less: implement waiting for input using select(). Rather tricky business.

But we do not read entire input anymore up-front.

1 files changed, 516 insertions, 454 deletions

diff --git a/miscutils/less.c b/miscutils/less.c
index 03b9397..6615889 100644
--- a/miscutils/less.c
+++ b/miscutils/less.c
@@ -26,26 +26,9 @@
 #include "xregex.h"
 #endif
 
-
-/* These are the escape sequences corresponding to special keys */
-#define REAL_KEY_UP 'A'
-#define REAL_KEY_DOWN 'B'
-#define REAL_KEY_RIGHT 'C'
-#define REAL_KEY_LEFT 'D'
-#define REAL_PAGE_UP '5'
-#define REAL_PAGE_DOWN '6'
-#define REAL_KEY_HOME '7'
-#define REAL_KEY_END '8'
-
-/* These are the special codes assigned by this program to the special keys */
-#define KEY_UP 20
-#define KEY_DOWN 21
-#define KEY_RIGHT 22
-#define KEY_LEFT 23
-#define PAGE_UP 24
-#define PAGE_DOWN 25
-#define KEY_HOME 26
-#define KEY_END 27
+/* FIXME: currently doesn't work right */
+#undef ENABLE_FEATURE_LESS_FLAGCS
+#define ENABLE_FEATURE_LESS_FLAGCS 0
 
 /* The escape codes for highlighted and normal text */
 #define HIGHLIGHT "\033[7m"
@@ -55,124 +38,103 @@
 /* The escape code to clear to end of line */
 #define CLEAR_2_EOL "\033[K"
 
-#define MAXLINES CONFIG_FEATURE_LESS_MAXLINES
+/* These are the escape sequences corresponding to special keys */
+enum {
+	REAL_KEY_UP = 'A',
+	REAL_KEY_DOWN = 'B',
+	REAL_KEY_RIGHT = 'C',
+	REAL_KEY_LEFT = 'D',
+	REAL_PAGE_UP = '5',
+	REAL_PAGE_DOWN = '6',
+	REAL_KEY_HOME = '7',
+	REAL_KEY_END = '8',
+
+/* These are the special codes assigned by this program to the special keys */
+	KEY_UP = 20,
+	KEY_DOWN = 21,
+	KEY_RIGHT = 22,
+	KEY_LEFT = 23,
+	PAGE_UP = 24,
+	PAGE_DOWN = 25,
+	KEY_HOME = 26,
+	KEY_END = 27,
+
+/* Absolute max of lines eaten */
+	MAXLINES = CONFIG_FEATURE_LESS_MAXLINES,
+
+/* This many "after the end" lines we will show (at max) */
+	TILDES = 1,
+};
+
+static unsigned max_displayed_line;
+static unsigned width;
+static const char *empty_line_marker = "~";
 
-static int height;
-static int width;
-static char **files;
 static char *filename;
+static char **files;
+static unsigned num_files = 1;
+static unsigned current_file = 1;
 static const char **buffer;
-static char **flines;
-static int current_file = 1;
-static int line_pos;
-static int num_flines;
-static int num_files = 1;
-static const char *empty_line_marker = "~";
+static const char **flines;
+static int cur_fline; /* signed */
+static unsigned max_fline;
+static unsigned max_lineno; /* this one tracks linewrap */
+
+static ssize_t eof_error = 1; /* eof if 0, error if < 0 */
+static char terminated = 1;
+static size_t readpos;
+static size_t readeof;
+/* last position in last line, taking into account tabs */
+static size_t linepos;
 
 /* Command line options */
-#define FLAG_E 1
-#define FLAG_M (1<<1)
-#define FLAG_m (1<<2)
-#define FLAG_N (1<<3)
-#define FLAG_TILDE (1<<4)
+enum {
+	FLAG_E = 1,
+	FLAG_M = 1 << 1,
+	FLAG_m = 1 << 2,
+	FLAG_N = 1 << 3,
+	FLAG_TILDE = 1 << 4,
 /* hijack command line options variable for internal state vars */
-#define LESS_STATE_MATCH_BACKWARDS (1<<6)
+	LESS_STATE_MATCH_BACKWARDS = 1 << 15,
+};
 
 #if ENABLE_FEATURE_LESS_MARKS
-static int mark_lines[15][2];
-static int num_marks;
+static unsigned mark_lines[15][2];
+static unsigned num_marks;
 #endif
 
 #if ENABLE_FEATURE_LESS_REGEXP
-static int *match_lines;
-static int match_pos;
-static int num_matches;
+static unsigned *match_lines;
+static int match_pos; /* signed! */
+static unsigned num_matches;
 static regex_t pattern;
-static int pattern_valid;
+static unsigned pattern_valid;
 #endif
 
-/* Needed termios structures */
 static struct termios term_orig, term_vi;
 
 /* File pointer to get input from */
-static FILE *inp;
+static int kbd_fd;
 
 /* Reset terminal input to normal */
 static void set_tty_cooked(void)
 {
 	fflush(stdout);
-	tcsetattr(fileno(inp), TCSANOW, &term_orig);
+	tcsetattr(kbd_fd, TCSANOW, &term_orig);
 }
 
 /* Exit the program gracefully */
-static void tless_exit(int code)
+static void less_exit(int code)
 {
 	/* TODO: We really should save the terminal state when we start,
-		 and restore it when we exit. Less does this with the
-		 "ti" and "te" termcap commands; can this be done with
-		 only termios.h? */
+	 * and restore it when we exit. Less does this with the
+	 * "ti" and "te" termcap commands; can this be done with
+	 * only termios.h? */
 
 	putchar('\n');
 	fflush_stdout_and_exit(code);
 }
 
-/* Grab a character from input without requiring the return key. If the
-   character is ASCII \033, get more characters and assign certain sequences
-   special return codes. Note that this function works best with raw input. */
-static int tless_getch(void)
-{
-	int input;
-	/* Set terminal input to raw mode (taken from vi.c) */
-	tcsetattr(fileno(inp), TCSANOW, &term_vi);
- again:
-	input = getc(inp);
-	/* Detect escape sequences (i.e. arrow keys) and handle
-	   them accordingly */
-
-	if (input == '\033' && getc(inp) == '[') {
-		unsigned i;
-		input = getc(inp);
-		set_tty_cooked();
-
-		i = input - REAL_KEY_UP;
-		if (i < 4)
-			return 20 + i;
-		i = input - REAL_PAGE_UP;
-		if (i < 4)
-			return 24 + i;
-		return 0; /* ?? */
-	}
-	/* Reject almost all control chars */
-	if (input < ' ' && input != 0x0d && input != 8) goto again;
-	set_tty_cooked();
-	return input;
-}
-
-static char* tless_gets(int sz)
-{
-	int c;
-	int i = 0;
-	char *result = xzalloc(1);
-	while (1) {
-		c = tless_getch();
-		if (c == 0x0d)
-			return result;
-		if (c == 0x7f) c = 8;
-		if (c == 8 && i) {
-			printf("\x8 \x8");
-			i--;
-		}
-		if (c < ' ')
-			continue;
-		if (i >= width - sz - 1)
-			continue; /* len limit */
-		putchar(c);
-		result[i++] = c;
-		result = xrealloc(result, i+1);
-		result[i] = '\0';
-	}
-}
-
 /* Move the cursor to a position (x,y), where (0,0) is the
    top-left corner of the console */
 static void move_cursor(int line, int row)
@@ -182,7 +144,7 @@ static void move_cursor(int line, int row)
 
 static void clear_line(void)
 {
-	printf("\033[%u;0H" CLEAR_2_EOL, height);
+	printf("\033[%u;0H" CLEAR_2_EOL, max_displayed_line + 2);
 }
 
 static void print_hilite(const char *str)
@@ -193,90 +155,116 @@ static void print_hilite(const char *str)
 static void print_statusline(const char *str)
 {
 	clear_line();
-	printf(HIGHLIGHT"%.*s"NORMAL, width-1, str);
+	printf(HIGHLIGHT"%.*s"NORMAL, width - 1, str);
 }
 
-static void data_readlines(void)
+static void read_lines(void)
 {
-	unsigned i, pos;
-	unsigned lineno = 1;
-	int w = width;
-	char terminated, last_terminated = 1;
-	char *current_line, *p;
-	FILE *fp;
+	/* TODO: regexp match array should be updated too */
 
-	if (filename)
-		fp = xfopen(filename, "r");
-	else {
-		/* "less" with no arguments in argv[] */
-		fp = stdin;
-		/* For status line only */
-		filename = xstrdup(bb_msg_standard_input);
-	}
+#define readbuf bb_common_bufsiz1
+	char *current_line, *p;
+	int w = width;
+	char last_terminated = terminated;
 
-	flines = NULL;
-	if (option_mask32 & FLAG_N) {
+	if (option_mask32 & FLAG_N)
 		w -= 8;
+
+	current_line = xmalloc(w);
+	p = current_line;
+	max_fline += last_terminated;
+	if (!last_terminated) {
+		const char *cp = flines[max_fline];
+		if (option_mask32 & FLAG_N)
+			cp += 8;
+		strcpy(current_line, cp);
+		p += strlen(current_line);
 	}
-	for (i = 0; !feof(fp) && i <= MAXLINES; i++) {
-		flines = xrealloc(flines, (i+1) * sizeof(char *));
-		current_line = xmalloc(w);
+
+	while (1) {
  again:
-		p = current_line;
-		pos = 0;
+		*p = '\0';
 		terminated = 0;
 		while (1) {
-			int c = getc(fp);
-			if (c == '\t') pos += (pos^7) & 7;
-			pos++;
-			if (pos >= w) { ungetc(c, fp); break; }
-			if (c == EOF) break;
+			char c;
+			if (readpos >= readeof) {
+ndelay_on(0);
+				eof_error = safe_read(0, readbuf, sizeof(readbuf));
+ndelay_off(0);
+				readpos = 0;
+				readeof = eof_error;
+				if (eof_error < 0) {
+					readeof = 0;
+					if (errno != EAGAIN)
+						print_statusline("read error");
+				}
+				if (eof_error <= 0) {
+					goto reached_eof;
+				}
+			}
+			c = readbuf[readpos];
+			if (c == '\t')
+				linepos += (linepos^7) & 7;
+			linepos++;
+			if (linepos >= w)
+				break;
+			readpos++;
 			if (c == '\n') { terminated = 1; break; }
 			/* NUL is substituted by '\n'! */
 			if (c == '\0') c = '\n';
 			*p++ = c;
+			*p = '\0';
 		}
-		*p = '\0';
-		if (fp != stdin)
-			die_if_ferror(fp, filename);
-
 		/* Corner case: linewrap with only "" wrapping to next line */
 		/* Looks ugly on screen, so we do not store this empty line */
 		if (!last_terminated && !current_line[0]) {
 			last_terminated = 1;
-			lineno++;
+			max_lineno++;
 			goto again;
 		}
-
+ reached_eof:
 		last_terminated = terminated;
+		flines = xrealloc(flines, (max_fline+1) * sizeof(char *));
 		if (option_mask32 & FLAG_N) {
 			/* Width of 7 preserves tab spacing in the text */
-			flines[i] = xasprintf(
-				(lineno <= 9999999) ? "%7u %s" : "%07u %s",
-				lineno % 10000000, current_line);
+			flines[max_fline] = xasprintf(
+				(max_lineno <= 9999999) ? "%7u %s" : "%07u %s",
+				max_lineno % 10000000, current_line);
 			free(current_line);
 			if (terminated)
-				lineno++;
+				max_lineno++;
 		} else {
-			flines[i] = xrealloc(current_line, strlen(current_line)+1);
+			flines[max_fline] = xrealloc(current_line, strlen(current_line)+1);
 		}
+		if (max_fline >= MAXLINES)
+			break;
+		if (max_fline > cur_fline + max_displayed_line)
+			break;
+		if (eof_error <= 0) {
+			if (eof_error < 0 && errno == EAGAIN) {
+				/* not yet eof or error, reset flag (or else
+				 * we will hog CPU - select() will return
+				 * immediately */
+				eof_error = 1;
+			}
+			break;
+		}
+		max_fline++;
+		current_line = xmalloc(w);
+		p = current_line;
+		linepos = 0;
 	}
-	num_flines = i - 1; /* buggie: 'num_flines' must be 'max_fline' */
-
-	/* Reset variables for a new file */
-
-	line_pos = 0;
-
-	fclose(fp);
+#undef readbuf
 }
 
 #if ENABLE_FEATURE_LESS_FLAGS
 
-/* Interestingly, writing calc_percent as a function and not a prototype saves around 32 bytes
+/* Interestingly, writing calc_percent as a function saves around 32 bytes
  * on my build. */
 static int calc_percent(void)
 {
-	return ((100 * (line_pos + height - 2) / num_flines) + 1);
+	unsigned p = 100 * (cur_fline + max_displayed_line) / (max_fline + 1);
+	return p <= 100 ? p : 100;
 }
 
 /* Print a status line if -M was specified */
@@ -289,16 +277,16 @@ static void m_status_print(void)
 	if (num_files > 1)
 		printf(" (file %i of %i)", current_file, num_files);
 	printf(" lines %i-%i/%i ",
-			line_pos + 1, line_pos + height - 1,
-			num_flines + 1);
-	if (line_pos >= num_flines - height + 2) {
+			cur_fline + 1, cur_fline + max_displayed_line + 1,
+			max_fline + 1);
+	if (cur_fline >= max_fline - max_displayed_line) {
 		printf("(END)"NORMAL);
 		if (num_files > 1 && current_file != num_files)
-			printf(HIGHLIGHT" - next: %s "NORMAL, files[current_file]);
+			printf(HIGHLIGHT" - next: %s"NORMAL, files[current_file]);
 		return;
 	}
 	percentage = calc_percent();
-	printf("%i%% "NORMAL, percentage);
+	printf("%i%%"NORMAL, percentage);
 }
 
 #endif
@@ -318,15 +306,15 @@ static void status_print(void)
 #endif
 
 	clear_line();
-	if (line_pos && line_pos < num_flines - height + 2) {
+	if (cur_fline && cur_fline < max_fline - max_displayed_line) {
 		putchar(':');
 		return;
 	}
 	p = "(END)";
-	if (!line_pos)
+	if (!cur_fline)
 		p = filename;
 	if (num_files > 1) {
-		printf(HIGHLIGHT"%s (file %i of %i) "NORMAL,
+		printf(HIGHLIGHT"%s (file %i of %i)"NORMAL,
 				p, current_file, num_files);
 		return;
 	}
@@ -423,7 +411,7 @@ static void print_ascii(const char *str)
 		do {
 			if (*str == 0x7f)
 				*p++ = '?';
-			else if (*str == 0x9b)
+			else if (*str == (char)0x9b)
 			/* VT100's CSI, aka Meta-ESC. Who's inventor? */
 			/* I want to know who committed this sin */
 				*p++ = '{';
@@ -443,7 +431,7 @@ static void buffer_print(void)
 	int i;
 
 	move_cursor(0, 0);
-	for (i = 0; i < height - 1; i++)
+	for (i = 0; i <= max_displayed_line; i++)
 		if (pattern_valid)
 			print_found(buffer[i]);
 		else
@@ -451,111 +439,194 @@ static void buffer_print(void)
 	status_print();
 }
 
-/* Initialise the buffer */
-static void buffer_init(void)
+static void buffer_fill_and_print(void)
 {
 	int i;
-
-	/* Fill the buffer until the end of the file or the
-	   end of the buffer is reached */
-	for (i = 0; i < height - 1 && i <= num_flines; i++) {
-		buffer[i] = flines[i];
+	for (i = 0; i <= max_displayed_line && cur_fline + i <= max_fline; i++) {
+		buffer[i] = flines[cur_fline + i];
 	}
-
-	/* If the buffer still isn't full, fill it with blank lines */
-	for (; i < height - 1; i++) {
+	for (; i <= max_displayed_line; i++) {
 		buffer[i] = empty_line_marker;
 	}
+	buffer_print();
 }
 
 /* Move the buffer up and down in the file in order to scroll */
 static void buffer_down(int nlines)
 {
-	int i;
+	int diff;
+	cur_fline += nlines;
+	read_lines();
 
-	if (line_pos + (height - 3) + nlines < num_flines) {
-		line_pos += nlines;
-		for (i = 0; i < (height - 1); i++) {
-			buffer[i] = flines[line_pos + i];
-		}
-	} else {
+	if (cur_fline + max_displayed_line > max_fline + TILDES) {
+		cur_fline -= nlines;
+		diff = max_fline - (cur_fline + max_displayed_line) + TILDES;
 		/* As the number of lines requested was too large, we just move
 		to the end of the file */
-		while (line_pos + (height - 3) + 1 < num_flines) {
-			line_pos += 1;
-			for (i = 0; i < (height - 1); i++) {
-				buffer[i] = flines[line_pos + i];
-			}
-		}
+		if (diff > 0)
+			cur_fline += diff;
 	}
-
-	/* We exit if the -E flag has been set */
-	if ((option_mask32 & FLAG_E) && (line_pos + (height - 2) == num_flines))
-		tless_exit(0);
+	buffer_fill_and_print();
 }
 
 static void buffer_up(int nlines)
 {
-	int i;
+	cur_fline -= nlines;
+	if (cur_fline < 0) cur_fline = 0;
+	read_lines();
+	buffer_fill_and_print();
+}
 
-	line_pos -= nlines;
-	if (line_pos < 0) line_pos = 0;
-	for (i = 0; i < height - 1; i++) {
-		if (line_pos + i <= num_flines) {
-			buffer[i] = flines[line_pos + i];
-		} else {
-			buffer[i] = empty_line_marker;
-		}
+static void buffer_line(int linenum)
+{
+	if (linenum + max_displayed_line > max_fline)
+		linenum = max_fline - max_displayed_line + TILDES;
+	if (linenum < 0) linenum = 0;
+	cur_fline = linenum;
+	buffer_fill_and_print();
+}
+
+static void open_file_and_read_lines(void)
+{
+	if (filename) {
+		int fd = xopen(filename, O_RDONLY);
+		dup2(fd, 0);
+		if (fd) close(fd);
+	} else {
+		/* "less" with no arguments in argv[] */
+		/* For status line only */
+		filename = xstrdup(bb_msg_standard_input);
 	}
+	readpos = 0;
+	readeof = 0;
+	linepos = 0;
+	terminated = 1;
+	read_lines();
 }
 
-static void buffer_line(int linenum)
+/* Reinitialize everything for a new file - free the memory and start over */
+static void reinitialize(void)
 {
 	int i;
 
-	if (linenum < 0 || linenum > num_flines) {
-		clear_line();
-		printf(HIGHLIGHT"%s%u"NORMAL, "Cannot seek to line ", linenum + 1);
-		return;
+	if (flines) {
+		for (i = 0; i <= max_fline; i++)
+			free((void*)(flines[i]));
+		free(flines);
+		flines = NULL;
 	}
 
-	for (i = 0; i < height - 1; i++) {
-		if (linenum + i <= num_flines)
-			buffer[i] = flines[linenum + i];
-		else {
-			buffer[i] = empty_line_marker;
-		}
+	max_fline = -1;
+	cur_fline = 0;
+	max_lineno = 0;
+	open_file_and_read_lines();
+	buffer_fill_and_print();
+}
+
+static char* getch_nowait(void)
+{
+	static char input[16];
+	ssize_t sz;
+	fd_set readfds;
+ again:
+	fflush(stdout);
+	FD_ZERO(&readfds);
+	if (max_fline <= cur_fline + max_displayed_line && eof_error > 0) {
+		/* We are interested in stdin */
+		FD_SET(0, &readfds);
 	}
-	line_pos = linenum;
-	buffer_print();
+	FD_SET(kbd_fd, &readfds);
+	tcsetattr(kbd_fd, TCSANOW, &term_vi);
+	select(kbd_fd + 1, &readfds, NULL, NULL, NULL);
+
+	input[0] = '\0';
+	ndelay_on(kbd_fd);
+	sz = read(kbd_fd, input, sizeof(input));
+	ndelay_off(kbd_fd);
+	if (sz < 0) {
+		/* No keyboard input, but we have input on stdin! */
+		if (errno != EAGAIN) /* Huh?? */
+			return input;
+		read_lines();
+		buffer_fill_and_print();
+		goto again;
+	}
+	return input;
 }
 
-/* Reinitialise everything for a new file - free the memory and start over */
-static void reinitialise(void)
+/* Grab a character from input without requiring the return key. If the
+   character is ASCII \033, get more characters and assign certain sequences
+   special return codes. Note that this function works best with raw input. */
+static int less_getch(void)
 {
-	int i;
+	char *input;
+	unsigned i;
+ again:
+	input = getch_nowait();
+	/* Detect escape sequences (i.e. arrow keys) and handle
+	 * them accordingly */
 
-	for (i = 0; i <= num_flines; i++)
-		free(flines[i]);
-	free(flines);
+	if (input[0] == '\033' && input[1] == '[') {
+		set_tty_cooked();
+		i = input[2] - REAL_KEY_UP;
+		if (i < 4)
+			return 20 + i;
+		i = input[2] - REAL_PAGE_UP;
+		if (i < 4)
+			return 24 + i;
+		return 0;
+	}
+	/* Reject almost all control chars */
+	i = input[0];
+	if (i < ' ' && i != 0x0d && i != 8) goto again;
+	set_tty_cooked();
+	return i;
+}
 
-	data_readlines();
-	buffer_init();
-	buffer_print();
+static char* less_gets(int sz)
+{
+	char c;
+	int i = 0;
+	char *result = xzalloc(1);
+	while (1) {
+		fflush(stdout);
+
+		/* I be damned if I know why is it needed *repeatedly*,
+		 * but it is needed. Is it because of stdio? */
+		tcsetattr(kbd_fd, TCSANOW, &term_vi);
+
+		read(kbd_fd, &c, 1);
+		if (c == 0x0d)
+			return result;
+		if (c == 0x7f)
+			c = 8;
+		if (c == 8 && i) {
+			printf("\x8 \x8");
+			i--;
+		}
+		if (c < ' ')
+			continue;
+		if (i >= width - sz - 1)
+			continue; /* len limit */
+		putchar(c);
+		result[i++] = c;
+		result = xrealloc(result, i+1);
+		result[i] = '\0';
+	}
 }
 
 static void examine_file(void)
 {
 	print_statusline("Examine: ");
 	free(filename);
-	filename = tless_gets(sizeof("Examine: ")-1);
+	filename = less_gets(sizeof("Examine: ")-1);
 	/* files start by = argv. why we assume that argv is infinitely long??
 	files[num_files] = filename;
 	current_file = num_files + 1;
 	num_files++; */
 	files[0] = filename;
 	num_files = current_file = 1;
-	reinitialise();
+	reinitialize();
 }
 
 /* This function changes the file currently being paged. direction can be one of the following:
@@ -569,7 +640,7 @@ static void change_file(int direction)
 		current_file = direction ? current_file + direction : 1;
 		free(filename);
 		filename = xstrdup(files[current_file - 1]);
-		reinitialise();
+		reinitialize();
 	} else {
 		print_statusline(direction > 0 ? "No next file" : "No previous file");
 	}
@@ -579,19 +650,20 @@ static void remove_current_file(void)
 {
 	int i;
 
+	if (num_files < 2)
+		return;
+
 	if (current_file != 1) {
 		change_file(-1);
 		for (i = 3; i <= num_files; i++)
 			files[i - 2] = files[i - 1];
 		num_files--;
-		buffer_print();
 	} else {
 		change_file(1);
 		for (i = 2; i <= num_files; i++)
 			files[i - 2] = files[i - 1];
 		num_files--;
 		current_file--;
-		buffer_print();
 	}
 }
 
@@ -602,33 +674,31 @@ static void colon_process(void)
 	/* Clear the current line and print a prompt */
 	print_statusline(" :");
 
-	keypress = tless_getch();
+	keypress = less_getch();
 	switch (keypress) {
-		case 'd':
-			remove_current_file();
-			break;
-		case 'e':
-			examine_file();
-			break;
+	case 'd':
+		remove_current_file();
+		break;
+	case 'e':
+		examine_file();
+		break;
 #if ENABLE_FEATURE_LESS_FLAGS
-		case 'f':
-			m_status_print();
-			break;
+	case 'f':
+		m_status_print();
+		break;
 #endif
-		case 'n':
-			change_file(1);
-			break;
-		case 'p':
-			change_file(-1);
-			break;
-		case 'q':
-			tless_exit(0);
-			break;
-		case 'x':
-			change_file(0);
-			break;
-		default:
-			break;
+	case 'n':
+		change_file(1);
+		break;
+	case 'p':
+		change_file(-1);
+		break;
+	case 'q':
+		less_exit(0);
+		break;
+	case 'x':
+		change_file(0);
+		break;
 	}
 }
 
@@ -638,7 +708,7 @@ static int normalize_match_pos(int match)
 	if (match >= num_matches)
 		match_pos = num_matches - 1;
 	if (match < 0)
-		return (match_pos = 0);
+		match_pos = 0;
 	return match_pos;
 }
 
@@ -654,8 +724,8 @@ static void regex_process(void)
 	char *uncomp_regex, *err;
 
 	/* Reset variables */
-	match_lines = xrealloc(match_lines, sizeof(int));
-	match_lines[0] = -1;
+	free(match_lines);
+	match_lines = NULL;
 	match_pos = 0;
 	num_matches = 0;
 	if (pattern_valid) {
@@ -666,8 +736,8 @@ static void regex_process(void)
 	/* Get the uncompiled regular expression from the user */
 	clear_line();
 	putchar((option_mask32 & LESS_STATE_MATCH_BACKWARDS) ? '?' : '/');
-	uncomp_regex = tless_gets(1);
-	if (/*!uncomp_regex ||*/ !uncomp_regex[0]) {
+	uncomp_regex = less_gets(1);
+	if (!uncomp_regex[0]) {
 		free(uncomp_regex);
 		buffer_print();
 		return;
@@ -684,19 +754,19 @@ static void regex_process(void)
 	pattern_valid = 1;
 
 	/* Run the regex on each line of the current file */
-	for (match_pos = 0; match_pos <= num_flines; match_pos++) {
+	for (match_pos = 0; match_pos <= max_fline; match_pos++) {
 		if (regexec(&pattern, flines[match_pos], 0, NULL, 0) == 0) {
 			match_lines = xrealloc(match_lines, (num_matches+1) * sizeof(int));
 			match_lines[num_matches++] = match_pos;
 		}
 	}
 
-	if (num_matches == 0 || num_flines <= height - 2) {
+	if (num_matches == 0 || max_fline <= max_displayed_line) {
 		buffer_print();
 		return;
 	}
 	for (match_pos = 0; match_pos < num_matches; match_pos++) {
-		if (match_lines[match_pos] > line_pos)
+		if (match_lines[match_pos] > cur_fline)
 			break;
 	}
 	if (option_mask32 & LESS_STATE_MATCH_BACKWARDS) match_pos--;
@@ -719,7 +789,7 @@ static void number_process(int first_digit)
 
 	/* Receive input until a letter is given */
 	while (i < sizeof(num_input)-1) {
-		num_input[i] = tless_getch();
+		num_input[i] = less_getch();
 		if (!num_input[i] || !isdigit(num_input[i]))
 			break;
 		putchar(num_input[i]);
@@ -738,34 +808,38 @@ static void number_process(int first_digit)
 
 	/* We now know the number and the letter entered, so we process them */
 	switch (keypress) {
-		case KEY_DOWN: case 'z': case 'd': case 'e': case ' ': case '\015':
-			buffer_down(num);
-			break;
-		case KEY_UP: case 'b': case 'w': case 'y': case 'u':
-			buffer_up(num);
-			break;
-		case 'g': case '<': case 'G': case '>':
-			if (num_flines >= height - 2)
-				buffer_line(num - 1);
-			break;
-		case 'p': case '%':
-			buffer_line(((num / 100) * num_flines) - 1);
-			break;
+	case KEY_DOWN: case 'z': case 'd': case 'e': case ' ': case '\015':
+		buffer_down(num);
+		buffer_print();
+		break;
+	case KEY_UP: case 'b': case 'w': case 'y': case 'u':
+		buffer_up(num);
+		buffer_print();
+		break;
+	case 'g': case '<': case 'G': case '>':
+		cur_fline = num + max_displayed_line;
+	 	read_lines();
+		buffer_line(num - 1);
+		break;
+	case 'p': case '%':
+		num = num * (max_fline / 100); /* + max_fline / 2; */
+		cur_fline = num + max_displayed_line;
+	 	read_lines();
+		buffer_line(num);
+		break;
 #if ENABLE_FEATURE_LESS_REGEXP
-		case 'n':
-			goto_match(match_pos + num);
-			break;
-		case '/':
-			option_mask32 &= ~LESS_STATE_MATCH_BACKWARDS;
-			regex_process();
-			break;
-		case '?':
-			option_mask32 |= LESS_STATE_MATCH_BACKWARDS;
-			regex_process();
-			break;
+	case 'n':
+		goto_match(match_pos + num);
+		break;
+	case '/':
+		option_mask32 &= ~LESS_STATE_MATCH_BACKWARDS;
+		regex_process();
+		break;
+	case '?':
+		option_mask32 |= LESS_STATE_MATCH_BACKWARDS;
+		regex_process();
+		break;
 #endif
-		default:
-			break;
 	}
 }
 
@@ -776,23 +850,21 @@ static void flag_change(void)
 
 	clear_line();
 	putchar('-');
-	keypress = tless_getch();
+	keypress = less_getch();
 
 	switch (keypress) {
-		case 'M':
-			option_mask32 ^= FLAG_M;
-			break;
-		case 'm':
-			option_mask32 ^= FLAG_m;
-			break;
-		case 'E':
-			option_mask32 ^= FLAG_E;
-			break;
-		case '~':
-			option_mask32 ^= FLAG_TILDE;
-			break;
-		default:
-			break;
+	case 'M':
+		option_mask32 ^= FLAG_M;
+		break;
+	case 'm':
+		option_mask32 ^= FLAG_m;
+		break;
+	case 'E':
+		option_mask32 ^= FLAG_E;
+		break;
+	case '~':
+		option_mask32 ^= FLAG_TILDE;
+		break;
 	}
 }
 
@@ -803,27 +875,27 @@ static void show_flag_status(void)
 
 	clear_line();
 	putchar('_');
-	keypress = tless_getch();
+	keypress = less_getch();
 
 	switch (keypress) {
-		case 'M':
-			flag_val = option_mask32 & FLAG_M;
-			break;
-		case 'm':
-			flag_val = option_mask32 & FLAG_m;
-			break;
-		case '~':
-			flag_val = option_mask32 & FLAG_TILDE;
-			break;
-		case 'N':
-			flag_val = option_mask32 & FLAG_N;
-			break;
-		case 'E':
-			flag_val = option_mask32 & FLAG_E;
-			break;
-		default:
-			flag_val = 0;
-			break;
+	case 'M':
+		flag_val = option_mask32 & FLAG_M;
+		break;
+	case 'm':
+		flag_val = option_mask32 & FLAG_m;
+		break;
+	case '~':
+		flag_val = option_mask32 & FLAG_TILDE;
+		break;
+	case 'N':
+		flag_val = option_mask32 & FLAG_N;
+		break;
+	case 'E':
+		flag_val = option_mask32 & FLAG_E;
+		break;
+	default:
+		flag_val = 0;
+		break;
 	}
 
 	clear_line();
@@ -831,15 +903,6 @@ static void show_flag_status(void)
 }
 #endif
 
-static void full_repaint(void)
-{
-	int temp_line_pos = line_pos;
-	data_readlines();
-	buffer_init();
-	buffer_line(temp_line_pos);
-}
-
-
 static void save_input_to_file(void)
 {
 	char *current_line;
@@ -847,7 +910,7 @@ static void save_input_to_file(void)
 	FILE *fp;
 
 	print_statusline("Log file: ");
-	current_line = tless_gets(sizeof("Log file: ")-1);
+	current_line = less_gets(sizeof("Log file: ")-1);
 	if (strlen(current_line) > 0) {
 		fp = fopen(current_line, "w");
 		free(current_line);
@@ -855,7 +918,7 @@ static void save_input_to_file(void)
 			print_statusline("Error opening log file");
 			return;
 		}
-		for (i = 0; i < num_flines; i++)
+		for (i = 0; i < max_fline; i++)
 			fprintf(fp, "%s\n", flines[i]);
 		fclose(fp);
 		buffer_print();
@@ -871,16 +934,15 @@ static void add_mark(void)
 	int letter;
 
 	print_statusline("Mark: ");
-	letter = tless_getch();
+	letter = less_getch();
 
 	if (isalpha(letter)) {
-
 		/* If we exceed 15 marks, start overwriting previous ones */
 		if (num_marks == 14)
 			num_marks = 0;
 
 		mark_lines[num_marks][0] = letter;
-		mark_lines[num_marks][1] = line_pos;
+		mark_lines[num_marks][1] = cur_fline;
 		num_marks++;
 	} else {
 		print_statusline("Invalid mark letter");
@@ -893,7 +955,7 @@ static void goto_mark(void)
 	int i;
 
 	print_statusline("Go to mark: ");
-	letter = tless_getch();
+	letter = less_getch();
 	clear_line();
 
 	if (isalpha(letter)) {
@@ -915,17 +977,16 @@ static void goto_mark(void)
 static char opp_bracket(char bracket)
 {
 	switch (bracket) {
-		case '{': case '[':
-			return bracket + 2;
-		case '(':
-			return ')';
-		case '}': case ']':
-			return bracket - 2;
-		case ')':
-			return '(';
-		default:
-			return 0;
+	case '{': case '[':
+		return bracket + 2;
+	case '(':
+		return ')';
+	case '}': case ']':
+		return bracket - 2;
+	case ')':
+		return '(';
 	}
+	return 0;
 }
 
 static void match_right_bracket(char bracket)
@@ -933,11 +994,11 @@ static void match_right_bracket(char bracket)
 	int bracket_line = -1;
 	int i;
 
-	if (strchr(flines[line_pos], bracket) == NULL) {
+	if (strchr(flines[cur_fline], bracket) == NULL) {
 		print_statusline("No bracket in top line");
 		return;
 	}
-	for (i = line_pos + 1; i < num_flines; i++) {
+	for (i = cur_fline + 1; i < max_fline; i++) {
 		if (strchr(flines[i], opp_bracket(bracket)) != NULL) {
 			bracket_line = i;
 			break;
@@ -945,7 +1006,7 @@ static void match_right_bracket(char bracket)
 	}
 	if (bracket_line == -1)
 		print_statusline("No matching bracket found");
-	buffer_line(bracket_line - height + 2);
+	buffer_line(bracket_line - max_displayed_line);
 }
 
 static void match_left_bracket(char bracket)
@@ -953,12 +1014,12 @@ static void match_left_bracket(char bracket)
 	int bracket_line = -1;
 	int i;
 
-	if (strchr(flines[line_pos + height - 2], bracket) == NULL) {
+	if (strchr(flines[cur_fline + max_displayed_line], bracket) == NULL) {
 		print_statusline("No bracket in bottom line");
 		return;
 	}
 
-	for (i = line_pos + height - 2; i >= 0; i--) {
+	for (i = cur_fline + max_displayed_line; i >= 0; i--) {
 		if (strchr(flines[i], opp_bracket(bracket)) != NULL) {
 			bracket_line = i;
 			break;
@@ -974,105 +1035,104 @@ static void match_left_bracket(char bracket)
 static void keypress_process(int keypress)
 {
 	switch (keypress) {
-		case KEY_DOWN: case 'e': case 'j': case 0x0d:
-			buffer_down(1);
-			buffer_print();
-			break;
-		case KEY_UP: case 'y': case 'k':
-			buffer_up(1);
-			buffer_print();
-			break;
-		case PAGE_DOWN: case ' ': case 'z':
-			buffer_down(height - 1);
-			buffer_print();
-			break;
-		case PAGE_UP: case 'w': case 'b':
-			buffer_up(height - 1);
-			buffer_print();
-			break;
-		case 'd':
-			buffer_down((height - 1) / 2);
-			buffer_print();
-			break;
-		case 'u':
-			buffer_up((height - 1) / 2);
-			buffer_print();
-			break;
-		case KEY_HOME: case 'g': case 'p': case '<': case '%':
-			buffer_line(0);
-			break;
-		case KEY_END: case 'G': case '>':
-			buffer_line(num_flines - height + 2);
-			break;
-		case 'q': case 'Q':
-			tless_exit(0);
-			break;
+	case KEY_DOWN: case 'e': case 'j': case 0x0d:
+		buffer_down(1);
+		buffer_print();
+		break;
+	case KEY_UP: case 'y': case 'k':
+		buffer_up(1);
+		buffer_print();
+		break;
+	case PAGE_DOWN: case ' ': case 'z':
+		buffer_down(max_displayed_line + 1);
+		buffer_print();
+		break;
+	case PAGE_UP: case 'w': case 'b':
+		buffer_up(max_displayed_line + 1);
+		buffer_print();
+		break;
+	case 'd':
+		buffer_down((max_displayed_line + 1) / 2);
+		buffer_print();
+		break;
+	case 'u':
+		buffer_up((max_displayed_line + 1) / 2);
+		buffer_print();
+		break;
+	case KEY_HOME: case 'g': case 'p': case '<': case '%':
+		buffer_line(0);
+		break;
+	case KEY_END: case 'G': case '>':
+		cur_fline = MAXLINES;
+		read_lines();
+		buffer_line(cur_fline);
+		break;
+	case 'q': case 'Q':
+		less_exit(0);
+		break;
 #if ENABLE_FEATURE_LESS_MARKS
-		case 'm':
-			add_mark();
-			buffer_print();
-			break;
-		case '\'':
-			goto_mark();
-			buffer_print();
-			break;
+	case 'm':
+		add_mark();
+		buffer_print();
+		break;
+	case '\'':
+		goto_mark();
+		buffer_print();
+		break;
 #endif
-		case 'r':
-			buffer_print();
-			break;
-		case 'R':
-			full_repaint();
-			break;
-		case 's':
-			save_input_to_file();
-			break;
-		case 'E':
-			examine_file();
-			break;
+	case 'r': case 'R':
+		buffer_print();
+		break;
+	/*case 'R':
+		full_repaint();
+		break;*/
+	case 's':
+		save_input_to_file();
+		break;
+	case 'E':
+		examine_file();
+		break;
 #if ENABLE_FEATURE_LESS_FLAGS
-		case '=':
-			m_status_print();
-			break;
+	case '=':
+		m_status_print();
+		break;
 #endif
 #if ENABLE_FEATURE_LESS_REGEXP
-		case '/':
-			option_mask32 &= ~LESS_STATE_MATCH_BACKWARDS;
-			regex_process();
-			break;
-		case 'n':
-//printf("HERE 3\n");sleep(1);
-			goto_match(match_pos + 1);
-			break;
-		case 'N':
-			goto_match(match_pos - 1);
-			break;
-		case '?':
-			option_mask32 |= LESS_STATE_MATCH_BACKWARDS;
-			regex_process();
-			break;
+	case '/':
+		option_mask32 &= ~LESS_STATE_MATCH_BACKWARDS;
+		regex_process();
+		break;
+	case 'n':
+		goto_match(match_pos + 1);
+		break;
+	case 'N':
+		goto_match(match_pos - 1);
+		break;
+	case '?':
+		option_mask32 |= LESS_STATE_MATCH_BACKWARDS;
+		regex_process();
+		break;
 #endif
 #if ENABLE_FEATURE_LESS_FLAGCS
-		case '-':
-			flag_change();
-			buffer_print();
-			break;
-		case '_':
-			show_flag_status();
-			break;
+	case '-':
+		flag_change();
+		buffer_print();
+		break;
+	case '_':
+		show_flag_status();
+		break;
 #endif
 #if ENABLE_FEATURE_LESS_BRACKETS
-		case '{': case '(': case '[':
-			match_right_bracket(keypress);
-			break;
-		case '}': case ')': case ']':
-			match_left_bracket(keypress);
-			break;
+	case '{': case '(': case '[':
+		match_right_bracket(keypress);
+		break;
+	case '}': case ')': case ']':
+		match_left_bracket(keypress);
+		break;
 #endif
-		case ':':
-			colon_process();
-			break;
-		default:
-			break;
+	case ':':
+		colon_process();
+		break;
 	}
 
 	if (isdigit(keypress))
@@ -1092,8 +1152,8 @@ int less_main(int argc, char **argv)
 	getopt32(argc, argv, "EMmN~");
 	argc -= optind;
 	argv += optind;
-	files = argv;
 	num_files = argc;
+	files = argv;
 
 	/* Another popular pager, most, detects when stdout
 	 * is not a tty and turns into cat. This makes sense. */
@@ -1109,33 +1169,35 @@ int less_main(int argc, char **argv)
 	} else
 		filename = xstrdup(files[0]);
 
-	inp = xfopen(CURRENT_TTY, "r");
+	kbd_fd = xopen(CURRENT_TTY, O_RDONLY);
 
-	get_terminal_width_height(fileno(inp), &width, &height);
-	if (width < 10 || height < 3)
+	get_terminal_width_height(kbd_fd, &width, &max_displayed_line);
+	/* 20: two tabstops + 4 */
+	if (width < 20 || max_displayed_line < 3)
 		bb_error_msg_and_die("too narrow here");
+	max_displayed_line -= 2;
 
-	buffer = xmalloc(height * sizeof(char *));
+	buffer = xmalloc((max_displayed_line+1) * sizeof(char *));
 	if (option_mask32 & FLAG_TILDE)
 		empty_line_marker = "";
 
-	data_readlines();
-
-	tcgetattr(fileno(inp), &term_orig);
+	tcgetattr(kbd_fd, &term_orig);
 	signal(SIGTERM, sig_catcher);
 	signal(SIGINT, sig_catcher);
 	term_vi = term_orig;
-	term_vi.c_lflag &= (~ICANON & ~ECHO);
-	term_vi.c_iflag &= (~IXON & ~ICRNL);
-	term_vi.c_oflag &= (~ONLCR);
+	term_vi.c_lflag &= ~(ICANON | ECHO);
+	term_vi.c_iflag &= ~(IXON | ICRNL);
+	/*term_vi.c_oflag &= ~ONLCR;*/
 	term_vi.c_cc[VMIN] = 1;
 	term_vi.c_cc[VTIME] = 0;
 
-	buffer_init();
-	buffer_print();
+	/* Want to do it just once, but it doesn't work, */
+	/* so we are redoing it (see code above). Mystery... */
+	/*tcsetattr(kbd_fd, TCSANOW, &term_vi);*/
 
+	reinitialize();
 	while (1) {
-		keypress = tless_getch();
+		keypress = less_getch();
 		keypress_process(keypress);
 	}
 }