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incubator-nuttx/drivers/serial/pty.c

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/****************************************************************************
* drivers/serial/pty.c
*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership. The
* ASF licenses this file to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance with the
* License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
* License for the specific language governing permissions and limitations
* under the License.
*
****************************************************************************/
/****************************************************************************
* Included Files
****************************************************************************/
#include <nuttx/config.h>
#include <ctype.h>
#include <sys/types.h>
#include <sys/ioctl.h>
#include <stdbool.h>
#include <unistd.h>
#include <sched.h>
#include <termios.h>
#include <stdio.h>
#include <string.h>
#include <poll.h>
#include <fcntl.h>
#include <assert.h>
#include <errno.h>
#include <nuttx/ascii.h>
#include <nuttx/kmalloc.h>
#include <nuttx/mutex.h>
#include <nuttx/semaphore.h>
#include <nuttx/fs/fs.h>
#include <nuttx/serial/pty.h>
#include "pty.h"
/****************************************************************************
* Pre-processor Definitions
****************************************************************************/
/* Maximum number of threads than can be waiting for POLL events */
#ifndef CONFIG_DEV_PTY_NPOLLWAITERS
# define CONFIG_DEV_PTY_NPOLLWAITERS 2
#endif
/****************************************************************************
* Private Types
****************************************************************************/
struct pty_poll_s
{
FAR void *src;
FAR void *sink;
};
/* This device structure describes on memory of the PTY device pair */
struct pty_devpair_s;
struct pty_dev_s
{
FAR struct pty_devpair_s *pd_devpair;
struct file pd_src; /* Provides data to read() method (pipe output) */
struct file pd_sink; /* Accepts data from write() method (pipe input) */
bool pd_master; /* True: this is the master */
uint8_t pd_escape; /* Number of the character to be escaped */
tcflag_t pd_iflag; /* Terminal input modes */
tcflag_t pd_lflag; /* Terminal local modes */
tcflag_t pd_oflag; /* Terminal output modes */
struct pty_poll_s pd_poll[CONFIG_DEV_PTY_NPOLLWAITERS];
};
/* This structure describes the pipe pair */
struct pty_devpair_s
{
struct pty_dev_s pp_master; /* Maseter device */
struct pty_dev_s pp_slave; /* Slave device */
bool pp_susv1; /* SUSv1 or BSD style */
bool pp_locked; /* Slave is locked */
bool pp_unlinked; /* File has been unlinked */
uint8_t pp_minor; /* Minor device number */
uint16_t pp_nopen; /* Open file count */
sem_t pp_slavesem; /* Slave lock semaphore */
mutex_t pp_lock; /* Mutual exclusion */
};
/****************************************************************************
* Private Function Prototypes
****************************************************************************/
static void pty_destroy(FAR struct pty_devpair_s *devpair);
static int pty_pipe(FAR struct pty_devpair_s *devpair);
static int pty_open(FAR struct file *filep);
static int pty_close(FAR struct file *filep);
static ssize_t pty_read(FAR struct file *filep, FAR char *buffer,
size_t buflen);
static ssize_t pty_write(FAR struct file *filep, FAR const char *buffer,
size_t buflen);
static int pty_ioctl(FAR struct file *filep, int cmd, unsigned long arg);
static int pty_poll(FAR struct file *filep, FAR struct pollfd *fds,
bool setup);
#ifndef CONFIG_DISABLE_PSEUDOFS_OPERATIONS
static int pty_unlink(FAR struct inode *inode);
#endif
/****************************************************************************
* Private Data
****************************************************************************/
static const struct file_operations g_pty_fops =
{
pty_open, /* open */
pty_close, /* close */
pty_read, /* read */
pty_write, /* write */
NULL, /* seek */
pty_ioctl, /* ioctl */
NULL, /* mmap */
NULL, /* truncate */
pty_poll /* poll */
#ifndef CONFIG_DISABLE_PSEUDOFS_OPERATIONS
, pty_unlink /* unlink */
#endif
};
/****************************************************************************
* Private Functions
****************************************************************************/
/****************************************************************************
* Name: pty_destroy
****************************************************************************/
static void pty_destroy(FAR struct pty_devpair_s *devpair)
{
char devname[16];
if (devpair->pp_susv1)
{
/* Free this minor number so that it can be reused */
ptmx_minor_free(devpair->pp_minor);
/* Un-register the slave device */
snprintf(devname, sizeof(devname), "/dev/pts/%u", devpair->pp_minor);
}
else
{
/* Un-register the master device (/dev/ptyN may have already been
* unlinked).
*/
snprintf(devname, sizeof(devname), "/dev/pty%u", devpair->pp_minor);
unregister_driver(devname);
/* Un-register the slave device */
snprintf(devname, sizeof(devname), "/dev/ttyp%u", devpair->pp_minor);
}
unregister_driver(devname);
/* And free the device structure */
nxmutex_destroy(&devpair->pp_lock);
nxsem_destroy(&devpair->pp_slavesem);
kmm_free(devpair);
}
/****************************************************************************
* Name: pty_pipe
****************************************************************************/
static int pty_pipe(FAR struct pty_devpair_s *devpair)
{
FAR struct file *pipe_a[2];
FAR struct file *pipe_b[2];
int ret;
/* Create two pipes:
*
* pipe_a: Master source, slave sink (TX, slave-to-master)
* pipe_b: Master sink, slave source (RX, master-to-slave)
*/
pipe_a[0] = &devpair->pp_master.pd_src;
pipe_a[1] = &devpair->pp_slave.pd_sink;
ret = file_pipe(pipe_a, CONFIG_PSEUDOTERM_TXBUFSIZE, O_CLOEXEC);
if (ret < 0)
{
return ret;
}
pipe_b[0] = &devpair->pp_slave.pd_src;
pipe_b[1] = &devpair->pp_master.pd_sink;
ret = file_pipe(pipe_b, CONFIG_PSEUDOTERM_RXBUFSIZE, O_CLOEXEC);
if (ret < 0)
{
file_close(pipe_a[0]);
file_close(pipe_a[1]);
}
return ret;
}
/****************************************************************************
* Name: pty_open
****************************************************************************/
static int pty_open(FAR struct file *filep)
{
FAR struct inode *inode;
FAR struct pty_dev_s *dev;
FAR struct pty_devpair_s *devpair;
int ret = OK;
inode = filep->f_inode;
dev = inode->i_private;
DEBUGASSERT(dev != NULL && dev->pd_devpair != NULL);
devpair = dev->pd_devpair;
/* Get exclusive access to the device structure */
ret = nxmutex_lock(&devpair->pp_lock);
if (ret < 0)
{
return ret;
}
/* Wait if this is an attempt to open the slave device and the slave
* device is locked.
*/
if (!dev->pd_master)
{
/* Slave... Check if the slave driver is locked. */
while (devpair->pp_locked)
{
/* Release the exclusive access before wait */
nxmutex_unlock(&devpair->pp_lock);
/* Wait until unlocked.
* We will also most certainly suspend here.
*/
ret = nxsem_wait(&devpair->pp_slavesem);
if (ret < 0)
{
return ret;
}
/* Restore the semaphore count */
DEBUGVERIFY(nxsem_post(&devpair->pp_slavesem));
/* Get exclusive access to the device structure. This might also
* cause suspension.
*/
ret = nxmutex_lock(&devpair->pp_lock);
if (ret < 0)
{
return ret;
}
}
}
/* First open? */
if (devpair->pp_nopen == 0)
{
/* Yes, create the internal pipe */
ret = pty_pipe(devpair);
}
/* Increment the count of open references on the driver */
if (ret >= 0)
{
devpair->pp_nopen++;
DEBUGASSERT(devpair->pp_nopen > 0);
}
nxmutex_unlock(&devpair->pp_lock);
return ret;
}
/****************************************************************************
* Name: pty_close
****************************************************************************/
static int pty_close(FAR struct file *filep)
{
FAR struct inode *inode;
FAR struct pty_dev_s *dev;
FAR struct pty_devpair_s *devpair;
int ret;
inode = filep->f_inode;
dev = inode->i_private;
DEBUGASSERT(dev != NULL && dev->pd_devpair != NULL);
devpair = dev->pd_devpair;
/* Get exclusive access */
ret = nxmutex_lock(&devpair->pp_lock);
if (ret < 0)
{
return ret;
}
/* Check if the decremented inode reference count would go to zero */
if (inode->i_crefs == 1)
{
/* Did the (single) master just close its reference? */
if (dev->pd_master && devpair->pp_susv1)
{
/* Yes, then we are essentially unlinked and when all of the
* slaves close there references, then the PTY should be
* destroyed.
*/
devpair->pp_unlinked = true;
}
/* Close the contained file structures */
file_close(&dev->pd_src);
file_close(&dev->pd_sink);
}
/* Is this the last open reference? If so, was the driver previously
* unlinked?
*/
DEBUGASSERT(devpair->pp_nopen > 0);
if (devpair->pp_nopen <= 1 && devpair->pp_unlinked)
{
/* Yes.. Free the device pair now (without freeing the semaphore) */
nxmutex_unlock(&devpair->pp_lock);
pty_destroy(devpair);
return OK;
}
else
{
/* Otherwise just decrement the open count */
devpair->pp_nopen--;
}
nxmutex_unlock(&devpair->pp_lock);
return OK;
}
/****************************************************************************
* Name: pty_read
****************************************************************************/
static ssize_t pty_read(FAR struct file *filep, FAR char *buffer, size_t len)
{
FAR struct inode *inode;
FAR struct pty_dev_s *dev;
ssize_t ntotal;
ssize_t i;
ssize_t j;
char ch;
inode = filep->f_inode;
dev = inode->i_private;
DEBUGASSERT(dev != NULL);
/* Do input processing if any is enabled
*
* Specifically not handled:
*
* All of the local modes; echo, line editing, etc.
* Anything to do with break or parity errors.
* ISTRIP - We should be 8-bit clean.
* IUCLC - Not Posix
* IXON/OXOFF - No xon/xoff flow control.
*/
if (dev->pd_iflag & (INLCR | IGNCR | ICRNL))
{
while ((ntotal = file_read(&dev->pd_src, buffer, len)) > 0)
{
for (i = j = 0; i < ntotal; i++)
{
/* Perform input processing */
ch = buffer[i];
/* \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)
{
buffer[j++] = ch;
}
}
/* Is the buffer not empty after process? */
if (j != 0)
{
/* Yes, we are done. */
ntotal = j;
break;
}
}
}
else
{
/* NOTE: the source pipe will block if no data is available in
* the pipe. Otherwise, it will return data from the pipe. If
* there are fewer than 'len' bytes in the, it will return with
* ntotal < len.
*
* 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.
*/
ntotal = file_read(&dev->pd_src, buffer, len);
}
if ((dev->pd_lflag & ECHO) && (ntotal > 0))
{
size_t n = 0;
for (i = j = 0; i < ntotal; i++)
{
ch = buffer[i];
/* Check for the beginning of a VT100 escape sequence, 3 byte */
if (ch == ASCII_ESC)
{
/* Mark that we should skip 2 more bytes */
dev->pd_escape = 2;
continue;
}
else if (dev->pd_escape == 2 && ch != ASCII_LBRACKET)
{
/* It's not an <esc>[x 3 byte sequence, show it */
dev->pd_escape = 0;
}
else if (dev->pd_escape > 0)
{
/* Skipping character count down */
if (--dev->pd_escape > 0)
{
continue;
}
}
/* Echo if the character in batch */
if (ch == '\n' || (n != 0 && j + n != i))
{
if (n != 0)
{
pty_write(filep, buffer + j, n);
n = 0;
}
if (ch == '\n')
{
pty_write(filep, "\r\n", 2);
continue;
}
}
/* Record the character can be echo */
if (!iscntrl(ch & 0xff) && n++ == 0)
{
j = i;
}
}
if (n != 0)
{
pty_write(filep, buffer + j, n);
}
}
return ntotal;
}
/****************************************************************************
* Name: pty_write
****************************************************************************/
static ssize_t pty_write(FAR struct file *filep,
FAR const char *buffer, size_t len)
{
FAR struct inode *inode;
FAR struct pty_dev_s *dev;
ssize_t ntotal;
ssize_t nwritten;
size_t i;
char ch;
inode = filep->f_inode;
dev = inode->i_private;
DEBUGASSERT(dev != NULL);
/* Do output post-processing */
if ((dev->pd_oflag & OPOST) != 0)
{
/* We will transfer one byte at a time, making the appropriae
* translations. Specifically not handled:
*
* OXTABS - primarily a full-screen terminal optimisation
* ONOEOT - Unix interoperability hack
* OLCUC - Not specified by POSIX
* ONOCR - low-speed interactive optimisation
*/
ntotal = 0;
for (i = 0; i < len; i++)
{
ch = *buffer++;
/* Mapping CR to NL? */
if (ch == '\r' && (dev->pd_oflag & OCRNL) != 0)
{
ch = '\n';
}
/* Are we interested in newline processing? */
if ((ch == '\n') && (dev->pd_oflag & (ONLCR | ONLRET)) != 0)
{
char cr = '\r';
/* Transfer the carriage return. This will block if the
* sink pipe is full.
*
* REVISIT: Should not block if the oflags include O_NONBLOCK.
* How would we ripple the O_NONBLOCK characteristic to the
* contained sink pipe? file_fcntl()? Or FIONSPACE? See the
* TODO comment at the top of this file.
*
* NOTE: The newline is not included in total number of bytes
* written. Otherwise, we would return more than the
* requested number of bytes.
*/
nwritten = file_write(&dev->pd_sink, &cr, 1);
if (nwritten < 0)
{
ntotal = nwritten;
break;
}
}
/* Transfer the (possibly translated) character.. This will block
* if the sink pipe is full
*
* REVISIT: Should not block if the oflags include O_NONBLOCK.
* How would we ripple the O_NONBLOCK characteristic to the
* contained sink pipe? file_fcntl()? Or FIONSPACe? See the
* TODO comment at the top of this file.
*/
nwritten = file_write(&dev->pd_sink, &ch, 1);
if (nwritten < 0)
{
ntotal = nwritten;
break;
}
/* Update the count of bytes transferred */
ntotal++;
}
}
else
{
/* Write the 'len' bytes to the sink pipe. This will block until all
* 'len' bytes have been written to the pipe.
*
* REVISIT: Should not block if the oflags include O_NONBLOCK.
* How would we ripple the O_NONBLOCK characteristic to the
* contained sink pipe? file_fcntl()? Or FIONSPACE? See the
* TODO comment at the top of this file.
*/
ntotal = file_write(&dev->pd_sink, buffer, len);
}
return ntotal;
}
/****************************************************************************
* Name: pty_ioctl
*
* Description:
* The standard ioctl method. This is where ALL of the PWM work is done.
*
****************************************************************************/
static int pty_ioctl(FAR struct file *filep, int cmd, unsigned long arg)
{
FAR struct inode *inode;
FAR struct pty_dev_s *dev;
FAR struct pty_devpair_s *devpair;
int ret;
inode = filep->f_inode;
dev = inode->i_private;
DEBUGASSERT(dev != NULL && dev->pd_devpair != NULL);
devpair = dev->pd_devpair;
/* Get exclusive access */
ret = nxmutex_lock(&devpair->pp_lock);
if (ret < 0)
{
return ret;
}
/* Handle IOCTL commands */
switch (cmd)
{
/* PTY IOCTL commands would be handled here */
case TIOCGPTN: /* Get Pty Number (of pty-mux device): FAR int* */
{
FAR int *ptyno = (FAR int *)((uintptr_t)arg);
if (ptyno == NULL)
{
ret = -EINVAL;
}
else
{
*ptyno = devpair->pp_minor;
ret = OK;
}
}
break;
case TIOCSPTLCK: /* Lock/unlock Pty: int */
{
if (arg == 0)
{
if (devpair->pp_locked)
{
/* Release any waiting threads */
ret = nxsem_post(&devpair->pp_slavesem);
if (ret >= 0)
{
devpair->pp_locked = false;
}
}
}
else if (!devpair->pp_locked)
{
/* Locking */
ret = nxsem_wait(&devpair->pp_slavesem);
if (ret >= 0)
{
devpair->pp_locked = true;
}
}
}
break;
case TIOCGPTLCK: /* Get Pty lock state: FAR int* */
{
FAR int *ptr = (FAR int *)((uintptr_t)arg);
if (ptr == NULL)
{
ret = -EINVAL;
}
else
{
*ptr = devpair->pp_locked;
ret = OK;
}
}
break;
case TCGETS:
{
FAR struct termios *termiosp = (FAR struct termios *)arg;
if (!termiosp)
{
ret = -EINVAL;
break;
}
/* And update with flags from this layer */
termiosp->c_iflag = dev->pd_iflag;
termiosp->c_oflag = dev->pd_oflag;
termiosp->c_lflag = dev->pd_lflag;
ret = OK;
}
break;
case TCSETS:
{
FAR struct termios *termiosp = (FAR struct termios *)arg;
if (!termiosp)
{
ret = -EINVAL;
break;
}
/* Update the flags we keep at this layer */
dev->pd_iflag = termiosp->c_iflag;
dev->pd_oflag = termiosp->c_oflag;
dev->pd_lflag = termiosp->c_lflag;
ret = OK;
}
break;
/* Get the number of bytes that are immediately available for reading
* from the source pipe.
*/
case FIONREAD:
{
ret = file_ioctl(&dev->pd_src, cmd, arg);
}
break;
/* Get the number of bytes waiting in the sink pipe (FIONWRITE) or the
* number of unused bytes in the sink pipe (FIONSPACE).
*/
case FIONWRITE:
case FIONSPACE:
{
ret = file_ioctl(&dev->pd_sink, cmd, arg);
}
break;
case FIONBIO:
{
ret = file_ioctl(&dev->pd_src, cmd, arg);
if (ret >= 0)
{
ret = file_ioctl(&dev->pd_sink, cmd, arg);
}
}
break;
/* Any unrecognized IOCTL commands will be passed to the contained
* pipe driver.
*
* REVISIT: We know for a fact that the pipe driver only supports
* FIONREAD, FIONWRITE, FIONSPACE and PIPEIOC_POLICY. The first two
* are handled above and PIPEIOC_POLICY should not be managed by
* applications -- it can break the PTY!
*/
default:
{
#if 0
ret = file_ioctl(&dev->pd_src, cmd, arg);
if (ret >= 0 || ret == -ENOTTY)
{
ret = file_ioctl(&dev->pd_sink, cmd, arg);
}
#else
ret = -ENOTTY;
#endif
}
break;
}
nxmutex_unlock(&devpair->pp_lock);
return ret;
}
/****************************************************************************
* Name: pty_poll
****************************************************************************/
static int pty_poll(FAR struct file *filep, FAR struct pollfd *fds,
bool setup)
{
FAR struct inode *inode;
FAR struct pty_dev_s *dev;
FAR struct pty_devpair_s *devpair;
FAR struct pty_poll_s *pollp = NULL;
int ret;
int i;
inode = filep->f_inode;
dev = inode->i_private;
devpair = dev->pd_devpair;
ret = nxmutex_lock(&devpair->pp_lock);
if (ret < 0)
{
return ret;
}
if (setup)
{
for (i = 0; i < CONFIG_DEV_PTY_NPOLLWAITERS; i++)
{
if (dev->pd_poll[i].src == NULL && dev->pd_poll[i].sink == NULL)
{
pollp = &dev->pd_poll[i];
break;
}
}
if (i >= CONFIG_DEV_PTY_NPOLLWAITERS)
{
ret = -EBUSY;
goto errout;
}
}
else
{
pollp = (FAR struct pty_poll_s *)fds->priv;
}
/* POLLIN: Data may be read without blocking. */
if ((fds->events & POLLIN) != 0)
{
fds->priv = pollp->src;
ret = file_poll(&dev->pd_src, fds, setup);
if (ret < 0)
{
goto errout;
}
pollp->src = fds->priv;
}
/* POLLOUT: Normal data may be written without blocking. */
if ((fds->events & POLLOUT) != 0)
{
fds->priv = pollp->sink;
ret = file_poll(&dev->pd_sink, fds, setup);
if (ret < 0)
{
if (pollp->src)
{
fds->priv = pollp->src;
file_poll(&dev->pd_src, fds, false);
pollp->src = NULL;
}
goto errout;
}
pollp->sink = fds->priv;
}
if (setup)
{
fds->priv = pollp;
}
errout:
nxmutex_unlock(&devpair->pp_lock);
return ret;
}
/****************************************************************************
* Name: pty_unlink
****************************************************************************/
#ifndef CONFIG_DISABLE_PSEUDOFS_OPERATIONS
static int pty_unlink(FAR struct inode *inode)
{
FAR struct pty_dev_s *dev;
FAR struct pty_devpair_s *devpair;
int ret;
DEBUGASSERT(inode->i_private != NULL);
dev = inode->i_private;
devpair = dev->pd_devpair;
DEBUGASSERT(dev->pd_devpair != NULL);
/* Get exclusive access */
ret = nxmutex_lock(&devpair->pp_lock);
if (ret < 0)
{
return ret;
}
/* Indicate that the driver has been unlinked */
devpair->pp_unlinked = true;
/* If there are no further open references to the driver, then commit
* Hara-Kiri now.
*/
if (devpair->pp_nopen == 0)
{
nxmutex_unlock(&devpair->pp_lock);
pty_destroy(devpair);
return OK;
}
nxmutex_unlock(&devpair->pp_lock);
return OK;
}
#endif
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: pty_register2
*
* Description:
* Create and register PTY master and slave devices. The slave side of
* the interface is always locked initially. The master must call
* unlockpt() before the slave device can be opened.
*
* Input Parameters:
* minor - The number that qualifies the naming of the created devices.
* susv1 - select SUSv1 or BSD behaviour
*
* Returned Value:
* 0 is returned on success; otherwise, the negative error code return
* appropriately.
*
****************************************************************************/
int pty_register2(int minor, bool susv1)
{
FAR struct pty_devpair_s *devpair;
char devname[16];
int ret;
/* Allocate a device instance */
devpair = kmm_zalloc(sizeof(struct pty_devpair_s));
if (devpair == NULL)
{
return -ENOMEM;
}
/* Initialize semaphores & mutex */
nxsem_init(&devpair->pp_slavesem, 0, 0);
nxmutex_init(&devpair->pp_lock);
/* Map CR -> NL from terminal input (master)
* For some usage like adb shell:
* adb shell write \r -> nsh read \n and echo input
* nsh write \n -> adb shell read \r\n
*/
devpair->pp_susv1 = susv1;
devpair->pp_minor = minor;
devpair->pp_locked = true;
devpair->pp_master.pd_devpair = devpair;
devpair->pp_master.pd_master = true;
devpair->pp_master.pd_oflag = OPOST | OCRNL;
devpair->pp_slave.pd_devpair = devpair;
devpair->pp_slave.pd_oflag = OPOST | ONLCR;
devpair->pp_slave.pd_lflag = ECHO;
/* Register the master device
*
* BSD style (deprecated): /dev/ptyN
* SUSv1 style: Master: /dev/ptmx (multiplexor, see ptmx.c)
*
* Where N is the minor number
*/
snprintf(devname, sizeof(devname), "/dev/pty%d", minor);
ret = register_driver(devname, &g_pty_fops, 0666, &devpair->pp_master);
if (ret < 0)
{
goto errout_with_devpair;
}
/* Register the slave device
*
* BSD style (deprecated): /dev/ttypN
* SUSv1 style: /dev/pts/N
*
* Where N is the minor number
*/
if (susv1)
{
snprintf(devname, sizeof(devname), "/dev/pts/%d", minor);
}
else
{
snprintf(devname, sizeof(devname), "/dev/ttyp%d", minor);
}
ret = register_driver(devname, &g_pty_fops, 0666, &devpair->pp_slave);
if (ret < 0)
{
goto errout_with_master;
}
return OK;
errout_with_master:
snprintf(devname, sizeof(devname), "/dev/pty%d", minor);
unregister_driver(devname);
errout_with_devpair:
nxmutex_destroy(&devpair->pp_lock);
nxsem_destroy(&devpair->pp_slavesem);
kmm_free(devpair);
return ret;
}
/****************************************************************************
* Name: pty_register
*
* Description:
* Create and register PTY master and slave devices. The master device
* will be registered at /dev/ptyN and slave at /dev/ttypN where N is
* the provided minor number.
*
* The slave side of the interface is always locked initially. The
* master must call unlockpt() before the slave device can be opened.
*
* Input Parameters:
* minor - The number that qualifies the naming of the created devices.
*
* Returned Value:
* Zero (OK) is returned on success; a negated errno value is returned on
* any failure.
*
****************************************************************************/
int pty_register(int minor)
{
return pty_register2(minor, false);
}
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