You shouldn't be using ioctl in perl. If your structure and C's disagree even slightly, then weird things can happen. If your structure and perl's completely agree, weird things can still happen. There may be memory alignment considerations and the like which rearrange or misalign the members from the arrangement you expected, only the C compiler's judgement should be trusted on that.
I seem to remember 'struct flock''s arrangement does seem to be different in OSX than in Linux, too. Something about one of the types involved not actually being an integer anymore.
Fortunately, perl has a built-in flock function so you don't need to call ioctl yourself. It's not even a module, it comes with standard perl.
Last edited by Corona688; 11-30-2011 at 03:29 PM..
Please help if you are familiar with Mac OSX. I downloaded OpenSSH for a newer version of SSH than what comes with OS 10.1. What a mistake! Now every time I try to make a connection to my remote server I get an message that ssh was built against version such and such and I have version such and... (2 Replies)
I finally broke down and decided to buy a new piece of hardware. I think I made the right decision when I chose an Apple iBook - OSX is incredible! I haven't used a Mac since System7.5, and 10.2 is just blowing me away!
Best of all, it's easy to use for people who are not used to Mac, but if I... (5 Replies)
I'm currently looking for an emulation program that would allow me to open and run osx app.s and programs on a windows xp based system.
if not is there a unix/linux/lindows program that may do the same? (3 Replies)
Hello,
I am trying to write a simple program with functions in the ncurses library, on a Mac running OSX 10.2.8, with the compiler and libraries that were included in the Dec 2002 Developer's tools release (the last one that runs on Jaguar, as far as I know). When I try to compile, I get... (2 Replies)
Hi,
I have installed bash 3.2 via darwin ports, however when I try and change the shell i.e. chsh -s /opt/local/bin/bash is says its a non-standard shell? but if i run ./bash i get a new bash prompt with version 3.2?
Thanks (3 Replies)
I've got this problem. My computers and external hard drives are converting many of my files to a Unix Executable File which has a grey terminal looking icon. I don't understand what is causing this to happen. It is happening to a large number of my image file of different formats and also... (1 Reply)
Hi,
Unless I am missing some serious differences in Mac and linux in terms of C programming, I dont know why this would happen. Please take a look at the following piece of code fragment:
bool add_input_to_db(Cons *new_data) {
// Set the attributes of the lock
struct flock fl =... (3 Replies)
Hey guyz,
Is it possible to build user-mode linux kernel on MAC OSX?
Please I need a reply asap as I have an assignment that I need to do.
Thanks!
Adel (1 Reply)
Discussion started by: aje02
1 Replies
LEARN ABOUT NETBSD
flock
FLOCK(2) BSD System Calls Manual FLOCK(2)NAME
flock -- apply or remove an advisory lock on an open file
LIBRARY
Standard C Library (libc, -lc)
SYNOPSIS
#include <fcntl.h>
#define LOCK_SH 1 /* shared lock */
#define LOCK_EX 2 /* exclusive lock */
#define LOCK_NB 4 /* don't block when locking */
#define LOCK_UN 8 /* unlock */
int
flock(int fd, int operation);
DESCRIPTION
flock() applies or removes an advisory lock on the file associated with the file descriptor fd. A lock is applied by specifying an operation
parameter that is one of LOCK_SH or LOCK_EX with the optional addition of LOCK_NB. To unlock an existing lock operation should be LOCK_UN.
Advisory locks allow cooperating processes to perform consistent operations on files, but do not guarantee consistency (i.e., processes may
still access files without using advisory locks possibly resulting in inconsistencies).
The locking mechanism allows two types of locks: shared locks and exclusive locks. At any time multiple shared locks may be applied to a
file, but at no time are multiple exclusive, or both shared and exclusive, locks allowed simultaneously on a file.
A shared lock may be upgraded to an exclusive lock, and vice versa, simply by specifying the appropriate lock type; this results in the pre-
vious lock being released and the new lock applied (possibly after other processes have gained and released the lock).
Requesting a lock on an object that is already locked normally causes the caller to be blocked until the lock may be acquired. If LOCK_NB is
included in operation, then this will not happen; instead the call will fail and the error EAGAIN will be returned.
NOTES
Locks are on files, not file descriptors. That is, file descriptors duplicated through dup(2) or fork(2) do not result in multiple instances
of a lock, but rather multiple references to a single lock. If a process holding a lock on a file forks and the child explicitly unlocks the
file, the parent will lose its lock.
Processes blocked awaiting a lock may be awakened by signals.
RETURN VALUES
Zero is returned if the operation was successful; on an error a -1 is returned and an error code is left in the global location errno.
ERRORS
The flock() call fails if:
[EAGAIN] The file is locked and the LOCK_NB option was specified.
[EBADF] The argument fd is an invalid descriptor.
[EINVAL] The argument operation does not include exactly one of LOCK_EX, LOCK_SH, or LOCK_UN.
[EOPNOTSUPP] The argument fd refers to an object other than a file.
SEE ALSO close(2), dup(2), execve(2), fork(2), open(2), flockfile(3), lockf(3)HISTORY
The flock() function call appeared in 4.2BSD.
BSD October 15, 2011 BSD