file/src/funcs.c

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00001 /*
00002  * Copyright (c) Christos Zoulas 2003.
00003  * All Rights Reserved.
00004  * 
00005  * Redistribution and use in source and binary forms, with or without
00006  * modification, are permitted provided that the following conditions
00007  * are met:
00008  * 1. Redistributions of source code must retain the above copyright
00009  *    notice immediately at the beginning of the file, without modification,
00010  *    this list of conditions, and the following disclaimer.
00011  * 2. Redistributions in binary form must reproduce the above copyright
00012  *    notice, this list of conditions and the following disclaimer in the
00013  *    documentation and/or other materials provided with the distribution.
00014  *  
00015  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
00016  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
00017  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
00018  * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE FOR
00019  * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
00020  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
00021  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
00022  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
00023  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
00024  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
00025  * SUCH DAMAGE.
00026  */
00027 #include "file.h"
00028 #include "magic.h"
00029 #include <stdarg.h>
00030 #include <stdlib.h>
00031 #include <string.h>
00032 #include <ctype.h>
00033 #if defined(HAVE_WCHAR_H)
00034 #include <wchar.h>
00035 #endif
00036 #if defined(HAVE_WCTYPE_H)
00037 #include <wctype.h>
00038 #endif
00039 #if defined(HAVE_LIMITS_H)
00040 #include <limits.h>
00041 #endif
00042 #ifndef SIZE_T_MAX
00043 #ifdef __LP64__
00044 #define SIZE_T_MAX (size_t)0xfffffffffffffffffU
00045 #else
00046 #define SIZE_T_MAX (size_t)0xffffffffU
00047 #endif
00048 #endif
00049 
00050 #ifndef lint
00051 FILE_RCSID("@(#)$File: funcs.c,v 1.32 2007/05/24 17:22:27 christos Exp $")
00052 #endif  /* lint */
00053 
00054 #ifndef HAVE_VSNPRINTF
00055 int vsnprintf(char *, size_t, const char *, va_list)
00056         /*@*/;
00057 #endif
00058 
00059 /*
00060  * Like printf, only we print to a buffer and advance it.
00061  */
00062 protected int
00063 file_printf(struct magic_set *ms, const char *fmt, ...)
00064 {
00065         va_list ap;
00066         size_t len, size;
00067         char *buf;
00068 
00069         va_start(ap, fmt);
00070 
00071         if ((len = vsnprintf(ms->o.ptr, ms->o.left, fmt, ap)) >= ms->o.left) {
00072                 long diff;      /* XXX: really ptrdiff_t */
00073 
00074                 va_end(ap);
00075                 size = (ms->o.size - ms->o.left) + len + 1024;
00076                 if ((buf = realloc(ms->o.buf, size)) == NULL) {
00077                         file_oomem(ms, size);
00078                         return -1;
00079                 }
00080                 diff = ms->o.ptr - ms->o.buf;
00081                 ms->o.ptr = buf + diff;
00082                 ms->o.buf = buf;
00083                 ms->o.left = size - diff;
00084                 ms->o.size = size;
00085 
00086                 va_start(ap, fmt);
00087                 len = vsnprintf(ms->o.ptr, ms->o.left, fmt, ap);
00088         }
00089         va_end(ap);
00090         ms->o.ptr += len;
00091         ms->o.left -= len;
00092         return 0;
00093 }
00094 
00095 /*
00096  * error - print best error message possible
00097  */
00098 /*VARARGS*/
00099 private void
00100 file_error_core(struct magic_set *ms, int error, const char *f, va_list va,
00101     uint32_t lineno)
00102         /*@modifies ms @*/
00103 {
00104         size_t len;
00105         /* Only the first error is ok */
00106         if (ms->haderr)
00107                 return;
00108         len = 0;
00109         if (lineno != 0) {
00110                 (void)snprintf(ms->o.buf, ms->o.size, "line %u: ", lineno);
00111                 len = strlen(ms->o.buf);
00112         }
00113         (void)vsnprintf(ms->o.buf + len, ms->o.size - len, f, va);
00114         if (error > 0) {
00115                 len = strlen(ms->o.buf);
00116                 (void)snprintf(ms->o.buf + len, ms->o.size - len, " (%s)",
00117                     strerror(error));
00118         }
00119         ms->haderr++;
00120         ms->error = error;
00121 }
00122 
00123 /*VARARGS*/
00124 protected void
00125 file_error(struct magic_set *ms, int error, const char *f, ...)
00126 {
00127         va_list va;
00128         va_start(va, f);
00129         file_error_core(ms, error, f, va, 0);
00130         va_end(va);
00131 }
00132 
00133 /*
00134  * Print an error with magic line number.
00135  */
00136 /*VARARGS*/
00137 protected void
00138 file_magerror(struct magic_set *ms, const char *f, ...)
00139 {
00140         va_list va;
00141         va_start(va, f);
00142         file_error_core(ms, 0, f, va, ms->line);
00143         va_end(va);
00144 }
00145 
00146 protected void
00147 file_oomem(struct magic_set *ms, size_t len)
00148 {
00149         file_error(ms, errno, "cannot allocate %zu bytes", len);
00150 }
00151 
00152 protected void
00153 file_badseek(struct magic_set *ms)
00154 {
00155         file_error(ms, errno, "error seeking");
00156 }
00157 
00158 protected void
00159 file_badread(struct magic_set *ms)
00160 {
00161         file_error(ms, errno, "error reading");
00162 }
00163 
00164 #ifndef COMPILE_ONLY
00165 protected int
00166 file_buffer(struct magic_set *ms, int fd, const char *inname, const void *buf,
00167     size_t nb)
00168 {
00169     int m;
00170 
00171 #ifdef __EMX__
00172     if ((ms->flags & MAGIC_NO_CHECK_APPTYPE) == 0 && inname) {
00173         switch (file_os2_apptype(ms, inname, buf, nb)) {
00174         case -1:
00175             return -1;
00176         case 0:
00177             break;
00178         default:
00179             return 1;
00180         }
00181     }
00182 #endif
00183 
00184     /* try compression stuff */
00185     if ((ms->flags & MAGIC_NO_CHECK_COMPRESS) != 0 ||
00186         (m = file_zmagic(ms, fd, inname, buf, nb)) == 0) {
00187         /* Check if we have a tar file */
00188         if ((ms->flags & MAGIC_NO_CHECK_TAR) != 0 ||
00189             (m = file_is_tar(ms, buf, nb)) == 0) {
00190             /* try tests in /etc/magic (or surrogate magic file) */
00191             if ((ms->flags & MAGIC_NO_CHECK_SOFT) != 0 ||
00192                 (m = file_softmagic(ms, buf, nb)) == 0) {
00193                 /* try known keywords, check whether it is ASCII */
00194                 if ((ms->flags & MAGIC_NO_CHECK_ASCII) != 0 ||
00195                     (m = file_ascmagic(ms, buf, nb)) == 0) {
00196                     /* abandon hope, all ye who remain here */
00197                     if (file_printf(ms, ms->flags & MAGIC_MIME ?
00198                         (nb ? "application/octet-stream" :
00199                             "application/empty") :
00200                         (nb ? "data" :
00201                             "empty")) == -1)
00202                             return -1;
00203                     m = 1;
00204                 }
00205             }
00206         }
00207     }
00208 #ifdef BUILTIN_ELF
00209     if ((ms->flags & MAGIC_NO_CHECK_ELF) == 0 && m == 1 && nb > 5 && fd != -1) {
00210         /*
00211          * We matched something in the file, so this *might*
00212          * be an ELF file, and the file is at least 5 bytes
00213          * long, so if it's an ELF file it has at least one
00214          * byte past the ELF magic number - try extracting
00215          * information from the ELF headers that cannot easily
00216          * be extracted with rules in the magic file.
00217          */
00218         (void)file_tryelf(ms, fd, buf, nb);
00219     }
00220 #endif
00221     return m;
00222 }
00223 #endif
00224 
00225 protected int
00226 file_reset(struct magic_set *ms)
00227 {
00228         if (ms->mlist == NULL) {
00229                 file_error(ms, 0, "no magic files loaded");
00230                 return -1;
00231         }
00232         ms->o.ptr = ms->o.buf;
00233         ms->o.left = ms->o.size;
00234         ms->haderr = 0;
00235         ms->error = -1;
00236         return 0;
00237 }
00238 
00239 #define OCTALIFY(n, o)  \
00240         /*LINTED*/ \
00241         (void)(*(n)++ = '\\', \
00242         *(n)++ = (((uint32_t)*(o) >> 6) & 3) + '0', \
00243         *(n)++ = (((uint32_t)*(o) >> 3) & 7) + '0', \
00244         *(n)++ = (((uint32_t)*(o) >> 0) & 7) + '0', \
00245         (o)++)
00246 
00247 protected const char *
00248 file_getbuffer(struct magic_set *ms)
00249 {
00250         char *pbuf, *op, *np;
00251         size_t psize, len;
00252 
00253         if (ms->haderr)
00254                 return NULL;
00255 
00256         if (ms->flags & MAGIC_RAW)
00257                 return ms->o.buf;
00258 
00259         len = ms->o.size - ms->o.left;
00260         /* * 4 is for octal representation, + 1 is for NUL */
00261         if (len > (SIZE_T_MAX - 1) / 4) {
00262                 file_oomem(ms, len);
00263                 return NULL;
00264         }
00265         psize = len * 4 + 1;
00266         if (ms->o.psize < psize) {
00267                 if ((pbuf = realloc(ms->o.pbuf, psize)) == NULL) {
00268                         file_oomem(ms, psize);
00269                         return NULL;
00270                 }
00271                 ms->o.psize = psize;
00272                 ms->o.pbuf = pbuf;
00273         }
00274 
00275 #if defined(HAVE_WCHAR_H) && defined(HAVE_MBRTOWC) && defined(HAVE_WCWIDTH)
00276         {
00277                 mbstate_t state;
00278                 wchar_t nextchar;
00279                 int mb_conv = 1;
00280                 size_t bytesconsumed;
00281                 char *eop;
00282                 (void)memset(&state, 0, sizeof(mbstate_t));
00283 
00284                 np = ms->o.pbuf;
00285                 op = ms->o.buf;
00286                 eop = op + strlen(ms->o.buf);
00287 
00288                 while (op < eop) {
00289                         bytesconsumed = mbrtowc(&nextchar, op,
00290                             (size_t)(eop - op), &state);
00291                         if (bytesconsumed == (size_t)(-1) ||
00292                             bytesconsumed == (size_t)(-2)) {
00293                                 mb_conv = 0;
00294                                 break;
00295                         }
00296 
00297                         if (iswprint(nextchar)) {
00298                                 (void)memcpy(np, op, bytesconsumed);
00299                                 op += bytesconsumed;
00300                                 np += bytesconsumed;
00301                         } else {
00302                                 while (bytesconsumed-- > 0)
00303                                         OCTALIFY(np, op);
00304         }
00305                 }
00306                 *np = '\0';
00307 
00308                 /* Parsing succeeded as a multi-byte sequence */
00309                 if (mb_conv != 0)
00310                         return ms->o.pbuf;
00311         }
00312 #endif
00313 
00314         for (np = ms->o.pbuf, op = ms->o.buf; *op; op++) {
00315                 if (isprint((unsigned char)*op)) {
00316                         *np++ = *op;    
00317                 } else {
00318                         OCTALIFY(np, op);
00319                 }
00320         }
00321         *np = '\0';
00322         return ms->o.pbuf;
00323 }
00324 
00325 protected int
00326 file_check_mem(struct magic_set *ms, unsigned int level)
00327 {
00328         size_t len;
00329 
00330         if (level >= ms->c.len) {
00331                 len = (ms->c.len += 20) * sizeof(*ms->c.li);
00332                 ms->c.li = (ms->c.li == NULL) ? malloc(len) :
00333                     realloc(ms->c.li, len);
00334                 if (ms->c.li == NULL) {
00335                         file_oomem(ms, len);
00336                         return -1;
00337                 }
00338         }
00339         ms->c.li[level].got_match = 0;
00340 #ifdef ENABLE_CONDITIONALS
00341         ms->c.li[level].last_match = 0;
00342         ms->c.li[level].last_cond = COND_NONE;
00343 #endif /* ENABLE_CONDITIONALS */
00344         return 0;
00345 }
00346 /*
00347  * Yes these wrappers suffer from buffer overflows, but if your OS does not
00348  * have the real functions, maybe you should consider replacing your OS?
00349  */
00350 #ifndef HAVE_VSNPRINTF
00351 int
00352 vsnprintf(char *buf, size_t len, const char *fmt, va_list ap)
00353 {
00354         return vsprintf(buf, fmt, ap);
00355 }
00356 #endif
00357 
00358 #ifndef HAVE_SNPRINTF
00359 /*ARGSUSED*/
00360 int
00361 snprintf(char *buf, size_t len, const char *fmt, ...)
00362 {
00363         int rv;
00364         va_list ap;
00365         va_start(ap, fmt);
00366         rv = vsprintf(buf, fmt, ap);
00367         va_end(ap);
00368         return rv;
00369 }
00370 #endif

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