Heapsort has O(n·log(n)) worst case runtime and O(1) space usage, which
is better than current implementation's best case, while still keeping
the code simple.
Co-authored-by: Jonas 'Sortie' Termansen <sortie@maxsi.org>
Firstly, lots of places in editor(1) would do a move from (x₀,y₀) to
(x,y) by first moving to (x,y₀) or (x₀,y) and only then (x,y). If the
intermediate positions were not valid cursor positions, this might cause
out of bounds access. Categorically fixed this by removing functions for
moving only horizontally or only vertically.
Secondly, editor_select_set() would set the column before setting the
line. Since the code for setting the column accesses the currently set
line at the new cursor position, it might cause out of bounds access
even on valid cursor positions. Fixed this by swapping the order in
which column and row are set.
Thirdly, the order of arguments passed to row_column_smallest() and
row_column_biggest() was wrong, with column being passed before the row,
even though they were defined the other way. However, this did not
result in out of bounds memory accesses due to the parameters to
editor_cursor_set() also being swapped at relevant callsites.
Finally, the boundary condition for control-down was off by one.
A line longer than 2G might overflow the size_t containing the buffer
length on 32-bit platform. Fix is to use reallocarray with second
parameter twice the size of the element to double the buffer size, since
it will error out if there was an overflow.
Previously command-not-found(1) encoded all its suggestions in code.
This changes it to use a data table to make it easier to understand and
to modify with new suggestions.
The idle thread is now actually run when the system is idle because it
truly goes idle. The idle thread is made power efficient by using the hlt
instruction rather than a busy loop.
The new futex(2) system call is used to implement fast user-space mutexes,
condition variables, and semaphores. The same backend and design is used as
kutexes for truly sleeping kernel mutexes and condition variables.
The new exit_thread(2) flag EXIT_THREAD_FUTEX_WAKE wakes a futex.
Sleeping on clocks in the kernel now uses timers for true sleep.
The interrupt worker thread now truly sleeps when idle.
Kernel threads are now named.
This is a compatible ABI change.
b commonly corresponds to Page Up, and f is added to match.
j and k for lines, ^F and ^B for pages, and g and G for home/end are from vi.
C-n and C-p for lines and C-v and M-v for pages are from Emacs.
< and > for home/end allow using Emacs M-< and M->, tho they are from less(1).
Since this is a console program, ctrl + letter gets mapped to a
control character in the range 1 to 26. Most of these control
characters are no longer in use and can safely be assumed to be
result of ctrl + letter, but ^I maps to the tab character.
I chose ^G since the keybind is memorable, and a user is unlikely
to try to type the BEL character.
Juhani Krekelä
Jonas 'Sortie' Termansen