/***********************************************************************
*                                                                      *
*               This software is part of the ast package               *
*          Copyright (c) 1992-2012 AT&T Intellectual Property          *
*          Copyright (c) 2020-2024 Contributors to ksh 93u+m           *
*                      and is licensed under the                       *
*                 Eclipse Public License, Version 2.0                  *
*                                                                      *
*                A copy of the License is available at                 *
*      https://www.eclipse.org/org/documents/epl-2.0/EPL-2.0.html      *
*         (with md5 checksum 84283fa8859daf213bdda5a9f8d1be1d)         *
*                                                                      *
*                 Glenn Fowler <gsf@research.att.com>                  *
*                  David Korn <dgk@research.att.com>                   *
*                  Martijn Dekker <martijn@inlv.org>                   *
*            Johnothan King <johnothanking@protonmail.com>             *
*                                                                      *
***********************************************************************/
/*
 * David Korn
 * Glenn Fowler
 * AT&T Bell Laboratories
 *
 * cmp
 */

static const char usage[] =
"[-?\n@(#)$Id: cmp (AT&T Research) 2010-04-11 $\n]"
"[--catalog?" ERROR_CATALOG "]"
"[+NAME?cmp - compare two files]"
"[+DESCRIPTION?\bcmp\b compares two files \afile1\a and \afile2\a. "
    "\bcmp\b writes no output if the files are the same. By default, if the "
    "files differ, the byte and line number at which the first difference "
    "occurred are written to standard output. Bytes and lines are numbered "
    "beginning with 1.]"
"[+?If \askip1\a or \askip2\a are specified, or the \b-i\b option is "
    "specified, initial bytes of the corresponding file are skipped before "
    "beginning the compare. The skip values are in bytes or can have a "
    "suffix of \bk\b for kilobytes or \bm\b for megabytes.]"
"[+?If either \afile1\a or \afiles2\a is \b-\b, \bcmp\b uses standard "
    "input starting at the current location.]"
"[b:print-bytes?Print differing bytes as 3 digit octal values.]"
"[c:print-chars?Print differing bytes as follows: non-space printable "
    "characters as themselves; space and control characters as \b^\b "
    "followed by a letter of the alphabet; and characters with the high bit "
    "set as the lower 7 bit character prefixed by \bM^\b for 7 bit space and "
    "non-printable characters and \bM-\b for all other characters. If the 7 "
    "bit character encoding is not ASCII then the characters are converted "
    "to ASCII to determine \ahigh bit set\a, and if set it is cleared and "
    "converted back to the native encoding. Multibyte characters in the "
    "current locale are treated as printable characters.]"
"[d:differences?Print at most \adifferences\a differences using "
    "\b--verbose\b output format. \b--differences=0\b is equivalent to "
    "\b--silent\b.]#[differences]"
"[i:ignore-initial|skip?Skip the first \askip1\a bytes in \afile1\a "
    "and the first \askip2\a bytes in \afile2\a. If \askip2\a is omitted "
    "then \askip1\a is used.]:[skip1[::skip2]]:=0::0]"
"[l:verbose?Write the decimal byte number and the differing bytes (in "
    "octal) for each difference.]"
"[n:count|bytes?Compare at most \acount\a bytes.]#[count]"
"[s:quiet|silent?Write nothing for differing files; return non-zero exit "
    "status only.]"
"\n"
"\nfile1 file2 [skip1 [skip2]]\n"
"\n"
"[+EXIT STATUS?]"
    "{"
        "[+0?The files or portions compared are identical.]"
        "[+1?The files are different.]"
        "[+>1?An error occurred.]"
    "}"
"[+SEE ALSO?\bcomm\b(1), \bdiff\b(1), \bcat\b(1)]"
;

#include <cmd.h>
#include <ls.h>
#include <ctype.h>
#include <ccode.h>

#define CMP_VERBOSE	0x01
#define CMP_SILENT	0x02
#define CMP_CHARS	0x04
#define CMP_BYTES	0x08

static void
pretty(Sfio_t *out, int o, int delim, int flags)
{
	int	c;
	int	m;
	char*	s;
	char	buf[10];

	s = buf;
	if ((flags & CMP_BYTES) || !(flags & CMP_CHARS))
	{
		*s++ = ' ';
		if ((flags & CMP_CHARS) && delim != -1)
			*s++ = ' ';
		*s++ = '0' + ((o >> 6) & 07);
		*s++ = '0' + ((o >> 3) & 07);
		*s++ = '0' + (o & 07);
	}
	if (flags & CMP_CHARS)
	{
		*s++ = ' ';
		c = ccmapc(o, CC_NATIVE, CC_ASCII);
		if (c & 0x80)
		{
			m = 1;
			*s++ = 'M';
			c &= 0x7f;
			o = ccmapc(c, CC_ASCII, CC_NATIVE);
		}
		else
			m = 0;
		if (isspace(o) || !isprint(o))
		{
			if (!m)
				*s++ = ' ';
			*s++ = '^';
			c ^= 0x40;
			o = ccmapc(c, CC_ASCII, CC_NATIVE);
		}
		else if (m)
			*s++ = '-';
		else
		{
			*s++ = ' ';
			*s++ = ' ';
		}
		*s++ = o;
	}
	*s = 0;
	sfputr(out, buf, delim);
}

/*
 * compare two files
 */

static int
cmp(const char* file1, Sfio_t* f1, const char* file2, Sfio_t* f2, int flags, Sfoff_t count, Sfoff_t differences)
{
	int		c1;
	int		c2;
	unsigned char*	p1 = 0;
	unsigned char*	p2 = 0;
	Sfoff_t	lines = 1;
	unsigned char*	e1 = 0;
	unsigned char*	e2 = 0;
	Sfoff_t		pos = 0;
	int		n1 = 0;
	int		ret = 0;
	unsigned char*	last;

	for (;;)
	{
		if ((c1 = e1 - p1) <= 0)
		{
			if (count > 0 && !(count -= n1))
				return ret;
			if (!(p1 = (unsigned char*)sfreserve(f1, SFIO_UNBOUND, 0)) || (c1 = sfvalue(f1)) <= 0)
			{
				if (sferror(f1))
				{
					error(ERROR_exit(2), "read error on %s", file1);
					UNREACHABLE();
				}
				if ((e2 - p2) > 0 || sfreserve(f2, SFIO_UNBOUND, 0) && sfvalue(f2) > 0)
				{
					ret = 1;
					if (!(flags & CMP_SILENT))
					{
						error(ERROR_exit(1), "EOF on %s", file1);
						UNREACHABLE();
					}
				}
				if (sferror(f2))
				{
					error(ERROR_exit(2), "read error on %s", file2);
					UNREACHABLE();
				}
				return ret;
			}
			if (count > 0 && c1 > count)
				c1 = (int)count;
			e1 = p1 + c1;
			n1 = c1;
		}
		if ((c2 = e2 - p2) <= 0)
		{
			if (!(p2 = (unsigned char*)sfreserve(f2, SFIO_UNBOUND, 0)) || (c2 = sfvalue(f2)) <= 0)
			{
				if (sferror(f2))
				{
					error(ERROR_exit(2), "read error on %s", file2);
					UNREACHABLE();
				}
				if (!(flags & CMP_SILENT))
				{
					error(ERROR_exit(1), "EOF on %s", file2);
					UNREACHABLE();
				}
				return 1;
			}
			e2 = p2 + c2;
		}
		if (c1 > c2)
			c1 = c2;
		pos += c1;
		if (flags & CMP_SILENT)
		{
			if (memcmp(p1, p2, c1))
				return 1;
			p1 += c1;
			p2 += c1;
		}
		else
		{
			last = p1 + c1;
			while (p1 < last)
			{
				if ((c1 = *p1++) != *p2++)
				{
					if (differences >= 0)
					{
						if (!differences)
							return 1;
						differences--;
					}
					if (flags & CMP_VERBOSE)
						sfprintf(sfstdout, "%6I*d", sizeof(pos), pos - (last - p1));
					else
						sfprintf(sfstdout, "%s %s differ: char %I*d, line %I*u", file1, file2, sizeof(pos), pos - (last - p1), sizeof(lines), lines);
					if (flags & (CMP_BYTES|CMP_CHARS|CMP_VERBOSE))
					{
						sfputc(sfstdout, (flags & CMP_VERBOSE) ? ' ' : ',');
						pretty(sfstdout, c1, -1, flags);
						pretty(sfstdout, *(p2-1), '\n', flags);
					}
					else
						sfputc(sfstdout, '\n');
					if (!differences || differences < 0 && !(flags & CMP_VERBOSE))
						return 1;
					ret = 1;
				}
				if (c1 == '\n')
					lines++;
			}
		}
	}
}

int
b_cmp(int argc, char** argv, Shbltin_t* context)
{
	char*		s;
	char*		e;
	char*		file1;
	char*		file2;
	int		n;
	struct stat	s1;
	struct stat	s2;

	Sfio_t*		f1 = 0;
	Sfio_t*		f2 = 0;
	Sfoff_t		o1 = 0;
	Sfoff_t		o2 = 0;
	Sfoff_t		count = -1;
	Sfoff_t		differences = -1;
	int		flags = 0;

	NoP(argc);
	cmdinit(argc, argv, context, ERROR_CATALOG, 0);
	for (;;)
	{
		switch (optget(argv, usage))
		{
		case 'b':
			flags |= CMP_BYTES;
			continue;
		case 'c':
			flags |= CMP_CHARS;
			continue;
		case 'd':
			flags |= CMP_VERBOSE;
			differences = opt_info.number;
			continue;
		case 'i':
			o1 = strtoll(opt_info.arg, &e, 0);
			if (*e == ':')
				o2 = strtoll(e + 1, &e, 0);
			else
				o2 = o1;
			if (*e)
			{
				error(2, "%s: skip1:skip2 expected", opt_info.arg);
				break;
			}
			continue;
		case 'l':
			flags |= CMP_VERBOSE;
			continue;
		case 'n':
			count = opt_info.number;
			continue;
		case 's':
			flags |= CMP_SILENT;
			continue;
		case ':':
			error(2, "%s", opt_info.arg);
			break;
		case '?':
			error(ERROR_usage(2), "%s", opt_info.arg);
			UNREACHABLE();
		}
		break;
	}
	argv += opt_info.index;
	if (error_info.errors || !(file1 = *argv++) || !(file2 = *argv++))
	{
		error(ERROR_usage(2), "%s", optusage(NULL));
		UNREACHABLE();
	}
	n = 2;
	if (streq(file1, "-"))
		f1 = sfstdin;
	else if (!(f1 = sfopen(NULL, file1, "r")))
	{
		if (!(flags & CMP_SILENT))
			error(ERROR_system(0), "%s: cannot open", file1);
		goto done;
	}
	if (streq(file2, "-"))
		f2 = sfstdin;
	else if (!(f2 = sfopen(NULL, file2, "r")))
	{
		if (!(flags & CMP_SILENT))
			error(ERROR_system(0), "%s: cannot open", file2);
		goto done;
	}
	if (s = *argv++)
	{
		o1 = strtoll(s, &e, 0);
		if (*e)
		{
			error(ERROR_exit(0), "%s: %s: invalid skip", file1, s);
			goto done;
		}
		if (s = *argv++)
		{
			o2 = strtoll(s, &e, 0);
			if (*e)
			{
				error(ERROR_exit(0), "%s: %s: invalid skip", file2, s);
				goto done;
			}
		}
		if (*argv)
		{
			error(ERROR_usage(0), "%s", optusage(NULL));
			goto done;
		}
	}
	if (o1 && sfseek(f1, o1, SEEK_SET) != o1)
	{
		if (!(flags & CMP_SILENT))
			error(ERROR_exit(0), "EOF on %s", file1);
		n = 1;
		goto done;
	}
	if (o2 && sfseek(f2, o2, SEEK_SET) != o2)
	{
		if (!(flags & CMP_SILENT))
			error(ERROR_exit(0), "EOF on %s", file2);
		n = 1;
		goto done;
	}
	if (fstat(sffileno(f1), &s1))
		error(ERROR_system(0), "%s: cannot stat", file1);
	else if (fstat(sffileno(f2), &s2))
		error(ERROR_system(0), "%s: cannot stat", file1);
	else if (s1.st_ino == s2.st_ino && s1.st_dev == s2.st_dev && o1 == o2)
		n = 0;
	else
		n = ((flags & CMP_SILENT) && S_ISREG(s1.st_mode) && S_ISREG(s2.st_mode) && (s1.st_size - o1) != (s2.st_size - o2)) ? 1 : cmp(file1, f1, file2, f2, flags, count, differences);
 done:
	if (f1 && f1 != sfstdin)
		sfclose(f1);
	if (f2 && f2 != sfstdin)
		sfclose(f2);
	return n;
}
