diff options
Diffstat (limited to 'src/magic.c')
| -rw-r--r-- | src/magic.c | 485 |
1 files changed, 485 insertions, 0 deletions
diff --git a/src/magic.c b/src/magic.c new file mode 100644 index 0000000..bc382e8 --- /dev/null +++ b/src/magic.c @@ -0,0 +1,485 @@ +/* + * Copyright (c) Christos Zoulas 2003. + * All Rights Reserved. + * + * 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. + */ + +#ifdef WIN32 +#include <windows.h> +#include <shlwapi.h> +#endif + +#include "file.h" + +#ifndef lint +FILE_RCSID("@(#)$File: magic.c,v 1.78 2013/01/07 18:20:19 christos Exp $") +#endif /* lint */ + +#include "magic.h" + +#include <stdlib.h> +#include <unistd.h> +#include <string.h> +#ifdef QUICK +#include <sys/mman.h> +#endif +#ifdef HAVE_LIMITS_H +#include <limits.h> /* for PIPE_BUF */ +#endif + +#if defined(HAVE_UTIMES) +# include <sys/time.h> +#elif defined(HAVE_UTIME) +# if defined(HAVE_SYS_UTIME_H) +# include <sys/utime.h> +# elif defined(HAVE_UTIME_H) +# include <utime.h> +# endif +#endif + +#ifdef HAVE_UNISTD_H +#include <unistd.h> /* for read() */ +#endif + +#ifndef PIPE_BUF +/* Get the PIPE_BUF from pathconf */ +#ifdef _PC_PIPE_BUF +#define PIPE_BUF pathconf(".", _PC_PIPE_BUF) +#else +#define PIPE_BUF 512 +#endif +#endif + +private void close_and_restore(const struct magic_set *, const char *, int, + const struct stat *); +private int unreadable_info(struct magic_set *, mode_t, const char *); +private const char* get_default_magic(void); +#ifndef COMPILE_ONLY +private const char *file_or_fd(struct magic_set *, const char *, int); +#endif + +#ifndef STDIN_FILENO +#define STDIN_FILENO 0 +#endif + +private const char * +get_default_magic(void) +{ + static const char hmagic[] = "/.magic/magic.mgc"; + static char *default_magic; + char *home, *hmagicpath; + +#ifndef WIN32 + struct stat st; + + if (default_magic) { + free(default_magic); + default_magic = NULL; + } + if ((home = getenv("HOME")) == NULL) + return MAGIC; + + if (asprintf(&hmagicpath, "%s/.magic.mgc", home) < 0) + return MAGIC; + if (stat(hmagicpath, &st) == -1) { + free(hmagicpath); + if (asprintf(&hmagicpath, "%s/.magic", home) < 0) + return MAGIC; + if (stat(hmagicpath, &st) == -1) + goto out; + if (S_ISDIR(st.st_mode)) { + free(hmagicpath); + if (asprintf(&hmagicpath, "%s/%s", home, hmagic) < 0) + return MAGIC; + if (access(hmagicpath, R_OK) == -1) + goto out; + } + } + + if (asprintf(&default_magic, "%s:%s", hmagicpath, MAGIC) < 0) + goto out; + free(hmagicpath); + return default_magic; +out: + default_magic = NULL; + free(hmagicpath); + return MAGIC; +#else + char *hmagicp = hmagicpath; + char *tmppath = NULL; + +#define APPENDPATH() \ + do { \ + if (tmppath && access(tmppath, R_OK) != -1) { \ + if (hmagicpath == NULL) \ + hmagicpath = tmppath; \ + else { \ + if (asprintf(&hmagicp, "%s%c%s", hmagicpath, \ + PATHSEP, tmppath) >= 0) { \ + free(hmagicpath); \ + hmagicpath = hmagicp; \ + } \ + free(tmppath); \ + } \ + tmppath = NULL; \ + } \ + } while (/*CONSTCOND*/0) + + if (default_magic) { + free(default_magic); + default_magic = NULL; + } + + /* First, try to get user-specific magic file */ + if ((home = getenv("LOCALAPPDATA")) == NULL) { + if ((home = getenv("USERPROFILE")) != NULL) + if (asprintf(&tmppath, + "%s/Local Settings/Application Data%s", home, + hmagic) < 0) + tmppath = NULL; + } else { + if (asprintf(&tmppath, "%s%s", home, hmagic) < 0) + tmppath = NULL; + } + + APPENDPATH(); + + /* Second, try to get a magic file from Common Files */ + if ((home = getenv("COMMONPROGRAMFILES")) != NULL) { + if (asprintf(&tmppath, "%s%s", home, hmagic) >= 0) + APPENDPATH(); + } + + /* Third, try to get magic file relative to dll location */ + LPTSTR dllpath = malloc(sizeof(*dllpath) * (MAX_PATH + 1)); + dllpath[MAX_PATH] = 0; /* just in case long path gets truncated and not null terminated */ + if (GetModuleFileNameA(NULL, dllpath, MAX_PATH)){ + PathRemoveFileSpecA(dllpath); + if (strlen(dllpath) > 3 && + stricmp(&dllpath[strlen(dllpath) - 3], "bin") == 0) { + if (asprintf(&tmppath, + "%s/../share/misc/magic.mgc", dllpath) >= 0) + APPENDPATH(); + } else { + if (asprintf(&tmppath, + "%s/share/misc/magic.mgc", dllpath) >= 0) + APPENDPATH(); + else if (asprintf(&tmppath, + "%s/magic.mgc", dllpath) >= 0) + APPENDPATH(); + } + } + + /* Don't put MAGIC constant - it likely points to a file within MSys + tree */ + default_magic = hmagicpath; + return default_magic; +#endif +} + +public const char * +magic_getpath(const char *magicfile, int action) +{ + if (magicfile != NULL) + return magicfile; + + magicfile = getenv("MAGIC"); + if (magicfile != NULL) + return magicfile; + + return action == FILE_LOAD ? get_default_magic() : MAGIC; +} + +public struct magic_set * +magic_open(int flags) +{ + return file_ms_alloc(flags); +} + +private int +unreadable_info(struct magic_set *ms, mode_t md, const char *file) +{ + /* We cannot open it, but we were able to stat it. */ + if (access(file, W_OK) == 0) + if (file_printf(ms, "writable, ") == -1) + return -1; + if (access(file, X_OK) == 0) + if (file_printf(ms, "executable, ") == -1) + return -1; + if (S_ISREG(md)) + if (file_printf(ms, "regular file, ") == -1) + return -1; + if (file_printf(ms, "no read permission") == -1) + return -1; + return 0; +} + +public void +magic_close(struct magic_set *ms) +{ + if (ms == NULL) + return; + file_ms_free(ms); +} + +/* + * load a magic file + */ +public int +magic_load(struct magic_set *ms, const char *magicfile) +{ + if (ms == NULL) + return -1; + return file_apprentice(ms, magicfile, FILE_LOAD); +} + +public int +magic_compile(struct magic_set *ms, const char *magicfile) +{ + if (ms == NULL) + return -1; + return file_apprentice(ms, magicfile, FILE_COMPILE); +} + +public int +magic_check(struct magic_set *ms, const char *magicfile) +{ + if (ms == NULL) + return -1; + return file_apprentice(ms, magicfile, FILE_CHECK); +} + +public int +magic_list(struct magic_set *ms, const char *magicfile) +{ + if (ms == NULL) + return -1; + return file_apprentice(ms, magicfile, FILE_LIST); +} + +private void +close_and_restore(const struct magic_set *ms, const char *name, int fd, + const struct stat *sb) +{ + if (fd == STDIN_FILENO) + return; + (void) close(fd); + + if ((ms->flags & MAGIC_PRESERVE_ATIME) != 0) { + /* + * Try to restore access, modification times if read it. + * This is really *bad* because it will modify the status + * time of the file... And of course this will affect + * backup programs + */ +#ifdef HAVE_UTIMES + struct timeval utsbuf[2]; + (void)memset(utsbuf, 0, sizeof(utsbuf)); + utsbuf[0].tv_sec = sb->st_atime; + utsbuf[1].tv_sec = sb->st_mtime; + + (void) utimes(name, utsbuf); /* don't care if loses */ +#elif defined(HAVE_UTIME_H) || defined(HAVE_SYS_UTIME_H) + struct utimbuf utbuf; + + (void)memset(&utbuf, 0, sizeof(utbuf)); + utbuf.actime = sb->st_atime; + utbuf.modtime = sb->st_mtime; + (void) utime(name, &utbuf); /* don't care if loses */ +#endif + } +} + +#ifndef COMPILE_ONLY + +/* + * find type of descriptor + */ +public const char * +magic_descriptor(struct magic_set *ms, int fd) +{ + if (ms == NULL) + return NULL; + return file_or_fd(ms, NULL, fd); +} + +/* + * find type of named file + */ +public const char * +magic_file(struct magic_set *ms, const char *inname) +{ + if (ms == NULL) + return NULL; + return file_or_fd(ms, inname, STDIN_FILENO); +} + +private const char * +file_or_fd(struct magic_set *ms, const char *inname, int fd) +{ + int rv = -1; + unsigned char *buf; + struct stat sb; + ssize_t nbytes = 0; /* number of bytes read from a datafile */ + int ispipe = 0; + + /* + * one extra for terminating '\0', and + * some overlapping space for matches near EOF + */ +#define SLOP (1 + sizeof(union VALUETYPE)) + if ((buf = CAST(unsigned char *, malloc(HOWMANY + SLOP))) == NULL) + return NULL; + + if (file_reset(ms) == -1) + goto done; + + switch (file_fsmagic(ms, inname, &sb)) { + case -1: /* error */ + goto done; + case 0: /* nothing found */ + break; + default: /* matched it and printed type */ + rv = 0; + goto done; + } + + if (inname == NULL) { + if (fstat(fd, &sb) == 0 && S_ISFIFO(sb.st_mode)) + ispipe = 1; + } else { + int flags = O_RDONLY|O_BINARY; + + if (stat(inname, &sb) == 0 && S_ISFIFO(sb.st_mode)) { +#ifdef O_NONBLOCK + flags |= O_NONBLOCK; +#endif + ispipe = 1; + } + + errno = 0; + if ((fd = open(inname, flags)) < 0) { + if (unreadable_info(ms, sb.st_mode, inname) == -1) + goto done; + rv = 0; + goto done; + } +#ifdef O_NONBLOCK + if ((flags = fcntl(fd, F_GETFL)) != -1) { + flags &= ~O_NONBLOCK; + (void)fcntl(fd, F_SETFL, flags); + } +#endif + } + + /* + * try looking at the first HOWMANY bytes + */ + if (ispipe) { + ssize_t r = 0; + + while ((r = sread(fd, (void *)&buf[nbytes], + (size_t)(HOWMANY - nbytes), 1)) > 0) { + nbytes += r; + if (r < PIPE_BUF) break; + } + + if (nbytes == 0) { + /* We can not read it, but we were able to stat it. */ + if (unreadable_info(ms, sb.st_mode, inname) == -1) + goto done; + rv = 0; + goto done; + } + + } else { + if ((nbytes = read(fd, (char *)buf, HOWMANY)) == -1) { + file_error(ms, errno, "cannot read `%s'", inname); + goto done; + } + } + + (void)memset(buf + nbytes, 0, SLOP); /* NUL terminate */ + if (file_buffer(ms, fd, inname, buf, (size_t)nbytes) == -1) + goto done; + rv = 0; +done: + free(buf); + close_and_restore(ms, inname, fd, &sb); + return rv == 0 ? file_getbuffer(ms) : NULL; +} + + +public const char * +magic_buffer(struct magic_set *ms, const void *buf, size_t nb) +{ + if (ms == NULL) + return NULL; + if (file_reset(ms) == -1) + return NULL; + /* + * The main work is done here! + * We have the file name and/or the data buffer to be identified. + */ + if (file_buffer(ms, -1, NULL, buf, nb) == -1) { + return NULL; + } + return file_getbuffer(ms); +} +#endif + +public const char * +magic_error(struct magic_set *ms) +{ + if (ms == NULL) + return "Magic database is not open"; + return (ms->event_flags & EVENT_HAD_ERR) ? ms->o.buf : NULL; +} + +public int +magic_errno(struct magic_set *ms) +{ + if (ms == NULL) + return EINVAL; + return (ms->event_flags & EVENT_HAD_ERR) ? ms->error : 0; +} + +public int +magic_setflags(struct magic_set *ms, int flags) +{ + if (ms == NULL) + return -1; +#if !defined(HAVE_UTIME) && !defined(HAVE_UTIMES) + if (flags & MAGIC_PRESERVE_ATIME) + return -1; +#endif + ms->flags = flags; + return 0; +} + +public int +magic_version(void) +{ + return MAGIC_VERSION; +} |