230131249 / linux-file-io-systems-locking

Ex07-Linux File-IO Systems-locking

Linux-File-IO-Systems-locking

Ex07-Linux File-IO Systems-locking

AIM:

To Write a C program that illustrates files copying and locking

DESIGN STEPS:

Step 1:

Navigate to any Linux environment installed on the system or installed inside a virtual environment like virtual box/vmware or online linux JSLinux (https://bellard.org/jslinux/vm.html?url=alpine-x86.cfg&mem=192) or docker.

Step 2:

Write the C Program using Linux IO Systems locking

Step 3:

Execute the C Program for the desired output.

PROGRAM:

1.To Write a C program that illustrates files copying

include <sys/stat.h> #include <fcntl.h> #include <stdlib.h> int main() { char block[1024]; int in, out; int nread; in = open("filecopy.c", O_RDONLY); out = open("file.out", O_WRONLY|O_CREAT, S_IRUSR|S_IWUSR); while((nread = read(in,block,sizeof(block))) > 0) write(out,block,nread); exit(0);}

2.To Write a C program that illustrates files locking

#include <fcntl.h> #include <stdio.h> #include <string.h> #include <unistd.h> #include <sys/file.h> int main (int argc, char* argv[]) { char* file = argv[1]; int fd; struct flock lock; printf ("opening %s\n", file); /* Open a file descriptor to the file. */ fd = open (file, O_WRONLY); // acquire shared lock if (flock(fd, LOCK_SH) == -1) { printf("error"); }else {printf("Acquiring shared lock using flock"); } getchar(); // non-atomically upgrade to exclusive lock // do it in non-blocking mode, i.e. fail if can't upgrade immediately if (flock(fd, LOCK_EX | LOCK_NB) == -1) { printf("error"); }else {printf("Acquiring exclusive lock using flock");} getchar(); // release lock // lock is also released automatically when close() is called or process exits if (flock(fd, LOCK_UN) == -1) { printf("error"); }else{ printf("unlocking"); } getchar(); close (fd); return 0; }

OUTPUT

RESULT:

The programs are executed successfully.