->addr);
        while ((value = dbm_macro_next()) != NULL) {
                if (output == NULL) {
                        oldoutput = "";
                        sep = "";
                } else {
                        oldoutput = output;
                        sep = " # ";
                }
                mandoc_asprintf(&newoutput, "%s%s%s", oldoutput, sep, value);
                free(output);
                output = newoutput;
        }
        return output;
}

/*
 * Compile a set of string tokens into an expression.
 * Tokens in "argv" are assumed to be individual expression atoms (e.g.,
 * "(", "foo=bar", etc.).
 */
static struct expr *
exprcomp(const struct mansearch *search, int argc, char *argv[], int *argi)
{
        struct expr     *parent, *child;
        int              needterm, nested;

        if ((nested = *argi) == argc)
                return NULL;
        needterm = 1;
        parent = child = NULL;
        while (*argi < argc) {
                if (strcmp(")", argv[*argi]) == 0) {
                        if (needterm)
                                warnx("missing term "
                                    "before closing parenthesis");
                        needterm = 0;
                        if (nested)
                                break;
                        warnx("ignoring unmatched right parenthesis");
                        ++*argi;
                        continue;
                }
                if (strcmp("-o", argv[*argi]) == 0) {
                        if (needterm) {
                                if (*argi > 0)
                                        warnx("ignoring -o after %s",
                                            argv[*argi - 1]);
                                else
                                        warnx("ignoring initial -o");
                        }
                        needterm = 1;
                        ++*argi;
                        continue;
                }
                needterm = 0;
                if (child == NULL) {
                        child = expr_and(search, argc, argv, argi);
                        continue;
                }
                if (parent == NULL) {
                        parent = mandoc_calloc(1, sizeof(*parent));
                        parent->type = EXPR_OR;
                        parent->next = NULL;
                        parent->child = child;
                }
                child->next = expr_and(search, argc, argv, argi);
                child = child->next;
        }
        if (needterm && *argi)
                warnx("ignoring trailing %s", argv[*argi - 1]);
        return parent == NULL ? child : parent;
}

static struct expr *
expr_and(const struct mansearch *search, int argc, char *argv[], int *argi)
{
        struct expr     *parent, *child;
        int              needterm;

        needterm = 1;
        parent = child = NULL;
        while (*argi < argc) {
                if (strcmp(")", argv[*argi]) == 0) {
                        if (needterm)
                                warnx("missing term "
                                    "before closing parenthesis");
                        needterm = 0;
                        break;
                }
                if (strcmp("-o", argv[*argi]) == 0)
                        break;
                if (strcmp("-a", argv[*argi]) == 0) {
                        if (needterm) {
                                if (*argi > 0)
                                        warnx("ignoring -a after %s",
                                            argv[*argi - 1]);
                                else
                                        warnx("ignoring initial -a");
                        }
                        needterm = 1;
                        ++*argi;
                        continue;
                }
                if (needterm == 0)
                        break;
                if (child == NULL) {
                        child = exprterm(search, argc, argv, argi);
                        if (child != NULL)
                                needterm = 0;
                        continue;
                }
                needterm = 0;
                if (parent == NULL) {
                        parent = mandoc_calloc(1, sizeof(*parent));
                        parent->type = EXPR_AND;
                        parent->next = NULL;
                        parent->child = child;
                }
                child->next = exprterm(search, argc, argv, argi);
                if (child->next != NULL) {
                        child = child->next;
                        needterm = 0;
                }
        }
        if (needterm && *argi)
                warnx("ignoring trailing %s", argv[*argi - 1]);
        return parent == NULL ? child : parent;
}

static struct expr *
exprterm(const struct mansearch *search, int argc, char *argv[], int *argi)
{
        char             errbuf[BUFSIZ];
        struct expr     *e;
        char            *key, *val;
        uint64_t         iterbit;
        int              cs, i, irc;

        if (strcmp("(", argv[*argi]) == 0) {
                ++*argi;
                e = exprcomp(search, argc, argv, argi);
                if (*argi < argc) {
                        assert(strcmp(")", argv[*argi]) == 0);
                        ++*argi;
                } else
                        warnx("unclosed parenthesis");
                return e;
        }

        if (strcmp("-i", argv[*argi]) == 0 && *argi + 1 < argc) {
                cs = 0;
                ++*argi;
        } else
                cs = 1;

        e = mandoc_calloc(1, sizeof(*e));
        e->type = EXPR_TERM;
        e->bits = 0;
        e->next = NULL;
        e->child = NULL;

        if (search->argmode == ARG_NAME) {
                e->bits = TYPE_Nm;
                e->match.type = DBM_EXACT;
                e->match.str = argv[(*argi)++];
                return e;
        }

        /*
         * Separate macro keys from search string.
         * If needed, request regular expression handling.
         */

        if (search->argmode == ARG_WORD) {
                e->bits = TYPE_Nm;
                e->match.type = DBM_REGEX;
                mandoc_asprintf(&val, "[[:<:]]%s[[:>:]]", argv[*argi]);
                cs = 0;
        } else if ((val = strpbrk(argv[*argi], "=~")) == NULL) {
                e->bits = TYPE_Nm | TYPE_Nd;
                e->match.type = DBM_REGEX;
                val = argv[*argi];
                cs = 0;
        } else {
                if (val == argv[*argi])
                        e->bits = TYPE_Nm | TYPE_Nd;
                if (*val == '=') {
                        e->match.type = DBM_SUB;
                        e->match.str = val + 1;
                } else
                        e->match.type = DBM_REGEX;
                *val++ = '\0';
                if (strstr(argv[*argi], "arch") != NULL)
                        cs = 0;
        }

        /* Compile regular expressions. */

        if (e->match.type == DBM_REGEX) {
                e->match.re = mandoc_malloc(sizeof(*e->match.re));
                irc = regcomp(e->match.re, val,
                    REG_EXTENDED | REG_NOSUB | (cs ? 0 : REG_ICASE));
                if (irc) {
                        regerror(irc, e->match.re, errbuf, sizeof(errbuf));
                        warnx("regcomp /%s/: %s", val, errbuf);
                }
                if (search->argmode == ARG_WORD)
                        free(val);
                if (irc) {
                        free(e->match.re);
                        free(e);
                        ++*argi;
                        return NULL;
                }
        }

        if (e->bits) {
                ++*argi;
                return e;
        }

        /*
         * Parse out all possible fields.
         * If the field doesn't resolve, bail.
         */

        while (NULL != (key = strsep(&argv[*argi], ","))) {
                if ('\0' == *key)
                        continue;
                for (i = 0, iterbit = 1; i < KEY_MAX; i++, iterbit <<= 1) {
                        if (0 == strcasecmp(key, mansearch_keynames[i])) {
                                e->bits |= iterbit;
                                break;
                        }
                }
                if (i == KEY_MAX) {
                        if (strcasecmp(key, "any"))
                                warnx("treating unknown key "
                                    "\"%s\" as \"any\"", key);
                        e->bits |= ~0ULL;
                }
        }

        ++*argi;
        return e;
}

static void
exprfree(struct expr *e)
{
        if (e->next != NULL)
                exprfree(e->next);
        if (e->child != NULL)
                exprfree(e->child);
        free(e);
}