[CRIU] [PATCH] show: logic for optionaly files introduced

[Kinsbursky Stanislav]

Some dump files (like UTS and IPC ns files) may not present after dump. But
"show all" call have to take it into account and fail trying to open dump
these files.
"Opt" variable in struct cr_fd_desc_tmpl has been introduced to solve this
problem. If this variable is set, then open failure for such files doesn't
lead to failure of whole "show all" sequence.
Also, added check for file validity of UTS ns file descriptor before
show_utsns() call.

Signed-off-by: Stanislav Kinsbursky <skinsbursky at parallels.com>

---
 crtools.c         |    6 ++++++
 include/crtools.h |    1 +
 namespaces.c      |    3 ++-
 3 files changed, 9 insertions(+), 1 deletions(-)

diff --git a/crtools.c b/crtools.c
index 8cfe866..6600451 100644
--- a/crtools.c
+++ b/crtools.c
@@ -109,12 +109,14 @@ struct cr_fd_desc_tmpl fdset_template[CR_FD_MAX] = {
 	[CR_FD_UTSNS] = {
 		.fmt	= FMT_FNAME_UTSNS,
 		.magic	= UTSNS_MAGIC,
+		.opt	= 1,
 	},
 
 	/* IPC namespace variables */
 	[CR_FD_IPCNS_VAR] = {
 		.fmt	= FMT_FNAME_IPCNS_VAR,
 		.magic	= IPCNS_VAR_MAGIC,
+		.opt	= 1,
 	},
 };
 
@@ -194,6 +196,8 @@ struct cr_fdset *cr_fdset_open(int pid, unsigned long use_mask, struct cr_fdset
 
 		ret = open(path, O_RDWR | O_CREAT | O_EXCL, CR_FD_PERM);
 		if (ret < 0) {
+			if (fdset_template[i].opt)
+				continue;
 			pr_perror("Unable to open %s", path);
 			goto err;
 		}
@@ -237,6 +241,8 @@ struct cr_fdset *prep_cr_fdset_for_restore(int pid, unsigned long use_mask)
 
 		ret = open(path, O_RDWR, CR_FD_PERM);
 		if (ret < 0) {
+			if (fdset_template[i].opt)
+				continue;
 			pr_perror("Unable to open %s", path);
 			goto err;
 		}
diff --git a/include/crtools.h b/include/crtools.h
index acb6a6d..ff28f62 100644
--- a/include/crtools.h
+++ b/include/crtools.h
@@ -60,6 +60,7 @@ struct cr_options {
 struct cr_fd_desc_tmpl {
 	const char	*fmt;			/* format for the name */
 	u32		magic;			/* magic in the header */
+	bool		opt;			/* optional presence flag */
 };
 
 extern struct cr_fd_desc_tmpl fdset_template[CR_FD_MAX];
diff --git a/namespaces.c b/namespaces.c
index 1e245b8..8a7cdb1 100644
--- a/namespaces.c
+++ b/namespaces.c
@@ -122,7 +122,8 @@ int try_show_namespaces(int ns_pid)
 	if (!fdset)
 		return -1;
 
-	show_utsns(fdset->fds[CR_FD_UTSNS]);
+	if (fdset->fds[CR_FD_UTSNS] != -1)
+		show_utsns(fdset->fds[CR_FD_UTSNS]);
 
 	close_cr_fdset(&fdset);
 	return 0;