file/src/apprentice.c

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/*
 * Copyright (c) Ian F. Darwin 1986-1995.
 * Software written by Ian F. Darwin and others;
 * maintained 1995-present by Christos Zoulas and others.
 * 
 * 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 immediately at the beginning of the file, without modification,
 *    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 AND CONTRIBUTORS ``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 OR CONTRIBUTORS 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.
 */
/*
 * apprentice - make one pass through /etc/magic, learning its secrets.
 */

#include "file.h"
#include "magic.h"
#include <stdlib.h>
#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif
#include <string.h>
#include <assert.h>
#include <ctype.h>
#include <fcntl.h>
#include <sys/stat.h>
#include <sys/param.h>
#ifdef QUICK
#include <sys/mman.h>
#endif

#ifndef lint
FILE_RCSID("@(#)$File: apprentice.c,v 1.104 2007/01/19 19:54:39 christos Exp $")
#endif  /* lint */

#define EATAB {while (isascii((unsigned char) *l) && \
                      isspace((unsigned char) *l))  ++l;}
#define LOWCASE(l) (isupper((unsigned char) (l)) ? \
                        tolower((unsigned char) (l)) : (l))
/*
 * Work around a bug in headers on Digital Unix.
 * At least confirmed for: OSF1 V4.0 878
 */
#if defined(__osf__) && defined(__DECC)
#ifdef MAP_FAILED
#undef MAP_FAILED
#endif
#endif

#ifndef MAP_FAILED
#define MAP_FAILED (void *) -1
#endif

#ifndef MAP_FILE
#define MAP_FILE 0
#endif

#ifndef MAXPATHLEN
#define MAXPATHLEN      1024
#endif

struct magic_entry {
        struct magic *mp;       
        uint32_t cont_count;
        uint32_t max_count;
};
    
/*@unchecked@*/ /*@observer@*/
int file_formats[FILE_NAMES_SIZE];
/*@unchecked@*/
const size_t file_nformats = FILE_NAMES_SIZE;
/*@unchecked@*/ /*@observer@*/
const char *file_names[FILE_NAMES_SIZE];
/*@unchecked@*/
const size_t file_nnames = FILE_NAMES_SIZE;

/*@unchecked@*/
private size_t maxmagic = 0;
/*@unchecked@*/
private size_t magicsize = sizeof(struct magic);

private int getvalue(struct magic_set *ms, struct magic *m, const char **p,
    int action)
        /*@globals fileSystem @*/
        /*@modifies ms, m, *p, fileSystem @*/;
private int hextoint(int c)
        /*@*/;
/*@observer@*/ /*@null@*/
private const char * getstr(struct magic_set *ms, const char *s, char *p,
    int plen, int *slen, int action)
        /*@globals fileSystem @*/
        /*@modifies ms, *p, *slen, fileSystem @*/;
private int parse(struct magic_set *ms, struct magic_entry **mentryp,
    uint32_t *nmentryp, const char *line, size_t lineno, int action)
        /*@globals maxmagic, fileSystem @*/
        /*@modifies ms, *mentryp, *nmentryp, maxmagic, fileSystem @*/;
private void eatsize(const char **p)
        /*@modifies *p @*/;
private int apprentice_1(struct magic_set *ms, const char *fn, int action,
    struct mlist *mlist)
        /*@globals fileSystem, internalState @*/
        /*@modifies ms, mlist, fileSystem, internalState @*/;
private size_t apprentice_magic_strength(const struct magic *m)
        /*@globals fileSystem @*/
        /*@modifies fileSystem @*/;
private int apprentice_sort(const void *a, const void *b)
        /*@globals fileSystem @*/
        /*@modifies fileSystem @*/;
private int apprentice_file(struct magic_set *ms, struct magic **magicp,
    uint32_t *nmagicp, const char *fn, int action)
        /*@globals maxmagic, fileSystem @*/
        /*@modifies ms, *magicp, *nmagicp, maxmagic, fileSystem @*/;
private void byteswap(struct magic *magic, uint32_t nmagic)
        /*@modifies magic @*/;
private void bs1(struct magic *m)
        /*@modifies m @*/;
private uint16_t swap2(uint16_t sv)
        /*@*/;
private uint32_t swap4(uint32_t sv)
        /*@*/;
private uint64_t swap8(uint64_t sv)
        /*@*/;
private char * mkdbname(const char *fn, /*@returned@*/ char *buf, size_t bufsiz, int strip)
        /*@modifies buf @*/;
private int apprentice_map(struct magic_set *ms, struct magic **magicp,
    uint32_t *nmagicp, const char *fn)
        /*@globals fileSystem, internalState @*/
        /*@modifies ms, *magicp, *nmagicp, fileSystem, internalState @*/;
private int apprentice_compile(struct magic_set *ms, struct magic **magicp,
    uint32_t *nmagicp, const char *fn)
        /*@globals fileSystem, internalState @*/
        /*@modifies ms, *magicp, *nmagicp, fileSystem, internalState @*/;
private int check_format_type(const char *ptr, int type)
        /*@*/;
private int check_format(struct magic_set *ms, struct magic *m)
        /*@modifies ms @*/;

#ifdef COMPILE_ONLY

int main(int, char *[]);

int
main(int argc, char *argv[])
{
        int ret;
        struct magic_set *ms;
        char *progname;

        if ((progname = strrchr(argv[0], '/')) != NULL)
                progname++;
        else
                progname = argv[0];

        if (argc != 2) {
                (void)fprintf(stderr, "Usage: %s file\n", progname);
                return 1;
        }

        if ((ms = magic_open(MAGIC_CHECK)) == NULL) {
                (void)fprintf(stderr, "%s: %s\n", progname, strerror(errno));
                return 1;
        }
        ret = magic_compile(ms, argv[1]) == -1 ? 1 : 0;
        if (ret == 1)
                (void)fprintf(stderr, "%s: %s\n", progname, magic_error(ms));
        magic_close(ms);
        return ret;
}
#endif /* COMPILE_ONLY */

/*@unchecked@*/ /*@observer@*/
static const struct type_tbl_s {
/*@observer@*/ /*@relnull@*/
        const char *name;
        const size_t len;
        const int type;
        const int format;
} type_tbl[] = {
# define XX(s)          s, (sizeof(s) - 1)
# define XX_NULL        NULL, 0
        { XX("byte"),           FILE_BYTE,              FILE_FMT_NUM },
        { XX("short"),          FILE_SHORT,             FILE_FMT_NUM },
        { XX("default"),        FILE_DEFAULT,           FILE_FMT_STR },
        { XX("long"),           FILE_LONG,              FILE_FMT_NUM },
        { XX("string"),         FILE_STRING,            FILE_FMT_STR },
        { XX("date"),           FILE_DATE,              FILE_FMT_STR },
        { XX("beshort"),        FILE_BESHORT,           FILE_FMT_NUM },
        { XX("belong"),         FILE_BELONG,            FILE_FMT_NUM },
        { XX("bedate"),         FILE_BEDATE,            FILE_FMT_STR },
        { XX("leshort"),        FILE_LESHORT,           FILE_FMT_NUM },
        { XX("lelong"),         FILE_LELONG,            FILE_FMT_NUM },
        { XX("ledate"),         FILE_LEDATE,            FILE_FMT_STR },
        { XX("pstring"),        FILE_PSTRING,           FILE_FMT_STR },
        { XX("ldate"),          FILE_LDATE,             FILE_FMT_STR },
        { XX("beldate"),        FILE_BELDATE,           FILE_FMT_STR },
        { XX("leldate"),        FILE_LELDATE,           FILE_FMT_STR },
        { XX("regex"),          FILE_REGEX,             FILE_FMT_STR },
        { XX("bestring16"),     FILE_BESTRING16,        FILE_FMT_STR },
        { XX("lestring16"),     FILE_LESTRING16,        FILE_FMT_STR },
        { XX("search"),         FILE_SEARCH,            FILE_FMT_STR },
        { XX("medate"),         FILE_MEDATE,            FILE_FMT_STR },
        { XX("meldate"),        FILE_MELDATE,           FILE_FMT_STR },
        { XX("melong"),         FILE_MELONG,            FILE_FMT_NUM },
        { XX("quad"),           FILE_QUAD,              FILE_FMT_QUAD },
        { XX("lequad"),         FILE_LEQUAD,            FILE_FMT_QUAD },
        { XX("bequad"),         FILE_BEQUAD,            FILE_FMT_QUAD },
        { XX("qdate"),          FILE_QDATE,             FILE_FMT_STR },
        { XX("leqdate"),        FILE_LEQDATE,           FILE_FMT_STR },
        { XX("beqdate"),        FILE_BEQDATE,           FILE_FMT_STR },
        { XX("qldate"),         FILE_QLDATE,            FILE_FMT_STR },
        { XX("leqldate"),       FILE_LEQLDATE,          FILE_FMT_STR },
        { XX("beqldate"),       FILE_BEQLDATE,          FILE_FMT_STR },
        { XX_NULL,              FILE_INVALID,           FILE_FMT_NONE },
# undef XX
# undef XX_NULL
};

private int
get_type(const char *l, const char **t)
        /*@modifies *t @*/
{
        const struct type_tbl_s *p;

        for (p = type_tbl; p->name; p++) {
                if (strncmp(l, p->name, p->len) == 0) {
                        if (t)
                                *t = l + p->len;
                        break;
                }
        }
        return p->type;
}

private void
init_file_tables(void)
        /*@globals file_names, file_formats @*/
        /*@modifies file_names, file_formats @*/
{
        static int done = 0;
        const struct type_tbl_s *p;

        if (done)
                return;
        done++;

/*@-dependenttrans@*/
        for (p = type_tbl; p->name; p++) {
                assert(p->type < FILE_NAMES_SIZE);
                file_names[p->type] = p->name;
                file_formats[p->type] = p->format;
        }
/*@=dependenttrans@*/
}

/*
 * Handle one file.
 */
private int
apprentice_1(struct magic_set *ms, const char *fn, int action,
    struct mlist *mlist)
{
        struct magic *magic = NULL;
        uint32_t nmagic = 0;
        struct mlist *ml;
        int rv = -1;
        int mapped;

        if (magicsize != FILE_MAGICSIZE) {
                file_error(ms, 0, "magic element size %lu != %lu",
                    (unsigned long)sizeof(*magic),
                    (unsigned long)FILE_MAGICSIZE);
                return -1;
        }

        if (action == FILE_COMPILE) {
                rv = apprentice_file(ms, &magic, &nmagic, fn, action);
                if (rv != 0)
                        return -1;
                rv = apprentice_compile(ms, &magic, &nmagic, fn);
                free(magic);
                return rv;
        }
#ifndef COMPILE_ONLY
        if ((rv = apprentice_map(ms, &magic, &nmagic, fn)) == -1) {
                if (ms->flags & MAGIC_CHECK)
                        file_magwarn(ms, "using regular magic file `%s'", fn);
                rv = apprentice_file(ms, &magic, &nmagic, fn, action);
                if (rv != 0)
                        return -1;
                mapped = 0;
        }

        mapped = rv;
             
        if (magic == NULL || nmagic == 0) {
                file_delmagic(magic, mapped, nmagic);
                return -1;
        }

        if ((ml = malloc(sizeof(*ml))) == NULL) {
                file_delmagic(magic, mapped, nmagic);
                file_oomem(ms, sizeof(*ml));
                return -1;
        }

        ml->magic = magic;
        ml->nmagic = nmagic;
        ml->mapped = mapped;

        mlist->prev->next = ml;
        ml->prev = mlist->prev;
        ml->next = mlist;
        mlist->prev = ml;

        return 0;
#endif /* COMPILE_ONLY */
}

protected void
file_delmagic(struct magic *p, int type, size_t entries)
{
        if (p == NULL)
                return;
        switch (type) {
        case 2:
                p--;
                (void)munmap((void *)p, sizeof(*p) * (entries + 1));
                break;
        case 1:
                p--;
                /*@fallthrough@*/
        case 0:
                free(p);
                break;
        default:
                abort();
        }
}


/* const char *fn: list of magic files */
protected struct mlist *
file_apprentice(struct magic_set *ms, const char *fn, int action)
{
        char *p, *mfn, *afn = NULL;
        int file_err, errs = -1;
        struct mlist *mlist;
        static const char mime[] = ".mime";

        init_file_tables();

        if (fn == NULL)
                fn = getenv("MAGIC");
        if (fn == NULL)
                fn = MAGIC;

        if ((fn = mfn = strdup(fn)) == NULL) {
                file_oomem(ms, strlen(fn));
                return NULL;
        }

        if ((mlist = malloc(sizeof(*mlist))) == NULL) {
                free(mfn);
                file_oomem(ms, sizeof(*mlist));
                return NULL;
        }
        mlist->next = mlist->prev = mlist;

        while (fn) {
                p = strchr(fn, PATHSEP);
                if (p)
                        *p++ = '\0';
                if (*fn == '\0')
                        break;
                if (ms->flags & MAGIC_MIME) {
                        size_t len = strlen(fn) + sizeof(mime);
                        if ((afn = malloc(len)) == NULL) {
                                free(mfn);
                                free(mlist);
                                file_oomem(ms, len);
                                return NULL;
                        }
                        (void)strcpy(afn, fn);
                        (void)strcat(afn, mime);
                        fn = afn;
                }
                file_err = apprentice_1(ms, fn, action, mlist);
                if (file_err > errs)
                        errs = file_err;
                if (afn) {
                        free(afn);
                        afn = NULL;
                }
                fn = p;
        }
        if (errs == -1) {
                free(mfn);
                free(mlist);
                mlist = NULL;
                file_error(ms, 0, "could not find any magic files!");
                return NULL;
        }
        free(mfn);
        return mlist;
}

/*
 * Get weight of this magic entry, for sorting purposes.
 */
private size_t
apprentice_magic_strength(const struct magic *m)
{
#define MULT 10
        size_t val = 2 * MULT;  /* baseline strength */

        switch (m->type) {
        case FILE_DEFAULT:      /* make sure this sorts last */
                return 0;

        case FILE_BYTE:
                val += 1 * MULT;
                break;

        case FILE_SHORT:
        case FILE_LESHORT:
        case FILE_BESHORT:
                val += 2 * MULT;
                break;

        case FILE_LONG:
        case FILE_LELONG:
        case FILE_BELONG:
        case FILE_MELONG:
                val += 4 * MULT;
                break;

        case FILE_PSTRING:
        case FILE_STRING:
                val += m->vallen * MULT;
                break;

        case FILE_BESTRING16:
        case FILE_LESTRING16:
                val += m->vallen * MULT / 2;
                break;

        case FILE_SEARCH:
        case FILE_REGEX:
                val += m->vallen;
                break;

        case FILE_DATE:
        case FILE_LEDATE:
        case FILE_BEDATE:
        case FILE_MEDATE:
        case FILE_LDATE:
        case FILE_LELDATE:
        case FILE_BELDATE:
        case FILE_MELDATE:
                val += 4 * MULT;
                break;

        case FILE_QUAD:
        case FILE_BEQUAD:
        case FILE_LEQUAD:
        case FILE_QDATE:
        case FILE_LEQDATE:
        case FILE_BEQDATE:
        case FILE_QLDATE:
        case FILE_LEQLDATE:
        case FILE_BEQLDATE:
                val += 8 * MULT;
                break;

        default:
                val = 0;
                (void)fprintf(stderr, "Bad type %d\n", m->type);
                abort();
        }

        switch (m->reln) {
        case 'x':       /* matches anything penalize */
                val = 0;
                break;

        case '!':
        case '=':       /* Exact match, prefer */
                val += MULT;
                break;

        case '>':
        case '<':       /* comparison match reduce strength */
                val -= 2 * MULT;
                break;

        case '^':
        case '&':       /* masking bits, we could count them too */
                val -= MULT;
                break;

        default:
                (void)fprintf(stderr, "Bad relation %c\n", m->reln);
                abort();
        }

        if (val == 0)   /* ensure we only return 0 for FILE_DEFAULT */
                val = 1;

        return val;
}

/*  
 * Sort callback for sorting entries by "strength" (basically length)
 */
private int
apprentice_sort(const void *a, const void *b)
{
        const struct magic_entry *ma = a;
        const struct magic_entry *mb = b;
        size_t sa = apprentice_magic_strength(ma->mp);
        size_t sb = apprentice_magic_strength(mb->mp);
        if (sa == sb)
                return 0;
        else if (sa > sb)
                return -1;
        else
                return 1;
}

/*
 * parse from a file
 * const char *fn: name of magic file
 */
private int
apprentice_file(struct magic_set *ms, struct magic **magicp, uint32_t *nmagicp,
    const char *fn, int action)
{
        private const char hdr[] =
                "cont\toffset\ttype\topcode\tmask\tvalue\tdesc";
        FILE *f;
        char line[BUFSIZ+1];
        int errs = 0;
        struct magic_entry *marray;
        uint32_t marraycount, i, mentrycount = 0;
        size_t lineno = 0;

        ms->flags |= MAGIC_CHECK;       /* Enable checks for parsed files */

        f = fopen(ms->file = fn, "r");
        if (f == NULL) {
                if (errno != ENOENT)
                        file_error(ms, errno, "cannot read magic file `%s'",
                            fn);
                return -1;
        }

        maxmagic = MAXMAGIS;
        if ((marray = calloc(maxmagic, sizeof(*marray))) == NULL) {
                (void)fclose(f);
                file_oomem(ms, maxmagic * sizeof(*marray));
                return -1;
        }
        marraycount = 0;

        /* print silly verbose header for USG compat. */
        if (action == FILE_CHECK)
                (void)fprintf(stderr, "%s\n", hdr);

        /* read and parse this file */
        for (ms->line = 1; fgets(line, BUFSIZ, f) != NULL; ms->line++) {
                size_t len;
                len = strlen(line);
                if (len == 0) /* null line, garbage, etc */
                        continue;
                if (line[len - 1] == '\n') {
                        lineno++;
                line[len - 1] = '\0'; /* delete newline */
                }
                if (line[0] == '\0')    /* empty, do not parse */
                        continue;
                if (line[0] == '#')     /* comment, do not parse */
                        continue;
                if (parse(ms, &marray, &marraycount, line, lineno, action) != 0)
                        errs++;
        }

        (void)fclose(f);
        if (errs)
                goto out;

#ifndef NOORDER
        qsort(marray, marraycount, sizeof(*marray), apprentice_sort);
        /*
         * Make sure that any level 0 "default" line is last (if one exists).
         */
        for (i = 0; i < marraycount; i++) {
                if (marray[i].mp->cont_level == 0 &&
                    marray[i].mp->type == FILE_DEFAULT) {
                        while (++i < marraycount)
                                if (marray[i].mp->cont_level == 0)
                                        /*@innerbreak@*/ break;
                        if (i != marraycount) {
                                ms->line = marray[i].mp->lineno; /* XXX - Ugh! */
                                file_magwarn(ms,
                                    "level 0 \"default\" did not sort last");
                        }
                        break;                                      
                }
        }
#endif

        for (i = 0; i < marraycount; i++)
                mentrycount += marray[i].cont_count;

        if ((*magicp = malloc(sizeof(**magicp) * mentrycount)) == NULL) {
                file_oomem(ms, sizeof(**magicp) * mentrycount);
                errs++;
                goto out;
        }

        mentrycount = 0;
        for (i = 0; i < marraycount; i++) {
                (void)memcpy(*magicp + mentrycount, marray[i].mp,
                    marray[i].cont_count * sizeof(**magicp));
                mentrycount += marray[i].cont_count;
        }
out:
        for (i = 0; i < marraycount; i++)
                free(marray[i].mp);
        free(marray);
        if (errs) {
                *magicp = NULL;
                *nmagicp = 0;
        return errs;
        } else {
                *nmagicp = mentrycount;
                return 0;
        }

}

/*
 * extend the sign bit if the comparison is to be signed
 */
protected uint64_t
file_signextend(struct magic_set *ms, struct magic *m, uint64_t v)
{
        if (!(m->flag & UNSIGNED)) {
                switch(m->type) {
                /*
                 * Do not remove the casts below.  They are
                 * vital.  When later compared with the data,
                 * the sign extension must have happened.
                 */
                case FILE_BYTE:
                        v = (char) v;
                        break;
                case FILE_SHORT:
                case FILE_BESHORT:
                case FILE_LESHORT:
                        v = (short) v;
                        break;
                case FILE_DATE:
                case FILE_BEDATE:
                case FILE_LEDATE:
                case FILE_MEDATE:
                case FILE_LDATE:
                case FILE_BELDATE:
                case FILE_LELDATE:
                case FILE_MELDATE:
                case FILE_LONG:
                case FILE_BELONG:
                case FILE_LELONG:
                case FILE_MELONG:
                        v = (int32_t) v;
                        break;
                case FILE_QUAD:
                case FILE_BEQUAD:
                case FILE_LEQUAD:
                case FILE_QDATE:
                case FILE_QLDATE:
                case FILE_BEQDATE:
                case FILE_BEQLDATE:
                case FILE_LEQDATE:
                case FILE_LEQLDATE:
                        v = (int64_t) v;
                        break;
                case FILE_STRING:
                case FILE_PSTRING:
                case FILE_BESTRING16:
                case FILE_LESTRING16:
                case FILE_REGEX:
                case FILE_SEARCH:
                case FILE_DEFAULT:
                        break;
                default:
                        if (ms->flags & MAGIC_CHECK)
                            file_magwarn(ms, "cannot happen: m->type=%d\n",
                                    m->type);
                        return ~0U;
                }
        }
        return v;
}

private int
string_modifier_check(struct magic_set *ms, struct magic const *m)
        /*@globals fileSystem @*/
        /*@modifies ms, fileSystem @*/
{
        if ((ms->flags & MAGIC_CHECK) == 0)
                return 0;

        switch (m->type) {
        case FILE_BESTRING16:
        case FILE_LESTRING16:
                if (m->str_flags != 0) {
                        file_magwarn(ms, "no modifiers allowed for 16-bit strings\n");
                        return -1;
                }
                break;
        case FILE_STRING:
        case FILE_PSTRING:
                if ((m->str_flags & REGEX_OFFSET_START) != 0) {
                        file_magwarn(ms, "'/%c' only allowed on regex and search\n",
                            CHAR_REGEX_OFFSET_START);
                        return -1;
                }
                break;
        case FILE_SEARCH:
                break;
        case FILE_REGEX:
                if ((m->str_flags & STRING_COMPACT_BLANK) != 0) {
                        file_magwarn(ms, "'/%c' not allowed on regex\n",
                            CHAR_COMPACT_BLANK);
                        return -1;
                }
                if ((m->str_flags & STRING_COMPACT_OPTIONAL_BLANK) != 0) {
                        file_magwarn(ms, "'/%c' not allowed on regex\n",
                            CHAR_COMPACT_OPTIONAL_BLANK);
                        return -1;
                }
                break;
        default:
                file_magwarn(ms, "coding error: m->type=%d\n",
                    m->type);
                return -1;
        }
        return 0;
}

private int
get_op(char c)
        /*@*/
{
        switch (c) {
        case '&':
                return FILE_OPAND;
        case '|':
                return FILE_OPOR;
        case '^':
                return FILE_OPXOR;
        case '+':
                return FILE_OPADD;
        case '-':
                return FILE_OPMINUS;
        case '*':
                return FILE_OPMULTIPLY;
        case '/':
                return FILE_OPDIVIDE;
        case '%':
                return FILE_OPMODULO;
        default:
                return -1;
        }
}

#ifdef ENABLE_CONDITIONALS
private int
get_cond(const char *l, const char **t)
        /*@modifies *t @*/
{
        /*@observer@*/
        static struct cond_tbl_s {
        /*@observer@*/ /*@null@*/
                const char *name;
                const size_t len;
                const int cond;
        } cond_tbl[] = {
                { "if",         2,      COND_IF },
                { "elif",       4,      COND_ELIF },
                { "else",       4,      COND_ELSE },
                { NULL,         0,      COND_NONE },
        };
        struct cond_tbl_s *p;

        for (p = cond_tbl; p->name; p++) {
                if (strncmp(l, p->name, p->len) == 0 &&
                    isspace((unsigned char)l[p->len])) {
                        if (t)
                                *t = l + p->len;
                        break;
                }
        }
        return p->cond;
}

private int
check_cond(struct magic_set *ms, int cond, uint32_t cont_level)
        /*@globals fileSystem @*/
        /*@modifies ms, fileSystem @*/
{
        int last_cond;
        last_cond = ms->c.li[cont_level].last_cond;

        switch (cond) {
        case COND_IF:
                if (last_cond != COND_NONE && last_cond != COND_ELIF) {
                        if (ms->flags & MAGIC_CHECK)
                                file_magwarn(ms, "syntax error: `if'");
                        return -1;
                }
                last_cond = COND_IF;
                break;

        case COND_ELIF:
                if (last_cond != COND_IF && last_cond != COND_ELIF) {
                        if (ms->flags & MAGIC_CHECK)
                                file_magwarn(ms, "syntax error: `elif'");
                        return -1;
                }
                last_cond = COND_ELIF;
                break;

        case COND_ELSE:
                if (last_cond != COND_IF && last_cond != COND_ELIF) {
                        if (ms->flags & MAGIC_CHECK)
                                file_magwarn(ms, "syntax error: `else'");
                        return -1;
                }
                last_cond = COND_NONE;
                break;

        case COND_NONE:
                last_cond = COND_NONE;
                break;
        }

        ms->c.li[cont_level].last_cond = last_cond;
        return 0;
}
#endif /* ENABLE_CONDITIONALS */

/*
 * parse one line from magic file, put into magic[index++] if valid
 */
private int
parse(struct magic_set *ms, struct magic_entry **mentryp, uint32_t *nmentryp, 
    const char *line, size_t lineno, int action)
{
#ifdef ENABLE_CONDITIONALS
        static uint32_t last_cont_level = 0;
#endif
        size_t i;
        struct magic_entry *me;
        struct magic *m;
        const char *l = line;
        char *t;
        int op;
        uint32_t cont_level;

        cont_level = 0;

        while (*l == '>') {
                ++l;            /* step over */
                cont_level++; 
        }
#ifdef ENABLE_CONDITIONALS
        if (cont_level == 0 || cont_level > last_cont_level)
                if (file_check_mem(ms, cont_level) == -1)
                        return -1;
        last_cont_level = cont_level;
#endif

#define ALLOC_CHUNK     (size_t)10
#define ALLOC_INCR      (size_t)200

        if (cont_level != 0) {
                if (*nmentryp == 0) {
                        file_error(ms, 0, "No current entry for continuation");
                        return -1;
                }
                me = &(*mentryp)[*nmentryp - 1];
                if (me->cont_count == me->max_count) {
                        struct magic *nm;
                        size_t cnt = me->max_count + ALLOC_CHUNK;
                        if ((nm = realloc(me->mp, sizeof(*nm) * cnt)) == NULL) {
                                file_oomem(ms, sizeof(*nm) * cnt);
                                return -1;
                        }
                        me->mp = m = nm;
                        me->max_count = cnt;
                }
                m = &me->mp[me->cont_count++];
                (void)memset(m, 0, sizeof(*m));
                m->cont_level = cont_level;
        } else {
                if (*nmentryp == maxmagic) {
                        struct magic_entry *mp;

                maxmagic += ALLOC_INCR;
/*@i@*/                 if ((mp = realloc(*mentryp, sizeof(*mp) * maxmagic)) ==
                            NULL) {
                                file_oomem(ms, sizeof(*mp) * maxmagic);
                        return -1;
                }
                        (void)memset(&mp[*nmentryp], 0, sizeof(*mp) *
                            ALLOC_INCR);
                        *mentryp = mp;
                }
                me = &(*mentryp)[*nmentryp];
                if (me->mp == NULL) {
                        if ((m = malloc(sizeof(*m) * ALLOC_CHUNK)) == NULL) {
                                file_oomem(ms, sizeof(*m) * ALLOC_CHUNK);
                                return -1;
        }
                        me->mp = m;
                        me->max_count = ALLOC_CHUNK;
                } else
                        m = me->mp;
                (void)memset(m, 0, sizeof(*m));
        m->cont_level = 0;
                me->cont_count = 1;
        }
        m->lineno = lineno;

        if (*l == '&') {  /* m->cont_level == 0 checked below. */
                ++l;            /* step over */
                m->flag |= OFFADD;
        }
        if (*l == '(') {
                ++l;            /* step over */
                m->flag |= INDIR;
                if (m->flag & OFFADD)
                        m->flag = (m->flag & ~OFFADD) | INDIROFFADD;

                if (*l == '&') {  /* m->cont_level == 0 checked below */
                ++l;            /* step over */
                m->flag |= OFFADD;
        }
        }
        /* Indirect offsets are not valid at level 0. */
        if (m->cont_level == 0 && (m->flag & (OFFADD | INDIROFFADD)))
                if (ms->flags & MAGIC_CHECK)
                        file_magwarn(ms, "relative offset at level 0");

        /* get offset, then skip over it */
        m->offset = (uint32_t)strtoul(l, &t, 0);
        if (l == t)
                if (ms->flags & MAGIC_CHECK)
                        file_magwarn(ms, "offset `%s' invalid", l);
        l = t;

        if (m->flag & INDIR) {
                m->in_type = FILE_LONG;
                m->in_offset = 0;
                /*
                 * read [.lbs][+-]nnnnn)
                 */
                if (*l == '.') {
                        l++;
                        switch (*l) {
                        case 'l':
                                m->in_type = FILE_LELONG;
                                break;
                        case 'L':
                                m->in_type = FILE_BELONG;
                                break;
                        case 'm':
                                m->in_type = FILE_MELONG;
                                break;
                        case 'h':
                        case 's':
                                m->in_type = FILE_LESHORT;
                                break;
                        case 'H':
                        case 'S':
                                m->in_type = FILE_BESHORT;
                                break;
                        case 'c':
                        case 'b':
                        case 'C':
                        case 'B':
                                m->in_type = FILE_BYTE;
                                break;
                        default:
                                if (ms->flags & MAGIC_CHECK)