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