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utils: add shared mount point detection

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Signed-off-by: Liza Tretyakova <elizabet.tretyakova@gmail.com>
This commit is contained in:
Liza Tretyakova
2018-05-02 10:47:15 +03:00
committed by Christian Brauner
parent 0d190408c2
commit f6310f1844
2 changed files with 21 additions and 13 deletions
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33
src/lxc/utils.c
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@@ -1219,19 +1219,12 @@ uint64_t fnv_64a_buf(void *buf, size_t len, uint64_t hval)
return hval;
}
/*
* Detect whether / is mounted MS_SHARED. The only way I know of to
* check that is through /proc/self/mountinfo.
* I'm only checking for /. If the container rootfs or mount location
* is MS_SHARED, but not '/', then you're out of luck - figuring that
* out would be too much work to be worth it.
*/
int detect_shared_rootfs(void)
bool is_shared_mountpoint(const char *path)
{
char buf[LXC_LINELEN], *p;
char buf[LXC_LINELEN];
FILE *f;
int i;
char *p2;
char *p, *p2;
f = fopen("/proc/self/mountinfo", "r");
if (!f)
@@ -1248,17 +1241,31 @@ int detect_shared_rootfs(void)
continue;
*p2 = '\0';
if (strcmp(p + 1, "/") == 0) {
/* This is '/'. Is it shared? */
if (strcmp(p + 1, path) == 0) {
/* This is the path. Is it shared? */
p = strchr(p2 + 1, ' ');
if (p && strstr(p, "shared:")) {
fclose(f);
return 1;
return true;
}
}
}
fclose(f);
return false;
}
/*
* Detect whether / is mounted MS_SHARED. The only way I know of to
* check that is through /proc/self/mountinfo.
* I'm only checking for /. If the container rootfs or mount location
* is MS_SHARED, but not '/', then you're out of luck - figuring that
* out would be too much work to be worth it.
*/
int detect_shared_rootfs(void)
{
if (is_shared_mountpoint("/"))
return 1;
return 0;
}

1
src/lxc/utils.h
View File

@@ -502,6 +502,7 @@ extern bool dir_exists(const char *path);
#define FNV1A_64_INIT ((uint64_t)0xcbf29ce484222325ULL)
extern uint64_t fnv_64a_buf(void *buf, size_t len, uint64_t hval);
extern bool is_shared_mountpoint(const char *path);
extern int detect_shared_rootfs(void);
extern bool detect_ramfs_rootfs(void);
extern char *on_path(const char *cmd, const char *rootfs);