]>
git.ipfire.org Git - thirdparty/cups.git/blob - cups/backchannel.c
2 * "$Id: backchannel.c 7616 2008-05-28 00:34:13Z mike $"
4 * Backchannel functions for CUPS.
6 * Copyright 2007-2010 by Apple Inc.
7 * Copyright 1997-2007 by Easy Software Products.
9 * These coded instructions, statements, and computer programs are the
10 * property of Apple Inc. and are protected by Federal copyright
11 * law. Distribution and use rights are outlined in the file "LICENSE.txt"
12 * which should have been included with this file. If this file is
13 * file is missing or damaged, see the license at "http://www.cups.org/".
15 * This file is subject to the Apple OS-Developed Software exception.
19 * cupsBackChannelRead() - Read data from the backchannel.
20 * cupsBackChannelWrite() - Write data to the backchannel.
21 * cups_setup() - Setup select()
25 * Include necessary headers...
34 # include <sys/time.h>
42 static void cups_setup(fd_set
*set
, struct timeval
*tval
,
47 * 'cupsBackChannelRead()' - Read data from the backchannel.
49 * Reads up to "bytes" bytes from the backchannel/backend. The "timeout"
50 * parameter controls how many seconds to wait for the data - use 0.0 to
51 * return immediately if there is no data, -1.0 to wait for data indefinitely.
53 * @since CUPS 1.2/Mac OS X 10.5@
56 ssize_t
/* O - Bytes read or -1 on error */
57 cupsBackChannelRead(char *buffer
, /* I - Buffer to read into */
58 size_t bytes
, /* I - Bytes to read */
59 double timeout
) /* I - Timeout in seconds, typically 0.0 to poll */
61 fd_set input
; /* Input set */
62 struct timeval tval
; /* Timeout value */
63 int status
; /* Select status */
67 * Wait for input ready.
72 cups_setup(&input
, &tval
, timeout
);
75 status
= select(4, &input
, NULL
, NULL
, NULL
);
77 status
= select(4, &input
, NULL
, NULL
, &tval
);
79 while (status
< 0 && errno
!= EINTR
&& errno
!= EAGAIN
);
82 return (-1); /* Timeout! */
85 * Read bytes from the pipe...
89 return ((ssize_t
)_read(3, buffer
, (unsigned)bytes
));
91 return (read(3, buffer
, bytes
));
97 * 'cupsBackChannelWrite()' - Write data to the backchannel.
99 * Writes "bytes" bytes to the backchannel/filter. The "timeout" parameter
100 * controls how many seconds to wait for the data to be written - use
101 * 0.0 to return immediately if the data cannot be written, -1.0 to wait
104 * @since CUPS 1.2/Mac OS X 10.5@
107 ssize_t
/* O - Bytes written or -1 on error */
108 cupsBackChannelWrite(
109 const char *buffer
, /* I - Buffer to write */
110 size_t bytes
, /* I - Bytes to write */
111 double timeout
) /* I - Timeout in seconds, typically 1.0 */
113 fd_set output
; /* Output set */
114 struct timeval tval
; /* Timeout value */
115 int status
; /* Select status */
116 ssize_t count
; /* Current bytes */
117 size_t total
; /* Total bytes */
126 while (total
< bytes
)
129 * Wait for write-ready...
134 cups_setup(&output
, &tval
, timeout
);
137 status
= select(4, NULL
, &output
, NULL
, NULL
);
139 status
= select(4, NULL
, &output
, NULL
, &tval
);
141 while (status
< 0 && errno
!= EINTR
&& errno
!= EAGAIN
);
144 return (-1); /* Timeout! */
147 * Write bytes to the pipe...
151 count
= (ssize_t
)_write(3, buffer
, (unsigned)(bytes
- total
));
153 count
= write(3, buffer
, bytes
- total
);
159 * Write error - abort on fatal errors...
162 if (errno
!= EINTR
&& errno
!= EAGAIN
)
168 * Write succeeded, update buffer pointer and total count...
176 return ((ssize_t
)bytes
);
181 * 'cups_setup()' - Setup select()
185 cups_setup(fd_set
*set
, /* I - Set for select() */
186 struct timeval
*tval
, /* I - Timer value */
187 double timeout
) /* I - Timeout in seconds */
189 tval
->tv_sec
= (int)timeout
;
190 tval
->tv_usec
= (int)(1000000.0 * (timeout
- tval
->tv_sec
));
198 * End of "$Id: backchannel.c 7616 2008-05-28 00:34:13Z mike $".