/*
 * $FreeBSD$
 */

#include <sys/types.h>
#include <sys/param.h>
#include <sys/fcntl.h>
#include <sys/mman.h>
#include <sys/queue.h>
#include <sys/stat.h>
#include <dirent.h>
#include <errno.h>
#include <stdlib.h>
#include <string.h>

#include "debug.h"
#include "rtld.h"
#include "libmap.h"

#ifndef _PATH_LIBMAP_CONF
#define _PATH_LIBMAP_CONF       "/etc/libmap.conf"
#endif

TAILQ_HEAD(lm_list, lm);
struct lm {
        char *f;
        char *t;
        TAILQ_ENTRY(lm) lm_link;
};

TAILQ_HEAD(lmp_list, lmp) lmp_head = TAILQ_HEAD_INITIALIZER(lmp_head);
struct lmp {
        char *p;
        enum { T_EXACT=0, T_BASENAME, T_DIRECTORY } type;
        struct lm_list lml;
        TAILQ_ENTRY(lmp) lmp_link;
};

static TAILQ_HEAD(lmc_list, lmc) lmc_head = TAILQ_HEAD_INITIALIZER(lmc_head);
struct lmc {
        char *path;
        TAILQ_ENTRY(lmc) next;
};

static int lm_count;

static void lmc_parse(char *, size_t);
static void lmc_parse_file(char *);
static void lmc_parse_dir(char *);
static void lm_add(const char *, const char *, const char *);
static void lm_free(struct lm_list *);
static char *lml_find(struct lm_list *, const char *);
static struct lm_list *lmp_find(const char *);
static struct lm_list *lmp_init(char *);
static const char *quickbasename(const char *);

#define iseol(c)        (((c) == '#') || ((c) == '\0') || \
                         ((c) == '\n') || ((c) == '\r'))

/*
 * Do not use ctype.h macros, which rely on working TLS.  It is
 * too early to have thread-local variables functional.
 */
#define rtld_isspace(c) ((c) == ' ' || (c) == '\t')

int
lm_init(char *libmap_override)
{
        char *p;

        dbg("lm_init(\"%s\")", libmap_override);
        TAILQ_INIT(&lmp_head);

        lmc_parse_file(_PATH_LIBMAP_CONF);

        if (libmap_override) {
                /*
                 * Do some character replacement to make $LDLIBMAP look
                 * like a text file, then parse it.
                 */
                libmap_override = xstrdup(libmap_override);
                for (p = libmap_override; *p; p++) {
                        switch (*p) {
                        case '=':
                                *p = ' ';
                                break;
                        case ',':
                                *p = '\n';
                                break;
                        }
                }
                lmc_parse(libmap_override, p - libmap_override);
                free(libmap_override);
        }

        return (lm_count == 0);
}

static void
lmc_parse_file(char *path)
{
        struct lmc *p;
        struct stat st;
        int fd;
        char *rpath;
        char *lm_map;

        rpath = realpath(path, NULL);
        if (rpath == NULL)
                return;

        TAILQ_FOREACH(p, &lmc_head, next) {
                if (strcmp(p->path, rpath) == 0) {
                        free(rpath);
                        return;
                }
        }

        fd = open(rpath, O_RDONLY | O_CLOEXEC);
        if (fd == -1) {
                dbg("lm_parse_file: open(\"%s\") failed, %s", rpath,
                    rtld_strerror(errno));
                free(rpath);
                return;
        }
        if (fstat(fd, &st) == -1) {
                close(fd);
                dbg("lm_parse_file: fstat(\"%s\") failed, %s", rpath,
                    rtld_strerror(errno));
                free(rpath);
                return;
        }
        lm_map = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
        if (lm_map == (const char *)MAP_FAILED) {
                close(fd);
                dbg("lm_parse_file: mmap(\"%s\") failed, %s", rpath,
                    rtld_strerror(errno));
                free(rpath);
                return;
        }
        close(fd);
        p = xmalloc(sizeof(struct lmc));
        p->path = rpath;
        TAILQ_INSERT_HEAD(&lmc_head, p, next);
        lmc_parse(lm_map, st.st_size);
        munmap(lm_map, st.st_size);
}

static void
lmc_parse_dir(char *idir)
{
        DIR *d;
        struct dirent *dp;
        struct lmc *p;
        char conffile[MAXPATHLEN];
        char *ext;
        char *rpath;

        rpath = realpath(idir, NULL);
        if (rpath == NULL)
                return;

        TAILQ_FOREACH(p, &lmc_head, next) {
                if (strcmp(p->path, rpath) == 0) {
                        free(rpath);
                        return;
                }
        }
        d = opendir(idir);
        if (d == NULL) {
                free(rpath);
                return;
        }

        p = xmalloc(sizeof(struct lmc));
        p->path = rpath;
        TAILQ_INSERT_HEAD(&lmc_head, p, next);

        while ((dp = readdir(d)) != NULL) {
                if (dp->d_ino == 0)
                        continue;
                if (dp->d_type != DT_REG)
                        continue;
                ext = strrchr(dp->d_name, '.');
                if (ext == NULL)
                        continue;
                if (strcmp(ext, ".conf") != 0)
                        continue;
                if (strlcpy(conffile, idir, MAXPATHLEN) >= MAXPATHLEN)
                        continue; /* too long */
                if (strlcat(conffile, "/", MAXPATHLEN) >= MAXPATHLEN)
                        continue; /* too long */
                if (strlcat(conffile, dp->d_name, MAXPATHLEN) >= MAXPATHLEN)
                        continue; /* too long */
                lmc_parse_file(conffile);
        }
        closedir(d);
}

static void
lmc_parse(char *lm_p, size_t lm_len)
{
        char *cp, *f, *t, *c, *p;
        char prog[MAXPATHLEN];
        /* allow includedir + full length path */
        char line[MAXPATHLEN + 13];
        size_t cnt;
        int i;

        cnt = 0;
        p = NULL;
        while (cnt < lm_len) {
                i = 0;
                while (cnt < lm_len && lm_p[cnt] != '\n' &&
                    i < sizeof(line) - 1) {
                        line[i] = lm_p[cnt];
                        cnt++;
                        i++;
                }
                line[i] = '\0';
                while (cnt < lm_len && lm_p[cnt] != '\n')
                        cnt++;
                /* skip over nl */
                cnt++;

                cp = &line[0];
                t = f = c = NULL;

                /* Skip over leading space */
                while (rtld_isspace(*cp)) cp++;

                /* Found a comment or EOL */
                if (iseol(*cp)) continue;

                /* Found a constraint selector */
                if (*cp == '[') {
                        cp++;

                        /* Skip leading space */
                        while (rtld_isspace(*cp)) cp++;

                        /* Found comment, EOL or end of selector */
                        if  (iseol(*cp) || *cp == ']')
                                continue;

                        c = cp++;
                        /* Skip to end of word */
                        while (!rtld_isspace(*cp) && !iseol(*cp) && *cp != ']')
                                cp++;

                        /* Skip and zero out trailing space */
                        while (rtld_isspace(*cp)) *cp++ = '\0';

                        /* Check if there is a closing brace */
                        if (*cp != ']') continue;

                        /* Terminate string if there was no trailing space */
                        *cp++ = '\0';

                        /*
                         * There should be nothing except whitespace or comment
                          from this point to the end of the line.
                         */
                        while(rtld_isspace(*cp)) cp++;
                        if (!iseol(*cp)) continue;

                        if (strlcpy(prog, c, sizeof prog) >= sizeof prog)
                                continue;
                        p = prog;
                        continue;
                }

                /* Parse the 'from' candidate. */
                f = cp++;
                while (!rtld_isspace(*cp) && !iseol(*cp)) cp++;

                /* Skip and zero out the trailing whitespace */
                while (rtld_isspace(*cp)) *cp++ = '\0';

                /* Found a comment or EOL */
                if (iseol(*cp)) continue;

                /* Parse 'to' mapping */
                t = cp++;
                while (!rtld_isspace(*cp) && !iseol(*cp)) cp++;

                /* Skip and zero out the trailing whitespace */
                while (rtld_isspace(*cp)) *cp++ = '\0';

                /* Should be no extra tokens at this point */
                if (!iseol(*cp)) continue;

                *cp = '\0';
                if (strcmp(f, "includedir") == 0)
                        lmc_parse_dir(t);
                else if (strcmp(f, "include") == 0)
                        lmc_parse_file(t);
                else
                        lm_add(p, f, t);
        }
}

static void
lm_free (struct lm_list *lml)
{
        struct lm *lm;

        dbg("%s(%p)", __func__, lml);

        while (!TAILQ_EMPTY(lml)) {
                lm = TAILQ_FIRST(lml);
                TAILQ_REMOVE(lml, lm, lm_link);
                free(lm->f);
                free(lm->t);
                free(lm);
        }
        return;
}

void
lm_fini (void)
{
        struct lmp *lmp;
        struct lmc *p;

        dbg("%s()", __func__);

        while (!TAILQ_EMPTY(&lmc_head)) {
                p = TAILQ_FIRST(&lmc_head);
                TAILQ_REMOVE(&lmc_head, p, next);
                free(p->path);
                free(p);
        }

        while (!TAILQ_EMPTY(&lmp_head)) {
                lmp = TAILQ_FIRST(&lmp_head);
                TAILQ_REMOVE(&lmp_head, lmp, lmp_link);
                free(lmp->p);
                lm_free(&lmp->lml);
                free(lmp);
        }
        return;
}

static void
lm_add (const char *p, const char *f, const char *t)
{
        struct lm_list *lml;
        struct lm *lm;

        if (p == NULL)
                p = "$DEFAULT$";

        dbg("%s(\"%s\", \"%s\", \"%s\")", __func__, p, f, t);

        if ((lml = lmp_find(p)) == NULL)
                lml = lmp_init(xstrdup(p));

        lm = xmalloc(sizeof(struct lm));
        lm->f = xstrdup(f);
        lm->t = xstrdup(t);
        TAILQ_INSERT_HEAD(lml, lm, lm_link);
        lm_count++;
}

char *
lm_find (const char *p, const char *f)
{
        struct lm_list *lml;
        char *t;

        dbg("%s(\"%s\", \"%s\")", __func__, p, f);

        if (p != NULL && (lml = lmp_find(p)) != NULL) {
                t = lml_find(lml, f);
                if (t != NULL) {
                        /*
                         * Add a global mapping if we have
                         * a successful constrained match.
                         */
                        lm_add(NULL, f, t);
                        return (t);
                }
        }
        lml = lmp_find("$DEFAULT$");
        if (lml != NULL)
                return (lml_find(lml, f));
        else
                return (NULL);
}

/* Given a libmap translation list and a library name, return the
   replacement library, or NULL */
char *
lm_findn (const char *p, const char *f, const int n)
{
        char pathbuf[64], *s, *t;

        if (n < sizeof(pathbuf) - 1)
                s = pathbuf;
        else
                s = xmalloc(n + 1);
        memcpy(s, f, n);
        s[n] = '\0';
        t = lm_find(p, s);
        if (s != pathbuf)
                free(s);
        return (t);
}

static char *
lml_find (struct lm_list *lmh, const char *f)
{
        struct lm *lm;

        dbg("%s(%p, \"%s\")", __func__, lmh, f);

        TAILQ_FOREACH(lm, lmh, lm_link)
                if (strcmp(f, lm->f) == 0)
                        return (lm->t);
        return (NULL);
}

/* Given an executable name, return a pointer to the translation list or
   NULL if no matches */
static struct lm_list *
lmp_find (const char *n)
{
        struct lmp *lmp;

        dbg("%s(\"%s\")", __func__, n);

        TAILQ_FOREACH(lmp, &lmp_head, lmp_link)
                if ((lmp->type == T_EXACT && strcmp(n, lmp->p) == 0) ||
                    (lmp->type == T_DIRECTORY && strncmp(n, lmp->p, strlen(lmp->p)) == 0) ||
                    (lmp->type == T_BASENAME && strcmp(quickbasename(n), lmp->p) == 0))
                        return (&lmp->lml);
        return (NULL);
}

static struct lm_list *
lmp_init (char *n)
{
        struct lmp *lmp;

        dbg("%s(\"%s\")", __func__, n);

        lmp = xmalloc(sizeof(struct lmp));
        lmp->p = n;
        if (n[strlen(n)-1] == '/')
                lmp->type = T_DIRECTORY;
        else if (strchr(n,'/') == NULL)
                lmp->type = T_BASENAME;
        else
                lmp->type = T_EXACT;
        TAILQ_INIT(&lmp->lml);
        TAILQ_INSERT_HEAD(&lmp_head, lmp, lmp_link);

        return (&lmp->lml);
}

/* libc basename is overkill.  Return a pointer to the character after the
   last /, or the original string if there are no slashes. */
static const char *
quickbasename (const char *path)
{
        const char *p = path;
        for (; *path; path++) {
                if (*path == '/')
                        p = path+1;
        }
        return (p);
}