Open System Services System Calls Reference Manual (G06.28+)

System Functions (s and S) spt_writex(2)
• If the O_NONBLOCK flag is set, the spt_writex() function returns the
value -1 and errno is set to [EAGAIN].
When attempting to write to a socket and with no space available for data:
• If the O_NONBLOCK flag is not set, the spt_writex() function blocks
until space becomes available.
• If the O_NONBLOCK flag is set, the spt_writex() function returns the
value -1 and sets errno to [EAGAIN]. The O_NONBLOCK flag has no
effect if there is space available.
Upon successful completion, the spt_writex() function marks the st_ctime and
st_mtime fields of the file for update and clears the set-user-ID and set-group-ID
attributes if the file is a regular file.
The spt_fcntlx( ) function provides more information about record locks.
If it is interrupted by a signal before it writes any data, the spt_writex() function
returns the value -1 with errno set to [EINTR]. If it is interrupted by a signal
after it has successfully written some data, the spt_writex() function returns the
number of bytes that it has written.
Use on Guardian Objects
Attempting to write to a Guardian file (that is, a file in /G) that is locked causes the spt_writex()
function to return -1 and set errno to [EGUARDIANLOCKED].
NOTES
The macro to map write() to spt_writex() is available in C applications when
SPT_THREAD_AWARE_NONBLOCK has been defined in the following manner before
including spthread.h:
#define SPT_THREAD_AWARE_NONBLOCK
The alias to link write() to spt_writex() is available in C++ applications when
SPT_THREAD_AWARE_PRAGMA_NONBLOCK has been defined in the following manner
before including spthread.h:
#define SPT_THREAD_AWARE_PRAGMA_NONBLOCK
RETURN VALUES
Upon successful completion, the spt_writex() function returns the number of bytes that were
actually written. Otherwise, the value -1 is returned, and errno is set to indicate the error.
If the file descriptor becomes invalid (is closed by another thread), -1 is returned with an errno
value of [EBADF]. If a signal is received via the pthread_kill() function and is not blocked,
ignored, or handled, -1 is returned with an errno value of [EINTR].
ERRORS
If any of these conditions occurs, the spt_writex() function sets errno to the corresponding
value:
[EAGAIN] One of these conditions exists:
• An attempt was made to write to a file descriptor that
cannot accept data, and the O_NONBLOCK flag is set.
• A write to a pipe (FIFO file) of PIPE_BUF bytes or less
is requested, O_NONBLOCK is set, and fewer than
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