update

Signed-off-by: Wenchao Hao <haowenchao2@huawei.com>

mmap/mmap.c

@@ -0,0 +1,76 @@
+#include <fcntl.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/mman.h>
+#include <sys/stat.h>
+#include <unistd.h>
+#include <string.h>
+
+#define handle_error(msg) \
+	do { perror(msg); exit(EXIT_FAILURE); } while (0)
+
+int main(int argc, char *argv[])
+{
+	int          fd;
+	char         *addr;
+	off_t        offset, pa_offset;
+	size_t       length;
+	ssize_t      s;
+	struct stat  sb;
+
+	if (argc < 3 || argc > 4) {
+		fprintf(stderr, "%s file offset [length]\n", argv[0]);
+		exit(EXIT_FAILURE);
+	}
+
+	fd = open(argv[1], O_RDWR);
+	if (fd == -1)
+		handle_error("open");
+
+	if (fstat(fd, &sb) == -1)           /* To obtain file size */
+		handle_error("fstat");
+
+	offset = atoi(argv[2]);
+	pa_offset = offset & ~(sysconf(_SC_PAGE_SIZE) - 1);
+	/* offset for mmap() must be page aligned */
+
+	if (offset >= sb.st_size) {
+		fprintf(stderr, "offset is past end of file\n");
+		exit(EXIT_FAILURE);
+	}
+
+	if (argc == 4) {
+		length = atoi(argv[3]);
+		if (offset + length > sb.st_size)
+			length = sb.st_size - offset;
+		/* Can't display bytes past end of file */
+
+	} else {    /* No length arg ==> display to end of file */
+		length = sb.st_size - offset;
+	}
+
+	addr = mmap(NULL, length + offset - pa_offset, PROT_READ | PROT_WRITE,
+			MAP_SHARED, fd, pa_offset);
+	if (addr == MAP_FAILED)
+		handle_error("mmap");
+
+	printf("address is 0x%x\n", (unsigned long)addr);
+
+	//write(fd, "", 1);
+	memcpy(addr, "haowenchao", 11);
+	msync(addr, sb.st_size, MS_SYNC);
+
+	s = write(STDOUT_FILENO, addr + offset - pa_offset, length);
+	if (s != length) {
+		if (s == -1)
+			handle_error("write");
+
+		fprintf(stderr, "partial write");
+		exit(EXIT_FAILURE);
+	}
+
+	munmap(addr, length + offset - pa_offset);
+	close(fd);
+
+	exit(EXIT_SUCCESS);
+}

mmap/write.c

@@ -0,0 +1,30 @@
+#include <unistd.h>
+#include <fcntl.h>
+#include <sys/mman.h>
+#include <string.h>
+#include <stdio.h>
+
+int main(int argc, char **argv)
+{
+	int fd = open(argv[1], O_RDWR | O_CREAT, (mode_t)0600);
+	const char *text = "hello";
+	size_t textsize = strlen(text) + 1;
+	char *map;
+
+	lseek(fd, textsize-1, SEEK_SET);
+	write(fd, "", 1);
+
+	map = mmap(0, textsize, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
+	printf("address is 0x%x\n", (unsigned long)map);
+
+	memcpy(map, text, strlen(text));
+
+	//while(1);
+
+	msync(map, textsize, MS_SYNC);
+	munmap(map, textsize);
+
+	close(fd);
+	return 0;
+}
+