utils.c

/**************************************************************************
 *   utils.c  --  This file is part of GNU nano.                          *
 *                                                                        *
 *   Copyright (C) 1999-2011, 2013-2017 Free Software Foundation, Inc.    *
 *   Copyright (C) 2016 Benno Schulenberg                                 *
 *                                                                        *
 *   GNU nano is free software: you can redistribute it and/or modify     *
 *   it under the terms of the GNU General Public License as published    *
 *   by the Free Software Foundation, either version 3 of the License,    *
 *   or (at your option) any later version.                               *
 *                                                                        *
 *   GNU nano is distributed in the hope that it will be useful,          *
 *   but WITHOUT ANY WARRANTY; without even the implied warranty          *
 *   of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.              *
 *   See the GNU General Public License for more details.                 *
 *                                                                        *
 *   You should have received a copy of the GNU General Public License    *
 *   along with this program.  If not, see http://www.gnu.org/licenses/.  *
 *                                                                        *
 **************************************************************************/

#include "proto.h"

#include <errno.h>
#ifdef HAVE_PWD_H
#include <pwd.h>
#endif
#include <string.h>
#include <unistd.h>

/* Return the user's home directory.  We use $HOME, and if that fails,
 * we fall back on the home directory of the effective user ID. */
void get_homedir(void)
{
    if (homedir == NULL) {
	const char *homenv = getenv("HOME");

#ifdef HAVE_PWD_H
	/* When HOME isn't set, or when we're root, get the home directory
	 * from the password file instead. */
	if (homenv == NULL || geteuid() == 0) {
	    const struct passwd *userage = getpwuid(geteuid());

	    if (userage != NULL)
		homenv = userage->pw_dir;
	}
#endif

	/* Only set homedir if some home directory could be determined,
	 * otherwise keep homedir NULL. */
	if (homenv != NULL && strcmp(homenv, "") != 0)
	    homedir = mallocstrcpy(NULL, homenv);
    }
}

#ifdef ENABLE_LINENUMBERS
/* Return the number of digits that the given integer n takes up. */
int digits(ssize_t n)
{
    if (n < 100000) {
	if (n < 1000) {
	    if (n < 100)
		return 2;
	    else
		return 3;
	} else {
	    if (n < 10000)
		return 4;
	    else
		return 5;
	}
    } else {
	if (n < 10000000) {
	    if (n < 1000000)
		return 6;
	    else
		return 7;
	} else {
	    if (n < 100000000)
		return 8;
	    else
		return 9;
	}
    }
}
#endif

/* Read an integer from str.  If it parses okay, store it in *result
 * and return TRUE; otherwise, return FALSE. */
bool parse_num(const char *str, ssize_t *result)
{
    char *first_error;
    ssize_t value;

    /* The manual page for strtol() says this is required. */
    errno = 0;

    value = (ssize_t)strtol(str, &first_error, 10);

    if (errno == ERANGE || *str == '\0' || *first_error != '\0')
	return FALSE;

    *result = value;

    return TRUE;
}

/* Read two numbers, separated by a comma, from str, and store them in
 * *line and *column.  Return FALSE on error, and TRUE otherwise. */
bool parse_line_column(const char *str, ssize_t *line, ssize_t *column)
{
    bool retval;
    char *firstpart;
    const char *comma;

    while (*str == ' ')
	str++;

    comma = strpbrk(str, "m,. /;");

    if (comma == NULL)
	return parse_num(str, line);

    retval = parse_num(comma + 1, column);

    if (comma == str)
	return retval;

    firstpart = mallocstrcpy(NULL, str);
    firstpart[comma - str] = '\0';

    retval = parse_num(firstpart, line) && retval;

    free(firstpart);

    return retval;
}

/* Reduce the memory allocation of a string to what is needed. */
void snuggly_fit(char **str)
{
    if (*str != NULL)
	*str = charealloc(*str, strlen(*str) + 1);
}

/* Null a string at a certain index and align it. */
void null_at(char **data, size_t index)
{
    *data = charealloc(*data, index + 1);
    (*data)[index] = '\0';
}

/* For non-null-terminated lines.  A line, by definition, shouldn't
 * normally have newlines in it, so encode its nulls as newlines. */
void unsunder(char *str, size_t true_len)
{
    for (; true_len > 0; true_len--, str++) {
	if (*str == '\0')
	    *str = '\n';
    }
}

/* For non-null-terminated lines.  A line, by definition, shouldn't
 * normally have newlines in it, so decode its newlines as nulls. */
void sunder(char *str)
{
    for (; *str != '\0'; str++) {
	if (*str == '\n')
	    *str = '\0';
    }
}

/* Fix the regex if we're on platforms which require an adjustment
 * from GNU-style to BSD-style word boundaries. */
const char *fixbounds(const char *r)
{
#ifndef GNU_WORDBOUNDS
    int i, j = 0;
    char *r2 = charalloc(strlen(r) * 5);
    char *r3;

#ifdef DEBUG
    fprintf(stderr, "fixbounds(): Start string = \"%s\"\n", r);
#endif

    for (i = 0; i < strlen(r); i++) {
	if (r[i] != '\0' && r[i] == '\\' && (r[i + 1] == '>' || r[i + 1] == '<')) {
	    strcpy(&r2[j], "[[:");
	    r2[j + 3] = r[i + 1];
	    strcpy(&r2[j + 4], ":]]");
	    i++;
	    j += 6;
	} else
	    r2[j] = r[i];
	j++;
    }
    r2[j] = '\0';
    r3 = mallocstrcpy(NULL, r2);
    free(r2);
#ifdef DEBUG
    fprintf(stderr, "fixbounds(): Ending string = \"%s\"\n", r3);
#endif
    return (const char *) r3;
#endif /* !GNU_WORDBOUNDS */

    return r;
}

#ifndef DISABLE_SPELLER
/* Is the word starting at the given position in buf and of the given length
 * a separate word?  That is: is it not part of a longer word?*/
bool is_separate_word(size_t position, size_t length, const char *buf)
{
    char before[MAXCHARLEN], after[MAXCHARLEN];
    size_t word_end = position + length;

    /* Get the characters before and after the word, if any. */
    parse_mbchar(buf + move_mbleft(buf, position), before, NULL);
    parse_mbchar(buf + word_end, after, NULL);

    /* If the word starts at the beginning of the line OR the character before
     * the word isn't a letter, and if the word ends at the end of the line OR
     * the character after the word isn't a letter, we have a whole word. */
    return ((position == 0 || !is_alpha_mbchar(before)) &&
		(buf[word_end] == '\0' || !is_alpha_mbchar(after)));
}
#endif /* !DISABLE_SPELLER */

/* Return the position of the needle in the haystack, or NULL if not found.
 * When searching backwards, we will find the last match that starts no later
 * than the given start; otherwise, we find the first match starting no earlier
 * than start.  If we are doing a regexp search, and we find a match, we fill
 * in the global variable regmatches with at most 9 subexpression matches. */
const char *strstrwrapper(const char *haystack, const char *needle,
	const char *start)
{
    if (*needle == '\0') {
#ifndef NANO_TINY
	statusline(ALERT, "Searching for nothing -- please report a bug");
#endif
	return (char *)start;
    }

    if (ISSET(USE_REGEXP)) {
	if (ISSET(BACKWARDS_SEARCH)) {
	    size_t last_find, ceiling, far_end;
	    size_t floor = 0, next_rung = 0;
		/* The start of the search range, and the next start. */

	    if (regexec(&search_regexp, haystack, 1, regmatches, 0) != 0)
		return NULL;

	    far_end = strlen(haystack);
	    ceiling = start - haystack;
	    last_find = regmatches[0].rm_so;

	    /* A result beyond the search range also means: no match. */
	    if (last_find > ceiling)
		return NULL;

	    /* Move the start-of-range forward until there is no more match;
	     * then the last match found is the first match backwards. */
	    while (regmatches[0].rm_so <= ceiling) {
		floor = next_rung;
		last_find = regmatches[0].rm_so;
		/* If this is the last possible match, don't try to advance. */
		if (last_find == ceiling)
		    break;
		next_rung = move_mbright(haystack, last_find);
		regmatches[0].rm_so = next_rung;
		regmatches[0].rm_eo = far_end;
		if (regexec(&search_regexp, haystack, 1, regmatches,
					REG_STARTEND) != 0)
		    break;
	    }

	    /* Find the last match again, to get possible submatches. */
	    regmatches[0].rm_so = floor;
	    regmatches[0].rm_eo = far_end;
	    if (regexec(&search_regexp, haystack, 10, regmatches,
					REG_STARTEND) != 0)
		return NULL;

	    return haystack + regmatches[0].rm_so;
	}

	/* Do a forward regex search from the starting point. */
	regmatches[0].rm_so = start - haystack;
	regmatches[0].rm_eo = strlen(haystack);
	if (regexec(&search_regexp, haystack, 10, regmatches,
					REG_STARTEND) != 0)
	    return NULL;
	else
	    return haystack + regmatches[0].rm_so;
    }
    if (ISSET(CASE_SENSITIVE)) {
	if (ISSET(BACKWARDS_SEARCH))
	    return revstrstr(haystack, needle, start);
	else
	    return strstr(start, needle);
    } else if (ISSET(BACKWARDS_SEARCH))
	return mbrevstrcasestr(haystack, needle, start);

    return mbstrcasestr(start, needle);
}

/* This is a wrapper for the perror() function.  The wrapper temporarily
 * leaves curses mode, calls perror() (which writes to stderr), and then
 * reenters curses mode, updating the screen in the process.  Note that
 * nperror() causes the window to flicker once. */
void nperror(const char *s)
{
    endwin();
    perror(s);
    doupdate();
}

/* This is a wrapper for the malloc() function that properly handles
 * things when we run out of memory.  Thanks, BG, many people have been
 * asking for this... */
void *nmalloc(size_t howmuch)
{
    void *r = malloc(howmuch);

    if (r == NULL && howmuch != 0)
	die(_("nano is out of memory!"));

    return r;
}

/* This is a wrapper for the realloc() function that properly handles
 * things when we run out of memory. */
void *nrealloc(void *ptr, size_t howmuch)
{
    void *r = realloc(ptr, howmuch);

    if (r == NULL && howmuch != 0)
	die(_("nano is out of memory!"));

    return r;
}

/* Allocate and copy the first n characters of the given src string, after
 * freeing the destination.  Usage: "dest = mallocstrncpy(dest, src, n);". */
char *mallocstrncpy(char *dest, const char *src, size_t n)
{
    if (src == NULL)
	src = "";

    if (src != dest)
	free(dest);

    dest = charalloc(n);
    strncpy(dest, src, n);

    return dest;
}

/* Free the dest string and return a malloc'ed copy of src.  Should be used as:
 * "dest = mallocstrcpy(dest, src);". */
char *mallocstrcpy(char *dest, const char *src)
{
    return mallocstrncpy(dest, src, (src == NULL) ? 1 : strlen(src) + 1);
}

/* Free the string at dest and return the string at src. */
char *free_and_assign(char *dest, char *src)
{
    free(dest);
    return src;
}

/* When not in softwrap mode, nano scrolls horizontally within a line in
 * chunks (a bit smaller than the chunks used in softwrapping).  Return the
 * column number of the first character displayed in the edit window when the
 * cursor is at the given column.  Note that (0 <= column -
 * get_page_start(column) < COLS). */
size_t get_page_start(size_t column)
{
    if (column < editwincols - 1 || ISSET(SOFTWRAP) || column == 0)
	return 0;
    else if (editwincols > 8)
	return column - 7 - (column - 7) % (editwincols - 8);
    else
	return column - (editwincols - 2);
}

/* Return the placewewant associated with current_x, i.e. the zero-based
 * column position of the cursor. */
size_t xplustabs(void)
{
    return strnlenpt(openfile->current->data, openfile->current_x);
}

/* Return the index in text of the character that (when displayed) will
 * not overshoot the given column. */
size_t actual_x(const char *text, size_t column)
{
    const char *start = text;
	/* From where we start walking through the text. */
    size_t width = 0;
	/* The current accumulated span, in columns. */

    while (*text != '\0') {
	int charlen = parse_mbchar(text, NULL, &width);

	if (width > column)
	    break;

	text += charlen;
    }

    return (text - start);
}

/* A strnlen() with tabs and multicolumn characters factored in:
 * how many columns wide are the first maxlen bytes of text? */
size_t strnlenpt(const char *text, size_t maxlen)
{
    size_t width = 0;
	/* The screen display width to text[maxlen]. */

    if (maxlen == 0)
	return 0;

    while (*text != '\0') {
	int charlen = parse_mbchar(text, NULL, &width);

	if (maxlen <= charlen)
	    break;

	maxlen -= charlen;
	text += charlen;
    }

    return width;
}

/* Return the number of columns that the given text occupies. */
size_t strlenpt(const char *text)
{
    size_t span = 0;

    while (*text != '\0')
	text += parse_mbchar(text, NULL, &span);

    return span;
}

/* Append a new magicline to filebot. */
void new_magicline(void)
{
    openfile->filebot->next = make_new_node(openfile->filebot);
    openfile->filebot->next->data = mallocstrcpy(NULL, "");
    openfile->filebot = openfile->filebot->next;
    openfile->totsize++;
}

#if !defined(NANO_TINY) || defined(ENABLE_HELP)
/* Remove the magicline from filebot, if there is one and it isn't the
 * only line in the file.  Assume that edittop and current are not at
 * filebot. */
void remove_magicline(void)
{
    if (openfile->filebot->data[0] == '\0' &&
		openfile->filebot != openfile->fileage) {
	openfile->filebot = openfile->filebot->prev;
	free_filestruct(openfile->filebot->next);
	openfile->filebot->next = NULL;
	openfile->totsize--;
    }
}
#endif

#ifndef NANO_TINY
/* Set top_x and bot_x to the top and bottom x-coordinates of the mark,
 * respectively, based on the locations of top and bot.  If
 * right_side_up isn't NULL, set it to TRUE if the mark begins with
 * (mark_begin, mark_begin_x) and ends with (current, current_x), or
 * FALSE otherwise. */
void mark_order(const filestruct **top, size_t *top_x, const filestruct
	**bot, size_t *bot_x, bool *right_side_up)
{
    if ((openfile->current->lineno == openfile->mark_begin->lineno &&
		openfile->current_x > openfile->mark_begin_x) ||
		openfile->current->lineno > openfile->mark_begin->lineno) {
	*top = openfile->mark_begin;
	*top_x = openfile->mark_begin_x;
	*bot = openfile->current;
	*bot_x = openfile->current_x;
	if (right_side_up != NULL)
	    *right_side_up = TRUE;
    } else {
	*bot = openfile->mark_begin;
	*bot_x = openfile->mark_begin_x;
	*top = openfile->current;
	*top_x = openfile->current_x;
	if (right_side_up != NULL)
	    *right_side_up = FALSE;
    }
}

/* Given a line number, return a pointer to the corresponding struct. */
filestruct *fsfromline(ssize_t lineno)
{
    filestruct *f = openfile->current;

    if (lineno <= openfile->current->lineno)
	while (f->lineno != lineno && f->prev != NULL)
	    f = f->prev;
    else
	while (f->lineno != lineno && f->next != NULL)
	    f = f->next;

    if (f->lineno != lineno) {
	statusline(ALERT, _("Internal error: can't match line %ld.  "
			"Please save your work."), (long)lineno);
	return NULL;
    }

    return f;
}
#endif /* !NANO_TINY */

/* Count the number of characters from begin to end, and return it. */
size_t get_totsize(const filestruct *begin, const filestruct *end)
{
    const filestruct *line;
    size_t totsize = 0;

    /* Sum the number of characters (plus a newline) in each line. */
    for (line = begin; line != end->next; line = line->next)
	totsize += mbstrlen(line->data) + 1;

    /* The last line of a file doesn't have a newline -- otherwise it
     * wouldn't be the last line -- so subtract 1 when at EOF. */
    if (line == NULL)
	totsize--;

    return totsize;
}

#ifdef DEBUG
/* Dump the given buffer to stderr. */
void dump_filestruct(const filestruct *inptr)
{
    if (inptr == openfile->fileage)
	fprintf(stderr, "Dumping file buffer to stderr...\n");
    else if (inptr == cutbuffer)
	fprintf(stderr, "Dumping cutbuffer to stderr...\n");
    else
	fprintf(stderr, "Dumping a buffer to stderr...\n");

    while (inptr != NULL) {
	fprintf(stderr, "(%ld) %s\n", (long)inptr->lineno, inptr->data);
	inptr = inptr->next;
    }
}

/* Dump the current buffer to stderr in reverse. */
void dump_filestruct_reverse(void)
{
    const filestruct *fileptr = openfile->filebot;

    while (fileptr != NULL) {
	fprintf(stderr, "(%ld) %s\n", (long)fileptr->lineno,
		fileptr->data);
	fileptr = fileptr->prev;
    }
}
#endif /* DEBUG */