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/*
* Backchannel functions for CUPS.
*
* Copyright 2007-2014 by Apple Inc.
* Copyright 1997-2007 by Easy Software Products.
*
* Licensed under Apache License v2.0. See the file "LICENSE" for more information.
*/
/*
* Include necessary headers...
*/
#include "cups.h"
#include "sidechannel.h"
#include <errno.h>
#ifdef _WIN32
# include <io.h>
# include <fcntl.h>
#else
# include <sys/time.h>
#endif /* _WIN32 */
/*
* Local functions...
*/
static void cups_setup(fd_set *set, struct timeval *tval,
double timeout);
/*
* 'cupsBackChannelRead()' - Read data from the backchannel.
*
* Reads up to "bytes" bytes from the backchannel/backend. The "timeout"
* parameter controls how many seconds to wait for the data - use 0.0 to
* return immediately if there is no data, -1.0 to wait for data indefinitely.
*
* @since CUPS 1.2/macOS 10.5@
*/
ssize_t /* O - Bytes read or -1 on error */
cupsBackChannelRead(char *buffer, /* I - Buffer to read into */
size_t bytes, /* I - Bytes to read */
double timeout) /* I - Timeout in seconds, typically 0.0 to poll */
{
fd_set input; /* Input set */
struct timeval tval; /* Timeout value */
int status; /* Select status */
/*
* Wait for input ready.
*/
do
{
cups_setup(&input, &tval, timeout);
if (timeout < 0.0)
status = select(4, &input, NULL, NULL, NULL);
else
status = select(4, &input, NULL, NULL, &tval);
}
while (status < 0 && errno != EINTR && errno != EAGAIN);
if (status < 0)
return (-1); /* Timeout! */
/*
* Read bytes from the pipe...
*/
#ifdef _WIN32
return ((ssize_t)_read(3, buffer, (unsigned)bytes));
#else
return (read(3, buffer, bytes));
#endif /* _WIN32 */
}
/*
* 'cupsBackChannelWrite()' - Write data to the backchannel.
*
* Writes "bytes" bytes to the backchannel/filter. The "timeout" parameter
* controls how many seconds to wait for the data to be written - use
* 0.0 to return immediately if the data cannot be written, -1.0 to wait
* indefinitely.
*
* @since CUPS 1.2/macOS 10.5@
*/
ssize_t /* O - Bytes written or -1 on error */
cupsBackChannelWrite(
const char *buffer, /* I - Buffer to write */
size_t bytes, /* I - Bytes to write */
double timeout) /* I - Timeout in seconds, typically 1.0 */
{
fd_set output; /* Output set */
struct timeval tval; /* Timeout value */
int status; /* Select status */
ssize_t count; /* Current bytes */
size_t total; /* Total bytes */
/*
* Write all bytes...
*/
total = 0;
while (total < bytes)
{
/*
* Wait for write-ready...
*/
do
{
cups_setup(&output, &tval, timeout);
if (timeout < 0.0)
status = select(4, NULL, &output, NULL, NULL);
else
status = select(4, NULL, &output, NULL, &tval);
}
while (status < 0 && errno != EINTR && errno != EAGAIN);
if (status <= 0)
return (-1); /* Timeout! */
/*
* Write bytes to the pipe...
*/
#ifdef _WIN32
count = (ssize_t)_write(3, buffer, (unsigned)(bytes - total));
#else
count = write(3, buffer, bytes - total);
#endif /* _WIN32 */
if (count < 0)
{
/*
* Write error - abort on fatal errors...
*/
if (errno != EINTR && errno != EAGAIN)
return (-1);
}
else
{
/*
* Write succeeded, update buffer pointer and total count...
*/
buffer += count;
total += (size_t)count;
}
}
return ((ssize_t)bytes);
}
/*
* 'cups_setup()' - Setup select()
*/
static void
cups_setup(fd_set *set, /* I - Set for select() */
struct timeval *tval, /* I - Timer value */
double timeout) /* I - Timeout in seconds */
{
tval->tv_sec = (int)timeout;
tval->tv_usec = (int)(1000000.0 * (timeout - tval->tv_sec));
FD_ZERO(set);
FD_SET(3, set);
}
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