You know I don't ever FD_ZERO anything. But I do FD_CLR stuff. How should I FD_ZERO stuff?
FD_CLR is in the loop below:
Also when there is only one user and it aborts, the command list displays:
And when there are two users and it aborts, the command list displays:
Both of the bottom code are kind of the two loops I posted. You could pretty much copy the main and run it if you comment out a few lines that it is dependent on.
---------- Post updated at 10:43 PM ---------- Previous update was at 10:26 PM ----------
Alright I wanna add that I do FD_ZERO like this before my infinity loop:
Requirements:
A server program should read a file and send the message to the client . if the file is not there, then switch to the receive part of the same program and receive any messages from the socket. If no messages to receive then switch to send part of the program to... (2 Replies)
I ran degugger in C++ and the followings are the message I got:
Program received signal SIGABRT, Aborted.
0x002a57a2 in _dl_sysinfo_int80 () from /lib/ld-linux.so.2
(gdb) info s
#0 0x002a57a2 in _dl_sysinfo_int80 () from /lib/ld-linux.so.2
#1 0x002e97f5 in raise () from /lib/tls/libc.so.6... (1 Reply)
Dear all,
I used debugger from C++ and these are the message I got:
Program received signal SIGSEGV, Segmentation fault.
0x00323fc0 in free () from /lib/tls/libc.so.6
(gdb) info s
#0 0x00323fc0 in free () from /lib/tls/libc.so.6
#1 0x00794fa1 in operator delete () from... (5 Replies)
Hi,
I would like to write a program to receive the GPS data and then send the data via network to other program.
All of the program is not write yet(include host and sender)
All of the server OS is unix or linux
Could you mind to give me some idea to do this?
Thanks so much!
Ken
... (2 Replies)
Hello,
One of our customer is getting segmentation fault when he runs his shell script which invokes our executable on AIX 6.1.
On AIX 5.3, there were no issues.
Here is the truss output.
811242: __loadx(0x0A040000, 0xF0D3A26C, 0x00000000, 0x00000009, 0x00000000) = 0xF026E884... (0 Replies)
Hi to all,
i am trying to make mksysb backup of a NIM client machine from NIM master and while i am reading that the backup is done successfully i get an error message below and it doesnt exit the smit screen. also the status of the command appears to be running.
is there anybody who knows why... (3 Replies)
I am making a command line program in C using XCode. When running the program, it initially does what it is supposed to do (asks me for a file path). However, when I type in a valid and existing file path, it gives me the following error:
Program received signal: “EXC_BAD_ACCESS”.... (6 Replies)
in a single main() function,so need signal handling. Use Posix Message Queue IPC mechanism , can ignore the priority and other linked list message,to implement the scenario:
client:Knock Knock
server:who's there
client: Eric
Server:Eric,Welcome.
client:exit
all process terminated
... (1 Reply)
hi all
I am getting following error while taking backup
using the command
ufsdump 0ubf 512 /dev/rmt/0cbn /database/backup2/rman_backup/level0 >> /database/backup2/backup_tape/level0_rman_06sep12 2>&1;
from the log i got the error
bash# tail -f level0_rman_06sep12
DUMP: Date of... (3 Replies)
I am trying to learn C and while trying out some code, the program is getting aborted while I am calling free().
Here is the code:
#include <stdlib.h>
#include <stdio.h>
void print_by_ptr(char **str) {
printf("<%s>\n",*str);
printf("Now I am modifying the str.\n");
*str =... (3 Replies)
Discussion started by: chacko193
3 Replies
LEARN ABOUT MOJAVE
fd_set
SELECT(2) BSD System Calls Manual SELECT(2)NAME
FD_CLR, FD_COPY, FD_ISSET, FD_SET, FD_ZERO, select -- synchronous I/O multiplexing
SYNOPSIS
#include <sys/select.h>
void
FD_CLR(fd, fd_set *fdset);
void
FD_COPY(fd_set *fdset_orig, fd_set *fdset_copy);
int
FD_ISSET(fd, fd_set *fdset);
void
FD_SET(fd, fd_set *fdset);
void
FD_ZERO(fd_set *fdset);
int
select(int nfds, fd_set *restrict readfds, fd_set *restrict writefds, fd_set *restrict errorfds, struct timeval *restrict timeout);
DESCRIPTION
select() examines the I/O descriptor sets whose addresses are passed in readfds, writefds, and errorfds to see if some of their descriptors
are ready for reading, are ready for writing, or have an exceptional condition pending, respectively. The first nfds descriptors are checked
in each set; i.e., the descriptors from 0 through nfds-1 in the descriptor sets are examined. (Example: If you have set two file descriptors
"4" and "17", nfds should not be "2", but rather "17 + 1" or "18".) On return, select() replaces the given descriptor sets with subsets
consisting of those descriptors that are ready for the requested operation. select() returns the total number of ready descriptors in all
the sets.
The descriptor sets are stored as bit fields in arrays of integers. The following macros are provided for manipulating such descriptor sets:
FD_ZERO(&fdset) initializes a descriptor set fdset to the null set. FD_SET(fd, &fdset) includes a particular descriptor fd in fdset.
FD_CLR(fd, &fdset) removes fd from fdset. FD_ISSET(fd, &fdset) is non-zero if fd is a member of fdset, zero otherwise. FD_COPY(&fdset_orig,
&fdset_copy) replaces an already allocated &fdset_copy file descriptor set with a copy of &fdset_orig. The behavior of these macros is unde-
fined if a descriptor value is less than zero or greater than or equal to FD_SETSIZE, which is normally at least equal to the maximum number
of descriptors supported by the system.
If timeout is a non-nil pointer, it specifies a maximum interval to wait for the selection to complete. If timeout is a nil pointer, the
select blocks indefinitely. To effect a poll, the timeout argument should be non-nil, pointing to a zero-valued timeval structure. Timeout
is not changed by select(), and may be reused on subsequent calls, however it is good style to re-initialize it before each invocation of
select().
Any of readfds, writefds, and errorfds may be given as nil pointers if no descriptors are of interest.
RETURN VALUES
select() returns the number of ready descriptors that are contained in the descriptor sets, or -1 if an error occurred. If the time limit
expires, select() returns 0. If select() returns with an error, including one due to an interrupted call, the descriptor sets will be unmod-
ified and the global variable errno will be set to indicate the error.
ERRORS
An error return from select() indicates:
[EAGAIN] The kernel was (perhaps temporarily) unable to allocate the requested number of file descriptors.
[EBADF] One of the descriptor sets specified an invalid descriptor.
[EINTR] A signal was delivered before the time limit expired and before any of the selected events occurred.
[EINVAL] The specified time limit is invalid. One of its components is negative or too large.
[EINVAL] ndfs is greater than FD_SETSIZE and _DARWIN_UNLIMITED_SELECT is not defined.
LEGACY SYNOPSIS
#include <sys/select.h>
- or -
#include <sys/types.h>
#include <sys/time.h>
#include <unistd.h>
FD_SET(fd, &fdset);
FD_CLR(fd, &fdset);
FD_ISSET(fd, &fdset);
FD_COPY(&fdset_orig, &fdset_copy);
FD_ZERO(&fdset);
COMPATIBILITY
select() now returns with errno set to EINVAL when nfds is greater than FD_SETSIZE. Use a smaller value for nfds or compile with -D_DAR-
WIN_UNLIMITED_SELECT.
SEE ALSO accept(2), connect(2), connectx(2), getdtablesize(2), gettimeofday(2), read(2), recv(2), send(2), write(2), compat(5)BUGS
Although the provision of getdtablesize(2) was intended to allow user programs to be written independent of the kernel limit on the number of
open files, the dimension of a sufficiently large bit field for select remains a problem. The default size FD_SETSIZE (currently 1024) is
somewhat smaller than the current kernel limit to the number of open files. However, in order to accommodate programs which might poten-
tially use a larger number of open files with select, it is possible to increase this size within a program by providing a larger definition
of FD_SETSIZE before the inclusion of <sys/types.h>.
select() should probably have been designed to return the time remaining from the original timeout, if any, by modifying the time value in
place. However, it is unlikely this semantic will ever be implemented, as the change would cause source code compatibility problems. In
general it is unwise to assume that the timeout value will be unmodified by the select() call, and the caller should reinitialize it on each
invocation.
HISTORY
The select() function call appeared in 4.2BSD.
4.2 Berkeley Distribution March 18, 2015 4.2 Berkeley Distribution