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pty: Move the post process after reading the buffer

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to simplify the code logic

Signed-off-by: Xiang Xiao <xiaoxiang@xiaomi.com>
This commit is contained in:
Xiang Xiao 2022-02-19 21:33:04 +08:00 committed by Petro Karashchenko
parent 630b55feec
commit a5a25f72ab
1 changed files with 22 additions and 98 deletions
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120
drivers/serial/pty.c
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@ -408,10 +408,9 @@ static ssize_t pty_read(FAR struct file *filep, FAR char *buffer, size_t len)
FAR struct pty_dev_s *dev;
ssize_t ntotal;
#ifdef CONFIG_SERIAL_TERMIOS
ssize_t nread;
size_t i;
ssize_t i;
ssize_t j;
char ch;
int ret;
#endif
DEBUGASSERT(filep != NULL && filep->f_inode != NULL);
@ -433,119 +432,44 @@ static ssize_t pty_read(FAR struct file *filep, FAR char *buffer, size_t len)
if (dev->pd_iflag & (INLCR | IGNCR | ICRNL))
{
/* We will transfer one byte at a time, making the appropriate
* translations.
*/
ntotal = 0;
for (i = 0; i < len; i++)
while ((ntotal = file_read(&dev->pd_src, buffer, len)) > 0)
{
/* This logic should return if the pipe becomes empty after some
* bytes were read from the pipe. If we have already read some
* data, we use the FIONREAD ioctl to test if there are more bytes
* in the pipe.
*
* REVISIT: An alternative design might be to (1) configure the
* source file as non-blocking, then (2) wait using poll() for the
* first byte to be received. (3) Subsequent bytes would
* use file_read() without polling and would (4) terminate when no
* data is returned.
*/
if (ntotal > 0)
for (i = j = 0; i < ntotal; i++)
{
int nsrc;
/* Perform input processing */
/* There are inherent race conditions in this test. We lock
* the scheduler before the test and after the file_read()
* below to eliminate one race: (a) We detect that there is
* data in the source file, (b) we are suspended and another
* thread reads the data, emptying the fifo, then (c) we
* resume and call file_read(), blocking indefinitely.
*/
ch = buffer[i];
sched_lock();
/* \n -> \r or \r -> \n translation? */
/* Check how many bytes are waiting in the pipe */
ret = file_ioctl(&dev->pd_src, FIONREAD,
(unsigned long)((uintptr_t)&nsrc));
if (ret < 0)
if (ch == '\n' && (dev->pd_iflag & INLCR) != 0)
{
sched_unlock();
ntotal = ret;
break;
ch = '\r';
}
else if (ch == '\r' && (dev->pd_iflag & ICRNL) != 0)
{
ch = '\n';
}
/* Break out of the loop and return ntotal if the pipe is
* empty. This is another race: There fifo was empty when we
* called file_ioctl() above, but it might not be empty right
* now. Losing that race should not lead to any bad behaviors,
* however, we the caller will get those bytes on the next
* read.
/* Discarding \r ? Print character if (1) character is not \r
* or if (2) we were not asked to ignore \r.
*/
if (nsrc < 1)
if (ch != '\r' || (dev->pd_iflag & IGNCR) == 0)
{
sched_unlock();
break;
buffer[j++] = ch;
}
/* Read one byte from the source the byte. This should not
* block.
*/
nread = file_read(&dev->pd_src, &ch, 1);
sched_unlock();
}
else
{
/* Read one byte from the source the byte. This call will
* block if the source pipe is empty.
*
* REVISIT: Should not block if the oflags include O_NONBLOCK.
* How would we ripple the O_NONBLOCK characteristic to the
* contained source pipe? file_fcntl()? Or FIONREAD? See the
* TODO comment at the top of this file.
*/
nread = file_read(&dev->pd_src, &ch, 1);
}
/* Check if file_read was successful */
/* Is the buffer not empty after process? */
if (nread < 0)
if (j != 0)
{
ntotal = nread;
/* Yes, we are done. */
ntotal = j;
break;
}
/* Perform input processing */
/* \n -> \r or \r -> \n translation? */
if (ch == '\n' && (dev->pd_iflag & INLCR) != 0)
{
ch = '\r';
}
else if (ch == '\r' && (dev->pd_iflag & ICRNL) != 0)
{
ch = '\n';
}
/* Discarding \r ? Print character if (1) character is not \r or
* if (2) we were not asked to ignore \r.
*/
if (ch != '\r' || (dev->pd_iflag & IGNCR) == 0)
{
/* Transfer the (possibly translated) character and update the
* count of bytes transferred.
*/
*buffer++ = ch;
ntotal++;
}
}
}
else