<Ctrl+numeric slash> does not invoke Go To Line, so it is fitting
that <Esc> <Esc> <numeric slash> does neither. If some user does
want the double escape plus slash to work, they can use --raw.
(Also, if someone really uses <Esc> <Esc> <numeric slash>, they
probably also type the desired line number on the numeric keypad,
and for that to work they needed to have NumLock engaged, and in
that case the double escape plus slash will work fine.)
(Getting rid of this numeric-slash support makes the three-escapes
case very similar to the one-escape case, allowing the first to be
folded into the latter in the next commit.)
With the two situations that need to preserve the escape counter
now returning directly, the resetting of this counter can happen
at the end of each case block.
The escape-parsing routine nowadays returns FOREIGN_SEQUENCE instead
of ERR when encountering an unknown sequence. So, with the two cases
that demand ERR now handled directly, there is no need to check for
ERR any more.
There is no need to reset the digit counter (because this counter
matters only when the escape counter equals two) -- resetting the
escape counter is enough.
The digit counter will be reset to zero the next time when <Esc>
is pressed, and the byte holder gets re-initialized when the next
first digit is pressed. And the escape counter is reset to zero
after returning from a result-giving call of get_byte_kbinput().
When get_byte_kbinput() is called, it has already been determined that
the keyboard input is a digit from zero to nine (or from zero to two
for the first digit), so there is no need to check this again.
When <Esc><Esc> is followed by digit 0 or 1 or 2 but then NOT two more
digits follow, then both the escape counter and the digit counter should
start afresh when a new ESC code arrives.
This fixes https://savannah.gnu.org/bugs/?58788.
Bug existed since before version 2.0.6.
Root has carte blanche to both read unreadable files and write
unwritable files -- the file system does not prevent this. So,
alert root when opening a file that is intended to be read-only.
This fulfills https://savannah.gnu.org/bugs/?58685.
Requested-by: Marius Bakke <mbakke@fastmail.com>
Also, remove an unneeded 'if', as parse_escape_sequence() is only
ever called when there are at least two bytes after the Esc code.
(If there were not, the 'for' loop after calling convert_sequence()
would use an uninitialized 'consumed' value.)
Rereading is unlikely to fail, but *if* it fails, maybe there is a
serious problem and the user wants to try and fix it before saving
the buffer and thus overwriting the original file.
After thinking about it, I don't like it that nano makes an unrequested
failsafe backup: in the vast, vast majority of cases it is a waste both
of time and of disk wear. If the user is worried about data loss, they
can use --backup. The fsync() after writing out the buffer (added in
commit a84cdaaa) already reduces the chances on data loss somewhat.
Benno Schulenberg