[CRIU] [PATCH] mount: resolve parent mount of symbolic link correctly

[Pavel Emelyanov]

On 07/26/2016 01:42 AM, Andrew Vagin wrote:
> On Mon, Jul 25, 2016 at 02:26:01PM +0000, Katerina Koukiou wrote:
>> When using --root option in criu dump, when the mountpoint passed
>> contains a symbolic link, criu does not resolve its parent correctly.
>> e.g when passing --root /run/rootfs, dump finishes successfully;
>> but when /var/run/rootfs is passed, where /var/run is symbolic link to
>> /run it exits with error "New root and old root are the same".
>>
>> Signed-off-by: Katerina Koukiou <k.koukiou at gmail.com>
>> ---
>>  criu/mount.c | 10 +++++++++-
>>  1 file changed, 9 insertions(+), 1 deletion(-)
>>
>> diff --git a/criu/mount.c b/criu/mount.c
>> index 7c280c0..0cd83af 100644
>> --- a/criu/mount.c
>> +++ b/criu/mount.c
>> @@ -3420,6 +3420,8 @@ int prepare_mnt_ns(void)
>>  			return -1;
>>  	} else {
>>  		struct mount_info *mi;
>> +		char *ret;
>> +		char path[PATH_MAX + 1];
> 
> PATH_MAX is enough, it includes '\0'
>>  
>>  		/*
>>  		 * The whole tree of mountpoints is to be moved into one
>> @@ -3428,8 +3430,14 @@ int prepare_mnt_ns(void)
>>  		 * with a single umount call later.
>>  		 */
>>  
>> +		ret = realpath(opts.root, path);
> 
> realpath returns a string, but a type of ret is int.

No, there's new char *ret in this block :)

>> +		if (!ret) {
>> +			pr_err("Unable to find real path for %s\n", opts.root);
>> +			return -1;
>> +		}
>> +
>>  		/* moving a mount residing under a shared mount is invalid. */
>> -		mi = mount_resolve_path(ns.mnt.mntinfo_tree, opts.root);
>> +		mi = mount_resolve_path(ns.mnt.mntinfo_tree, path);
>>  		if (mi == NULL) {
>>  			pr_err("Unable to find mount point for %s\n", opts.root);
>>  			return -1;
>> -- 
>> 2.7.3
>>
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