cmd/std/file.c

/***********************************************************************
*                                                                      *
*               This software is part of the ast package               *
*          Copyright (c) 1989-2012 AT&T Intellectual Property          *
*                      and is licensed under the                       *
*                 Eclipse Public License, Version 1.0                  *
*                    by AT&T Intellectual Property                     *
*                                                                      *
*                A copy of the License is available at                 *
*          http://www.eclipse.org/org/documents/epl-v10.html           *
*         (with md5 checksum b35adb5213ca9657e911e9befb180842)         *
*                                                                      *
*              Information and Software Systems Research               *
*                            AT&T Research                             *
*                           Florham Park NJ                            *
*                                                                      *
*                 Glenn Fowler <gsf@research.att.com>                  *
*                                                                      *
***********************************************************************/
#pragma prototyped
/*
 * Glenn Fowler
 * AT&T Research
 *
 * file -- determine file type
 *
 * the sum of the hacks {s5,v10,planix} is _____ than the parts
 */

static const char usage[] =
"[-?\n@(#)$Id: file (AT&T Research) 2011-08-01 $\n]"
USAGE_LICENSE
"[+NAME?file - determine file type]"
"[+DESCRIPTION?\bfile\b tests and attempts to classify each \afile\a argument."
"   Non-regular files are classified by their \bstat\b(2) types. Empty and"
"   non-readable regular files are classified as such. Otherwise a data"
"   block is read from \afile\a and this is used to match against the"
"   \amagic\a file(s) (see \bMAGIC FILE\b below). Files with less than 1024"
"   bytes of data are labelled \bsmall\b to note that the sample may"
"   be too small for an accurate classification. Failing a content match,"
"   the file name extension may be used to classify. As a last resort"
"   statistical sampling is done for a small range of languages and"
"   applications. Failed matches usually result in the less informative"
"   \bascii text\b or \bbinary data\b.]"

"[a:all?List all magic table matches.]"
"[b:brief|no-filename?Suppress the output line file name prefix.]"
"[c:mime?List the \bmime\b(1) classification for each \afile\a. Although the"
"   default descriptions are fairly consistent, use \b--mime\b for"
"   precise classification matching.]"
"[d:default-magic?Equivalent to \b--magic=-\b.]"
"[f:files|file-list?\afile\a contains list of file names, one per line, that"
"   are classified.]:[file]"
"[i:ignore-magic?Equivalent to \b--magic=/dev/null\b.]"
"[l:list?The loaded \amagic\a files are listed and then \bfile\b exits.]"
"[M:magic?\afile\a is loaded as a \amagic\a file. More than one \b--magic\b"
"   option may be specified; the precedence is from left to right. The"
"   first \b--magic\b option causes the default system \amagic\a file to"
"   be ignored; the file \b-\b may then be specified to explicitly"
"   load the default system \amagic\a file. To ignore all magic files"
"   specify the file \b/dev/null\b and no others.]:[file]"
"[m:append-magic?\afile\a is loaded as a \amagic\a file. Equivalent to the"
"   \b--magic\b option, except that the default system \amagic\a file is"
"   still loaded last. If \b--magic\b is also specified then the default"
"   system \amagic\a is only loaded if explicity specified.]:[file]"
"[p:pattern|match?Only files with descriptions matching the \bsh\b(1)"
"   match \apattern\a are listed. \bfile\b exits with status 0 if any"
"   files match, 0 otherwise.]:[pattern]"
"[q:quiet|silent?Do not list matching \b--pattern\b files.]"
"[L:logical|dereference?Follow symbolic links.]"
"[P|h:physical?Don't follow symbolic links.]"
"[w:warn?Enable magic file parse warning messages.]"

"\n"
"\n[ file ... ]\n"
"\n"

"[+MAGIC FILE?A \amagic\a file specifies file content and name match"
"   expressions, descriptions, and \bmime\b(1) classifications. Each line"
"   in the file consists of five \btab\b separated fields:]{"
"   [+[op]]offset?\aoffset\a determines tha data location for the content"
"       test. \b(@\b\aexpression\a\b)\b specifies an indirect offset,"
"       i.e., the offset is the numeric contents of the data"
"       location at \aexpression\a. The default indirect numeric size"
"       is 4 bytes; a \bB\b suffix denotes 1 byte, \bH\b denotes 2"
"       bytes, and \bQ\b denotes 8 bytes. \aoffset\a may also be one"
"       of { \batime\b \bblocks\b \bctime\b \bfstype\b \bgid\b"
"       \bmode\b \bmtime\b \bname\b \bnlink\b \bsize\b \buid\b } to"
"       access \bstat\b(2) information for the current file. The"
"       optional \aop\a specifies relationships with surrounding"
"       \amagic\a lines:]{"
"       [++?previous fields in block match, current optional]"
"       [+&?previous and current fields in block match]"
"       [+|?previous fields in block do not match, subsequent skipped]"
"       [+{?start nesting block]"
"       [+}?end nesting block]"
"       [+c{?function declaration and call (1 char names)]"
"       [+}?function return]"
"       [+c()?function call]"
"   }"
"   [+type?The content data type:]{"
"       [+byte?1 byte integer]"
"       [+short?2 byte integer]"
"       [+long?4 byte integer]"
"       [+quad?8 byte integer]"
"       [+date?4 byte time_t]"
"       [+version?4 byte unsigned integer of the form \aYYYYMMDD\a"
"           for \aYYYY-MM-DD\a, 0x\aYYZZ\a for \aYY.ZZ\a, or"
"           0x\aWWXXYYZZ\a for \aWW.XX.YY.ZZ\a]"
"       [+edit?substitute operator for string data:"
"           %\aold\a%\anew\a%[glu]], where \b%\b is any delimiter]"
"       [+match?case insensitive \bsh\b(1) match pattern operator"
"           for string data]"
"   }"
"   [+[mask]]operator?\amask\a is an optional \b&\b\anumber\a that is"
"       masked (bit \band\b) with the content data before"
"       comparison. \aoperator\a is one of { \b< <= > >= != ==\b }."
"       Numeric values may be decimal, octal or hex.]"
"   [+description?The description text. Care was taken to maintain"
"       consistency between all descriptions, i.e., character case,"
"       grammatical parts placement, and punctuation, making"
"       description pattern matches feasible. \adescription\a may"
"       contain one \bprintf\b(3) format specification for the"
"       current data value at \aoffset\a.]"
"   [+mime?The \bmime\b(1) type/subtype. This provides a standard"
"       and consistent matching key space.]"
"}"

"[+FILES]{"
"   [+lib/file/magic?Default magic file on \b$PATH\b.]"
"}"

"[+SEE ALSO?\bfind\b(1), \bls\b(1), \bmime\b(1), \btw\b(1)]"
;

#include <ast.h>
#include <magic.h>
#include <ctype.h>
#include <error.h>

#define MAGIC_BRIEF (MAGIC_USER<<0)
#define MAGIC_LIST  (MAGIC_USER<<1)
#define MAGIC_LOAD  (MAGIC_USER<<2)
#define MAGIC_PHYSICAL  (MAGIC_USER<<3)
#define MAGIC_SILENT    (MAGIC_USER<<4)

static int
type(Magic_t* mp, char* file, const char* pattern, register Magicdisc_t* disc)
{
    char*       s;
    char*       e;
    Sfio_t*     fp;
    struct stat*    sp;
    struct stat st;

    sp = ((disc->flags & MAGIC_PHYSICAL) ? lstat(file, &st) : stat(file, &st)) ? (struct stat*)0 : &st;
    fp = (sp && S_ISREG(sp->st_mode)) ? sfopen(NiL, file, "r") : (Sfio_t*)0;
    s = magictype(mp, fp, file, sp);
    if (fp)
        sfclose(fp);
    e = pathcanon(file, 0, 0);
    if (!pattern)
    {
        if (!(disc->flags & MAGIC_BRIEF))
            sfprintf(sfstdout, "%s:\t%s", file, e - file > 6 ? "" : "\t");
        sfprintf(sfstdout, "%s\n", s);
        return 1;
    }
    else if (strmatch(s, pattern))
    {
        if (!(disc->flags & MAGIC_SILENT))
            sfprintf(sfstdout, "%s\n", file);
        return 1;
    }
    return 0;
}

int
main(int argc, register char** argv)
{
    register Magic_t*   mp;
    register char*      p;
    char*           pattern = 0;
    Sfio_t*         list = 0;
    int         hit;
    Magicdisc_t     disc;

    NoP(argc);
    error_info.id = "file";
    disc.version = MAGIC_VERSION;
    disc.flags = 0;
    disc.errorf = errorf;
    if (!(mp = magicopen(&disc)))
        error(3, "out of space");
    for (;;)
    {
        switch (optget(argv, usage))
        {
        case 'a':
            disc.flags |= MAGIC_ALL;
            continue;
        case 'b':
            disc.flags |= MAGIC_BRIEF;
            continue;
        case 'c':
            disc.flags |= MAGIC_MIME;
            continue;
        case 'd':
            if (magicload(mp, NiL, 0))
                error(3, "cannot load default magic file");
            disc.flags |= MAGIC_LOAD;
            continue;
        case 'f':
            if (streq(opt_info.arg, "-") || streq(opt_info.arg, "/dev/stdin") || streq(opt_info.arg, "/dev/fd/0"))
                list = sfstdin;
            else if (!(list = sfopen(NiL, opt_info.arg, "r")))
                error(3, "cannot open %s", opt_info.arg);
            continue;
        case 'i':
            disc.flags |= MAGIC_LOAD;
            continue;
        case 'l':
            disc.flags |= MAGIC_LIST|MAGIC_VERBOSE;
            continue;
        case 'L':
            disc.flags &= ~MAGIC_PHYSICAL;
            continue;
        case 'm':
            if (magicload(mp, opt_info.arg, 0))
                error(3, "%s: cannot load magic file", opt_info.arg);
            continue;
        case 'M':
            if (magicload(mp, opt_info.arg, 0))
                error(3, "%s: cannot load magic file", opt_info.arg);
            disc.flags |= MAGIC_LOAD;
            continue;
        case 'p':
            pattern = opt_info.arg;
            continue;
        case 'P':
        case 'h':
            disc.flags |= MAGIC_PHYSICAL;
            continue;
        case 'q':
            disc.flags |= MAGIC_SILENT;
            continue;
        case 'w':
            disc.flags |= MAGIC_VERBOSE;
            continue;
        case '?':
            error(ERROR_USAGE|4, "%s", opt_info.arg);
            continue;
        case ':':
            error(2, "%s", opt_info.arg);
            continue;
        }
        break;
    }
    if (error_info.errors)
        error(ERROR_USAGE|4, "%s", optusage(NiL));
    argv += opt_info.index;
    if (!(disc.flags & MAGIC_LOAD) && magicload(mp, NiL, 0))
        error(3, "$%s,%s: cannot load default magic file", MAGIC_FILE_ENV, MAGIC_FILE);
    if (disc.flags & MAGIC_LIST)
    {
        magiclist(mp, sfstdout);
        hit = 1;
    }
    else
    {
        hit = 0;
        if (!list && !*argv)
            list = sfstdin;
        if (list)
            while (p = sfgetr(list, '\n', 1))
                if (*p)
                    hit |= type(mp, p, pattern, &disc);
        while (p = *argv++)
            if (*p)
                hit |= type(mp, p, pattern, &disc);
    }
    return !hit;
}