CSAPP: Use memory mapping to copy any file on disk to stdout.

mmapcopy.c

// Use memory mapping to copy any file on disk to stdout.

#include <unistd.h>
#include <sys/mman.h>
#include <stdio.h>
#include <fcntl.h>


int main(int argc, char **argv) {
        long sz;

        // Open file.
        FILE * fp = fopen(argv[1], "r");

        // Get file size.
        fseek(fp, 0L, SEEK_END);
        sz = ftell(fp);
        fseek(fp, 0L, SEEK_SET);
        fclose(fp);

        // Map memory.
        int fd = open(argv[1], O_RDONLY);
        char *bufp = mmap(NULL, sz, PROT_READ, MAP_PRIVATE, fd, 0);

        // Print.
        write(1, bufp, sz);

        return 0;
}