Adding upstream version 3:4.8.30.upstream/3%4.8.30

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 900 insertions, 0 deletions

diff --git a/src/editor/editbuffer.c b/src/editor/editbuffer.c
new file mode 100644
index 0000000..24bc7ee
--- /dev/null
+++ b/src/editor/editbuffer.c
@@ -0,0 +1,900 @@
+/*
+   Editor text keep buffer.
+
+   Copyright (C) 2013-2023
+   Free Software Foundation, Inc.
+
+   Written by:
+   Andrew Borodin <aborodin@vmail.ru> 2013
+
+   This file is part of the Midnight Commander.
+
+   The Midnight Commander 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.
+
+   The Midnight Commander 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/>.
+ */
+
+/** \file
+ *  \brief Source: editor text keep buffer.
+ *  \author Andrew Borodin
+ *  \date 2013
+ */
+
+#include <config.h>
+
+#include <ctype.h>              /* isdigit() */
+#include <stdlib.h>
+#include <string.h>
+#include <sys/types.h>
+
+#include "lib/global.h"
+
+#include "lib/vfs/vfs.h"
+
+#include "edit-impl.h"
+#include "editbuffer.h"
+
+/* --------------------------------------------------------------------------------------------- */
+/*-
+ *
+ * here's a quick sketch of the layout: (don't run this through indent.)
+ *
+ *                                       |
+ * \0\0\0\0\0m e _ f i l e . \nf i n . \n|T h i s _ i s _ s o\0\0\0\0\0\0\0\0\0
+ * ______________________________________|______________________________________
+ *                                       |
+ * ...  |  b2[2]   |  b2[1]   |  b2[0]   |  b1[0]   |  b1[1]   |  b1[2]   | ...
+ *      |->        |->        |->        |->        |->        |->        |
+ *                                       |
+ *           _<------------------------->|<----------------->_
+ *                       curs2           |       curs1
+ *           ^                           |                   ^
+ *           |                          ^|^                  |
+ *         cursor                       |||                cursor
+ *                                      |||
+ *                              file end|||file beginning
+ *                                       |
+ *                                       |
+ *
+ *           _
+ * This_is_some_file
+ * fin.
+ *
+ *
+ * This is called a "gap buffer".
+ * See also:
+ * http://en.wikipedia.org/wiki/Gap_buffer
+ * http://stackoverflow.com/questions/4199694/data-structure-for-text-editor
+ */
+
+/*** global variables ****************************************************************************/
+
+/*** file scope macro definitions ****************************************************************/
+
+/*
+ * The editor keeps data in two arrays of buffers.
+ * All buffers have the same size, which must be a power of 2.
+ */
+
+/* Configurable: log2 of the buffer size in bytes */
+#ifndef S_EDIT_BUF_SIZE
+#define S_EDIT_BUF_SIZE 16
+#endif
+
+/* Size of the buffer */
+#define EDIT_BUF_SIZE (((off_t) 1) << S_EDIT_BUF_SIZE)
+
+/* Buffer mask (used to find cursor position relative to the buffer) */
+#define M_EDIT_BUF_SIZE (EDIT_BUF_SIZE - 1)
+
+/*** file scope type declarations ****************************************************************/
+
+/*** forward declarations (file scope functions) *************************************************/
+
+/*** file scope variables ************************************************************************/
+
+/* --------------------------------------------------------------------------------------------- */
+/*** file scope functions ************************************************************************/
+/* --------------------------------------------------------------------------------------------- */
+/**
+  * Get pointer to byte at specified index
+  *
+  * @param buf pointer to editor buffer
+  * @param byte_index byte index
+  *
+  * @return NULL if byte_index is negative or larger than file size; pointer to byte otherwise.
+  */
+static char *
+edit_buffer_get_byte_ptr (const edit_buffer_t * buf, off_t byte_index)
+{
+    void *b;
+
+    if (byte_index >= (buf->curs1 + buf->curs2) || byte_index < 0)
+        return NULL;
+
+    if (byte_index >= buf->curs1)
+    {
+        off_t p;
+
+        p = buf->curs1 + buf->curs2 - byte_index - 1;
+        b = g_ptr_array_index (buf->b2, p >> S_EDIT_BUF_SIZE);
+        return (char *) b + EDIT_BUF_SIZE - 1 - (p & M_EDIT_BUF_SIZE);
+    }
+
+    b = g_ptr_array_index (buf->b1, byte_index >> S_EDIT_BUF_SIZE);
+    return (char *) b + (byte_index & M_EDIT_BUF_SIZE);
+}
+
+/* --------------------------------------------------------------------------------------------- */
+/*** public functions ****************************************************************************/
+/* --------------------------------------------------------------------------------------------- */
+/**
+ * Initialize editor buffers.
+ *
+ * @param buf pointer to editor buffer
+ */
+
+void
+edit_buffer_init (edit_buffer_t * buf, off_t size)
+{
+    buf->b1 = g_ptr_array_new_full (32, g_free);
+    buf->b2 = g_ptr_array_new_full (32, g_free);
+
+    buf->curs1 = 0;
+    buf->curs2 = 0;
+
+    buf->size = size;
+    buf->lines = 0;
+}
+
+/* --------------------------------------------------------------------------------------------- */
+/**
+ * Clean editor buffers.
+ *
+ * @param buf pointer to editor buffer
+ */
+
+void
+edit_buffer_clean (edit_buffer_t * buf)
+{
+    if (buf->b1 != NULL)
+        g_ptr_array_free (buf->b1, TRUE);
+
+    if (buf->b2 != NULL)
+        g_ptr_array_free (buf->b2, TRUE);
+}
+
+/* --------------------------------------------------------------------------------------------- */
+/**
+  * Get byte at specified index
+  *
+  * @param buf pointer to editor buffer
+  * @param byte_index byte index
+  *
+  * @return '\n' if byte_index is negative or larger than file size; byte at byte_index otherwise.
+  */
+
+int
+edit_buffer_get_byte (const edit_buffer_t * buf, off_t byte_index)
+{
+    char *p;
+
+    p = edit_buffer_get_byte_ptr (buf, byte_index);
+
+    return (p != NULL) ? *(unsigned char *) p : '\n';
+}
+
+/* --------------------------------------------------------------------------------------------- */
+
+#ifdef HAVE_CHARSET
+/**
+  * Get utf-8 symbol at specified index
+  *
+  * @param buf pointer to editor buffer
+  * @param byte_index byte index
+  * @param char_length length of returned symbol
+  *
+  * @return '\n' if byte_index is negative or larger than file size;
+  *         0 if utf-8 symbol at specified index is invalid;
+  *         utf-8 symbol otherwise
+  */
+
+int
+edit_buffer_get_utf (const edit_buffer_t * buf, off_t byte_index, int *char_length)
+{
+    gchar *str = NULL;
+    gunichar res;
+    gunichar ch;
+    gchar *next_ch = NULL;
+
+    if (byte_index >= (buf->curs1 + buf->curs2) || byte_index < 0)
+    {
+        *char_length = 0;
+        return '\n';
+    }
+
+    str = edit_buffer_get_byte_ptr (buf, byte_index);
+    if (str == NULL)
+    {
+        *char_length = 0;
+        return 0;
+    }
+
+    res = g_utf8_get_char_validated (str, -1);
+    if (res == (gunichar) (-2) || res == (gunichar) (-1))
+    {
+        /* Retry with explicit bytes to make sure it's not a buffer boundary */
+        size_t i;
+        gchar utf8_buf[UTF8_CHAR_LEN + 1];
+
+        for (i = 0; i < UTF8_CHAR_LEN; i++)
+            utf8_buf[i] = edit_buffer_get_byte (buf, byte_index + i);
+        utf8_buf[i] = '\0';
+        res = g_utf8_get_char_validated (utf8_buf, -1);
+    }
+
+    if (res == (gunichar) (-2) || res == (gunichar) (-1))
+    {
+        ch = *str;
+        *char_length = 0;
+    }
+    else
+    {
+        ch = res;
+        /* Calculate UTF-8 char length */
+        next_ch = g_utf8_next_char (str);
+        *char_length = next_ch - str;
+    }
+
+    return (int) ch;
+}
+
+/* --------------------------------------------------------------------------------------------- */
+/**
+  * Get utf-8 symbol before specified index
+  *
+  * @param buf pointer to editor buffer
+  * @param byte_index byte index
+  * @param char_length length of returned symbol
+  *
+  * @return 0 if byte_index is negative or larger than file size;
+  *         1-byte value before specified index if utf-8 symbol before specified index is invalid;
+  *         utf-8 symbol otherwise
+  */
+
+int
+edit_buffer_get_prev_utf (const edit_buffer_t * buf, off_t byte_index, int *char_length)
+{
+    size_t i;
+    gchar utf8_buf[3 * UTF8_CHAR_LEN + 1];
+    gchar *str;
+    gchar *cursor_buf_ptr;
+    gunichar res;
+
+    if (byte_index > (buf->curs1 + buf->curs2) || byte_index <= 0)
+    {
+        *char_length = 0;
+        return 0;
+    }
+
+    for (i = 0; i < (3 * UTF8_CHAR_LEN); i++)
+        utf8_buf[i] = edit_buffer_get_byte (buf, byte_index + i - (2 * UTF8_CHAR_LEN));
+    utf8_buf[i] = '\0';
+
+    cursor_buf_ptr = utf8_buf + (2 * UTF8_CHAR_LEN);
+    str = g_utf8_find_prev_char (utf8_buf, cursor_buf_ptr);
+
+    if (str == NULL || g_utf8_next_char (str) != cursor_buf_ptr)
+    {
+        *char_length = 1;
+        return *(cursor_buf_ptr - 1);
+    }
+
+    res = g_utf8_get_char_validated (str, -1);
+    if (res == (gunichar) (-2) || res == (gunichar) (-1))
+    {
+        *char_length = 1;
+        return *(cursor_buf_ptr - 1);
+    }
+
+    *char_length = cursor_buf_ptr - str;
+    return (int) res;
+}
+#endif /* HAVE_CHARSET */
+
+/* --------------------------------------------------------------------------------------------- */
+/**
+ * Count lines in editor buffer.
+ *
+ * @param buf editor buffer
+ * @param first start byte offset
+ * @param last finish byte offset
+ *
+ * @return line numbers between "first" and "last" bytes
+ */
+
+long
+edit_buffer_count_lines (const edit_buffer_t * buf, off_t first, off_t last)
+{
+    long lines = 0;
+
+    first = MAX (first, 0);
+    last = MIN (last, buf->size);
+
+    while (first < last)
+        if (edit_buffer_get_byte (buf, first++) == '\n')
+            lines++;
+
+    return lines;
+}
+
+/* --------------------------------------------------------------------------------------------- */
+/**
+ * Get "begin-of-line" offset of line contained specified byte offset
+ *
+ * @param buf editor buffer
+ * @param current byte offset
+ *
+ * @return index of first char of line
+ */
+
+off_t
+edit_buffer_get_bol (const edit_buffer_t * buf, off_t current)
+{
+    if (current <= 0)
+        return 0;
+
+    for (; edit_buffer_get_byte (buf, current - 1) != '\n'; current--)
+        ;
+
+    return current;
+}
+
+/* --------------------------------------------------------------------------------------------- */
+/**
+ * Get "end-of-line" offset of line contained specified byte offset
+ *
+ * @param buf editor buffer
+ * @param current byte offset
+ *
+ * @return index of last char of line + 1
+ */
+
+off_t
+edit_buffer_get_eol (const edit_buffer_t * buf, off_t current)
+{
+    if (current >= buf->size)
+        return buf->size;
+
+    for (; edit_buffer_get_byte (buf, current) != '\n'; current++)
+        ;
+
+    return current;
+}
+
+/* --------------------------------------------------------------------------------------------- */
+/**
+ * Get word from specified offset.
+ *
+ * @param buf editor buffer
+ * @param current start_pos offset
+ * @param start actual start word ofset
+ * @param cut 
+ *
+ * @return word as newly allocated object
+ */
+
+GString *
+edit_buffer_get_word_from_pos (const edit_buffer_t * buf, off_t start_pos, off_t * start,
+                               gsize * cut)
+{
+    off_t word_start;
+    gsize cut_len = 0;
+    GString *match_expr;
+    int c1, c2;
+
+    for (word_start = start_pos; word_start != 0; word_start--, cut_len++)
+    {
+        c1 = edit_buffer_get_byte (buf, word_start);
+        c2 = edit_buffer_get_byte (buf, word_start - 1);
+
+        if (is_break_char (c1) != is_break_char (c2) || c1 == '\n' || c2 == '\n')
+            break;
+    }
+
+    match_expr = g_string_sized_new (16);
+
+    do
+    {
+        c1 = edit_buffer_get_byte (buf, word_start + match_expr->len);
+        c2 = edit_buffer_get_byte (buf, word_start + match_expr->len + 1);
+        g_string_append_c (match_expr, c1);
+    }
+    while (!(is_break_char (c1) != is_break_char (c2) || c1 == '\n' || c2 == '\n'));
+
+    *start = word_start;
+    *cut = cut_len;
+
+    return match_expr;
+}
+
+/* --------------------------------------------------------------------------------------------- */
+/**
+ * Find first character of current word
+ *
+ * @param buf editor buffer
+ * @param word_start position of first character of current word
+ * @param word_len length of current word
+ *
+ * @return TRUE if first character of word is found and this character is not 1) a digit and
+ *         2) a begin of file, FALSE otherwise
+ */
+
+gboolean
+edit_buffer_find_word_start (const edit_buffer_t * buf, off_t * word_start, gsize * word_len)
+{
+    int c;
+    off_t i;
+
+    /* return if at begin of file */
+    if (buf->curs1 <= 0)
+        return FALSE;
+
+    c = edit_buffer_get_previous_byte (buf);
+    /* return if not at end or in word */
+    if (is_break_char (c))
+        return FALSE;
+
+    /* search start of word */
+    for (i = 1;; i++)
+    {
+        int last;
+
+        last = c;
+        c = edit_buffer_get_byte (buf, buf->curs1 - i - 1);
+
+        if (is_break_char (c))
+        {
+            /* return if word starts with digit */
+            if (isdigit (last))
+                return FALSE;
+
+            break;
+        }
+    }
+
+    /* success */
+    *word_start = buf->curs1 - i;       /* start found */
+    *word_len = (gsize) i;
+
+    return TRUE;
+}
+
+/* --------------------------------------------------------------------------------------------- */
+/**
+ * Basic low level single character buffer alterations and movements at the cursor: insert character
+ * at the cursor position and move right.
+ *
+ * @param buf pointer to editor buffer
+ * @param c character to insert
+ */
+
+void
+edit_buffer_insert (edit_buffer_t * buf, int c)
+{
+    void *b;
+    off_t i;
+
+    i = buf->curs1 & M_EDIT_BUF_SIZE;
+
+    /* add a new buffer if we've reached the end of the last one */
+    if (i == 0)
+        g_ptr_array_add (buf->b1, g_malloc0 (EDIT_BUF_SIZE));
+
+    /* perform the insertion */
+    b = g_ptr_array_index (buf->b1, buf->curs1 >> S_EDIT_BUF_SIZE);
+    *((unsigned char *) b + i) = (unsigned char) c;
+
+    /* update cursor position */
+    buf->curs1++;
+
+    /* update file length */
+    buf->size++;
+}
+
+/* --------------------------------------------------------------------------------------------- */
+/**
+ * Basic low level single character buffer alterations and movements at the cursor: insert character
+ * at the cursor position and move left.
+ *
+ * @param buf pointer to editor buffer
+ * @param c character to insert
+ */
+
+void
+edit_buffer_insert_ahead (edit_buffer_t * buf, int c)
+{
+    void *b;
+    off_t i;
+
+    i = buf->curs2 & M_EDIT_BUF_SIZE;
+
+    /* add a new buffer if we've reached the end of the last one */
+    if (i == 0)
+        g_ptr_array_add (buf->b2, g_malloc0 (EDIT_BUF_SIZE));
+
+    /* perform the insertion */
+    b = g_ptr_array_index (buf->b2, buf->curs2 >> S_EDIT_BUF_SIZE);
+    *((unsigned char *) b + EDIT_BUF_SIZE - 1 - i) = (unsigned char) c;
+
+    /* update cursor position */
+    buf->curs2++;
+
+    /* update file length */
+    buf->size++;
+}
+
+/* --------------------------------------------------------------------------------------------- */
+/**
+ * Basic low level single character buffer alterations and movements at the cursor: delete character
+ * at the cursor position.
+ *
+ * @param buf pointer to editor buffer
+ * @param c character to insert
+ */
+
+int
+edit_buffer_delete (edit_buffer_t * buf)
+{
+    void *b;
+    unsigned char c;
+    off_t prev;
+    off_t i;
+
+    prev = buf->curs2 - 1;
+
+    b = g_ptr_array_index (buf->b2, prev >> S_EDIT_BUF_SIZE);
+    i = prev & M_EDIT_BUF_SIZE;
+    c = *((unsigned char *) b + EDIT_BUF_SIZE - 1 - i);
+
+    if (i == 0)
+    {
+        guint j;
+
+        j = buf->b2->len - 1;
+        b = g_ptr_array_index (buf->b2, j);
+        g_ptr_array_remove_index (buf->b2, j);
+    }
+
+    buf->curs2 = prev;
+
+    /* update file length */
+    buf->size--;
+
+    return c;
+}
+
+/* --------------------------------------------------------------------------------------------- */
+/**
+ * Basic low level single character buffer alterations and movements at the cursor: delete character
+ * before the cursor position and move left.
+ *
+ * @param buf pointer to editor buffer
+ * @param c character to insert
+ */
+
+int
+edit_buffer_backspace (edit_buffer_t * buf)
+{
+    void *b;
+    unsigned char c;
+    off_t prev;
+    off_t i;
+
+    prev = buf->curs1 - 1;
+
+    b = g_ptr_array_index (buf->b1, prev >> S_EDIT_BUF_SIZE);
+    i = prev & M_EDIT_BUF_SIZE;
+    c = *((unsigned char *) b + i);
+
+    if (i == 0)
+    {
+        guint j;
+
+        j = buf->b1->len - 1;
+        b = g_ptr_array_index (buf->b1, j);
+        g_ptr_array_remove_index (buf->b1, j);
+    }
+
+    buf->curs1 = prev;
+
+    /* update file length */
+    buf->size--;
+
+    return c;
+}
+
+/* --------------------------------------------------------------------------------------------- */
+/**
+ * Calculate forward offset with specified number of lines.
+ *
+ * @param buf editor buffer
+ * @param current current offset
+ * @param lines number of lines to move forward
+ * @param upto offset to count lines between current and upto.
+ *
+ * @return If lines is zero returns the count of lines from current to upto.
+ *         If upto is zero returns offset of lines forward current.
+ *         Else returns forward offset with specified number of lines
+ */
+
+off_t
+edit_buffer_get_forward_offset (const edit_buffer_t * buf, off_t current, long lines, off_t upto)
+{
+    if (upto != 0)
+        return (off_t) edit_buffer_count_lines (buf, current, upto);
+
+    lines = MAX (lines, 0);
+
+    while (lines-- != 0)
+    {
+        long next;
+
+        next = edit_buffer_get_eol (buf, current) + 1;
+        if (next > buf->size)
+            break;
+        current = next;
+    }
+
+    return current;
+}
+
+/* --------------------------------------------------------------------------------------------- */
+/**
+ * Calculate backward offset with specified number of lines.
+ *
+ * @param buf editor buffer
+ * @param current current offset
+ * @param lines number of lines to move backward
+ *
+ * @return backward offset with specified number of lines.
+ */
+
+off_t
+edit_buffer_get_backward_offset (const edit_buffer_t * buf, off_t current, long lines)
+{
+    lines = MAX (lines, 0);
+    current = edit_buffer_get_bol (buf, current);
+
+    while (lines-- != 0 && current != 0)
+        current = edit_buffer_get_bol (buf, current - 1);
+
+    return current;
+}
+
+/* --------------------------------------------------------------------------------------------- */
+/**
+ * Load file into editor buffer
+ *
+ * @param buf pointer to editor buffer
+ * @param fd file descriptor
+ * @param size file size
+ *
+ * @return number of read bytes
+ */
+
+off_t
+edit_buffer_read_file (edit_buffer_t * buf, int fd, off_t size,
+                       edit_buffer_read_file_status_msg_t * sm, gboolean * aborted)
+{
+    off_t ret = 0;
+    off_t i, j;
+    off_t data_size;
+    void *b;
+    status_msg_t *s = STATUS_MSG (sm);
+    unsigned short update_cnt = 0;
+
+    *aborted = FALSE;
+
+    buf->lines = 0;
+    buf->curs2 = size;
+    i = buf->curs2 >> S_EDIT_BUF_SIZE;
+
+    /* fill last part of b2 */
+    data_size = buf->curs2 & M_EDIT_BUF_SIZE;
+    if (data_size != 0)
+    {
+        b = g_malloc0 (EDIT_BUF_SIZE);
+        g_ptr_array_add (buf->b2, b);
+        b = (char *) b + EDIT_BUF_SIZE - data_size;
+        ret = mc_read (fd, b, data_size);
+
+        /* count lines */
+        for (j = 0; j < ret; j++)
+            if (*((char *) b + j) == '\n')
+                buf->lines++;
+
+        if (ret < 0 || ret != data_size)
+            return ret;
+    }
+
+    /* fulfill other parts of b2 from end to begin */
+    data_size = EDIT_BUF_SIZE;
+    for (--i; i >= 0; i--)
+    {
+        off_t sz;
+
+        b = g_malloc0 (data_size);
+        g_ptr_array_add (buf->b2, b);
+        sz = mc_read (fd, b, data_size);
+        if (sz >= 0)
+            ret += sz;
+
+        /* count lines */
+        for (j = 0; j < sz; j++)
+            if (*((char *) b + j) == '\n')
+                buf->lines++;
+
+        if (s != NULL && s->update != NULL)
+        {
+            update_cnt = (update_cnt + 1) & 0xf;
+            if (update_cnt == 0)
+            {
+                /* FIXME: overcare */
+                if (sm->buf == NULL)
+                    sm->buf = buf;
+
+                sm->loaded = ret;
+                if (s->update (s) == B_CANCEL)
+                {
+                    *aborted = TRUE;
+                    return (-1);
+                }
+            }
+        }
+
+        if (sz != data_size)
+            break;
+    }
+
+    /* reverse buffer */
+    for (i = 0; i < (off_t) buf->b2->len / 2; i++)
+    {
+        void **b1, **b2;
+
+        b1 = &g_ptr_array_index (buf->b2, i);
+        b2 = &g_ptr_array_index (buf->b2, buf->b2->len - 1 - i);
+
+        b = *b1;
+        *b1 = *b2;
+        *b2 = b;
+
+        if (s != NULL && s->update != NULL)
+        {
+            update_cnt = (update_cnt + 1) & 0xf;
+            if (update_cnt == 0)
+            {
+                sm->loaded = ret;
+                if (s->update (s) == B_CANCEL)
+                {
+                    *aborted = TRUE;
+                    return (-1);
+                }
+            }
+        }
+    }
+
+    return ret;
+}
+
+/* --------------------------------------------------------------------------------------------- */
+/**
+ * Write editor buffer content to file
+ *
+ * @param buf pointer to editor buffer
+ * @param fd file descriptor
+ *
+ * @return number of written bytes
+ */
+
+off_t
+edit_buffer_write_file (edit_buffer_t * buf, int fd)
+{
+    off_t ret = 0;
+    off_t i;
+    off_t data_size, sz;
+    void *b;
+
+    /* write all fulfilled parts of b1 from begin to end */
+    if (buf->b1->len != 0)
+    {
+        data_size = EDIT_BUF_SIZE;
+        for (i = 0; i < (off_t) buf->b1->len - 1; i++)
+        {
+            b = g_ptr_array_index (buf->b1, i);
+            sz = mc_write (fd, b, data_size);
+            if (sz >= 0)
+                ret += sz;
+            else if (i == 0)
+                ret = sz;
+            if (sz != data_size)
+                return ret;
+        }
+
+        /* write last partially filled part of b1 */
+        data_size = ((buf->curs1 - 1) & M_EDIT_BUF_SIZE) + 1;
+        b = g_ptr_array_index (buf->b1, i);
+        sz = mc_write (fd, b, data_size);
+        if (sz >= 0)
+            ret += sz;
+        if (sz != data_size)
+            return ret;
+    }
+
+    /* write b2 from end to begin, if b2 contains some data */
+    if (buf->b2->len != 0)
+    {
+        /* write last partially filled part of b2 */
+        i = buf->b2->len - 1;
+        b = g_ptr_array_index (buf->b2, i);
+        data_size = ((buf->curs2 - 1) & M_EDIT_BUF_SIZE) + 1;
+        sz = mc_write (fd, (char *) b + EDIT_BUF_SIZE - data_size, data_size);
+        if (sz >= 0)
+            ret += sz;
+
+        if (sz == data_size)
+        {
+            /* write other fulfilled parts of b2 from end to begin */
+            data_size = EDIT_BUF_SIZE;
+            while (--i >= 0)
+            {
+                b = g_ptr_array_index (buf->b2, i);
+                sz = mc_write (fd, b, data_size);
+                if (sz >= 0)
+                    ret += sz;
+                if (sz != data_size)
+                    break;
+            }
+        }
+    }
+
+    return ret;
+}
+
+/* --------------------------------------------------------------------------------------------- */
+/**
+ * Calculate percentage of specified character offset
+ *
+ * @param buf pointer to editor buffer
+ * @param p character offset
+ *
+ * @return percentage of specified character offset
+ */
+
+int
+edit_buffer_calc_percent (const edit_buffer_t * buf, off_t offset)
+{
+    int percent;
+
+    if (buf->size == 0)
+        percent = 0;
+    else if (offset >= buf->size)
+        percent = 100;
+    else if (offset > (INT_MAX / 100))
+        percent = offset / (buf->size / 100);
+    else
+        percent = offset * 100 / buf->size;
+
+    return percent;
+}
+
+/* --------------------------------------------------------------------------------------------- */