/* * mapper.c -- simple file that mmap()s a file region and prints it */#include <stdio.h>#include <stdlib.h>#include <string.h>#include <unistd.h>#include <sys/mman.h>#include <errno.h>int main(int argc, char **argv){    char *fname;    FILE *f;    unsigned int offset, len;    void *address;    if (argc !=4       || sscanf(argv[2],"%i", &offset) != 1       || sscanf(argv[3],"%i", &len) != 1) {        fprintf(stderr, "%s: Usage \"%s <file> <offset> <len>\"\n", argv[0],                argv[0]);        exit(1);    }    fname=argv[1];    if (!(f=fopen(fname,"r"))) {        fprintf(stderr, "%s: %s: %s\n", argv[0], fname, strerror(errno));        exit(1);    }    address=mmap(0, len, PROT_READ, MAP_FILE | MAP_PRIVATE, fileno(f), offset);    if (address == (void *)-1) {        fprintf(stderr,"%s: mmap(): %s\n",argv[0],strerror(errno));        exit(1);    }    fclose(f);    fprintf(stderr, "mapped \"%s\" from %i to %i\n",            fname, offset, offset+len);    fwrite(address, 1, len, stdout);    return 0;}