robot36/mmap_file.c

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

int mmap_file_ro(void **p, char *name, size_t *size)
{
	*size = 0;
	int fd = open(name, O_RDONLY);
	if (fd == -1) {
		perror("open");
		return 0;
	}

	struct stat sb;
	if (fstat(fd, &sb) == -1) {
		perror("fstat");
		close(fd);
		return 0;
	}

	if (!S_ISREG(sb.st_mode)) {
		fprintf(stderr, "%s not a file\n", name);
		close(fd);
		return 0;
	}

	*p = mmap(0, sb.st_size, PROT_READ, MAP_SHARED, fd, 0);
	if (*p == MAP_FAILED) {
		perror("mmap");
		close(fd);
		return 0; 
	}

	if (close(fd) == -1) {
		perror ("close");
		return 0; 
	}
	*size = sb.st_size;
	return 1;
}

int mmap_file_rw(void **p, char *name, size_t size)
{
	int fd = open(name, O_RDWR|O_CREAT|O_TRUNC, S_IRUSR|S_IWUSR|S_IRGRP|S_IROTH);
	if (fd == -1) {
		perror("open");
		return 0;
	}

	struct stat sb;
	if (fstat(fd, &sb) == -1) {
		perror("fstat");
		close(fd);
		return 0;
	}

	if (!S_ISREG(sb.st_mode)) {
		fprintf(stderr, "%s not a file\n", name);
		close(fd);
		return 0;
	}

	if (lseek(fd, size - 1, SEEK_SET) == -1) {
		perror("lseek");
		close(fd);
		return 0;
	}

	if (write(fd, "", 1) != 1) {
		perror("write");
		close(fd);
		return 0;
	}

	*p = mmap(0, size, PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0);
	if (*p == MAP_FAILED) {
		perror("mmap");
		close(fd);
		return 0; 
	}

	if (close(fd) == -1) {
		perror ("close");
		return 0; 
	}
	return 1;
}
int munmap_file(void *p, size_t size)
{
	if (munmap(p, size) == -1) {
		perror("munmap");
		return 0;
	}
	return 1;
}