posix

问题 I must do a program with POSIX threads with gcc and when i try to compile it, the terminal show a message like: /tmp/ccw594wa.o: In function main': POSIX.c:(.text+0xda): undefined reference to pthread_create' POSIX.c:(.text+0x102): undefined reference to `pthread_create' collect2: ld devolvió el estado de salida 1 can someone help me to identify the error cause??, the program has to implemente the producer-consumer algorithm to do some task, my code (unfinished) is the next one #include

问题 I am trying to traverse through a directory whose path is given but the following program is not going inside the directories and is stuck in infinit loop. What is the problem in this code: void func(char path[]); int main(int argc, char *argv) { char buf[255]; getcwd(buf,255); func(buf); } void func(char path[]) { DIR *dirp; struct stat states; struct dirent *direntp; dirp=opendir(path); chdir(path); while((direntp=readdir(dirp))!=NULL) { if(S_ISDIR(states.st_mode))//true than returns zero {

问题 I found this answer on how to set a timeout for posix socket. The linux part of that answer: // LINUX struct timeval tv; tv.tv_sec = timeout_in_seconds; tv.tv_usec = 0; setsockopt(sockfd, SOL_SOCKET, SO_RCVTIMEO, (const char*)&tv, sizeof tv); and the quote from the posix documentation: SO_RCVTIMEO Sets the timeout value that specifies the maximum amount of time an input function waits until it completes. It accepts a timeval structure with the number of seconds and microseconds specifying the

问题 I'm trying to figure out what is blocking my program. I'm running a server that uses POSIX threads. I have to for my computer programming lab. The main function listens for new connections. Once it accepts a connection, it creates a new thread by passing the FD to the thread. I'm able to successfully connect to the server using multiple telnet/client connections. I can send data to the server successfully once, but if I try sending again the server won't do anything. Part of the main function

问题 The select function blocks the calling process until there is activity on any of the specified sets of file descriptors [...] A file descriptor is considered ready for reading if a read call will not block. (See: https://www.gnu.org/software/libc/manual/html_node/Waiting-for-I_002fO.html) So I expected, that select in the following program would immediately return in the 2nd, ... iteration, if you enter a string > 4 characters in the first iteration. However it does not. Just after pressing

问题 #include<iostream> #include<unistd.h> #include<stdio.h> using namespace std; int main() { fork(); fork(); fork(); fork(); printf("*"); /*This prints 16 stars*/ return 0; } When working with fork() , why does it print 16 *'s? I understand that fork() generates a new child process that both execute the same process which would explain why one fork generates 2 stars but, with four forks it prints 16 which I can see that it doubles with each fork() . But I am not understanding why. Is each fork

问题 I'm testing POSIX skin in Xenomai. I'm trying to read and write from some GPIOs on a Raspberry Pi, and when I execute the program, there is an increasing number of context switching (in /proc/xenomai/stat/). The main of the program maps the GPIOs to memory and starts the pthreads. The pthread that makes trouble is this: void *productive_thread(void *arg) { struct timespec delay, sleep; unsigned long over; delay.tv_sec = 0; delay.tv_nsec = 10000; // 10 usec sleep.tv_sec = 0; sleep.tv_nsec = *

问题 I want to start a timer and have a function called when it expires. Googling finds lots of examples, including the example in the manual, all of which use sigaction() to set a signal handler. However, @Patryk says in this question that we can just void cbf(union sigval); struct sigevent sev; timer_t timer; sev.sigev_notify = SIGEV_THREAD; sev.sigev_notify_function = cbf; //this function will be called when timer expires sev.sigev_value.sival_ptr = (void*) arg;//this argument will be passed to

问题 I am trying to use C code written on a Linux platform on Mac OS X. I am running into an error related to timers: ../src/stinger/timer.c:61:1: error: unknown type name 'clockid_t' ../src/stinger/timer.c:74:2: error: #error "Cannot find a clock!" which points to this section of code. static clockid_t clockid; #if defined(CLOCK_REALTIME_ID) #define CLKID CLOCK_REALTIME_ID #define CLKIDNAME "CLOCK_REALTIME_ID" #elif defined(CLOCK_THREAD_CPUTIME_ID) #define CLKID CLOCK_THREAD_CPUTIME_ID #define

问题 I'm investigating a problem on Android where an IOException is getting thrown because of a failure to close a file: java.io.IOException: close failed: EIO (I/O error) at libcore.io.IoUtils.close(IoUtils.java:41) at java.io.FileInputStream.close(FileInputStream.java:121) at com.adamrosenfield.wordswithcrosses.io.JPZIO.convertJPZPuzzle(JPZIO.java:191) at com.adamrosenfield.wordswithcrosses.net.AbstractJPZDownloader.download(AbstractJPZDownloader.java:56) at com.adamrosenfield.wordswithcrosses