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Copy pathTask P01 (2nd solution).c
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Copy pathTask P01 (2nd solution).c
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68 lines (55 loc) · 1.6 KB
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/*
T1 - Да се напише програма на C, която приема аргумент - име на файл. Програмата да:
- записва във файла 'fo'
- създава child процес, който записва 'bar\n'
- parent-а, след като изчака child процеса, записва 'o\n'
*/
#include <stdlib.h>
#include <err.h>
#include <fcntl.h>
#include <unistd.h>
#include <errno.h>
int main(int argc, char **argv){
if(argc != 2)
errx(1, "Invalid number of arguments. Uage: %s <filepath>", argv[0]);
const char *file = argv[1];
ssize_t fd = open(file, O_CREAT | O_TRUNC | O_RDWR, 0644);
if(fd == -1)
err(2, "could not open file %s", file);
if(write(fd, "fo", 2) != 2){
const int olderrno = errno;
close(fd);
errno = olderrno;
err(3, "could not write to file %s", file);
}
close(fd);
const pid_t child = fork();
if(child == -1)
err(4, "could not fork process for child");
if(child == 0){ // we are in child process
fd = open(file, O_APPEND | O_WRONLY);
if(fd == -1)
err(5, "could not open file %s", file);
if(write(fd, "bar\n", 4) != 4){
const int olderrno = errno;
close(fd);
errno = olderrno;
err(6, "could not write to file %s", file);
}
close(fd);
exit(0);
}
if(wait(NULL) == -1)
err(7, "could not wait for child process");
fd = open(file, O_APPEND | O_WRONLY);
if(fd == -1)
err(8, "could not open file %s", file);
if(write(fd, "o\n", 2) != 2){
const int olderrno = errno;
close(fd);
errno = olderrno;
err(9, "could not write to file %s", file);
}
close(fd);
exit(0);
}