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NetBSD/dist/file/apprentice.c

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/* $NetBSD: apprentice.c,v 1.2 2003/02/23 23:34:21 pooka Exp $ */
/*
* apprentice - make one pass through /etc/magic, learning its secrets.
*
* Copyright (c) Ian F. Darwin, 1987.
* Written by Ian F. Darwin.
*
* This software is not subject to any license of the American Telephone
* and Telegraph Company or of the Regents of the University of California.
*
* Permission is granted to anyone to use this software for any purpose on
* any computer system, and to alter it and redistribute it freely, subject
* to the following restrictions:
*
* 1. The author is not responsible for the consequences of use of this
* software, no matter how awful, even if they arise from flaws in it.
*
* 2. The origin of this software must not be misrepresented, either by
* explicit claim or by omission. Since few users ever read sources,
* credits must appear in the documentation.
*
* 3. Altered versions must be plainly marked as such, and must not be
* misrepresented as being the original software. Since few users
* ever read sources, credits must appear in the documentation.
*
* 4. This notice may not be removed or altered.
*/
#include "file.h"
#include <stdlib.h>
#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif
#include <string.h>
#include <ctype.h>
#include <fcntl.h>
#ifdef QUICK
#include <sys/mman.h>
#endif
#ifndef lint
#if 0
FILE_RCSID("@(#)Id: apprentice.c,v 1.49 2002/07/03 19:00:41 christos Exp ")
#else
__RCSID("$NetBSD: apprentice.c,v 1.2 2003/02/23 23:34:21 pooka Exp $");
#endif
#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
#ifdef __EMX__
char PATHSEP=';';
#else
char PATHSEP=':';
#endif
static int getvalue(struct magic *, char **);
static int hextoint(int);
static char *getstr(char *, char *, int, int *);
static int parse(struct magic **, uint32_t *, char *, int);
static void eatsize(char **);
static int apprentice_1(const char *, int);
static int apprentice_file(struct magic **, uint32_t *, const char *, int);
static void byteswap(struct magic *, uint32_t);
static void bs1(struct magic *);
static uint16_t swap2(uint16_t);
static uint32_t swap4(uint32_t);
static char *mkdbname(const char *);
static int apprentice_map(struct magic **, uint32_t *, const char *, int);
static int apprentice_compile(struct magic **, uint32_t *, const char *, int);
static int maxmagic = 0;
struct mlist mlist;
#ifdef COMPILE_ONLY
const char *magicfile;
char *progname;
int lineno;
int main(int, char *[]);
int
main(int argc, char *argv[])
{
int ret;
if ((progname = strrchr(argv[0], '/')) != NULL)
progname++;
else
progname = argv[0];
if (argc != 2) {
(void)fprintf(stderr, "usage: %s file\n", progname);
exit(1);
}
magicfile = argv[1];
exit(apprentice(magicfile, COMPILE));
}
#endif /* COMPILE_ONLY */
/*
* Handle one file.
*/
static int
apprentice_1(const char *fn, int action)
{
struct magic *magic = NULL;
uint32_t nmagic = 0;
struct mlist *ml;
int rv = -1;
if (action == COMPILE) {
rv = apprentice_file(&magic, &nmagic, fn, action);
if (rv == 0)
return apprentice_compile(&magic, &nmagic, fn, action);
else
return rv;
}
#ifndef COMPILE_ONLY
if ((rv = apprentice_map(&magic, &nmagic, fn, action)) != 0)
(void)fprintf(stderr, "%s: Using regular magic file `%s'\n",
progname, fn);
if (rv != 0)
rv = apprentice_file(&magic, &nmagic, fn, action);
if (rv != 0)
return rv;
if ((ml = malloc(sizeof(*ml))) == NULL) {
(void) fprintf(stderr, "%s: Out of memory (%s).\n", progname,
strerror(errno));
if (action == CHECK)
return -1;
}
if (magic == NULL || nmagic == 0)
return rv;
ml->magic = magic;
ml->nmagic = nmagic;
mlist.prev->next = ml;
ml->prev = mlist.prev;
ml->next = &mlist;
mlist.prev = ml;
return rv;
#endif /* COMPILE_ONLY */
}
/* const char *fn: list of magic files */
int
apprentice(const char *fn, int action)
{
char *p, *mfn;
int file_err, errs = -1;
mlist.next = mlist.prev = &mlist;
mfn = malloc(strlen(fn)+1);
if (mfn == NULL) {
(void) fprintf(stderr, "%s: Out of memory (%s).\n", progname,
strerror(errno));
if (action == CHECK)
return -1;
else
exit(1);
}
fn = strcpy(mfn, fn);
while (fn) {
p = strchr(fn, PATHSEP);
if (p)
*p++ = '\0';
file_err = apprentice_1(fn, action);
if (file_err > errs)
errs = file_err;
fn = p;
}
if (errs == -1)
(void) fprintf(stderr, "%s: couldn't find any magic files!\n",
progname);
if (action == CHECK && errs)
exit(1);
free(mfn);
return errs;
}
/*
* parse from a file
* const char *fn: name of magic file
*/
static int
apprentice_file(struct magic **magicp, uint32_t *nmagicp, const char *fn,
int action)
{
static const char hdr[] =
"cont\toffset\ttype\topcode\tmask\tvalue\tdesc";
FILE *f;
char line[BUFSIZ+1];
int errs = 0;
f = fopen(fn, "r");
if (f == NULL) {
if (errno != ENOENT)
(void) fprintf(stderr,
"%s: can't read magic file %s (%s)\n",
progname, fn, strerror(errno));
return -1;
}
maxmagic = MAXMAGIS;
*magicp = (struct magic *) calloc(maxmagic, sizeof(struct magic));
if (*magicp == NULL) {
(void) fprintf(stderr, "%s: Out of memory (%s).\n", progname,
strerror(errno));
if (action == CHECK)
return -1;
}
/* parse it */
if (action == CHECK) /* print silly verbose header for USG compat. */
(void) printf("%s\n", hdr);
for (lineno = 1;fgets(line, BUFSIZ, f) != NULL; lineno++) {
if (line[0]=='#') /* comment, do not parse */
continue;
if (strlen(line) <= (unsigned)1) /* null line, garbage, etc */
continue;
line[strlen(line)-1] = '\0'; /* delete newline */
if (parse(magicp, nmagicp, line, action) != 0)
errs = 1;
}
(void) fclose(f);
if (errs) {
free(*magicp);
*magicp = NULL;
*nmagicp = 0;
}
return errs;
}
/*
* extend the sign bit if the comparison is to be signed
*/
uint32_t
signextend(struct magic *m, uint32_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 BYTE:
v = (char) v;
break;
case SHORT:
case BESHORT:
case LESHORT:
v = (short) v;
break;
case DATE:
case BEDATE:
case LEDATE:
case LDATE:
case BELDATE:
case LELDATE:
case LONG:
case BELONG:
case LELONG:
v = (int32_t) v;
break;
case STRING:
case PSTRING:
break;
case REGEX:
break;
default:
magwarn("can't happen: m->type=%d\n",
m->type);
return -1;
}
return v;
}
/*
* parse one line from magic file, put into magic[index++] if valid
*/
static int
parse(struct magic **magicp, uint32_t *nmagicp, char *l, int action)
{
int i = 0;
struct magic *m;
char *t;
#define ALLOC_INCR 200
if (*nmagicp + 1 >= maxmagic){
maxmagic += ALLOC_INCR;
if ((m = (struct magic *) realloc(*magicp,
sizeof(struct magic) * maxmagic)) == NULL) {
(void) fprintf(stderr, "%s: Out of memory (%s).\n",
progname, strerror(errno));
if (*magicp)
free(*magicp);
if (action == CHECK)
return -1;
else
exit(1);
}
*magicp = m;
memset(&(*magicp)[*nmagicp], 0, sizeof(struct magic)
* ALLOC_INCR);
}
m = &(*magicp)[*nmagicp];
m->flag = 0;
m->cont_level = 0;
while (*l == '>') {
++l; /* step over */
m->cont_level++;
}
if (m->cont_level != 0 && *l == '(') {
++l; /* step over */
m->flag |= INDIR;
}
if (m->cont_level != 0 && *l == '&') {
++l; /* step over */
m->flag |= OFFADD;
}
/* get offset, then skip over it */
m->offset = (int) strtoul(l,&t,0);
if (l == t)
magwarn("offset %s invalid", l);
l = t;
if (m->flag & INDIR) {
m->in_type = LONG;
m->in_offset = 0;
/*
* read [.lbs][+-]nnnnn)
*/
if (*l == '.') {
l++;
switch (*l) {
case 'l':
m->in_type = LELONG;
break;
case 'L':
m->in_type = BELONG;
break;
case 'h':
case 's':
m->in_type = LESHORT;
break;
case 'H':
case 'S':
m->in_type = BESHORT;
break;
case 'c':
case 'b':
case 'C':
case 'B':
m->in_type = BYTE;
break;
default:
magwarn("indirect offset type %c invalid", *l);
break;
}
l++;
}
if (*l == '~') {
m->in_op = OPINVERSE;
l++;
}
switch (*l) {
case '&':
m->in_op |= OPAND;
l++;
break;
case '|':
m->in_op |= OPOR;
l++;
break;
case '^':
m->in_op |= OPXOR;
l++;
break;
case '+':
m->in_op |= OPADD;
l++;
break;
case '-':
m->in_op |= OPMINUS;
l++;
break;
case '*':
m->in_op |= OPMULTIPLY;
l++;
break;
case '/':
m->in_op |= OPDIVIDE;
l++;
break;
case '%':
m->in_op |= OPMODULO;
l++;
break;
}
if (isdigit((unsigned char)*l))
m->in_offset = strtoul(l, &t, 0);
else
t = l;
if (*t++ != ')')
magwarn("missing ')' in indirect offset");
l = t;
}
while (isascii((unsigned char)*l) && isdigit((unsigned char)*l))
++l;
EATAB;
#define NBYTE 4
#define NSHORT 5
#define NLONG 4
#define NSTRING 6
#define NDATE 4
#define NBESHORT 7
#define NBELONG 6
#define NBEDATE 6
#define NLESHORT 7
#define NLELONG 6
#define NLEDATE 6
#define NPSTRING 7
#define NLDATE 5
#define NBELDATE 7
#define NLELDATE 7
#define NREGEX 5
if (*l == 'u') {
++l;
m->flag |= UNSIGNED;
}
/* get type, skip it */
if (strncmp(l, "char", NBYTE)==0) { /* HP/UX compat */
m->type = BYTE;
l += NBYTE;
} else if (strncmp(l, "byte", NBYTE)==0) {
m->type = BYTE;
l += NBYTE;
} else if (strncmp(l, "short", NSHORT)==0) {
m->type = SHORT;
l += NSHORT;
} else if (strncmp(l, "long", NLONG)==0) {
m->type = LONG;
l += NLONG;
} else if (strncmp(l, "string", NSTRING)==0) {
m->type = STRING;
l += NSTRING;
} else if (strncmp(l, "date", NDATE)==0) {
m->type = DATE;
l += NDATE;
} else if (strncmp(l, "beshort", NBESHORT)==0) {
m->type = BESHORT;
l += NBESHORT;
} else if (strncmp(l, "belong", NBELONG)==0) {
m->type = BELONG;
l += NBELONG;
} else if (strncmp(l, "bedate", NBEDATE)==0) {
m->type = BEDATE;
l += NBEDATE;
} else if (strncmp(l, "leshort", NLESHORT)==0) {
m->type = LESHORT;
l += NLESHORT;
} else if (strncmp(l, "lelong", NLELONG)==0) {
m->type = LELONG;
l += NLELONG;
} else if (strncmp(l, "ledate", NLEDATE)==0) {
m->type = LEDATE;
l += NLEDATE;
} else if (strncmp(l, "pstring", NPSTRING)==0) {
m->type = PSTRING;
l += NPSTRING;
} else if (strncmp(l, "ldate", NLDATE)==0) {
m->type = LDATE;
l += NLDATE;
} else if (strncmp(l, "beldate", NBELDATE)==0) {
m->type = BELDATE;
l += NBELDATE;
} else if (strncmp(l, "leldate", NLELDATE)==0) {
m->type = LELDATE;
l += NLELDATE;
} else if (strncmp(l, "regex", NREGEX)==0) {
m->type = REGEX;
l += sizeof("regex");
} else {
magwarn("type %s invalid", l);
return -1;
}
/* New-style anding: "0 byte&0x80 =0x80 dynamically linked" */
/* New and improved: ~ & | ^ + - * / % -- exciting, isn't it? */
if (*l == '~') {
if (STRING != m->type && PSTRING != m->type)
m->mask_op = OPINVERSE;
++l;
}
switch (*l) {
case '&':
m->mask_op |= OPAND;
++l;
m->mask = signextend(m, strtoul(l, &l, 0));
eatsize(&l);
break;
case '|':
m->mask_op |= OPOR;
++l;
m->mask = signextend(m, strtoul(l, &l, 0));
eatsize(&l);
break;
case '^':
m->mask_op |= OPXOR;
++l;
m->mask = signextend(m, strtoul(l, &l, 0));
eatsize(&l);
break;
case '+':
m->mask_op |= OPADD;
++l;
m->mask = signextend(m, strtoul(l, &l, 0));
eatsize(&l);
break;
case '-':
m->mask_op |= OPMINUS;
++l;
m->mask = signextend(m, strtoul(l, &l, 0));
eatsize(&l);
break;
case '*':
m->mask_op |= OPMULTIPLY;
++l;
m->mask = signextend(m, strtoul(l, &l, 0));
eatsize(&l);
break;
case '%':
m->mask_op |= OPMODULO;
++l;
m->mask = signextend(m, strtoul(l, &l, 0));
eatsize(&l);
break;
case '/':
if (STRING != m->type && PSTRING != m->type) {
m->mask_op |= OPDIVIDE;
++l;
m->mask = signextend(m, strtoul(l, &l, 0));
eatsize(&l);
} else {
m->mask = 0L;
while (!isspace(*++l)) {
switch (*l) {
case CHAR_IGNORE_LOWERCASE:
m->mask |= STRING_IGNORE_LOWERCASE;
break;
case CHAR_COMPACT_BLANK:
m->mask |= STRING_COMPACT_BLANK;
break;
case CHAR_COMPACT_OPTIONAL_BLANK:
m->mask |=
STRING_COMPACT_OPTIONAL_BLANK;
break;
default:
magwarn("string extension %c invalid",
*l);
return -1;
}
}
}
break;
}
/* We used to set mask to all 1's here, instead let's just not do anything
if mask = 0 (unless you have a better idea) */
EATAB;
switch (*l) {
case '>':
case '<':
/* Old-style anding: "0 byte &0x80 dynamically linked" */
case '&':
case '^':
case '=':
m->reln = *l;
++l;
if (*l == '=') {
/* HP compat: ignore &= etc. */
++l;
}
break;
case '!':
if (m->type != STRING && m->type != PSTRING) {
m->reln = *l;
++l;
break;
}
/* FALL THROUGH */
default:
if (*l == 'x' && isascii((unsigned char)l[1]) &&
isspace((unsigned char)l[1])) {
m->reln = *l;
++l;
goto GetDesc; /* Bill The Cat */
}
m->reln = '=';
break;
}
EATAB;
if (getvalue(m, &l))
return -1;
/*
* TODO finish this macro and start using it!
* #define offsetcheck {if (offset > HOWMANY-1)
* magwarn("offset too big"); }
*/
/*
* now get last part - the description
*/
GetDesc:
EATAB;
if (l[0] == '\b') {
++l;
m->nospflag = 1;
} else if ((l[0] == '\\') && (l[1] == 'b')) {
++l;
++l;
m->nospflag = 1;
} else
m->nospflag = 0;
while ((m->desc[i++] = *l++) != '\0' && i<MAXDESC)
/* NULLBODY */;
#ifndef COMPILE_ONLY
if (action == CHECK) {
mdump(m);
}
#endif
++(*nmagicp); /* make room for next */
return 0;
}
/*
* Read a numeric value from a pointer, into the value union of a magic
* pointer, according to the magic type. Update the string pointer to point
* just after the number read. Return 0 for success, non-zero for failure.
*/
static int
getvalue(struct magic *m, char **p)
{
int slen;
if (m->type == STRING || m->type == PSTRING || m->type == REGEX) {
*p = getstr(*p, m->value.s, sizeof(m->value.s), &slen);
m->vallen = slen;
} else
if (m->reln != 'x') {
m->value.l = signextend(m, strtoul(*p, p, 0));
eatsize(p);
}
return 0;
}
/*
* Convert a string containing C character escapes. Stop at an unescaped
* space or tab.
* Copy the converted version to "p", returning its length in *slen.
* Return updated scan pointer as function result.
*/
static char *
getstr(char *s, char *p, int plen, int *slen)
{
char *origs = s, *origp = p;
char *pmax = p + plen - 1;
int c;
int val;
while ((c = *s++) != '\0') {
if (isspace((unsigned char) c))
break;
if (p >= pmax) {
fprintf(stderr, "String too long: %s\n", origs);
break;
}
if(c == '\\') {
switch(c = *s++) {
case '\0':
goto out;
default:
*p++ = (char) c;
break;
case 'n':
*p++ = '\n';
break;
case 'r':
*p++ = '\r';
break;
case 'b':
*p++ = '\b';
break;
case 't':
*p++ = '\t';
break;
case 'f':
*p++ = '\f';
break;
case 'v':
*p++ = '\v';
break;
/* \ and up to 3 octal digits */
case '0':
case '1':
case '2':
case '3':
case '4':
case '5':
case '6':
case '7':
val = c - '0';
c = *s++; /* try for 2 */
if(c >= '0' && c <= '7') {
val = (val<<3) | (c - '0');
c = *s++; /* try for 3 */
if(c >= '0' && c <= '7')
val = (val<<3) | (c-'0');
else
--s;
}
else
--s;
*p++ = (char)val;
break;
/* \x and up to 2 hex digits */
case 'x':
val = 'x'; /* Default if no digits */
c = hextoint(*s++); /* Get next char */
if (c >= 0) {
val = c;
c = hextoint(*s++);
if (c >= 0)
val = (val << 4) + c;
else
--s;
} else
--s;
*p++ = (char)val;
break;
}
} else
*p++ = (char)c;
}
out:
*p = '\0';
*slen = p - origp;
return s;
}
/* Single hex char to int; -1 if not a hex char. */
static int
hextoint(int c)
{
if (!isascii((unsigned char) c))
return -1;
if (isdigit((unsigned char) c))
return c - '0';
if ((c >= 'a')&&(c <= 'f'))
return c + 10 - 'a';
if (( c>= 'A')&&(c <= 'F'))
return c + 10 - 'A';
return -1;
}
/*
* Print a string containing C character escapes.
*/
void
showstr(FILE *fp, const char *s, int len)
{
char c;
for (;;) {
c = *s++;
if (len == -1) {
if (c == '\0')
break;
}
else {
if (len-- == 0)
break;
}
if(c >= 040 && c <= 0176) /* TODO isprint && !iscntrl */
(void) fputc(c, fp);
else {
(void) fputc('\\', fp);
switch (c) {
case '\n':
(void) fputc('n', fp);
break;
case '\r':
(void) fputc('r', fp);
break;
case '\b':
(void) fputc('b', fp);
break;
case '\t':
(void) fputc('t', fp);
break;
case '\f':
(void) fputc('f', fp);
break;
case '\v':
(void) fputc('v', fp);
break;
default:
(void) fprintf(fp, "%.3o", c & 0377);
break;
}
}
}
}
/*
* eatsize(): Eat the size spec from a number [eg. 10UL]
*/
static void
eatsize(char **p)
{
char *l = *p;
if (LOWCASE(*l) == 'u')
l++;
switch (LOWCASE(*l)) {
case 'l': /* long */
case 's': /* short */
case 'h': /* short */
case 'b': /* char/byte */
case 'c': /* char/byte */
l++;
/*FALLTHROUGH*/
default:
break;
}
*p = l;
}
/*
* handle a compiled file.
*/
static int
apprentice_map(struct magic **magicp, uint32_t *nmagicp, const char *fn,
int action)
{
int fd;
struct stat st;
uint32_t *ptr;
uint32_t version;
int needsbyteswap;
char *dbname = mkdbname(fn);
void *mm;
if (dbname == NULL)
return -1;
if ((fd = open(dbname, O_RDONLY)) == -1)
return -1;
if (fstat(fd, &st) == -1) {
(void)fprintf(stderr, "%s: Cannot stat `%s' (%s)\n",
progname, dbname, strerror(errno));
goto error;
}
#ifdef QUICK
if ((mm = mmap(0, (size_t)st.st_size, PROT_READ|PROT_WRITE,
MAP_PRIVATE|MAP_FILE, fd, (off_t)0)) == MAP_FAILED) {
(void)fprintf(stderr, "%s: Cannot map `%s' (%s)\n",
progname, dbname, strerror(errno));
goto error;
}
#else
if ((mm = malloc((size_t)st.st_size)) == NULL) {
(void) fprintf(stderr, "%s: Out of memory (%s).\n", progname,
strerror(errno));
goto error;
}
if (read(fd, mm, (size_t)st.st_size) != (size_t)st.st_size) {
(void) fprintf(stderr, "%s: Read failed (%s).\n", progname,
strerror(errno));
goto error;
}
#endif
*magicp = mm;
(void)close(fd);
fd = -1;
ptr = (uint32_t *) *magicp;
if (*ptr != MAGICNO) {
if (swap4(*ptr) != MAGICNO) {
(void)fprintf(stderr, "%s: Bad magic in `%s'\n",
progname, dbname);
goto error;
}
needsbyteswap = 1;
} else
needsbyteswap = 0;
if (needsbyteswap)
version = swap4(ptr[1]);
else
version = ptr[1];
if (version != VERSIONNO) {
(void)fprintf(stderr,
"%s: version mismatch (%d != %d) in `%s'\n",
progname, version, VERSIONNO, dbname);
goto error;
}
*nmagicp = (st.st_size / sizeof(struct magic)) - 1;
(*magicp)++;
if (needsbyteswap)
byteswap(*magicp, *nmagicp);
return 0;
error:
if (fd != -1)
(void)close(fd);
if (mm) {
#ifdef QUICK
(void)munmap(mm, (size_t)st.st_size);
#else
free(mm);
#endif
} else {
*magicp = NULL;
*nmagicp = 0;
}
return -1;
}
/*
* handle an mmaped file.
*/
static int
apprentice_compile(struct magic **magicp, uint32_t *nmagicp, const char *fn,
int action)
{
int fd;
char *dbname = mkdbname(fn);
static const uint32_t ar[] = {
MAGICNO, VERSIONNO
};
if (dbname == NULL)
return -1;
if ((fd = open(dbname, O_WRONLY|O_CREAT|O_TRUNC, 0644)) == -1) {
(void)fprintf(stderr, "%s: Cannot open `%s' (%s)\n",
progname, dbname, strerror(errno));
return -1;
}
if (write(fd, ar, sizeof(ar)) != sizeof(ar)) {
(void)fprintf(stderr, "%s: error writing `%s' (%s)\n",
progname, dbname, strerror(errno));
return -1;
}
if (lseek(fd, sizeof(struct magic), SEEK_SET) != sizeof(struct magic)) {
(void)fprintf(stderr, "%s: error seeking `%s' (%s)\n",
progname, dbname, strerror(errno));
return -1;
}
if (write(fd, *magicp, sizeof(struct magic) * *nmagicp)
!= sizeof(struct magic) * *nmagicp) {
(void)fprintf(stderr, "%s: error writing `%s' (%s)\n",
progname, dbname, strerror(errno));
return -1;
}
(void)close(fd);
return 0;
}
/*
* make a dbname
*/
char *
mkdbname(const char *fn)
{
static const char ext[] = ".mgc";
static char *buf = NULL;
size_t len = strlen(fn) + sizeof(ext) + 1;
if (buf == NULL)
buf = malloc(len);
else
buf = realloc(buf, len);
if (buf == NULL) {
(void) fprintf(stderr, "%s: Out of memory (%s).\n", progname,
strerror(errno));
return NULL;
}
(void)strcpy(buf, fn);
(void)strcat(buf, ext);
return buf;
}
/*
* Byteswap an mmap'ed file if needed
*/
static void
byteswap(struct magic *magic, uint32_t nmagic)
{
uint32_t i;
for (i = 0; i < nmagic; i++)
bs1(&magic[i]);
}
/*
* swap a short
*/
static uint16_t
swap2(uint16_t sv)
{
uint16_t rv;
uint8_t *s = (uint8_t *) &sv;
uint8_t *d = (uint8_t *) &rv;
d[0] = s[1];
d[1] = s[0];
return rv;
}
/*
* swap an int
*/
static uint32_t
swap4(uint32_t sv)
{
uint32_t rv;
uint8_t *s = (uint8_t *) &sv;
uint8_t *d = (uint8_t *) &rv;
d[0] = s[3];
d[1] = s[2];
d[2] = s[1];
d[3] = s[0];
return rv;
}
/*
* byteswap a single magic entry
*/
static
void bs1(struct magic *m)
{
m->cont_level = swap2(m->cont_level);
m->offset = swap4(m->offset);
m->in_offset = swap4(m->in_offset);
if (m->type != STRING)
m->value.l = swap4(m->value.l);
m->mask = swap4(m->mask);
}
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