11-09-2007
Porter is right about keeping things simple in a signal handler. But there is more - do not call most routines in the standard C library - as Porter points out fflush() is one of them.
If you absolutely must do I/O use write(). The idea is that you call something that cannot be interrupted by another signal - this is called an atomic operation.
write() is "partially" guaranteed to be atomic, but is as close as you'll get. POSIX says write() must guarantee a write the size of PIPE_BUF bytes or smaller to be atomic. There are other I/O system calls that are like this.
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LEARN ABOUT HPUX
fflush_unlo
fclose(3S) fclose(3S)
NAME
fclose(), fflush(), fclose_unlocked(), fflush_unlocked() - close or flush a stream
SYNOPSIS
Obsolescent Interfaces
DESCRIPTION
causes any buffered data for the named stream to be written out, and the stream to be closed. Buffers allocated by the standard input/out-
put system may be freed.
is performed automatically for all open files upon calling exit(2).
If stream points to an output stream or an update stream in which the most recent operation was output, causes any buffered data for the
stream to be written to that file; otherwise any buffered data is discarded. The stream remains open.
If stream is a null pointer, performs this flushing action on all currently open streams.
Obsolescent Interfaces
and close or flush a stream.
RETURN VALUE
Upon successful completion, and return 0. Otherwise, they return EOF and set to indicate the error.
ERRORS
If or fails, is set to one of:
The flag is set for the file descriptor underlying stream and the process would be delayed in the write operation.
The file descriptor underlying
stream is not valid.
An attempt was made to write a file
that exceeds the process's file size limit or the maximum file size (see ulimit(2)).
or was interrupted by a signal.
The process is in a background process group
and is attempting to write to its controlling terminal, is set, the process is neither ignoring nor blocking the signal,
and the process group of the process is orphaned.
There was no free space remaining on the device containing the file.
An attempt was made to write to a pipe
that is not open for reading by any process. A signal is also sent to the process.
Additional values may be set by the underlying and functions (see write(2), lseek(2) and close(2)).
WARNINGS
and are obsolescent interfaces supported only for compatibility with existing DCE applications. New multithreaded applications should use
and
SEE ALSO
close(2), exit(2), lseek(2), write(2), flockfile(3S), fopen(3S), setbuf(3S), thread_safety(5).
STANDARDS CONFORMANCE
fclose(3S)