xref: /plan9-contrib/sys/src/cmd/file.c (revision 219b2ee8daee37f4aad58d63f21287faa8e4ffdc)

#include <u.h>
#include <libc.h>
#include <bio.h>
#include <ctype.h>
#include <mach.h>

/*
 * file - determine type of file
 */
#define	LENDIAN(p)	((p)[0] | ((p)[1]<<8) | ((p)[2]<<16) | ((p)[3]<<24))

uchar	buf[6000];
short	cfreq[140];
short	wfreq[50];
int	nbuf;
Dir	mbuf;
int	fd;
char 	*fname;
char	*slash;

enum
{
	Cword,
	Fword,
	Aword,
	Alword,
	I1,
	I2,
	I3,
	Clatin	= 128,
	Cbinary,
	Cnull,
	Ceascii,
	Cutf,
};
struct
{
	char*	word;
	int	class;
} dict[] =
{
	"TEXT",		Aword,
	"adt",		Alword,
	"aggr",		Alword,
	"alef",		Alword,
	"block",	Fword,
	"chan",		Alword,
	"char",		Cword,
	"common",	Fword,
	"data",		Fword,
	"dimension",	Fword,
	"double",	Cword,
	"extern",	Cword,
	"bio",		I2,
	"float",	Cword,
	"function",	Fword,
	"h",		I3,
	"include",	I1,
	"int",		Cword,
	"integer",	Fword,
	"libc",		I2,
	"long",		Cword,
	"real",		Fword,
	"register",	Cword,
	"short",	Cword,
	"static",	Cword,
	"stdio",	I2,
	"struct",	Cword,
	"subroutine",	Fword,
	"u",		I2,
	"void",		Cword,
};

	/* codes for 'mode' field in language structure */
enum	{
		Normal	= 0,
		First,		/* first entry for language spanning several ranges */
		Multi,		/* later entries "   "       "  ... */
		Shared,		/* codes used in several languages */
	};

struct
{
	int	mode;		/* see enum above */
	int 	count;
	int	low;
	int	high;
	char	*name;

} language[] =
{
	Normal, 0,	0x0080, 0x0080,	"Extended Latin",
	Normal,	0,	0x0100,	0x01FF,	"Extended Latin",
	Normal,	0,	0x0370,	0x03FF,	"Greek",
	Normal,	0,	0x0400,	0x04FF,	"Cyrillic",
	Normal,	0,	0x0530,	0x058F,	"Armenian",
	Normal,	0,	0x0590,	0x05FF,	"Hebrew",
	Normal,	0,	0x0600,	0x06FF,	"Arabic",
	Normal,	0,	0x0900,	0x097F,	"Devanagari",
	Normal,	0,	0x0980,	0x09FF,	"Bengali",
	Normal,	0,	0x0A00,	0x0A7F,	"Gurmukhi",
	Normal,	0,	0x0A80,	0x0AFF,	"Gujarati",
	Normal,	0,	0x0B00,	0x0B7F,	"Oriya",
	Normal,	0,	0x0B80,	0x0BFF,	"Tamil",
	Normal,	0,	0x0C00,	0x0C7F,	"Telugu",
	Normal,	0,	0x0C80,	0x0CFF,	"Kannada",
	Normal,	0,	0x0D00,	0x0D7F,	"Malayalam",
	Normal,	0,	0x0E00,	0x0E7F,	"Thai",
	Normal,	0,	0x0E80,	0x0EFF,	"Lao",
	Normal,	0,	0x1000,	0x105F,	"Tibetan",
	Normal,	0,	0x10A0,	0x10FF,	"Georgian",
	Normal,	0,	0x3040,	0x30FF,	"Japanese",
	Normal,	0,	0x3100,	0x312F,	"Chinese",
	First,	0,	0x3130,	0x318F,	"Korean",
	Multi,	0,	0x3400,	0x3D2F,	"Korean",
	Shared,	0,	0x4e00,	0x9fff,	"CJK",
	Normal,	0,	0,	0,	0,		/* terminal entry */
};


enum
{
	Fascii,		/* printable ascii */
	Flatin,		/* latin 1*/
	Futf,		/* UTf character set */
	Fbinary,	/* binary */
	Feascii,	/* ASCII with control chars */
	Fnull,		/* NULL in file */
} guess;

void	bump_utf_count(Rune);
void	filetype(int);
int	getfontnum(uchar *, uchar **);
int	isas(void);
int	isc(void);
int	iscint(void);
int	isenglish(void);
int	ismung(void);
int	isp9bit(void);
int	isp9font(void);
int	istring(void);
int	long0(void);
int	p9bitnum(uchar *);
int	p9subfont(uchar *);
void	print_utf(void);
int	short0(void);
void	type(char*, int);
int	utf_count(void);
void	wordfreq(void);

int	(*call[])(void) =
{
	long0,		/* recognizable by first 4 bytes */
	short0,		/* recognizable by first 2 bytes */
	istring,	/* recognizable by first string */
	iscint,		/* compiler/assembler intermediate */
	isc,		/* c & alef compiler key words */
	isas,		/* assembler key words */
	ismung,		/* entropy compressed/encrypted */
	isenglish,	/* char frequency English */
	isp9font,	/* plan 9 font */
	isp9bit,	/* plan 9 bitmap (as from /dev/window) */
	0
};

void
main(int argc, char *argv[])
{
	int i, j, maxlen;
	char *cp;
	Rune r;

	maxlen = 0;
	for(i = 1; i < argc; i++) {
		for (j = 0, cp = argv[i]; *cp; j++, cp += chartorune(&r, cp))
				;
		if(j > maxlen)
			maxlen = j;
	}
	if (argc <= 1) {
		print ("stdin: ");
		filetype(0);
	}
	else {
		for(i = 1; i < argc; i++)
			type(argv[i], maxlen);
	}
	exits(0);
}

void
type(char *file, int nlen)
{
	Rune r;
	int i;
	char *p;

	slash = 0;
	for (i = 0, p = file; *p; i++) {
		if (*p == '/')			/* find rightmost slash */
			slash = p;
		p += chartorune(&r, p);		/* count runes */
	}
	print("%s:%*s",file, nlen-i+1, "");
	fname = file;
	if ((fd = open(file, OREAD)) < 0) {
		print("cannot open\n");
		return;
	}
	filetype(fd);
	close(fd);
}

void
filetype(int fd)
{
	Rune r;
	int i, f, n;
	char *p, *eob;

	if(dirfstat(fd, &mbuf) < 0) {
		print("cannot stat\n");
		return;
	}
	if(mbuf.mode & CHDIR) {
		print("directory\n");
		return;
	}
	if(mbuf.type != 'M' && mbuf.type != '|') {
		print("special file #%c\n", mbuf.type);
		return;
	}
	nbuf = read(fd, buf, sizeof(buf));

	if(nbuf < 0) {
		print("cannot read\n");
		return;
	}
	if(nbuf == 0) {
		print("empty\n");
		return;
	}

	/*
	 * build histogram table
	 */
	memset(cfreq, 0, sizeof(cfreq));
	for (i = 0; language[i].name; i++)
		language[i].count = 0;
	eob = (char *)buf+nbuf;
	for(n = 0, p = (char *)buf; p < eob; n++) {
		if (!fullrune(p, eob-p) && eob-p < UTFmax)
			break;
		p += chartorune(&r, p);
		if (r == 0)
			f = Cnull;
		else if (r <= 0x7f) {
			if (!isprint(r) && !isspace(r))
				f = Ceascii;	/* ASCII control char */
			else f = r;
		} else if (r == 0x080) {
			bump_utf_count(r);
			f = Cutf;
		} else if (r < 0xA0)
				f = Cbinary;	/* Invalid Runes */
		else if (r <= 0xff)
				f = Clatin;	/* Latin 1 */
		else {
			bump_utf_count(r);
			f = Cutf;		/* UTF extension */
		}
		cfreq[f]++;			/* ASCII chars peg directly */
	}
	/*
	 * gross classify
	 */
	if (cfreq[Cbinary])
		guess = Fbinary;
	else if (cfreq[Cutf])
		guess = Futf;
	else if (cfreq[Clatin])
		guess = Flatin;
	else if (cfreq[Ceascii])
		guess = Feascii;
	else if (cfreq[Cnull] == n) {
		print("all null bytes\n");
		return;
	}
	else guess = Fascii;
	/*
	 * lookup dictionary words
	 */
	memset(wfreq, 0, sizeof(wfreq));
	if(guess == Fascii || guess == Flatin)
		wordfreq();
	/*
	 * call individual classify routines
	 */
	for(i=0; call[i]; i++)
		if((*call[i])())
			return;

	/*
	 * if all else fails,
	 * print out gross classification
	 */
	if (nbuf < 100)
		print("short ");
	if (guess == Fascii)
		print("Ascii\n");
	else if (guess == Feascii)
		print("extended ascii\n");
	else if (guess == Flatin)
		print("latin ascii\n");
	else if (guess == Futf && utf_count() < 4)
		print_utf();
	else print("binary\n");
}

void
bump_utf_count(Rune r)
{
	int low, high, mid;

	high = sizeof(language)/sizeof(language[0])-1;
	for (low = 0; low < high;) {
		mid = (low+high)/2;
		if (r >=language[mid].low) {
			if (r <= language[mid].high) {
				language[mid].count++;
				break;
			} else low = mid+1;
		} else high = mid;
	}
}

int
utf_count(void)
{
	int i, count;

	count = 0;
	for (i = 0; language[i].name; i++)
		if (language[i].count > 0)
			switch (language[i].mode) {
			case Normal:
			case First:
				count++;
				break;
			default:
				break;
			}
	return count;
}

int
chkascii(void)
{
	int i;

	for (i = 'a'; i < 'z'; i++)
		if (cfreq[i])
			return 1;
	for (i = 'A'; i < 'Z'; i++)
		if (cfreq[i])
			return 1;
	return 0;
}

int
find_first(char *name)
{
	int i;

	for (i = 0; language[i].name != 0; i++)
		if (language[i].mode == First
			&& strcmp(language[i].name, name) == 0)
			return i;
	return -1;
}

void
print_utf(void)
{
	int i, printed, j;

	if (chkascii()) {
		printed = 1;
		print("Ascii");
	} else
		printed = 0;
	for (i = 0; language[i].name; i++)
		if (language[i].count) {
			switch(language[i].mode) {
			case Multi:
				j = find_first(language[i].name);
				if (j < 0)
					break;
				if (language[j].count > 0)
					break;
				/* Fall through */
			case Normal:
			case First:
				if (printed)
					print(" & ");
				else printed = 1;
				print("%s", language[i].name);
				break;
			case Shared:
			default:
				break;
			}
		}
	if(!printed)
		print("UTF");
	print(" text\n");
}

void
wordfreq(void)
{
	int low, high, mid, r;
	uchar *p, *p2, c;

	p = buf;
	for(;;) {
		while (p < buf+nbuf && !isalpha(*p))
			p++;
		if (p >= buf+nbuf)
			return;
		p2 = p;
		while(p < buf+nbuf && isalpha(*p))
			p++;
		c = *p;
		*p = 0;
		high = sizeof(dict)/sizeof(dict[0]);
		for(low = 0;low < high;) {
			mid = (low+high)/2;
			r = strcmp(dict[mid].word, (char*)p2);
			if(r == 0) {
				wfreq[dict[mid].class]++;
				break;
			}
			if(r < 0)
				low = mid+1;
			else
				high = mid;
		}
		*p++ = c;
	}
}

int
long0(void)
{
	Fhdr f;

	seek(fd, 0, 0);		/* reposition to start of file */
	if (crackhdr(fd, &f)) {
		print("%s\n", f.name);
		return 1;
	}
	switch(LENDIAN(buf)) {
	case 0xf16df16d:
		print("pac1 audio file\n");
		return 1;
	case 0x31636170:
		print("pac3 audio file\n");
		return 1;
	case 0x32636170:
		print("pac4 audio file\n");
		return 1;
	default:
		return 0;
	}
	return 1;
}

int
short0(void)
{

	switch(LENDIAN(buf) & 0xffff) {
	case 070707:
		print("cpio archive\n");
		break;

	case 0x02f7:
		print("tex dvi\n");
		break;
	default:
		return 0;
	}
	return 1;
}

/*
 * initial words to classify file
 */
struct	FILE_STRING
{
	char 	*key;
	char	*filetype;
	int	length;
}	file_string[] =
{
	"!<arch>\n__.SYMDEF",	"archive random library",	16,
	"!<arch>\n",		"archive",			8,
	"070707",		"cpio archive - ascii header",	6,
	"#!/bin/rc",		"rc executable file",		9,
	"#!/bin/sh",		"sh executable file",		9,
	"%!",			"postscript",			2,
	"x T post",		"troff output for post",	8,
	"x T Latin1",		"troff output for Latin1",	10,
	"x T utf",		"troff output for UTF",		7,
	"x T 202",		"troff output for 202",		7,
	"x T aps",		"troff output for aps",		7,
	"GIF",			"GIF image", 			3,
	"\0PC Research, Inc", "ghostscript fax file",	23,
	0,0,0
};

int
istring(void)
{
	int i;
	struct FILE_STRING *p;

	for(p = file_string; p->key; p++) {
		if(nbuf >= p->length && !memcmp(buf, p->key, p->length)) {
			print("%s\n", p->filetype);
			return 1;
		}
	}
	if(strncmp((char*)buf, "TYPE=", 5) == 0) {	/* td */
		for(i = 5; i < nbuf; i++)
			if(buf[i] == '\n')
				break;
		print("%.*s picture\n", i-5, buf+5);
		return 1;
	}
	return 0;
}

int
iscint(void)
{
	int type;
	char *name;
	Biobuf b;

	if(Binit(&b, fd, OREAD) == Beof)
		return 0;
	seek(fd, 0, 0);
	type = objtype(&b, &name);
	if(type < 0)
		return 0;
	print("%s intermediate\n", name);
	return 1;
}

int
isc(void)
{
	int n;

	n = wfreq[I1];
	/*
	 * includes
	 */
	if(n >= 2 && wfreq[I2] >= n && wfreq[I3] >= n && cfreq['.'] >= n)
		goto yes;
	if(n >= 1 && wfreq[Alword] >= n && wfreq[I3] >= n && cfreq['.'] >= n)
		goto yes;
	/*
	 * declarations
	 */
	if(wfreq[Cword] >= 5 && cfreq[';'] >= 5)
		goto yes;
	/*
	 * assignments
	 */
	if(cfreq[';'] >= 10 && cfreq['='] >= 10 && wfreq[Cword] >= 1)
		goto yes;
	return 0;

yes:
	if(wfreq[Alword] > 0)
		print("alef program\n");
	else
		print("c program\n");
	return 1;
}

int
isas(void)
{

	/*
	 * includes
	 */
	if(wfreq[Aword] < 2)
		return 0;
	print("as program\n");
	return 1;
}

/*
 * low entropy means encrypted
 */
int
ismung(void)
{
	int i, bucket[8];
	float cs;

	if(nbuf < 64)
		return 0;
	memset(bucket, 0, sizeof(bucket));
	for(i=0; i<64; i++)
		bucket[(buf[i]>>5)&07] += 1;

	cs = 0.;
	for(i=0; i<8; i++)
		cs += (bucket[i]-8)*(bucket[i]-8);
	cs /= 8.;
	if(cs <= 24.322) {
		if(buf[0]==037 && buf[1]==0235)
			print("compressed\n");
		else
			print("encrypted\n");
		return 1;
	}
	return 0;
}

/*
 * english by punctuation and frequencies
 */
int
isenglish(void)
{
	int vow, comm, rare, badpun, punct;
	char *p;

	if(guess != Fascii && guess != Feascii)
		return 0;
	badpun = 0;
	punct = 0;
	for(p = (char *)buf; p < (char *)buf+nbuf-1; p++)
		switch(*p) {
		case '.':
		case ',':
		case ')':
		case '%':
		case ';':
		case ':':
		case '?':
			punct++;
			if(p[1] != ' ' && p[1] != '\n')
				badpun++;
		}
	if(badpun*5 > punct)
		return 0;
	if(cfreq['>']+cfreq['<']+cfreq['/'] > cfreq['e'])	/* shell file test */
		return 0;
	if(2*cfreq[';'] > cfreq['e'])
		return 0;

	vow = 0;
	for(p="AEIOU"; *p; p++) {
		vow += cfreq[*p];
		vow += cfreq[tolower(*p)];
	}
	comm = 0;
	for(p="ETAION"; *p; p++) {
		comm += cfreq[*p];
		comm += cfreq[tolower(*p)];
	}
	rare = 0;
	for(p="VJKQXZ"; *p; p++) {
		rare += cfreq[*p];
		rare += cfreq[tolower(*p)];
	}
	if(vow*5 >= nbuf-cfreq[' '] && comm >= 10*rare) {
		print("English text\n");
		return 1;
	}
	return 0;
}

/*
 * pick up a number with
 * syntax _*[0-9]+_
 */
#define	P9BITLEN	12
int
p9bitnum(uchar *bp)
{
	int n, c, len;

	len = P9BITLEN;
	while(*bp == ' ') {
		bp++;
		len--;
		if(len <= 0)
			return -1;
	}
	n = 0;
	while(len > 1) {
		c = *bp++;
		if(!isdigit(c))
			return -1;
		n = n*10 + c-'0';
		len--;
	}
	if(*bp != ' ')
		return -1;
	return n;
}

int
isp9bit(void)
{
	int ldep, lox, loy, hix, hiy, px;
	ulong t;
	long len;

	ldep = p9bitnum(buf + 0*P9BITLEN);
	lox = p9bitnum(buf + 1*P9BITLEN);
	loy = p9bitnum(buf + 2*P9BITLEN);
	hix = p9bitnum(buf + 3*P9BITLEN);
	hiy = p9bitnum(buf + 4*P9BITLEN);

	if(ldep < 0 || lox < 0 || loy < 0 || hix < 0 || hiy < 0)
		return 0;

	px = 1<<(3-ldep);	/* pixels per byte */
	/* set l to number of bytes of data per scan line */
	if(lox >= 0)
		len = (hix+px-1)/px - lox/px;
	else{	/* make positive before divide */
		t = (-lox)+px-1;
		t = (t/px)*px;
		len = (t+hix+px-1)/px;
	}
	len *= (hiy-loy);		/* col length */
	len += 5*P9BITLEN;		/* size of initial ascii */

	/*
	 * for bitmap file, length is non-zero and must match calculation above
	 * for /dev/window and /dev/screen the length is always zero
	 * for subfont, the subfont header should follow immediately.
	 */
	if (mbuf.length == 0)
		return 0;
	if (mbuf.length == len) {
		print("plan 9 bitmap\n");
		return 1;
	}
	if (p9subfont(buf+len)) {
		print("subfont file\n");
		return 1;
	}
	return 0;
}

int
p9subfont(uchar *p)
{
	int n, h, a;

		/* if bitmap too big, assume it's a subfont */
	if (p+3*P9BITLEN > buf+sizeof(buf))
		return 1;

	n = p9bitnum(p + 0*P9BITLEN);	/* char count */
	if (n < 0)
		return 0;
	h = p9bitnum(p + 1*P9BITLEN);	/* height */
	if (h < 0)
		return 0;
	a = p9bitnum(p + 2*P9BITLEN);	/* ascent */
	if (a < 0)
		return 0;
	return 1;
}

#define	WHITESPACE(c)		((c) == ' ' || (c) == '\t' || (c) == '\n')

int
isp9font(void)
{
	uchar *cp, *p;
	int i, n;
	char dbuf[DIRLEN];
	char pathname[1024];

	cp = buf;
	if (!getfontnum(cp, &cp))	/* height */
		return 0;
	if (!getfontnum(cp, &cp))	/* ascent */
		return 0;
	for (i = 0; 1; i++) {
		if (!getfontnum(cp, &cp))	/* min */
			break;
		if (!getfontnum(cp, &cp))	/* max */
			return 0;
		while (WHITESPACE(*cp))
			cp++;
		for (p = cp; *cp && !WHITESPACE(*cp); cp++)
				;
			/* construct a path name, if needed */
		n = 0;
		if (*p != '/' && slash) {
			n = slash-fname+1;
			if (n < sizeof(pathname))
				memcpy(pathname, fname, n);
			else n = 0;
		}
		if (n+cp-p < sizeof(pathname)) {
			memcpy(pathname+n, p, cp-p);
			n += cp-p;
			pathname[n] = 0;
			if (stat(pathname, dbuf) < 0)
				return 0;
		}
	}
	if (i) {
		print("font file\n");
		return 1;
	}
	return 0;
}

int
getfontnum(uchar *cp, uchar **rp)
{
	while (WHITESPACE(*cp))		/* extract ulong delimited by whitespace */
		cp++;
	if (*cp < '0' || *cp > '9')
		return 0;
	strtoul((char *)cp, (char **)rp, 0);
	if (!WHITESPACE(**rp))
		return 0;
	return 1;
}