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Update document.comb_x and comb_y when splitting lines.

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On 2008-09-05, it was reported to elinks-dev that ELinks hits an
internal error (bad alloc_header) when given a specific HTML file.
On 2008-09-09, out-of-range values of document->comb_x and
document->comb_y were noted as the cause of memory corruption.
Update those variables when splitting, aligning, or justifying a line.
Add many assertions to detect the bug if it occurs again.
This commit is contained in:
Kalle Olavi Niemitalo 2008-09-14 16:54:43 +03:00 committed by Kalle Olavi Niemitalo
parent 8548108e39
commit 0f6add14f2
1 changed files with 102 additions and 1 deletions
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103
src/document/html/renderer.c
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@ -232,7 +232,10 @@ realloc_spaces(struct part *part, int length)
/* When we clear chars we want to preserve and use the background colors
* already in place else we could end up ``staining'' the background especial
* when drawing table cells. So make the cleared chars share the colors in
* place. */
* place.
*
* This function does not update document.comb_x and document.comb_y.
* That is the caller's responsibility. */
static inline void
clear_hchars(struct html_context *html_context, int x, int y, int width)
{
@ -363,6 +366,66 @@ get_format_screen_char(struct html_context *html_context,
return &schar_cache;
}
/* document.comb_x and document.comb_y exist only when CONFIG_COMBINE
* is defined. assert() does nothing if CONFIG_FASTMEM is defined. */
#if defined(CONFIG_COMBINE) && !defined(CONFIG_FASTMEM)
/** Assert that path->document->comb_x and part->document->comb_y
* refer to an allocated struct screen_char, or comb_x is -1.
*
* The CONFIG_COMBINE variant of set_hline() can update the
* screen_char.data at these coordinates. Sometimes, the coordinates
* have not been valid, and the update has corrupted memory. These
* assertions should catch that bug if it happens again.
*
* @post This function can leave ::assert_failed set, so the caller
* should use ::if_assert_failed, perhaps with discard_comb_x_y(). */
static void
assert_comb_x_y_ok(const struct document *document)
{
assert(document);
if (document->comb_x != -1) {
assert(document->comb_y >= 0);
assert(document->comb_y < document->height);
assert(document->comb_x >= 0);
assert(document->comb_x < document->data[document->comb_y].length);
}
}
#else
# define assert_comb_x_y_ok(document) ((void) 0)
#endif
#ifdef CONFIG_COMBINE
/** Discard any combining characters that have not yet been combined
* with to the previous base character. */
static void
discard_comb_x_y(struct document *document)
{
document->comb_x = -1;
document->comb_y = -1;
document->combi_length = 0;
}
#else
# define discard_comb_x_y(document) ((void) 0)
#endif
#ifdef CONFIG_COMBINE
static void
move_comb_x_y(struct part *part, int xf, int yf, int xt, int yt)
{
if (part->document->comb_x != -1
&& part->document->comb_y == Y(yf)
&& part->document->comb_x >= X(xf)) {
if (yt >= 0) {
part->document->comb_x += xt - xf;
part->document->comb_y += yt - yf;
} else
discard_comb_x_y(part->document);
}
}
#else
# define move_comb_x_y(part, xf, yf, xt, yt) ((void) 0)
#endif
#ifdef CONFIG_UTF8
/* First possibly do the format change and then find out what coordinates
* to use since sub- or superscript might change them */
@ -405,6 +468,10 @@ set_hline(struct html_context *html_context, unsigned char *chars, int charslen,
if (part->document) {
struct document *const document = part->document;
assert_comb_x_y_ok(document);
if_assert_failed discard_comb_x_y(document);
/* Reallocate LINE(y).chars[] to large enough. The
* last parameter of realloc_line is the index of the
* last element to which we may want to write,
@ -452,7 +519,10 @@ set_hline(struct html_context *html_context, unsigned char *chars, int charslen,
goto good_char;
} else {
/* Still not full char */
assert_comb_x_y_ok(document);
LINE(y).length = orig_length;
assert_comb_x_y_ok(document);
if_assert_failed discard_comb_x_y(document);
return 0;
}
}
@ -499,6 +569,9 @@ good_char:
if (document->comb_x != -1) {
unicode_val_T prev = get_combined(document->combi, document->combi_length + 1);
assert_comb_x_y_ok(document);
if_assert_failed prev = UCS_NO_CHAR;
if (prev != UCS_NO_CHAR)
document->data[document->comb_y]
.chars[document->comb_x].data = prev;
@ -529,6 +602,8 @@ good_char:
#ifdef CONFIG_COMBINE
document->comb_x = X(x);
document->comb_y = Y(y);
assert_comb_x_y_ok(document);
if_assert_failed discard_comb_x_y(document);
#endif
copy_screen_chars(&POS(x++, y), schar, 1);
} /* while chars < end */
@ -559,7 +634,10 @@ good_char:
* which is the number of bytes, not the number of cells.
* Change the length to the correct size, but don't let it
* get smaller than it was on entry to this function. */
assert_comb_x_y_ok(document);
LINE(y).length = int_max(orig_length, X(x));
assert_comb_x_y_ok(document);
if_assert_failed discard_comb_x_y(document);
len = x - x2;
} else { /* part->document == NULL */
if (utf8) {
@ -765,6 +843,8 @@ move_links(struct html_context *html_context, int xf, int yf, int xt, int yt)
}
}
/* This function does not update document.comb_x and document.comb_y.
* That is the caller's responsibility. */
static inline void
copy_chars(struct html_context *html_context, int x, int y, int width, struct screen_char *d)
{
@ -800,10 +880,16 @@ move_chars(struct html_context *html_context, int x, int y, int nx, int ny)
if (LEN(y) - x <= 0) return;
copy_chars(html_context, nx, ny, LEN(y) - x, &POS(x, y));
assert_comb_x_y_ok(part->document);
move_comb_x_y(part, x, y, nx, ny);
LINE(y).length = X(x);
assert_comb_x_y_ok(part->document);
if_assert_failed discard_comb_x_y(part->document);
move_links(html_context, x, y, nx, ny);
}
/** Shift the line @a y to the right by @a shift character cells,
* and update document.comb_x and document.comb_y. */
static inline void
shift_chars(struct html_context *html_context, int y, int shift)
{
@ -826,11 +912,18 @@ shift_chars(struct html_context *html_context, int y, int shift)
copy_screen_chars(a, &POS(0, y), len);
assert_comb_x_y_ok(part->document);
if_assert_failed discard_comb_x_y(part->document);
clear_hchars(html_context, 0, y, shift);
copy_chars(html_context, shift, y, len, a);
fmem_free(a);
move_links(html_context, 0, y, shift, y);
move_comb_x_y(part, 0, y, shift, y);
assert_comb_x_y_ok(part->document);
if_assert_failed discard_comb_x_y(part->document);
}
static inline void
@ -846,8 +939,15 @@ del_chars(struct html_context *html_context, int x, int y)
assert(part && part->document && part->document->data);
if_assert_failed return;
assert_comb_x_y_ok(part->document);
if_assert_failed discard_comb_x_y(part->document);
LINE(y).length = X(x);
move_comb_x_y(part, x, y, -1, -1);
move_links(html_context, x, y, -1, -1);
assert_comb_x_y_ok(part->document);
if_assert_failed discard_comb_x_y(part->document);
}
#if TABLE_LINE_PADDING < 0
@ -1173,6 +1273,7 @@ justify_line(struct html_context *html_context, int y)
* link. */
new_spaces = new_start - prev_end - 1;
if (word && new_spaces) {
move_comb_x_y(part, prev_end + 1, y, new_start, y);
move_links(html_context, prev_end + 1, y, new_start, y);
insert_spaces_in_link(part,
new_start, y, new_spaces);