[CRIU] [PATCH 2/9] mount: Add helper for path length calculations
Pavel Emelyanov
xemul at parallels.com
Tue Nov 11 06:49:51 PST 2014
The path lenght is zero for the "/" one and strlen(path)
for all the others. This is done so to make it possible
to use this length to get tail-paths: if path_1 starts
with path_2 and both are absolute, then
path_1 + path_length(path_2)
would give the tail of the tail of path_1 relative to
path_2 even if the path_2 is just "/".
Signed-off-by: Pavel Emelyanov <xemul at parallels.com>
---
mount.c | 36 +++++++++++++++++++++++-------------
1 file changed, 23 insertions(+), 13 deletions(-)
diff --git a/mount.c b/mount.c
index d4db1ff..75fcfad 100644
--- a/mount.c
+++ b/mount.c
@@ -388,6 +388,25 @@ static struct mount_info *get_widest_peer(struct mount_info *m)
return NULL;
}
+static inline int path_length(char *path)
+{
+ int off;
+
+ off = strlen(path);
+ /*
+ * If we're pure / then set lenght to zero so that adding this
+ * value as sub-path offset would produce the correct result.
+ * E.g. the tail path of the "/foo/bar" relative to the "/foo"
+ * will be the "/foo/bar" + len("/foo") == "/bar", while the
+ * same relative to the "/" should be +0 to be the "/foo/bar",
+ * not +1 and the "foo/bar".
+ */
+ if (path[off - 1] == '/')
+ off--;
+
+ return off;
+}
+
static int validate_shared(struct mount_info *m)
{
struct mount_info *t, *ct, *cm, *tmp;
@@ -417,19 +436,10 @@ static int validate_shared(struct mount_info *m)
/* A set of childrent which ar visiable for both should be the same */
- t_root_len = strlen(t->root);
- m_root_len = strlen(m->root);
- tpm = strlen(t->mountpoint);
- mpm = strlen(m->mountpoint);
-
- if (t->root[t_root_len - 1] == '/')
- t_root_len--;
- if (m->root[m_root_len - 1] == '/')
- m_root_len--;
- if (t->mountpoint[tpm - 1] == '/')
- tpm--;
- if (m->mountpoint[mpm - 1] == '/')
- mpm--;
+ t_root_len = path_length(t->root);
+ m_root_len = path_length(m->root);
+ tpm = path_length(t->mountpoint);
+ mpm = path_length(m->mountpoint);
/* For example:
* t->root = / t->mp = ./zdtm/live/static/mntns_root_bind.test
--
1.8.4.2
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