/*	$Id: read.c,v 1.5 2011/03/22 09:50:11 kristaps Exp $ */
/*
 * Copyright (c) 2008, 2009, 2010, 2011 Kristaps Dzonsons <kristaps@bsd.lv>
 * Copyright (c) 2010, 2011 Ingo Schwarze <schwarze@openbsd.org>
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */
#include <sys/stat.h>
#include <sys/mman.h>

#include <assert.h>
#include <ctype.h>
#include <fcntl.h>
#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#include "mandoc.h"
#include "libmandoc.h"
#include "mdoc.h"
#include "man.h"

#ifndef MAP_FILE
#define	MAP_FILE	0
#endif

#define	REPARSE_LIMIT	1000

struct	buf {
	char	 	 *buf; /* binary input buffer */
	size_t		  sz; /* size of binary buffer */
};

struct	mparse {
	enum mandoclevel  file_status; /* status of current parse */
	enum mandoclevel  wlevel; /* ignore messages below this */
	int		  line; /* line number in the file */
	enum mparset	  inttype; /* which parser to use */
	struct man	 *pman; /* persistent man parser */
	struct mdoc	 *pmdoc; /* persistent mdoc parser */
	struct man	 *man; /* man parser */
	struct mdoc	 *mdoc; /* mdoc parser */
	struct roff	 *roff; /* roff parser (!NULL) */
	struct regset	  regs; /* roff registers */
	int		  reparse_count; /* finite interp. stack */
	mandocmsg	  mmsg; /* warning/error message handler */
	void		 *arg; /* argument to mmsg */
	const char	 *file; 
};

static	void	  resize_buf(struct buf *, size_t);
static	void	  mparse_buf_r(struct mparse *, struct buf, int);
static	void	  mparse_readfd_r(struct mparse *, int, const char *, int);
static	void	  pset(const char *, int, struct mparse *);
static	void	  pdesc(struct mparse *, const char *, int);
static	int	  read_whole_file(const char *, int, struct buf *, int *);
static	void	  mparse_end(struct mparse *);

static	const enum mandocerr	mandoclimits[MANDOCLEVEL_MAX] = {
	MANDOCERR_OK,
	MANDOCERR_WARNING,
	MANDOCERR_WARNING,
	MANDOCERR_ERROR,
	MANDOCERR_FATAL,
	MANDOCERR_MAX,
	MANDOCERR_MAX
};

static void
resize_buf(struct buf *buf, size_t initial)
{

	buf->sz = buf->sz > initial/2 ? 2 * buf->sz : initial;
	buf->buf = mandoc_realloc(buf->buf, buf->sz);
}

static void
pset(const char *buf, int pos, struct mparse *curp)
{
	int		 i;

	/*
	 * Try to intuit which kind of manual parser should be used.  If
	 * passed in by command-line (-man, -mdoc), then use that
	 * explicitly.  If passed as -mandoc, then try to guess from the
	 * line: either skip dot-lines, use -mdoc when finding `.Dt', or
	 * default to -man, which is more lenient.
	 *
	 * Separate out pmdoc/pman from mdoc/man: the first persists
	 * through all parsers, while the latter is used per-parse.
	 */

	if ('.' == buf[0] || '\'' == buf[0]) {
		for (i = 1; buf[i]; i++)
			if (' ' != buf[i] && '\t' != buf[i])
				break;
		if ('\0' == buf[i])
			return;
	}

	switch (curp->inttype) {
	case (MPARSE_MDOC):
		if (NULL == curp->pmdoc) 
			curp->pmdoc = mdoc_alloc(&curp->regs, curp);
		assert(curp->pmdoc);
		curp->mdoc = curp->pmdoc;
		return;
	case (MPARSE_MAN):
		if (NULL == curp->pman) 
			curp->pman = man_alloc(&curp->regs, curp);
		assert(curp->pman);
		curp->man = curp->pman;
		return;
	default:
		break;
	}

	if (pos >= 3 && 0 == memcmp(buf, ".Dd", 3))  {
		if (NULL == curp->pmdoc) 
			curp->pmdoc = mdoc_alloc(&curp->regs, curp);
		assert(curp->pmdoc);
		curp->mdoc = curp->pmdoc;
		return;
	} 

	if (NULL == curp->pman) 
		curp->pman = man_alloc(&curp->regs, curp);
	assert(curp->pman);
	curp->man = curp->pman;
}

/*
 * Main parse routine for an opened file.  This is called for each
 * opened file and simply loops around the full input file, possibly
 * nesting (i.e., with `so').
 */
static void
mparse_buf_r(struct mparse *curp, struct buf blk, int start)
{
	const struct tbl_span	*span;
	struct buf	 ln;
	enum rofferr	 rr;
	int		 i, of, rc;
	int		 pos; /* byte number in the ln buffer */
	int		 lnn; /* line number in the real file */
	unsigned char	 c;

	memset(&ln, 0, sizeof(struct buf));

	lnn = curp->line; 
	pos = 0; 

	for (i = 0; i < (int)blk.sz; ) {
		if (0 == pos && '\0' == blk.buf[i])
			break;

		if (start) {
			curp->line = lnn;
			curp->reparse_count = 0;
		}

		while (i < (int)blk.sz && (start || '\0' != blk.buf[i])) {

			/*
			 * When finding an unescaped newline character,
			 * leave the character loop to process the line.
			 * Skip a preceding carriage return, if any.
			 */

			if ('\r' == blk.buf[i] && i + 1 < (int)blk.sz &&
			    '\n' == blk.buf[i + 1])
				++i;
			if ('\n' == blk.buf[i]) {
				++i;
				++lnn;
				break;
			}

			/* 
			 * Warn about bogus characters.  If you're using
			 * non-ASCII encoding, you're screwing your
			 * readers.  Since I'd rather this not happen,
			 * I'll be helpful and drop these characters so
			 * we don't display gibberish.  Note to manual
			 * writers: use special characters.
			 */

			c = (unsigned char) blk.buf[i];

			if ( ! (isascii(c) && 
					(isgraph(c) || isblank(c)))) {
				mandoc_msg(MANDOCERR_BADCHAR, curp,
						curp->line, pos, "ignoring byte");
				i++;
				continue;
			}

			/* Trailing backslash = a plain char. */

			if ('\\' != blk.buf[i] || i + 1 == (int)blk.sz) {
				if (pos >= (int)ln.sz)
					resize_buf(&ln, 256);
				ln.buf[pos++] = blk.buf[i++];
				continue;
			}

			/*
			 * Found escape and at least one other character.
			 * When it's a newline character, skip it.
			 * When there is a carriage return in between,
			 * skip that one as well.
			 */

			if ('\r' == blk.buf[i + 1] && i + 2 < (int)blk.sz &&
			    '\n' == blk.buf[i + 2])
				++i;
			if ('\n' == blk.buf[i + 1]) {
				i += 2;
				++lnn;
				continue;
			}

			if ('"' == blk.buf[i + 1]) {
				i += 2;
				/* Comment, skip to end of line */
				for (; i < (int)blk.sz; ++i) {
					if ('\n' == blk.buf[i]) {
						++i;
						++lnn;
						break;
					}
				}

				/* Backout trailing whitespaces */
				for (; pos > 0; --pos) {
					if (ln.buf[pos - 1] != ' ')
						break;
					if (pos > 2 && ln.buf[pos - 2] == '\\')
						break;
				}
				break;
			}

			/* Some other escape sequence, copy & cont. */

			if (pos + 1 >= (int)ln.sz)
				resize_buf(&ln, 256);

			ln.buf[pos++] = blk.buf[i++];
			ln.buf[pos++] = blk.buf[i++];
		}

 		if (pos >= (int)ln.sz)
			resize_buf(&ln, 256);

		ln.buf[pos] = '\0';

		/*
		 * A significant amount of complexity is contained by
		 * the roff preprocessor.  It's line-oriented but can be
		 * expressed on one line, so we need at times to
		 * readjust our starting point and re-run it.  The roff
		 * preprocessor can also readjust the buffers with new
		 * data, so we pass them in wholesale.
		 */

		of = 0;

rerun:
		rr = roff_parseln
			(curp->roff, curp->line, 
			 &ln.buf, &ln.sz, of, &of);

		switch (rr) {
		case (ROFF_REPARSE):
			if (REPARSE_LIMIT >= ++curp->reparse_count)
				mparse_buf_r(curp, ln, 0);
			else
				mandoc_msg(MANDOCERR_ROFFLOOP, curp,
					curp->line, pos, NULL);
			pos = 0;
			continue;
		case (ROFF_APPEND):
			pos = (int)strlen(ln.buf);
			continue;
		case (ROFF_RERUN):
			goto rerun;
		case (ROFF_IGN):
			pos = 0;
			continue;
		case (ROFF_ERR):
			assert(MANDOCLEVEL_FATAL <= curp->file_status);
			break;
		case (ROFF_SO):
			mparse_readfd_r(curp, -1, ln.buf + of, 1);
			if (MANDOCLEVEL_FATAL <= curp->file_status)
				break;
			pos = 0;
			continue;
		default:
			break;
		}

		/*
		 * If we encounter errors in the recursive parse, make
		 * sure we don't continue parsing.
		 */

		if (MANDOCLEVEL_FATAL <= curp->file_status)
			break;

		/*
		 * If input parsers have not been allocated, do so now.
		 * We keep these instanced betwen parsers, but set them
		 * locally per parse routine since we can use different
		 * parsers with each one.
		 */

		if ( ! (curp->man || curp->mdoc))
			pset(ln.buf + of, pos - of, curp);

		/* 
		 * Lastly, push down into the parsers themselves.  One
		 * of these will have already been set in the pset()
		 * routine.
		 * If libroff returns ROFF_TBL, then add it to the
		 * currently open parse.  Since we only get here if
		 * there does exist data (see tbl_data.c), we're
		 * guaranteed that something's been allocated.
		 * Do the same for ROFF_EQN.
		 */

		rc = -1;

		if (ROFF_TBL == rr)
			while (NULL != (span = roff_span(curp->roff))) {
				rc = curp->man ?
					man_addspan(curp->man, span) :
					mdoc_addspan(curp->mdoc, span);
				if (0 == rc)
					break;
			}
		else if (ROFF_EQN == rr)
			rc = curp->mdoc ? 
				mdoc_addeqn(curp->mdoc, 
					roff_eqn(curp->roff)) :
				man_addeqn(curp->man,
					roff_eqn(curp->roff));
		else if (curp->man || curp->mdoc)
			rc = curp->man ?
				man_parseln(curp->man, 
					curp->line, ln.buf, of) :
				mdoc_parseln(curp->mdoc, 
					curp->line, ln.buf, of);

		if (0 == rc) {
			assert(MANDOCLEVEL_FATAL <= curp->file_status);
			break;
		}

		/* Temporary buffers typically are not full. */

		if (0 == start && '\0' == blk.buf[i])
			break;

		/* Start the next input line. */

		pos = 0;
	}

	free(ln.buf);
}

static void
pdesc(struct mparse *curp, const char *file, int fd)
{
	struct buf	 blk;
	int		 with_mmap;

	/*
	 * Run for each opened file; may be called more than once for
	 * each full parse sequence if the opened file is nested (i.e.,
	 * from `so').  Simply sucks in the whole file and moves into
	 * the parse phase for the file.
	 */

	if ( ! read_whole_file(file, fd, &blk, &with_mmap)) {
		curp->file_status = MANDOCLEVEL_SYSERR;
		return;
	}

	/* Line number is per-file. */

	curp->line = 1;

	mparse_buf_r(curp, blk, 1);

	if (with_mmap)
		munmap(blk.buf, blk.sz);
	else
		free(blk.buf);
}

static int
read_whole_file(const char *file, int fd, struct buf *fb, int *with_mmap)
{
	struct stat	 st;
	size_t		 off;
	ssize_t		 ssz;

	if (-1 == fstat(fd, &st)) {
		perror(file);
		return(0);
	}

	/*
	 * If we're a regular file, try just reading in the whole entry
	 * via mmap().  This is faster than reading it into blocks, and
	 * since each file is only a few bytes to begin with, I'm not
	 * concerned that this is going to tank any machines.
	 */

	if (S_ISREG(st.st_mode)) {
		if (st.st_size >= (1U << 31)) {
			fprintf(stderr, "%s: input too large\n", file);
			return(0);
		}
		*with_mmap = 1;
		fb->sz = (size_t)st.st_size;
		fb->buf = mmap(NULL, fb->sz, PROT_READ, 
				MAP_FILE|MAP_SHARED, fd, 0);
		if (fb->buf != MAP_FAILED)
			return(1);
	}

	/*
	 * If this isn't a regular file (like, say, stdin), then we must
	 * go the old way and just read things in bit by bit.
	 */

	*with_mmap = 0;
	off = 0;
	fb->sz = 0;
	fb->buf = NULL;
	for (;;) {
		if (off == fb->sz) {
			if (fb->sz == (1U << 31)) {
				fprintf(stderr, "%s: input too large\n", file);
				break;
			}
			resize_buf(fb, 65536);
		}
		ssz = read(fd, fb->buf + (int)off, fb->sz - off);
		if (ssz == 0) {
			fb->sz = off;
			return(1);
		}
		if (ssz == -1) {
			perror(file);
			break;
		}
		off += (size_t)ssz;
	}

	free(fb->buf);
	fb->buf = NULL;
	return(0);
}

static void
mparse_end(struct mparse *curp)
{

	if (MANDOCLEVEL_FATAL <= curp->file_status)
		return;

	if (curp->mdoc && ! mdoc_endparse(curp->mdoc)) {
		assert(MANDOCLEVEL_FATAL <= curp->file_status);
		return;
	}

	if (curp->man && ! man_endparse(curp->man)) {
		assert(MANDOCLEVEL_FATAL <= curp->file_status);
		return;
	}

#if 0
	/* FIXME: NOTE a parser may not have been assigned, yet. */

	if ( ! (curp->man || curp->mdoc)) {
		/* FIXME: make into an mandoc.h error. */
		fprintf(stderr, "%s: Not a manual\n", curp->file);
		curp->file_status = MANDOCLEVEL_FATAL;
		goto cleanup;
	}
#endif

	roff_endparse(curp->roff);
}

static void
mparse_readfd_r(struct mparse *curp, int fd, const char *file, int re)
{
	const char	*svfile;

	if (-1 == fd)
		if (-1 == (fd = open(file, O_RDONLY, 0))) {
			perror(file);
			curp->file_status = MANDOCLEVEL_SYSERR;
			return;
		}

	svfile = curp->file;
	curp->file = file;

	pdesc(curp, file, fd);

	if (0 == re && MANDOCLEVEL_FATAL > curp->file_status)
		mparse_end(curp);

	if (STDIN_FILENO != fd && -1 == close(fd))
		perror(file);

	curp->file = svfile;
}

enum mandoclevel
mparse_readfd(struct mparse *curp, int fd, const char *file)
{

	mparse_readfd_r(curp, fd, file, 0);
	return(curp->file_status);
}

struct mparse *
mparse_alloc(enum mparset inttype, enum mandoclevel wlevel, mandocmsg mmsg, void *arg)
{
	struct mparse	*curp;

	curp = mandoc_calloc(1, sizeof(struct mparse));

	curp->wlevel = wlevel;
	curp->mmsg = mmsg;
	curp->arg = arg;
	curp->inttype = inttype;

	curp->roff = roff_alloc(&curp->regs, curp);
	return(curp);
}

void
mparse_reset(struct mparse *curp)
{

	memset(&curp->regs, 0, sizeof(struct regset));

	roff_reset(curp->roff);

	if (curp->mdoc)
		mdoc_reset(curp->mdoc);
	if (curp->man)
		man_reset(curp->man);

	curp->file_status = MANDOCLEVEL_OK;
	curp->mdoc = NULL;
	curp->man = NULL;
}

void
mparse_free(struct mparse *curp)
{

	if (curp->pmdoc)
		mdoc_free(curp->pmdoc);
	if (curp->pman)
		man_free(curp->pman);
	if (curp->roff)
		roff_free(curp->roff);

	free(curp);
}

void
mparse_result(struct mparse *curp, struct mdoc **mdoc, struct man **man)
{

	*mdoc = curp->mdoc;
	*man = curp->man;
}

void
mandoc_vmsg(enum mandocerr t, struct mparse *m,
		int ln, int pos, const char *fmt, ...)
{
	char		 buf[256];
	va_list		 ap;

	va_start(ap, fmt);
	vsnprintf(buf, sizeof(buf) - 1, fmt, ap);
	va_end(ap);

	mandoc_msg(t, m, ln, pos, buf);
}

void
mandoc_msg(enum mandocerr er, struct mparse *m, 
		int ln, int col, const char *msg)
{
	enum mandoclevel level;

	level = MANDOCLEVEL_FATAL;
	while (er < mandoclimits[level])
		level--;

	if (level < m->wlevel)
		return;

	(*m->mmsg)(er, level, m->file, ln, col, msg);

	if (m->file_status < level)
		m->file_status = level;
}