Add less 643

third_party/less/ch.c

@@ -0,0 +1,939 @@
+/*
+ * Copyright (C) 1984-2023  Mark Nudelman
+ *
+ * You may distribute under the terms of either the GNU General Public
+ * License or the Less License, as specified in the README file.
+ *
+ * For more information, see the README file.
+ */
+
+
+/*
+ * Low level character input from the input file.
+ * We use these special purpose routines which optimize moving
+ * both forward and backward from the current read pointer.
+ */
+
+#include "less.h"
+#if MSDOS_COMPILER==WIN32C
+#include <errno.h>
+/* #include <windows.h> */
+#endif
+
+#if HAVE_PROCFS
+#include <sys/statfs.h>
+#if HAVE_LINUX_MAGIC_H
+#include <linux/magic.h>
+#endif
+#endif
+
+typedef POSITION BLOCKNUM;
+
+public int ignore_eoi;
+
+/*
+ * Pool of buffers holding the most recently used blocks of the input file.
+ * The buffer pool is kept as a doubly-linked circular list,
+ * in order from most- to least-recently used.
+ * The circular list is anchored by the file state "thisfile".
+ */
+struct bufnode {
+	struct bufnode *next, *prev;
+	struct bufnode *hnext, *hprev;
+};
+
+#define LBUFSIZE        8192
+struct buf {
+	struct bufnode node;
+	BLOCKNUM block;
+	unsigned int datasize;
+	unsigned char data[LBUFSIZE];
+};
+#define bufnode_buf(bn)  ((struct buf *) bn)
+
+/*
+ * The file state is maintained in a filestate structure.
+ * A pointer to the filestate is kept in the ifile structure.
+ */
+#define BUFHASH_SIZE    1024
+struct filestate {
+	struct bufnode buflist;
+	struct bufnode hashtbl[BUFHASH_SIZE];
+	int file;
+	int flags;
+	POSITION fpos;
+	int nbufs;
+	BLOCKNUM block;
+	unsigned int offset;
+	POSITION fsize;
+};
+
+#define ch_bufhead      thisfile->buflist.next
+#define ch_buftail      thisfile->buflist.prev
+#define ch_nbufs        thisfile->nbufs
+#define ch_block        thisfile->block
+#define ch_offset       thisfile->offset
+#define ch_fpos         thisfile->fpos
+#define ch_fsize        thisfile->fsize
+#define ch_flags        thisfile->flags
+#define ch_file         thisfile->file
+
+#define END_OF_CHAIN    (&thisfile->buflist)
+#define END_OF_HCHAIN(h) (&thisfile->hashtbl[h])
+#define BUFHASH(blk)    ((blk) & (BUFHASH_SIZE-1))
+
+/*
+ * Macros to manipulate the list of buffers in thisfile->buflist.
+ */
+#define FOR_BUFS(bn) \
+	for (bn = ch_bufhead;  bn != END_OF_CHAIN;  bn = bn->next)
+
+#define BUF_RM(bn) \
+	(bn)->next->prev = (bn)->prev; \
+	(bn)->prev->next = (bn)->next;
+
+#define BUF_INS_HEAD(bn) \
+	(bn)->next = ch_bufhead; \
+	(bn)->prev = END_OF_CHAIN; \
+	ch_bufhead->prev = (bn); \
+	ch_bufhead = (bn);
+
+#define BUF_INS_TAIL(bn) \
+	(bn)->next = END_OF_CHAIN; \
+	(bn)->prev = ch_buftail; \
+	ch_buftail->next = (bn); \
+	ch_buftail = (bn);
+
+/*
+ * Macros to manipulate the list of buffers in thisfile->hashtbl[n].
+ */
+#define FOR_BUFS_IN_CHAIN(h,bn) \
+	for (bn = thisfile->hashtbl[h].hnext;  \
+	     bn != END_OF_HCHAIN(h);  bn = bn->hnext)
+
+#define BUF_HASH_RM(bn) \
+	(bn)->hnext->hprev = (bn)->hprev; \
+	(bn)->hprev->hnext = (bn)->hnext;
+
+#define BUF_HASH_INS(bn,h) \
+	(bn)->hnext = thisfile->hashtbl[h].hnext; \
+	(bn)->hprev = END_OF_HCHAIN(h); \
+	thisfile->hashtbl[h].hnext->hprev = (bn); \
+	thisfile->hashtbl[h].hnext = (bn);
+
+static struct filestate *thisfile;
+static int ch_ungotchar = -1;
+static int maxbufs = -1;
+
+extern int autobuf;
+extern int sigs;
+extern int secure;
+extern int screen_trashed;
+extern int follow_mode;
+extern int waiting_for_data;
+extern constant char helpdata[];
+extern constant int size_helpdata;
+extern IFILE curr_ifile;
+#if LOGFILE
+extern int logfile;
+extern char *namelogfile;
+#endif
+
+static int ch_addbuf();
+
+
+/*
+ * Get the character pointed to by the read pointer.
+ */
+static int ch_get(void)
+{
+	struct buf *bp;
+	struct bufnode *bn;
+	int n;
+	int read_again;
+	int h;
+	POSITION pos;
+	POSITION len;
+
+	if (thisfile == NULL)
+		return (EOI);
+
+	/*
+	 * Quick check for the common case where 
+	 * the desired char is in the head buffer.
+	 */
+	if (ch_bufhead != END_OF_CHAIN)
+	{
+		bp = bufnode_buf(ch_bufhead);
+		if (ch_block == bp->block && ch_offset < bp->datasize)
+			return bp->data[ch_offset];
+	}
+
+	/*
+	 * Look for a buffer holding the desired block.
+	 */
+	waiting_for_data = FALSE;
+	h = BUFHASH(ch_block);
+	FOR_BUFS_IN_CHAIN(h, bn)
+	{
+		bp = bufnode_buf(bn);
+		if (bp->block == ch_block)
+		{
+			if (ch_offset >= bp->datasize)
+				/*
+				 * Need more data in this buffer.
+				 */
+				break;
+			goto found;
+		}
+	}
+	if (bn == END_OF_HCHAIN(h))
+	{
+		/*
+		 * Block is not in a buffer.  
+		 * Take the least recently used buffer 
+		 * and read the desired block into it.
+		 * If the LRU buffer has data in it, 
+		 * then maybe allocate a new buffer.
+		 */
+		if (ch_buftail == END_OF_CHAIN || 
+			bufnode_buf(ch_buftail)->block != -1)
+		{
+			/*
+			 * There is no empty buffer to use.
+			 * Allocate a new buffer if:
+			 * 1. We can't seek on this file and -b is not in effect; or
+			 * 2. We haven't allocated the max buffers for this file yet.
+			 */
+			if ((autobuf && !(ch_flags & CH_CANSEEK)) ||
+				(maxbufs < 0 || ch_nbufs < maxbufs))
+				if (ch_addbuf())
+					/*
+					 * Allocation failed: turn off autobuf.
+					 */
+					autobuf = OPT_OFF;
+		}
+		bn = ch_buftail;
+		bp = bufnode_buf(bn);
+		BUF_HASH_RM(bn); /* Remove from old hash chain. */
+		bp->block = ch_block;
+		bp->datasize = 0;
+		BUF_HASH_INS(bn, h); /* Insert into new hash chain. */
+	}
+
+	for (;;)
+	{
+		pos = (ch_block * LBUFSIZE) + bp->datasize;
+		if ((len = ch_length()) != NULL_POSITION && pos >= len)
+			/*
+			 * At end of file.
+			 */
+			return (EOI);
+
+		if (pos != ch_fpos)
+		{
+			/*
+			 * Not at the correct position: must seek.
+			 * If input is a pipe, we're in trouble (can't seek on a pipe).
+			 * Some data has been lost: just return "?".
+			 */
+			if (!(ch_flags & CH_CANSEEK))
+				return ('?');
+			if (lseek(ch_file, (off_t)pos, SEEK_SET) == BAD_LSEEK)
+			{
+				error("seek error", NULL_PARG);
+				clear_eol();
+				return (EOI);
+			}
+			ch_fpos = pos;
+		}
+
+		/*
+		 * Read the block.
+		 * If we read less than a full block, that's ok.
+		 * We use partial block and pick up the rest next time.
+		 */
+		if (ch_ungotchar != -1)
+		{
+			bp->data[bp->datasize] = ch_ungotchar;
+			n = 1;
+			ch_ungotchar = -1;
+		} else if (ch_flags & CH_HELPFILE)
+		{
+			bp->data[bp->datasize] = helpdata[ch_fpos];
+			n = 1;
+		} else
+		{
+			n = iread(ch_file, &bp->data[bp->datasize], 
+				(unsigned int)(LBUFSIZE - bp->datasize));
+		}
+
+		read_again = FALSE;
+		if (n == READ_INTR)
+		{
+			ch_fsize = pos;
+			return (EOI);
+		}
+		if (n == READ_AGAIN)
+		{
+			read_again = TRUE;
+			n = 0;
+		}
+		if (n < 0)
+		{
+#if MSDOS_COMPILER==WIN32C
+			if (errno != EPIPE)
+#endif
+			{
+				error("read error", NULL_PARG);
+				clear_eol();
+			}
+			n = 0;
+		}
+
+#if LOGFILE
+		/*
+		 * If we have a log file, write the new data to it.
+		 */
+		if (!secure && logfile >= 0 && n > 0)
+			write(logfile, (char *) &bp->data[bp->datasize], n);
+#endif
+
+		ch_fpos += n;
+		bp->datasize += n;
+
+		if (n == 0)
+		{
+			/* Either end of file or no data available.
+			 * read_again indicates the latter. */
+			if (!read_again)
+				ch_fsize = pos;
+			if (ignore_eoi || read_again)
+			{
+				/* Wait a while, then try again. */
+				if (!waiting_for_data)
+				{
+					PARG parg;
+					parg.p_string = wait_message();
+					ixerror("%s", &parg);
+					waiting_for_data = TRUE;
+				}
+				sleep_ms(50); /* Reduce system load */
+			}
+			if (ignore_eoi && follow_mode == FOLLOW_NAME && curr_ifile_changed())
+			{
+				/* screen_trashed=2 causes make_display to reopen the file. */
+				screen_trashed = 2;
+				return (EOI);
+			}
+			if (sigs)
+				return (EOI);
+		}
+
+		found:
+		if (ch_bufhead != bn)
+		{
+			/*
+			 * Move the buffer to the head of the buffer chain.
+			 * This orders the buffer chain, most- to least-recently used.
+			 */
+			BUF_RM(bn);
+			BUF_INS_HEAD(bn);
+
+			/*
+			 * Move to head of hash chain too.
+			 */
+			BUF_HASH_RM(bn);
+			BUF_HASH_INS(bn, h);
+		}
+
+		if (ch_offset < bp->datasize)
+			break;
+		/*
+		 * After all that, we still don't have enough data.
+		 * Go back and try again.
+		 */
+	}
+	return (bp->data[ch_offset]);
+}
+
+/*
+ * ch_ungetchar is a rather kludgy and limited way to push 
+ * a single char onto an input file descriptor.
+ */
+public void ch_ungetchar(int c)
+{
+	if (c != -1 && ch_ungotchar != -1)
+		error("ch_ungetchar overrun", NULL_PARG);
+	ch_ungotchar = c;
+}
+
+#if LOGFILE
+/*
+ * Close the logfile.
+ * If we haven't read all of standard input into it, do that now.
+ */
+public void end_logfile(void)
+{
+	static int tried = FALSE;
+
+	if (logfile < 0)
+		return;
+	if (!tried && ch_fsize == NULL_POSITION)
+	{
+		tried = TRUE;
+		ierror("Finishing logfile", NULL_PARG);
+		while (ch_forw_get() != EOI)
+			if (ABORT_SIGS())
+				break;
+	}
+	close(logfile);
+	logfile = -1;
+	free(namelogfile);
+	namelogfile = NULL;
+}
+
+/*
+ * Start a log file AFTER less has already been running.
+ * Invoked from the - command; see toggle_option().
+ * Write all the existing buffered data to the log file.
+ */
+public void sync_logfile(void)
+{
+	struct buf *bp;
+	struct bufnode *bn;
+	int warned = FALSE;
+	BLOCKNUM block;
+	BLOCKNUM nblocks;
+
+	if (logfile < 0)
+		return;
+	nblocks = (ch_fpos + LBUFSIZE - 1) / LBUFSIZE;
+	for (block = 0;  block < nblocks;  block++)
+	{
+		int wrote = FALSE;
+		FOR_BUFS(bn)
+		{
+			bp = bufnode_buf(bn);
+			if (bp->block == block)
+			{
+				write(logfile, (char *) bp->data, bp->datasize);
+				wrote = TRUE;
+				break;
+			}
+		}
+		if (!wrote && !warned)
+		{
+			error("Warning: log file is incomplete",
+				NULL_PARG);
+			warned = TRUE;
+		}
+	}
+}
+
+#endif
+
+/*
+ * Determine if a specific block is currently in one of the buffers.
+ */
+static int buffered(BLOCKNUM block)
+{
+	struct buf *bp;
+	struct bufnode *bn;
+	int h;
+
+	h = BUFHASH(block);
+	FOR_BUFS_IN_CHAIN(h, bn)
+	{
+		bp = bufnode_buf(bn);
+		if (bp->block == block)
+			return (TRUE);
+	}
+	return (FALSE);
+}
+
+/*
+ * Seek to a specified position in the file.
+ * Return 0 if successful, non-zero if can't seek there.
+ */
+public int ch_seek(POSITION pos)
+{
+	BLOCKNUM new_block;
+	POSITION len;
+
+	if (thisfile == NULL)
+		return (0);
+
+	len = ch_length();
+	if (pos < ch_zero() || (len != NULL_POSITION && pos > len))
+		return (1);
+
+	new_block = pos / LBUFSIZE;
+	if (!(ch_flags & CH_CANSEEK) && pos != ch_fpos && !buffered(new_block))
+	{
+		if (ch_fpos > pos)
+			return (1);
+		while (ch_fpos < pos)
+		{
+			if (ch_forw_get() == EOI)
+				return (1);
+			if (ABORT_SIGS())
+				return (1);
+		}
+		return (0);
+	}
+	/*
+	 * Set read pointer.
+	 */
+	ch_block = new_block;
+	ch_offset = pos % LBUFSIZE;
+	return (0);
+}
+
+/*
+ * Seek to the end of the file.
+ */
+public int ch_end_seek(void)
+{
+	POSITION len;
+
+	if (thisfile == NULL)
+		return (0);
+
+	if (ch_flags & CH_CANSEEK)
+		ch_fsize = filesize(ch_file);
+
+	len = ch_length();
+	if (len != NULL_POSITION)
+		return (ch_seek(len));
+
+	/*
+	 * Do it the slow way: read till end of data.
+	 */
+	while (ch_forw_get() != EOI)
+		if (ABORT_SIGS())
+			return (1);
+	return (0);
+}
+
+/*
+ * Seek to the last position in the file that is currently buffered.
+ */
+public int ch_end_buffer_seek(void)
+{
+	struct buf *bp;
+	struct bufnode *bn;
+	POSITION buf_pos;
+	POSITION end_pos;
+
+	if (thisfile == NULL || (ch_flags & CH_CANSEEK))
+		return (ch_end_seek());
+
+	end_pos = 0;
+	FOR_BUFS(bn)
+	{
+		bp = bufnode_buf(bn);
+		buf_pos = (bp->block * LBUFSIZE) + bp->datasize;
+		if (buf_pos > end_pos)
+			end_pos = buf_pos;
+	}
+
+	return (ch_seek(end_pos));
+}
+
+/*
+ * Seek to the beginning of the file, or as close to it as we can get.
+ * We may not be able to seek there if input is a pipe and the
+ * beginning of the pipe is no longer buffered.
+ */
+public int ch_beg_seek(void)
+{
+	struct bufnode *bn;
+	struct bufnode *firstbn;
+
+	/*
+	 * Try a plain ch_seek first.
+	 */
+	if (ch_seek(ch_zero()) == 0)
+		return (0);
+
+	/*
+	 * Can't get to position 0.
+	 * Look thru the buffers for the one closest to position 0.
+	 */
+	firstbn = ch_bufhead;
+	if (firstbn == END_OF_CHAIN)
+		return (1);
+	FOR_BUFS(bn)
+	{
+		if (bufnode_buf(bn)->block < bufnode_buf(firstbn)->block)
+			firstbn = bn;
+	}
+	ch_block = bufnode_buf(firstbn)->block;
+	ch_offset = 0;
+	return (0);
+}
+
+/*
+ * Return the length of the file, if known.
+ */
+public POSITION ch_length(void)
+{
+	if (thisfile == NULL)
+		return (NULL_POSITION);
+	if (ignore_eoi)
+		return (NULL_POSITION);
+	if (ch_flags & CH_HELPFILE)
+		return (size_helpdata);
+	if (ch_flags & CH_NODATA)
+		return (0);
+	return (ch_fsize);
+}
+
+/*
+ * Return the current position in the file.
+ */
+public POSITION ch_tell(void)
+{
+	if (thisfile == NULL)
+		return (NULL_POSITION);
+	return (ch_block * LBUFSIZE) + ch_offset;
+}
+
+/*
+ * Get the current char and post-increment the read pointer.
+ */
+public int ch_forw_get(void)
+{
+	int c;
+
+	if (thisfile == NULL)
+		return (EOI);
+	c = ch_get();
+	if (c == EOI)
+		return (EOI);
+	if (ch_offset < LBUFSIZE-1)
+		ch_offset++;
+	else
+	{
+		ch_block ++;
+		ch_offset = 0;
+	}
+	return (c);
+}
+
+/*
+ * Pre-decrement the read pointer and get the new current char.
+ */
+public int ch_back_get(void)
+{
+	if (thisfile == NULL)
+		return (EOI);
+	if (ch_offset > 0)
+		ch_offset --;
+	else
+	{
+		if (ch_block <= 0)
+			return (EOI);
+		if (!(ch_flags & CH_CANSEEK) && !buffered(ch_block-1))
+			return (EOI);
+		ch_block--;
+		ch_offset = LBUFSIZE-1;
+	}
+	return (ch_get());
+}
+
+/*
+ * Set max amount of buffer space.
+ * bufspace is in units of 1024 bytes.  -1 mean no limit.
+ */
+public void ch_setbufspace(int bufspace)
+{
+	if (bufspace < 0)
+		maxbufs = -1;
+	else
+	{
+		int lbufk = LBUFSIZE / 1024;
+		maxbufs = bufspace / lbufk + (bufspace % lbufk != 0);
+		if (maxbufs < 1)
+			maxbufs = 1;
+	}
+}
+
+/*
+ * Flush (discard) any saved file state, including buffer contents.
+ */
+public void ch_flush(void)
+{
+	struct bufnode *bn;
+
+	if (thisfile == NULL)
+		return;
+
+	if (!(ch_flags & CH_CANSEEK))
+	{
+		/*
+		 * If input is a pipe, we don't flush buffer contents,
+		 * since the contents can't be recovered.
+		 */
+		ch_fsize = NULL_POSITION;
+		return;
+	}
+
+	/*
+	 * Initialize all the buffers.
+	 */
+	FOR_BUFS(bn)
+	{
+		bufnode_buf(bn)->block = -1;
+	}
+
+	/*
+	 * Figure out the size of the file, if we can.
+	 */
+	ch_fsize = filesize(ch_file);
+
+	/*
+	 * Seek to a known position: the beginning of the file.
+	 */
+	ch_fpos = 0;
+	ch_block = 0; /* ch_fpos / LBUFSIZE; */
+	ch_offset = 0; /* ch_fpos % LBUFSIZE; */
+
+#if HAVE_PROCFS
+	/*
+	 * This is a kludge to workaround a Linux kernel bug: files in
+	 * /proc have a size of 0 according to fstat() but have readable 
+	 * data.  They are sometimes, but not always, seekable.
+	 * Force them to be non-seekable here.
+	 */
+	if (ch_fsize == 0)
+	{
+		struct statfs st;
+		if (fstatfs(ch_file, &st) == 0)
+		{
+			if (st.f_type == PROC_SUPER_MAGIC)
+			{
+				ch_fsize = NULL_POSITION;
+				ch_flags &= ~CH_CANSEEK;
+			}
+		}
+	}
+#endif
+
+	if (lseek(ch_file, (off_t)0, SEEK_SET) == BAD_LSEEK)
+	{
+		/*
+		 * Warning only; even if the seek fails for some reason,
+		 * there's a good chance we're at the beginning anyway.
+		 * {{ I think this is bogus reasoning. }}
+		 */
+		error("seek error to 0", NULL_PARG);
+	}
+}
+
+/*
+ * Allocate a new buffer.
+ * The buffer is added to the tail of the buffer chain.
+ */
+static int ch_addbuf(void)
+{
+	struct buf *bp;
+	struct bufnode *bn;
+
+	/*
+	 * Allocate and initialize a new buffer and link it 
+	 * onto the tail of the buffer list.
+	 */
+	bp = (struct buf *) calloc(1, sizeof(struct buf));
+	if (bp == NULL)
+		return (1);
+	ch_nbufs++;
+	bp->block = -1;
+	bn = &bp->node;
+
+	BUF_INS_TAIL(bn);
+	BUF_HASH_INS(bn, 0);
+	return (0);
+}
+
+/*
+ *
+ */
+static void init_hashtbl(void)
+{
+	int h;
+
+	for (h = 0;  h < BUFHASH_SIZE;  h++)
+	{
+		thisfile->hashtbl[h].hnext = END_OF_HCHAIN(h);
+		thisfile->hashtbl[h].hprev = END_OF_HCHAIN(h);
+	}
+}
+
+/*
+ * Delete all buffers for this file.
+ */
+static void ch_delbufs(void)
+{
+	struct bufnode *bn;
+
+	while (ch_bufhead != END_OF_CHAIN)
+	{
+		bn = ch_bufhead;
+		BUF_RM(bn);
+		free(bufnode_buf(bn));
+	}
+	ch_nbufs = 0;
+	init_hashtbl();
+}
+
+/*
+ * Is it possible to seek on a file descriptor?
+ */
+public int seekable(int f)
+{
+#if MSDOS_COMPILER
+	extern int fd0;
+	if (f == fd0 && !isatty(fd0))
+	{
+		/*
+		 * In MS-DOS, pipes are seekable.  Check for
+		 * standard input, and pretend it is not seekable.
+		 */
+		return (0);
+	}
+#endif
+	return (lseek(f, (off_t)1, SEEK_SET) != BAD_LSEEK);
+}
+
+/*
+ * Force EOF to be at the current read position.
+ * This is used after an ignore_eof read, during which the EOF may change.
+ */
+public void ch_set_eof(void)
+{
+	if (ch_fsize != NULL_POSITION && ch_fsize < ch_fpos)
+		ch_fsize = ch_fpos;
+}
+
+
+/*
+ * Initialize file state for a new file.
+ */
+public void ch_init(int f, int flags)
+{
+	/*
+	 * See if we already have a filestate for this file.
+	 */
+	thisfile = (struct filestate *) get_filestate(curr_ifile);
+	if (thisfile == NULL)
+	{
+		/*
+		 * Allocate and initialize a new filestate.
+		 */
+		thisfile = (struct filestate *) 
+				ecalloc(1, sizeof(struct filestate));
+		thisfile->buflist.next = thisfile->buflist.prev = END_OF_CHAIN;
+		thisfile->nbufs = 0;
+		thisfile->flags = flags;
+		thisfile->fpos = 0;
+		thisfile->block = 0;
+		thisfile->offset = 0;
+		thisfile->file = -1;
+		thisfile->fsize = NULL_POSITION;
+		init_hashtbl();
+		/*
+		 * Try to seek; set CH_CANSEEK if it works.
+		 */
+		if ((flags & CH_CANSEEK) && !seekable(f))
+			ch_flags &= ~CH_CANSEEK;
+		set_filestate(curr_ifile, (void *) thisfile);
+	}
+	if (thisfile->file == -1)
+		thisfile->file = f;
+	ch_flush();
+}
+
+/*
+ * Close a filestate.
+ */
+public void ch_close(void)
+{
+	int keepstate = FALSE;
+
+	if (thisfile == NULL)
+		return;
+
+	if ((ch_flags & (CH_CANSEEK|CH_POPENED|CH_HELPFILE)) && !(ch_flags & CH_KEEPOPEN))
+	{
+		/*
+		 * We can seek or re-open, so we don't need to keep buffers.
+		 */
+		ch_delbufs();
+	} else
+		keepstate = TRUE;
+	if (!(ch_flags & CH_KEEPOPEN))
+	{
+		/*
+		 * We don't need to keep the file descriptor open
+		 * (because we can re-open it.)
+		 * But don't really close it if it was opened via popen(),
+		 * because pclose() wants to close it.
+		 */
+		if (!(ch_flags & (CH_POPENED|CH_HELPFILE)))
+			close(ch_file);
+		ch_file = -1;
+	} else
+		keepstate = TRUE;
+	if (!keepstate)
+	{
+		/*
+		 * We don't even need to keep the filestate structure.
+		 */
+		free(thisfile);
+		thisfile = NULL;
+		set_filestate(curr_ifile, (void *) NULL);
+	}
+}
+
+/*
+ * Return ch_flags for the current file.
+ */
+public int ch_getflags(void)
+{
+	if (thisfile == NULL)
+		return (0);
+	return (ch_flags);
+}
+
+#if 0
+static void ch_dump(struct filestate *fs)
+{
+	struct buf *bp;
+	struct bufnode *bn;
+	unsigned char *s;
+
+	if (fs == NULL)
+	{
+		printf(" --no filestate\n");
+		return;
+	}
+	printf(" file %d, flags %x, fpos %x, fsize %x, blk/off %x/%x\n",
+		fs->file, fs->flags, fs->fpos, 
+		fs->fsize, fs->block, fs->offset);
+	printf(" %d bufs:\n", fs->nbufs);
+	for (bn = fs->next; bn != &fs->buflist;  bn = bn->next)
+	{
+		bp = bufnode_buf(bn);
+		printf("%x: blk %x, size %x \"",
+			bp, bp->block, bp->datasize);
+		for (s = bp->data;  s < bp->data + 30;  s++)
+			if (*s >= ' ' && *s < 0x7F)
+				printf("%c", *s);
+			else
+				printf(".");
+		printf("\"\n");
+	}
+}
+#endif