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Improve Magic Mount with proper precedence

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This commit is contained in:
topjohnwu 2017-05-09 01:09:32 +08:00
parent 543ee79720
commit bb96477779
2 changed files with 107 additions and 90 deletions
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194
jni/daemon/bootstages.c
View File

@ -25,14 +25,14 @@ static struct vector module_list;
* Node structure *
******************/
// Precedence: MODULE > SKEL > DUMMY
#define DO_NOTHING 0x0 /* intermediate node */
#define IS_MODULE 0x1 /* mount from module */
#define IS_DUMMY 0x2 /* mount from mirror */
#define IS_SKEL 0x4 /* mount from skeleton */
#define IS_DUMMY 0x1 /* mount from mirror */
#define IS_SKEL 0x2 /* mount from skeleton */
#define IS_MODULE 0x4 /* mount from module */
struct node_entry {
const char *module;
const char *module; /* Only used when status & IS_MODULE */
char *name;
uint8_t type;
uint8_t status;
@ -40,6 +40,10 @@ struct node_entry {
struct vector *children;
};
#define IS_DIR(n) (n->type == DT_DIR)
#define IS_LNK(n) (n->type == DT_LNK)
#define IS_REG(n) (n->type == DT_REG)
/******************
* Image handling *
******************/
@ -226,15 +230,6 @@ void exec_module_script(const char* stage) {
* Magic Mount *
***************/
static int hasChild(struct node_entry *node, const char *name) {
struct node_entry *child;
vec_for_each(node->children, child) {
if (strcmp(child->name, name) == 0)
return 1;
}
return 0;
}
static char *get_full_path(struct node_entry *node) {
char buffer[PATH_MAX], temp[PATH_MAX];
// Concat the paths
@ -248,6 +243,14 @@ static char *get_full_path(struct node_entry *node) {
return strdup(buffer);
}
// Free the node
static void destroy_node(struct node_entry *node) {
free(node->name);
vec_destroy(node->children);
free(node->children);
free(node);
}
// Free the node and all children recursively
static void destroy_subtree(struct node_entry *node) {
// Never free parent, since it shall be freed by themselves
@ -255,13 +258,11 @@ static void destroy_subtree(struct node_entry *node) {
vec_for_each(node->children, e) {
destroy_subtree(e);
}
free(node->name);
vec_destroy(node->children);
free(node->children);
free(node);
destroy_node(node);
}
static void insert_child(struct node_entry *p, struct node_entry *c) {
// Return the child
static struct node_entry *insert_child(struct node_entry *p, struct node_entry *c) {
c->parent = p;
if (p->children == NULL) {
p->children = xmalloc(sizeof(struct vector));
@ -270,27 +271,36 @@ static void insert_child(struct node_entry *p, struct node_entry *c) {
struct node_entry *e;
vec_for_each(p->children, e) {
if (strcmp(e->name, c->name) == 0) {
// Exist duplicate, replace
c->children = e->children;
free(e->name);
free(e);
vec_entry(p->children)[_] = c;
return;
// Exist duplicate
if (c->status > e->status) {
// Precedence is higher, replace with new node
c->children = e->children; // Preserve all children
free(e->name);
free(e);
vec_entry(p->children)[_] = c;
return c;
} else {
// Free the new entry, return old
destroy_node(c);
return e;
}
}
}
// New entry, push back
vec_push_back(p->children, c);
return c;
}
static void construct_tree(const char *module, const char *path, struct node_entry *parent) {
static void construct_tree(const char *module, struct node_entry *parent) {
DIR *dir;
struct dirent *entry;
struct node_entry *node;
snprintf(buf, PATH_MAX, "%s/%s/%s", MOUNTPOINT, module, path);
char *parent_path = get_full_path(parent);
snprintf(buf, PATH_MAX, "%s/%s%s", MOUNTPOINT, module, parent_path);
if (!(dir = opendir(buf)))
return;
goto cleanup;
while ((entry = xreaddir(dir))) {
if (strcmp(entry->d_name, ".") == 0 || strcmp(entry->d_name, "..") == 0)
@ -300,86 +310,83 @@ static void construct_tree(const char *module, const char *path, struct node_ent
node->module = module;
node->name = strdup(entry->d_name);
node->type = entry->d_type;
insert_child(parent, node);
char *real_path = get_full_path(node);
snprintf(buf, PATH_MAX, "%s/%s", parent_path, node->name);
// Check if the entry has a correspond target
if (entry->d_type == DT_LNK || access(real_path, F_OK) == -1) {
if (IS_LNK(node) || access(buf, F_OK) == -1) {
// Mark the parent folder as a skeleton
parent->status = IS_SKEL;
node->status = IS_MODULE;
} else {
if (entry->d_type == DT_DIR) {
// Check if marked as replace
snprintf(buf2, PATH_MAX, "%s/%s/%s/%s/.replace", MOUNTPOINT, module, path, entry->d_name);
if (access(buf2, F_OK) == 0) {
// Replace everything, mark as leaf
node->status = IS_MODULE;
} else {
// Travel deeper
snprintf(buf2, PATH_MAX, "%s/%s", path, entry->d_name);
char *new_path = strdup(buf2);
construct_tree(module, new_path, node);
free(new_path);
}
} else if (entry->d_type == DT_REG) {
// This is a leaf, mark as target
node->status = IS_MODULE;
parent->status |= IS_SKEL;
node->status |= IS_MODULE;
} else if (IS_DIR(node)) {
// Check if marked as replace
snprintf(buf2, PATH_MAX, "%s/%s%s/.replace", MOUNTPOINT, module, buf);
if (access(buf2, F_OK) == 0) {
// Replace everything, mark as leaf
node->status |= IS_MODULE;
}
} else if (IS_REG(node)) {
// This is a leaf, mark as target
node->status |= IS_MODULE;
}
node = insert_child(parent, node);
if (node->status == DO_NOTHING) {
// Intermediate node, travel deeper
construct_tree(module, node);
}
free(real_path);
}
closedir(dir);
cleanup:
free(parent_path);
}
static void clone_skeleton(struct node_entry *node, const char *real_path) {
static void clone_skeleton(struct node_entry *node) {
DIR *dir;
struct dirent *entry;
struct node_entry *dummy, *child;
// Clone the structure
if (!(dir = opendir(real_path)))
return;
char *full_path = get_full_path(node);
if (!(dir = opendir(full_path)))
goto cleanup;
while ((entry = xreaddir(dir))) {
if (strcmp(entry->d_name, ".") == 0 || strcmp(entry->d_name, "..") == 0)
continue;
if (!hasChild(node, entry->d_name)) {
// Create dummy node
dummy = xcalloc(sizeof(*dummy), 1);
dummy->name = strdup(entry->d_name);
dummy->type = entry->d_type;
dummy->status = IS_DUMMY;
insert_child(node, dummy);
}
// Create dummy node
dummy = xcalloc(sizeof(*dummy), 1);
dummy->name = strdup(entry->d_name);
dummy->type = entry->d_type;
dummy->status |= IS_DUMMY;
insert_child(node, dummy);
}
closedir(dir);
snprintf(buf, PATH_MAX, "%s%s", DUMMDIR, real_path);
snprintf(buf, PATH_MAX, "%s%s", DUMMDIR, full_path);
mkdir_p(buf, 0755);
clone_attr(real_path, buf);
bind_mount(buf, real_path);
clone_attr(full_path, buf);
bind_mount(buf, full_path);
vec_for_each(node->children, child) {
snprintf(buf, PATH_MAX, "%s%s/%s", DUMMDIR, real_path, child->name);
if (child->type == DT_DIR) {
snprintf(buf, PATH_MAX, "%s%s/%s", DUMMDIR, full_path, child->name);
// Create the dummy file/directory
if (IS_DIR(child))
xmkdir(buf, 0755);
} else if (child->type == DT_REG) {
else if (IS_REG(child))
close(open_new(buf));
}
if (child->status == IS_MODULE) {
if (child->status & IS_MODULE) {
// Mount from module file to dummy file
snprintf(buf2, PATH_MAX, "%s/%s%s/%s", MOUNTPOINT, child->module, real_path, child->name);
} else if (child->status == IS_DUMMY) {
// Mount from mirror to dummy file
snprintf(buf2, PATH_MAX, "%s%s/%s", MIRRDIR, real_path, child->name);
} else if (child->status == IS_SKEL) {
snprintf(buf2, PATH_MAX, "%s/%s%s/%s", MOUNTPOINT, child->module, full_path, child->name);
} else if (child->status & IS_SKEL) {
// It's another skeleton, recursive call and end
char *s = get_full_path(child);
clone_skeleton(child, s);
free(s);
clone_skeleton(child);
continue;
} else if (child->status & IS_DUMMY) {
// Mount from mirror to dummy file
snprintf(buf2, PATH_MAX, "%s%s/%s", MIRRDIR, full_path, child->name);
}
if (child->type == DT_LNK) {
if (IS_LNK(child)) {
// Symlink special treatments
char *temp = xmalloc(PATH_MAX);
xreadlink(buf2, temp, PATH_MAX);
@ -387,10 +394,13 @@ static void clone_skeleton(struct node_entry *node, const char *real_path) {
free(temp);
LOGI("cplink: %s -> %s\n", buf2, buf);
} else {
snprintf(buf, PATH_MAX, "%s/%s", real_path, child->name);
snprintf(buf, PATH_MAX, "%s/%s", full_path, child->name);
bind_mount(buf2, buf);
}
}
cleanup:
free(full_path);
}
static void magic_mount(struct node_entry *node) {
@ -405,18 +415,22 @@ static void magic_mount(struct node_entry *node) {
return;
}
if (node->status == DO_NOTHING) {
vec_for_each(node->children, child)
magic_mount(child);
} else {
real_path = get_full_path(node);
if (node->status == IS_MODULE) {
if (node->status) {
if (node->status & IS_MODULE) {
// The real deal, mount module item
real_path = get_full_path(node);
snprintf(buf, PATH_MAX, "%s/%s%s", MOUNTPOINT, node->module, real_path);
bind_mount(buf, real_path);
} else if (node->status == IS_SKEL) {
clone_skeleton(node, real_path);
free(real_path);
} else if (node->status & IS_SKEL) {
// The node is labeled to be cloned with skeleton, lets do it
clone_skeleton(node);
}
free(real_path);
// We should not see dummies, so no need to handle it here
} else {
// It's an intermediate node, travel deeper
vec_for_each(node->children, child)
magic_mount(child);
}
}
@ -599,7 +613,7 @@ void post_fs_data(int client) {
// Construct structure
has_modules = 1;
LOGI("%s: constructing magic mount structure\n", module);
construct_tree(module, "system", sys_root);
construct_tree(module, sys_root);
}
}

3
jni/utils/misc.c
View File

@ -267,8 +267,11 @@ int mkdir_p(const char *pathname, mode_t mode) {
int bind_mount(const char *from, const char *to) {
int ret = xmount(from, to, NULL, MS_BIND, NULL);
#ifdef DEBUG
LOGD("bind_mount: %s -> %s\n", from, to);
#else
LOGI("bind_mount: %s\n", to);
#endif
return ret;
}