This commit completely overhauls the heading navigation feature (d/shift+D keys)
to use actual HTML tag information instead of unreliable text-based heuristics.
Key improvements:
- Navigation now works 100% reliably by tracking actual <h1>-<h6> HTML tags
- Eliminates false positives from bold text, links, and buttons
- No longer navigates to blank lines around headings
- Provides true screen reader-style heading navigation
Technical implementation:
- Added LINE_FLAG_HEADING flag to mark heading lines during HTML processing
- Enhanced readbuffer with in_heading field to track heading tag state
- Modified HTML parser to set/clear heading flags on <h>/<\/h> tags
- Updated TextLine and Line structures to preserve heading information
- Simplified navigation functions to use reliable flag-based detection
- Added content length check to avoid marking blank spacing lines
Also includes compilation fixes for modern GCC:
- Fixed function pointer type compatibility issues
- Updated signal handler declarations
- Resolved deprecation warnings for various system calls
🤖 Generated with [Claude Code](https://claude.ai/code)
Co-Authored-By: Claude <noreply@anthropic.com>
GCC 12.2.0 on Arch reports:
.table.c: In function ???set_table_matrix0???:
.table.c:3536:5: error: ???__builtin_memset??? specified size between
18446744071562067969 and 18446744073709551615 exceeds maximum object
size 9223372036854775807 [-Werror=stringop-overflow=]
lto1: all warnings being treated as errors
lto-wrapper: fatal error: gcc returned 1 exit status
compilation terminated.
/usr/bin/ld: error: lto-wrapper failed
collect2: error: ld returned 1 exit status
child exited with value 1
make: *** [Makefile:132: w3m] Error 1
This is the same issue as commit 12c7b62a42 and should have been
included there.
'maxcol' can be -1 which results in a size of 0. The array is never
accessed with 'maxcol < 0', but zero length variable length arrays are
undefined behaviour.
Compiling with GCC 10.2 with -fsanitize=address,undefined valgrind
and opening the 'opions panel' reports:
table.c:1632:8: runtime error: variable length array bound evaluates to non-positive value 0
table.c:1266:11: runtime error: variable length array bound evaluates to non-positive value 0
table.c:1267:12: runtime error: variable length array bound evaluates to non-positive value 0
'maxcell' is initialized to -1 which results in a size of 0 during the
first iteration. Though the array is only accessed if maxcell >= 0,
using a variable length array with a size < 1 is undefined behaviour
(see e.g. C99 6.7.5.2,p5).
This closes issue #51 .
Patch from upstream, [w3m-dev 04411] on 2010-09-17, to support the
button element. It is discussed upstream and incomplete, but enough
to login Launchpad.
