pages: Accept pages images from versions v0.4 and below

After reworkring the way pagemap is stored the backward compatibility
was not preserved for patches simplicity. Time to return it back.
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

cr-restore.c

@@ -277,29 +277,47 @@ static int restore_priv_vma_content(pid_t pid)
 	vma = list_first_entry(&rst_vmas.h, struct vma_area, list);
 
 	fd = open_image_ro(CR_FD_PAGEMAP, (long)pid);
-	if (fd < 0)
+	if (fd < 0) {
+		fd_pg = open_image_ro(CR_FD_PAGES_OLD, pid);
+		if (fd_pg < 0)
 			return -1;
-
+	} else {
 		fd_pg = open_pages_image(O_RSTR, fd);
 		if (fd_pg < 0) {
 			close(fd);
 			return -1;
 		}
+	}
 
 	/*
 	 * Read page contents.
 	 */
 	while (1) {
+		unsigned long off, i, nr_pages;;
+
+		if (fd >= 0) {
 			PagemapEntry *pe;
-		unsigned long off, i;
 
 			ret = pb_read_one_eof(fd, &pe, PB_PAGEMAP);
 			if (ret <= 0)
 				break;
 
 			va = (unsigned long)decode_pointer(pe->vaddr);
+			nr_pages = pe->nr_pages;
+
+			pagemap_entry__free_unpacked(pe, NULL);
+		} else {
+			__u64 img_va;
+
+			ret = read_img_eof(fd_pg, &img_va);
+			if (ret <= 0)
+				break;
 
-		for (i = 0; i < pe->nr_pages; i++) {
+			va = (unsigned long)decode_pointer(img_va);
+			nr_pages = 1;
+		}
+
+		for (i = 0; i < nr_pages; i++) {
 			unsigned char buf[PAGE_SIZE];
 			void *p;
 
@@ -350,8 +368,6 @@ static int restore_priv_vma_content(pid_t pid)
 			memcpy(p, buf, PAGE_SIZE);
 			nr_restored++;
 		}
-
-		pagemap_entry__free_unpacked(pe, NULL);
 	}
 	close(fd_pg);
 	close(fd);

image.c

@@ -157,6 +157,8 @@ struct cr_fd_desc_tmpl fdset_template[CR_FD_MAX] = {
 	FD_ENTRY(FILE_LOCKS,	"filelocks-%d",	 show_file_locks),
 	FD_ENTRY(RLIMIT,	"rlimit",	 show_rlimit),
 	FD_ENTRY(PAGES,		"pages-%u",	 NULL),
+	FD_ENTRY(PAGES_OLD,	"pages-%d",	 NULL),
+	FD_ENTRY(SHM_PAGES_OLD, "pages-shmem-%ld", NULL),
 	FD_ENTRY(SIGNAL,	"signal-s-%d",	 show_siginfo), /* shared signals */
 	FD_ENTRY(PSIGNAL,	"signal-p-%d",	 show_siginfo), /* private signals */
 };

include/crtools.h

@@ -86,6 +86,9 @@ enum {
 	CR_FD_PAGES,
 	CR_FD_PSIGNAL,
 
+	CR_FD_PAGES_OLD,
+	CR_FD_SHM_PAGES_OLD,
+
 	CR_FD_MAX
 };
 

include/magic.h

@@ -72,4 +72,7 @@
 #define ROUTE_MAGIC		RAW_IMAGE_MAGIC
 #define TMPFS_MAGIC		RAW_IMAGE_MAGIC
 
+#define PAGES_OLD_MAGIC		PAGEMAP_MAGIC
+#define SHM_PAGES_OLD_MAGIC	PAGEMAP_MAGIC
+
 #endif /* __CR_MAGIC_H__ */

shmem.c

@@ -139,30 +139,51 @@ static int restore_shmem_content(void *addr, struct shmem_info *si)
 	int fd, fd_pg, ret = 0;
 
 	fd = open_image_ro(CR_FD_SHMEM_PAGEMAP, si->shmid);
-	if (fd < 0)
+	if (fd < 0) {
+		fd_pg = open_image_ro(CR_FD_SHM_PAGES_OLD, si->shmid);
+		if (fd_pg < 0)
 			goto err_unmap;
-
+	} else {
 		fd_pg = open_pages_image(O_RSTR, fd);
 		if (fd_pg < 0)
 			goto out_close;
+	}
 
 	while (1) {
+		unsigned long vaddr;
+		unsigned nr_pages;
+
+		if (fd >= 0) {
 			PagemapEntry *pe;
 
 			ret = pb_read_one_eof(fd, &pe, PB_PAGEMAP);
 			if (ret <= 0)
 				break;
 
-		if (pe->vaddr + pe->nr_pages * PAGE_SIZE > si->size)
+			vaddr = (unsigned long)decode_pointer(pe->vaddr);
+			nr_pages = pe->nr_pages;
+
+			pagemap_entry__free_unpacked(pe, NULL);
+		} else {
+			__u64 img_vaddr;
+
+			ret = read_img_eof(fd_pg, &img_vaddr);
+			if (ret <= 0)
 				break;
 
-		ret = read(fd_pg, addr + pe->vaddr, pe->nr_pages * PAGE_SIZE);
-		if (ret != pe->nr_pages * PAGE_SIZE) {
+			vaddr = (unsigned long)decode_pointer(img_vaddr);
+			nr_pages = 1;
+		}
+
+		if (vaddr + nr_pages * PAGE_SIZE > si->size)
+			break;
+
+		ret = read(fd_pg, addr + vaddr, nr_pages * PAGE_SIZE);
+		if (ret != nr_pages * PAGE_SIZE) {
 			ret = -1;
 			break;
 		}
 
-		pagemap_entry__free_unpacked(pe, NULL);
 	}
 
 	close(fd_pg);