|
Hopefully, this page is exactly what you are looking for, but if not, you can always find further assistance on Unix/Linux Forum!
LOCKFILE(3) Linux Programmer's Manual LOCKFILE(3)
NAME
flockfile, ftrylockfile, funlockfile - lock FILE for stdio
SYNOPSIS
#include <stdio.h>
void flockfile(FILE *filehandle);
int ftrylockfile(FILE *filehandle);
void funlockfile(FILE *filehandle);
DESCRIPTION
The stdio functions are thread-safe. This is achieved by assigning to
each FILE object a lockcount and (if the lockcount is non-zero) an own-
ing thread. For each library call, these functions wait until the FILE
object is no longer locked by a different thread, then lock it, do the
requested I/O, and unlock the object again.
(Note: this locking has nothing to do with the file locking done by
functions like flock(2) and lockf(3).)
All this is invisible to the C-programmer, but there may be two reasons
to wish for more detailed control. On the one hand, maybe a series of
I/O actions by one thread belongs together, and should not be inter-
rupted by the I/O of some other thread. On the other hand, maybe the
locking overhead should be avoided for greater efficiency.
To this end, a thread can explicitly lock the FILE object, then do its
series of I/O actions, then unlock. This prevents other threads from
coming in between. If the reason for doing this was to achieve greater
efficiency, one does the I/O with the non-locking versions of the stdio
functions: with getc_unlocked() and putc_unlocked() instead of getc()
and putc().
The flockfile() function waits for *filehandle to be no longer locked
by a different thread, then makes the current thread owner of *filehan-
dle, and increments the lockcount.
The funlockfile() function decrements the lock count.
The ftrylockfile() function is a non-blocking version of flockfile().
It does nothing in case some other thread owns *filehandle, and it
obtains ownership and increments the lockcount otherwise.
RETURN VALUE
The ftrylockfile() function returns zero for success (the lock was
obtained), and non-zero for failure.
ERRORS
None.
AVAILABILITY
These functions are available when _POSIX_THREAD_SAFE_FUNCTIONS is
defined. They are in libc since libc 5.1.1 and in glibc since glibc
2.0.
CONFORMING TO
POSIX.1-2001.
SEE ALSO
unlocked_stdio(3)
2001-10-18 LOCKFILE(3)
Man(1) output converted with
man2html and wrapped by fishsponge
This page was generated on Sat Sep 8 16:38:33 GMT 2007
|
Your favourite pages:
No pages logged yet.
Trying to save cookie... Top 10 most popular pages:
svn man page (6143 hits)
(FreeBSD 6.2)
sqlite3 man page (5592 hits)
(openSUSE 10.2)
adv_cap_autoneg man page (5041 hits)
(Solaris 10 11_06)
CPAN man page (4787 hits)
(Suse Linux 10.1)
ssh man page (4438 hits)
(Suse Linux 10.1)
ssh-socks5-proxy-connect man page (3506 hits)
(Solaris 10 11_06)
signal man page (3363 hits)
(Suse Linux 10.1)
netcat man page (3359 hits)
(Suse Linux 10.1)
pprosetup man page (2876 hits)
(Solaris 10 11_06)
startproc man page (2732 hits)
(Suse Linux 10.1)
|
Man Pages 
