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tty: n_tty: extract ECHO_OP processing to a separate function 

__process_echoes() contains ECHO_OPs processing. It is stuffed in a
while loop and the whole function is barely readable. Separate it to a
new function: n_tty_process_echo_ops().

Signed-off-by: "Jiri Slaby (SUSE)" <jirislaby@kernel.org>
Link: https://lore.kernel.org/r/20230827074147.2287-14-jirislaby@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Jiri Slaby (SUSE) 2023-08-27 09:41:46 +02:00 committed by Greg Kroah-Hartman
parent e30364c708
commit 2aa91851ff
1 changed files with 98 additions and 96 deletions
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194
drivers/tty/n_tty.c
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@ -582,6 +582,100 @@ break_out:
return i;
}
static int n_tty_process_echo_ops(struct tty_struct *tty, size_t *tail,
int space)
{
struct n_tty_data *ldata = tty->disc_data;
u8 op;
/*
* Since add_echo_byte() is called without holding output_lock, we
* might see only portion of multi-byte operation.
*/
if (MASK(ldata->echo_commit) == MASK(*tail + 1))
return -ENODATA;
/*
* If the buffer byte is the start of a multi-byte operation, get the
* next byte, which is either the op code or a control character value.
*/
op = echo_buf(ldata, *tail + 1);
switch (op) {
case ECHO_OP_ERASE_TAB: {
unsigned int num_chars, num_bs;
if (MASK(ldata->echo_commit) == MASK(*tail + 2))
return -ENODATA;
num_chars = echo_buf(ldata, *tail + 2);
/*
* Determine how many columns to go back in order to erase the
* tab. This depends on the number of columns used by other
* characters within the tab area. If this (modulo 8) count is
* from the start of input rather than from a previous tab, we
* offset by canon column. Otherwise, tab spacing is normal.
*/
if (!(num_chars & 0x80))
num_chars += ldata->canon_column;
num_bs = 8 - (num_chars & 7);
if (num_bs > space)
return -ENOSPC;
space -= num_bs;
while (num_bs--) {
tty_put_char(tty, '\b');
if (ldata->column > 0)
ldata->column--;
}
*tail += 3;
break;
}
case ECHO_OP_SET_CANON_COL:
ldata->canon_column = ldata->column;
*tail += 2;
break;
case ECHO_OP_MOVE_BACK_COL:
if (ldata->column > 0)
ldata->column--;
*tail += 2;
break;
case ECHO_OP_START:
/* This is an escaped echo op start code */
if (!space)
return -ENOSPC;
tty_put_char(tty, ECHO_OP_START);
ldata->column++;
space--;
*tail += 2;
break;
default:
/*
* If the op is not a special byte code, it is a ctrl char
* tagged to be echoed as "^X" (where X is the letter
* representing the control char). Note that we must ensure
* there is enough space for the whole ctrl pair.
*/
if (space < 2)
return -ENOSPC;
tty_put_char(tty, '^');
tty_put_char(tty, op ^ 0100);
ldata->column += 2;
space -= 2;
*tail += 2;
break;
}
return space;
}
/**
* __process_echoes - write pending echo characters
* @tty: terminal device
@ -617,104 +711,12 @@ static size_t __process_echoes(struct tty_struct *tty)
while (MASK(ldata->echo_commit) != MASK(tail)) {
c = echo_buf(ldata, tail);
if (c == ECHO_OP_START) {
u8 op;
bool space_left = true;
/*
* Since add_echo_byte() is called without holding
* output_lock, we might see only portion of multi-byte
* operation.
*/
if (MASK(ldata->echo_commit) == MASK(tail + 1))
int ret = n_tty_process_echo_ops(tty, &tail, space);
if (ret == -ENODATA)
goto not_yet_stored;
/*
* If the buffer byte is the start of a multi-byte
* operation, get the next byte, which is either the
* op code or a control character value.
*/
op = echo_buf(ldata, tail + 1);
switch (op) {
case ECHO_OP_ERASE_TAB: {
unsigned int num_chars, num_bs;
if (MASK(ldata->echo_commit) == MASK(tail + 2))
goto not_yet_stored;
num_chars = echo_buf(ldata, tail + 2);
/*
* Determine how many columns to go back
* in order to erase the tab.
* This depends on the number of columns
* used by other characters within the tab
* area. If this (modulo 8) count is from
* the start of input rather than from a
* previous tab, we offset by canon column.
* Otherwise, tab spacing is normal.
*/
if (!(num_chars & 0x80))
num_chars += ldata->canon_column;
num_bs = 8 - (num_chars & 7);
if (num_bs > space) {
space_left = false;
break;
}
space -= num_bs;
while (num_bs--) {
tty_put_char(tty, '\b');
if (ldata->column > 0)
ldata->column--;
}
tail += 3;
break;
}
case ECHO_OP_SET_CANON_COL:
ldata->canon_column = ldata->column;
tail += 2;
break;
case ECHO_OP_MOVE_BACK_COL:
if (ldata->column > 0)
ldata->column--;
tail += 2;
break;
case ECHO_OP_START:
/* This is an escaped echo op start code */
if (!space) {
space_left = false;
break;
}
tty_put_char(tty, ECHO_OP_START);
ldata->column++;
space--;
tail += 2;
break;
default:
/*
* If the op is not a special byte code,
* it is a ctrl char tagged to be echoed
* as "^X" (where X is the letter
* representing the control char).
* Note that we must ensure there is
* enough space for the whole ctrl pair.
*
*/
if (space < 2) {
space_left = false;
break;
}
tty_put_char(tty, '^');
tty_put_char(tty, op ^ 0100);
ldata->column += 2;
space -= 2;
tail += 2;
}
if (!space_left)
if (ret < 0)
break;
space = ret;
} else {
if (O_OPOST(tty)) {
int retval = do_output_char(c, tty, space);