[CRIU] [PATCH 7/8] files: add ability to set callbacks for character devices

[Andrey Vagin]

The difference in compare with unix sockets is that dump callbacks
for character devices can be executed to test, which callback can be
used for a given fd.

Signed-off-by: Andrey Vagin <avagin at openvz.org>
---
 files-reg.c            | 16 ++++++++++++++++
 files.c                | 14 ++++++++++++++
 include/criu-plugin.h  |  3 +++
 include/files.h        |  2 ++
 include/plugin.h       |  4 ++++
 plugin.c               | 21 +++++++++++++++++++++
 protobuf/regfile.proto |  1 +
 7 files changed, 61 insertions(+)

diff --git a/files-reg.c b/files-reg.c
index fb5d7ca..8d48bc0 100644
--- a/files-reg.c
+++ b/files-reg.c
@@ -20,6 +20,7 @@
 #include "protobuf/remap-file-path.pb-c.h"
 
 #include "files-reg.h"
+#include "plugin.h"
 
 /*
  * Ghost files are those not visible from the FS. Dumping them is
@@ -484,6 +485,13 @@ int dump_one_reg_file(int lfd, u32 id, const struct fd_parms *p)
 
 	RegFileEntry rfe = REG_FILE_ENTRY__INIT;
 
+	if (p->cb) {
+		if (p->cb(lfd, id, false))
+			return -1;
+		rfe.has_need_callback = true;
+		rfe.need_callback = true;
+	}
+
 	if (!p->link) {
 		if (fill_fdlink(lfd, p, &_link))
 			return -1;
@@ -583,6 +591,14 @@ static int do_open_reg(struct reg_file_info *rfi, void *arg)
 		return fd;
 	}
 
+	if (rfi->rfe->need_callback) {
+		if (cr_plugin_restore_file(fd, rfi->rfe->id)) {
+			pr_err("Unable to restore %#x\n", rfi->rfe->id);
+			close(fd);
+		}
+		return fd;
+	}
+
 	if ((rfi->rfe->pos != -1ULL) &&
 			lseek(fd, rfi->rfe->pos, SEEK_SET) < 0) {
 		pr_perror("Can't restore file pos");
diff --git a/files.c b/files.c
index 6eb7282..8ff05a3 100644
--- a/files.c
+++ b/files.c
@@ -39,6 +39,8 @@
 #include "protobuf.h"
 #include "protobuf/fs.pb-c.h"
 
+#include "plugin.h"
+
 #define FDESC_HASH_SIZE	64
 static struct hlist_head file_desc_hash[FDESC_HASH_SIZE];
 
@@ -276,7 +278,19 @@ static int dump_chrdev(struct fd_parms *p, int lfd, const int fdinfo)
 			break;
 		/* fallthrough */
 	default: {
+		cr_plugin_dump_file_t *cb;
 		char more[32];
+		int ret;
+
+		ret = cr_plugin_dump_file(lfd, 0, true, &cb);
+		if (ret < 0 && ret != CRIU_CB_SKIP)
+			return -1;
+
+		if (ret == 0) {
+			p->cb = cb;
+			ops = &regfile_dump_ops;
+			break;
+		}
 
 		sprintf(more, "%d:%d", maj, minor(p->stat.st_dev));
 		return dump_unsupp_fd(p, "chr", more);
diff --git a/include/criu-plugin.h b/include/criu-plugin.h
index d4ea30c..53efa41 100644
--- a/include/criu-plugin.h
+++ b/include/criu-plugin.h
@@ -21,6 +21,7 @@
 #define __CRIU_PLUGIN_H__
 
 #include <limits.h>
+#include <stdbool.h>
 
 typedef int (cr_plugin_init_t)(void);
 typedef void (cr_plugin_fini_t)(void);
@@ -31,6 +32,8 @@ typedef void (cr_plugin_fini_t)(void);
 typedef int (cr_plugin_dump_unix_sk_t)(int fd, int id);
 typedef int (cr_plugin_restore_unix_sk_t)(int id);
 
+typedef int (cr_plugin_dump_file_t)(int fd, int id, bool test_only);
+typedef int (cr_plugin_restore_file_t)(int fd, int id);
 
 extern void print_on_level(unsigned int loglevel, const char *format, ...)
 	__attribute__ ((__format__ (__printf__, 2, 3)));
diff --git a/include/files.h b/include/files.h
index d491cf1..85246dd 100644
--- a/include/files.h
+++ b/include/files.h
@@ -46,6 +46,8 @@ struct fd_parms {
 	struct fd_link	*link;
 
 	struct parasite_ctl *ctl;
+
+	cr_plugin_dump_file_t *cb;
 };
 
 #define FD_PARMS_INIT			\
diff --git a/include/plugin.h b/include/plugin.h
index a70dde3..b3d5f15 100644
--- a/include/plugin.h
+++ b/include/plugin.h
@@ -11,4 +11,8 @@ int cr_plugin_init(void);
 int cr_plugin_dump_unix_sk(int fd, int id);
 int cr_plugin_restore_unix_sk(int id);
 
+int cr_plugin_dump_file(int fd, int id, bool test_only,
+				cr_plugin_dump_file_t **cb);
+int cr_plugin_restore_file(int fd, int id);
+
 #endif
diff --git a/plugin.c b/plugin.c
index 114a507..2dc947f 100644
--- a/plugin.c
+++ b/plugin.c
@@ -17,6 +17,8 @@ struct cr_plugin_entry {
 
 		cr_plugin_dump_unix_sk_t *cr_plugin_dump_unix_sk;
 		cr_plugin_restore_unix_sk_t *cr_plugin_restore_unix_sk;
+		cr_plugin_dump_file_t *cr_plugin_dump_file;
+		cr_plugin_restore_file_t *cr_plugin_restore_file;
 	};
 
 	struct cr_plugin_entry *next;
@@ -27,6 +29,8 @@ struct cr_plugins {
 
 	struct cr_plugin_entry *cr_plugin_dump_unix_sk;
 	struct cr_plugin_entry *cr_plugin_restore_unix_sk;
+	struct cr_plugin_entry *cr_plugin_dump_file;
+	struct cr_plugin_entry *cr_plugin_restore_file;
 };
 
 struct cr_plugins cr_plugins;
@@ -77,6 +81,17 @@ int cr_plugin_restore_unix_sk(int ino)
 			(cr_plugin_restore_unix_sk_t **) NULL, ino);
 }
 
+int cr_plugin_dump_file(int fd, int id, bool test, cr_plugin_dump_file_t **cb)
+{
+	return run_plugin_funcs(cr_plugin_dump_file, cb, fd, id, test);
+}
+
+int cr_plugin_restore_file(int fd, int id)
+{
+	return run_plugin_funcs(cr_plugin_restore_file,
+				(cr_plugin_restore_file_t **) NULL, fd, id);
+}
+
 static int cr_lib_load(char *path)
 {
 	struct cr_plugin_entry *ce;
@@ -93,6 +108,9 @@ static int cr_lib_load(char *path)
 	add_plugin_func(cr_plugin_dump_unix_sk);
 	add_plugin_func(cr_plugin_restore_unix_sk);
 
+	add_plugin_func(cr_plugin_dump_file);
+	add_plugin_func(cr_plugin_restore_file);
+
 	ce = NULL;
 	f_fini = dlsym(h, "cr_plugin_fini");
 	if (f_fini) {
@@ -131,6 +149,9 @@ void cr_plugin_fini(void)
 	cr_plugin_free(cr_plugin_dump_unix_sk);
 	cr_plugin_free(cr_plugin_restore_unix_sk);
 
+	cr_plugin_free(cr_plugin_dump_file);
+	cr_plugin_free(cr_plugin_restore_file);
+
 	while (cr_plugins.cr_fini) {
 		ce = cr_plugins.cr_fini;
 		cr_plugins.cr_fini = cr_plugins.cr_fini->next;
diff --git a/protobuf/regfile.proto b/protobuf/regfile.proto
index d975ab0..925d39a 100644
--- a/protobuf/regfile.proto
+++ b/protobuf/regfile.proto
@@ -6,4 +6,5 @@ message reg_file_entry {
 	required uint64		pos	= 3;
 	required fown_entry	fown	= 5;
 	required string		name	= 6;
+	optional bool		need_callback = 7;
 }
-- 
1.8.3.1