/*
 */

#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"
#include "rtld_paths.h"
#include "rtld_libc.h"

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

static 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;
        dev_t dev;
        ino_t ino;
        TAILQ_ENTRY(lmc) next;
};

static int lm_count;

static void lmc_parse(char *, size_t);
static void lmc_parse_file(const char *);
static void lmc_parse_dir(const 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.  Rtld does
 * not support TLS for itself.
 */
#define rtld_isspace(c) ((c) == ' ' || (c) == '\t')

int
lm_init(const char *libmap_override)
{
        char *l, *p;

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

        lmc_parse_file(ld_path_libmap_conf);

        if (libmap_override != NULL) {
                /*
                 * Do some character replacement to make $LD_LIBMAP look
                 * like a text file, then parse it.
                 */
                l = xstrdup(libmap_override);
                for (p = l; *p != 0; p++) {
                        switch (*p) {
                        case '=':
                                *p = ' ';
                                break;
                        case ',':
                                *p = '\n';
                                break;
                        }
                }
                lmc_parse(l, p - l);
                free(l);
        }

        return (lm_count == 0);
}

static void
lmc_parse_file(const char *path)
{
        struct lmc *p;
        char *lm_map;
        struct stat st;
        ssize_t retval;
        int fd, saved_errno;

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

        fd = open(path, O_RDONLY | O_CLOEXEC);
        if (fd == -1) {
                dbg("lm_parse_file: open(\"%s\") failed, %s", path,
                    rtld_strerror(errno));
                return;
        }
        if (fstat(fd, &st) == -1) {
                dbg("lm_parse_file: fstat(\"%s\") failed, %s", path,
                    rtld_strerror(errno));
                close(fd);
                return;
        }

        TAILQ_FOREACH(p, &lmc_head, next) {
                if (p->dev == st.st_dev && p->ino == st.st_ino) {
                        close(fd);
                        return;
                }
        }

        lm_map = xmalloc(st.st_size);
        retval = read(fd, lm_map, st.st_size);
        saved_errno = errno;
        close(fd);
        if (retval != st.st_size) {
                if (retval == -1) {
                        dbg("lm_parse_file: read(\"%s\") failed, %s", path,
                            rtld_strerror(saved_errno));
                } else {
                        dbg("lm_parse_file: short read(\"%s\"), %zd vs %jd",
                            path, retval, (uintmax_t)st.st_size);
                }
                free(lm_map);
                return;
        }
        p = xmalloc(sizeof(struct lmc));
        p->path = xstrdup(path);
        p->dev = st.st_dev;
        p->ino = st.st_ino;
        TAILQ_INSERT_HEAD(&lmc_head, p, next);
        lmc_parse(lm_map, st.st_size);
        free(lm_map);
}

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

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

        p = xmalloc(sizeof(struct lmc));
        p->path = xstrdup(idir);
        p->dev = NODEV;
        p->ino = 0;
        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, 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);
        }
}

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);
        }
}

static void
lm_add(const char *p, const char *f, const char *t)
{
        struct lm_list *lml;
        struct lm *lm;
        const char *t1;

        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));

        t1 = lml_find(lml, f);
        if (t1 == NULL || strcmp(t1, t) != 0) {
                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));
        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 size_t 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;

        for (p = path; *path != '\0'; path++) {
                if (*path == '/')
                        p = path + 1;
        }
        return (p);
}