I have the following code which forks two new processes to take the contents of the stdout of one and saves it to a file. It runs just fine and saves the file, but after it returns the following line in the calling function (no matter what it is) throws a EXC_BAD_ACCESS error. Why?
void test(vector<string> inp,int i){
int fds[2]; // file descriptors
long count; // used for reading from stdout
int fd; // single file descriptor
char c; // used for writing and reading a character at a time
pid_t pid; // will hold process ID; used with fork()
pipe(fds);
// child process #1.
fd = open((inp[i+1]).c_str(), O_RDWR | O_CREAT, 0666);
if (fork() == 0) {
if (fd < 0) {
return;
}
dup2(fds[0], 0);
// Don't need stdout end of pipe.
close(fds[1]);
// Read from stdout...
while ((count = read(0, &c, 1)) > 0)
write(fd, &c, 1); // Write to file.
exit(0);
// child process #2
} else if ((pid = fork()) == 0) {
dup2(fds[1], 1);
// Don't need stdin end开发者_如何学Go of pipe.
close(fds[0]);
// Output contents of the given file to stdout.
char **arguments = getArguments(inp[i]);
execvp(arguments[0], arguments);
perror("execvp failed");
exit(0);
// parent process
} else {
waitpid(pid, NULL, 0);
close(fds[0]);
close(fds[1]);
}
}
This works well for me:
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <stdio.h>
#include <sys/wait.h>
void test(/*vector<string> inp,int i*/){
int fds[2]; // file descriptors
long count; // used for reading from stdout
int fd; // single file descriptor
char c; // used for writing and reading a character at a time
pid_t pid; // will hold process ID; used with fork()
pipe(fds);
// child process #1.
fd = open(/*(inp[i+1]).c_str()*/"/tmp/output", O_RDWR | O_CREAT, 0666);
if (fork() == 0) {
if (fd < 0) {
return;
}
dup2(fds[0], 0);
// Don't need stdout end of pipe.
close(fds[1]);
// Read from stdout...
while ((count = read(0, &c, 1)) > 0)
write(fd, &c, 1); // Write to file.
_exit(0);
// child process #2
} else if ((pid = fork()) == 0) {
dup2(fds[1], 1);
// Don't need stdin end of pipe.
close(fds[0]);
// Output contents of the given file to stdout.
char **arguments = new char*[2];/*getArguments(inp[i]);*/
arguments[0]=(char*)"/bin/bash";
arguments[1]=0;
execvp(arguments[0], arguments);
perror("execvp failed");
_exit(0);
// parent process
} else {
waitpid(pid, NULL, 0);
close(fds[0]);
close(fds[1]);
}
}
int main(int argc, char* argv[]){
test();
}
Try to tell where exactly your error appears or show more of your program, so i can try to replicate your conditions.
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