GCC Code Coverage Report
Directory: ./ Exec Total Coverage
File: usr.bin/less/less/../position.c Lines: 50 59 84.7 %
Date: 2017-11-13 Branches: 31 38 81.6 %

Line Branch Exec Source
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/*
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 * Copyright (C) 1984-2012  Mark Nudelman
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 * Modified for use with illumos by Garrett D'Amore.
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 * Copyright 2014 Garrett D'Amore <garrett@damore.org>
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 *
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 * You may distribute under the terms of either the GNU General Public
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 * License or the Less License, as specified in the README file.
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 *
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 * For more information, see the README file.
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 */
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/*
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 * Routines dealing with the "position" table.
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 * This is a table which tells the position (in the input file) of the
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 * first char on each currently displayed line.
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 *
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 * {{ The position table is scrolled by moving all the entries.
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 * Would be better to have a circular table
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 * and just change a couple of pointers. }}
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 */
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#include "less.h"
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#include "position.h"
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static off_t *table = NULL;	/* The position table */
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static int table_size;
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extern int sc_width, sc_height;
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/*
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 * Return the starting file position of a line displayed on the screen.
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 * The line may be specified as a line number relative to the top
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 * of the screen, but is usually one of these special cases:
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 *	the top (first) line on the screen
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 *	the second line on the screen
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 *	the bottom line on the screen
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 *	the line after the bottom line on the screen
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 */
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off_t
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position(int where)
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{
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	switch (where) {
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	case BOTTOM:
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		where = sc_height - 2;
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		break;
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	case BOTTOM_PLUS_ONE:
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		where = sc_height - 1;
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		break;
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	case MIDDLE:
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		where = (sc_height - 1) / 2;
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	}
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	return (table[where]);
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}
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/*
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 * Add a new file position to the bottom of the position table.
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 */
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void
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add_forw_pos(off_t pos)
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{
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	int i;
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	/*
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	 * Scroll the position table up.
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	 */
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	for (i = 1; i < sc_height; i++)
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		table[i-1] = table[i];
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	table[sc_height - 1] = pos;
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}
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/*
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 * Add a new file position to the top of the position table.
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 */
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void
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add_back_pos(off_t pos)
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{
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	int i;
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	/*
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	 * Scroll the position table down.
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	 */
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	for (i = sc_height - 1; i > 0; i--)
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		table[i] = table[i-1];
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	table[0] = pos;
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}
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/*
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 * Initialize the position table, done whenever we clear the screen.
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 */
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void
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pos_clear(void)
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{
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	int i;
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	for (i = 0; i < sc_height; i++)
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		table[i] = -1;
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}
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/*
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 * Allocate or reallocate the position table.
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 */
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void
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pos_init(void)
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{
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	struct scrpos scrpos;
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	if (sc_height <= table_size)
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		return;
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	/*
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	 * If we already have a table, remember the first line in it
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	 * before we free it, so we can copy that line to the new table.
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	 */
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	if (table != NULL) {
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		get_scrpos(&scrpos);
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		free(table);
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	} else {
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		scrpos.pos = -1;
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	}
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	table = ecalloc(sc_height, sizeof (off_t));
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	table_size = sc_height;
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	pos_clear();
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	if (scrpos.pos != -1)
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		table[scrpos.ln-1] = scrpos.pos;
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}
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/*
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 * See if the byte at a specified position is currently on the screen.
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 * Check the position table to see if the position falls within its range.
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 * Return the position table entry if found, -1 if not.
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 */
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int
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onscreen(off_t pos)
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{
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	int i;
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	if (pos < table[0])
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		return (-1);
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	for (i = 1; i < sc_height; i++)
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		if (pos < table[i])
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			return (i-1);
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	return (-1);
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}
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/*
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 * See if the entire screen is empty.
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 */
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int
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empty_screen(void)
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{
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	return (empty_lines(0, sc_height-1));
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}
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int
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empty_lines(int s, int e)
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{
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	int i;
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	for (i = s; i <= e; i++)
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		if (table[i] != -1 && table[i] != 0)
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			return (0);
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	return (1);
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}
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/*
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 * Get the current screen position.
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 * The screen position consists of both a file position and
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 * a screen line number where the file position is placed on the screen.
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 * Normally the screen line number is 0, but if we are positioned
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 * such that the top few lines are empty, we may have to set
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 * the screen line to a number > 0.
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 */
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void
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get_scrpos(struct scrpos *scrpos)
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{
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	int i;
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	/*
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	 * Find the first line on the screen which has something on it,
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	 * and return the screen line number and the file position.
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	 */
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	for (i = 0; i < sc_height; i++)
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		if (table[i] != -1) {
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			scrpos->ln = i+1;
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			scrpos->pos = table[i];
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			return;
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		}
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	/*
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	 * The screen is empty.
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	 */
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	scrpos->pos = -1;
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}
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/*
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 * Adjust a screen line number to be a simple positive integer
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 * in the range { 0 .. sc_height-2 }.
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 * (The bottom line, sc_height-1, is reserved for prompts, etc.)
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 * The given "sline" may be in the range { 1 .. sc_height-1 }
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 * to refer to lines relative to the top of the screen (starting from 1),
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 * or it may be in { -1 .. -(sc_height-1) } to refer to lines
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 * relative to the bottom of the screen.
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 */
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int
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adjsline(int sline)
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{
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	/*
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	 * Negative screen line number means
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	 * relative to the bottom of the screen.
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	 */
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	if (sline < 0)
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		sline += sc_height;
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	/*
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	 * Can't be less than 1 or greater than sc_height-1.
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	 */
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	if (sline <= 0)
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		sline = 1;
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	if (sline >= sc_height)
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		sline = sc_height - 1;
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	/*
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	 * Return zero-based line number, not one-based.
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	 */
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	return (sline-1);
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}