Hi,
If some one was to suggest, "increase your kernal tunables related to UDP, in particular the UDP send/recieve buffer size".... then what would they mean? :confused:
How can I find out what this current value is?
Thousand many thanks.
Neil (3 Replies)
Hi All,
I encountered a stange problem while doing a perl script to use socket. i need to transfer a file from client to sever. but error came as argument missing in send function.........Plz tell me the wt r the arguments in send and recv functions....... (0 Replies)
Hi,
Am very new to socket programming.
When we use UDP sockets to communicate between two processess,
will both the client/server socket be able to send/recv ?
meaning can sendto()/ recvfrom() be used on both server and client?
It could be useful even if anybody provide some link on socket... (1 Reply)
Hi,
I was porting ipv4 application to ipv6; i was done with TCP transports. Now i am facing problem with SCTp transport at runtime.
To test SCTP transport I am using following server and client socket programs. Server program runs fine, but client program fails giving Invalid Arguments for... (0 Replies)
I have set the receive buffer size of socket to max.
setsockopt(sd,SOL_SOCKET, SO_RCVBUF,&max,optval);
Am reading data from the socket in a loop(say max 100 bytes per recv)
while(1)
{
int rlen=recv(sd,(void *)buf, 100 , 0);
//err handle and processing
}
Assume my process is slow... (2 Replies)
char name;
printf ("Welcome to the server \n");
printf ("Enter user name: \n");
scanf ("%c", &name);
how can client send name to server:what should be the code?
int send ( int sid , const char ∗buffer Ptr , int len , int f l a g )
how can client receive ack from... (1 Reply)
Hello everybody,
Years ago i left in stand-by a project of mine where the main program was supposed to send thousands ARP frames over the socket as fast as it could; but because of a programming issue i couldn't continue it.
2 days ago I decided to solve that issue.
The thing is, when the... (4 Replies)
Discussion started by: Zykl0n-B
4 Replies
LEARN ABOUT DEBIAN
readlink
READLINK(2) Linux Programmer's Manual READLINK(2)NAME
readlink - read value of a symbolic link
SYNOPSIS
#include <unistd.h>
ssize_t readlink(const char *path, char *buf, size_t bufsiz);
Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
readlink():
_BSD_SOURCE || _XOPEN_SOURCE >= 500 || _XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED || _POSIX_C_SOURCE >= 200112L
DESCRIPTION
readlink() places the contents of the symbolic link path in the buffer buf, which has size bufsiz. readlink() does not append a null byte
to buf. It will truncate the contents (to a length of bufsiz characters), in case the buffer is too small to hold all of the contents.
RETURN VALUE
On success, readlink() returns the number of bytes placed in buf. On error, -1 is returned and errno is set to indicate the error.
ERRORS
EACCES Search permission is denied for a component of the path prefix. (See also path_resolution(7).)
EFAULT buf extends outside the process's allocated address space.
EINVAL bufsiz is not positive.
EINVAL The named file is not a symbolic link.
EIO An I/O error occurred while reading from the file system.
ELOOP Too many symbolic links were encountered in translating the pathname.
ENAMETOOLONG
A pathname, or a component of a pathname, was too long.
ENOENT The named file does not exist.
ENOMEM Insufficient kernel memory was available.
ENOTDIR
A component of the path prefix is not a directory.
CONFORMING TO
4.4BSD (readlink() first appeared in 4.2BSD), POSIX.1-2001.
NOTES
In versions of glibc up to and including glibc 2.4, the return type of readlink() was declared as int. Nowadays, the return type is
declared as ssize_t, as (newly) required in POSIX.1-2001.
Using a statically sized buffer might not provide enough room for the symbolic link contents. The required size for the buffer can be
obtained from the stat.st_size value returned by a call to lstat(2) on the link. However, the number of bytes written by readlink() should
be checked to make sure that the size of the symbolic link did not increase between the calls. Dynamically allocating the buffer for read-
link() also addresses a common portability problem when using PATH_MAX for the buffer size, as this constant is not guaranteed to be
defined per POSIX if the system does not have such limit.
EXAMPLE
The following program allocates the buffer needed by readlink() dynamically from the information provided by lstat(), making sure there's
no race condition between the calls.
#include <sys/types.h>
#include <sys/stat.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
int
main(int argc, char *argv[])
{
struct stat sb;
char *linkname;
ssize_t r;
if (argc != 2) {
fprintf(stderr, "Usage: %s <pathname>
", argv[0]);
exit(EXIT_FAILURE);
}
if (lstat(argv[1], &sb) == -1) {
perror("lstat");
exit(EXIT_FAILURE);
}
linkname = malloc(sb.st_size + 1);
if (linkname == NULL) {
fprintf(stderr, "insufficient memory
");
exit(EXIT_FAILURE);
}
r = readlink(argv[1], linkname, sb.st_size + 1);
if (r < 0) {
perror("lstat");
exit(EXIT_FAILURE);
}
if (r > sb.st_size) {
fprintf(stderr, "symlink increased in size "
"between lstat() and readlink()
");
exit(EXIT_FAILURE);
}
linkname[sb.st_size] = '