Many system calls will report the EINTR error code if a signal occurred while the system call was in progress. No error actually occurred, it’s just reported that way because the system isn’t able to resume the system call automatically. This coding pattern simply retries the system call when this happens, to ignore the interrupt. … Read more
To resurrect this old thread, I just did some simple test code: #include <thread> int main(int argc, char** argv) { for (volatile int i = 0; i < 500000; i++) std::thread([](){}).detach(); return 0; } I compiled it with g++ test.cpp -std=c++11 -lpthread -O3 -o test. I then ran it three times in a row on … Read more
That’s just the way it’s defined. From the Open Group page for the open() function O_NONBLOCK When opening a FIFO with O_RDONLY or O_WRONLY set: If O_NONBLOCK is set: An open() for reading only will return without delay. An open() for writing only will return an error if no process currently has the file open … Read more
Both methods are viable. mmap method is a little bit more restrictive then shmget, but easier to use. shmget is the old System V shared memory model and has the widest support. mmap/shm_open is the new POSIX way to do shared memory and is easier to use. If your OS permits the use of POSIX … Read more
POSIX is a superset of the standard C library, and it’s important to note that it defers to it. If C and POSIX is ever in conflict, C wins. Sockets, file descriptors, shared memory etc. are all part of POSIX, but do not exist in the C library. pthread.h is used for POSIX threads and … Read more
If you can assume POSIX (and thus the POSIX specification of time_t as seconds since the epoch), I would first use the POSIX formula to convert to seconds since the epoch: tm_sec + tm_min*60 + tm_hour*3600 + tm_yday*86400 + (tm_year-70)*31536000 + ((tm_year-69)/4)*86400 – ((tm_year-1)/100)*86400 + ((tm_year+299)/400)*86400 Next, use localtime((time_t []){0}) to get a struct tm … Read more
No, there are no non-greedy quantifiers in POSIX regular expressions. But there is a library that provides perl-like regular expressions for C: http://www.pcre.org/
Have you tried “man waitpid”? The value returned from the waitpid() call is an encoding of the exit value. There are a set of macros that will provide the original exit value. Or you can try right shifting the value by 8 bits, if you don’t care about portability. The portable version of your code … Read more
No idea about Windows, but the behavior you want is guaranteed by POSIX: If the listen queue is empty of connection requests and O_NONBLOCK is not set on the file descriptor for the socket, accept() shall block until a connection is present. If the listen() queue is empty of connection requests and O_NONBLOCK is set … Read more
From Bash FAQ: E10) Why does `cd //’ leave $PWD as `//’? POSIX.2, in its description of `cd’, says that *three* or more leading slashes may be replaced with a single slash when canonicalizing the current working directory. This is, I presume, for historical compatibility. Certain versions of Unix, and early network file systems, used … Read more