#include <poll.h>
#include <fcntl.h>
#include <stdbool.h>
+#include <string.h>
#include <sys/mman.h>
#include <sys/atomics.h>
#include <bionic_atomic_inline.h>
+#define ALIGN(x, a) (((x) + (a - 1)) & ~(a - 1))
+
struct prop_area {
- unsigned volatile count;
+ unsigned bytes_used;
unsigned volatile serial;
unsigned magic;
unsigned version;
- unsigned toc[1];
+ unsigned reserved[28];
+ char data[0];
};
typedef struct prop_area prop_area;
typedef struct prop_info prop_info;
+/*
+ * Properties are stored in a hybrid trie/binary tree structure.
+ * Each property's name is delimited at '.' characters, and the tokens are put
+ * into a trie structure. Siblings at each level of the trie are stored in a
+ * binary tree. For instance, "ro.secure"="1" could be stored as follows:
+ *
+ * +-----+ children +----+ children +--------+
+ * | |-------------->| ro |-------------->| secure |
+ * +-----+ +----+ +--------+
+ * / \ / |
+ * left / \ right left / | prop +===========+
+ * v v v +-------->| ro.secure |
+ * +-----+ +-----+ +-----+ +-----------+
+ * | net | | sys | | com | | 1 |
+ * +-----+ +-----+ +-----+ +===========+
+ */
+
+typedef volatile uint32_t prop_off_t;
+struct prop_bt {
+ char name[PROP_NAME_MAX];
+ uint8_t namelen;
+ uint8_t reserved[3];
+
+ prop_off_t prop;
+
+ prop_off_t left;
+ prop_off_t right;
+
+ prop_off_t children;
+};
+
+typedef struct prop_bt prop_bt;
+
static const char property_service_socket[] = "/dev/socket/" PROP_SERVICE_NAME;
static char property_filename[PATH_MAX] = PROP_FILENAME;
prop_area *__system_property_regions__[PA_REGION_COUNT] = { NULL, };
+const size_t PA_DATA_SIZE = PA_SIZE - sizeof(prop_area);
+
static int get_fd_from_env(void)
{
char *env = getenv("ANDROID_PROPERTY_WORKSPACE");
pa->magic = PROP_AREA_MAGIC;
pa->version = PROP_AREA_VERSION;
+ if (!region) {
+ /* reserve root node */
+ pa->bytes_used += sizeof(prop_bt);
+ }
+
/* plug into the lib property services */
__system_property_regions__[region] = pa;
return map_prop_region(0);
}
-int __system_property_foreach(
- void (*propfn)(const prop_info *pi, void *cookie),
- void *cookie)
+static void *new_prop_obj(size_t size, prop_off_t *off)
{
- size_t region;
+ prop_area *pa;
+ size_t i, idx;
+ size = ALIGN(size, sizeof(uint32_t));
- for (region = 0; region < PA_REGION_COUNT; region++) {
- prop_area *pa;
- unsigned i;
+ for (i = 0; i < PA_REGION_COUNT; i++) {
+ int err = map_prop_region_rw(i);
+ if (err < 0) {
+ return NULL;
+ }
- int err = map_prop_region(region);
- if (err < 0)
+ pa = __system_property_regions__[i];
+ if (pa->bytes_used + size <= PA_DATA_SIZE)
break;
- pa = __system_property_regions__[region];
+ }
- for (i = 0; i < pa->count; i++) {
- unsigned entry = pa->toc[i];
- prop_info *pi = TOC_TO_INFO(pa, entry);
- propfn(pi, cookie);
- }
+ if (i == PA_REGION_COUNT)
+ return NULL;
+
+ idx = pa->bytes_used;
+ *off = idx + i * PA_DATA_SIZE;
+ pa->bytes_used += size;
+ return pa->data + idx;
+}
+
+static prop_bt *new_prop_bt(const char *name, uint8_t namelen, prop_off_t *off)
+{
+ prop_off_t off_tmp;
+ prop_bt *bt = new_prop_obj(sizeof(prop_bt), &off_tmp);
+ if (bt) {
+ memcpy(bt->name, name, namelen);
+ bt->name[namelen] = '\0';
+ bt->namelen = namelen;
+ ANDROID_MEMBAR_FULL();
+ *off = off_tmp;
}
- return 0;
+ return bt;
}
-const prop_info *__system_property_find_nth(unsigned n)
+static prop_info *new_prop_info(const char *name, uint8_t namelen,
+ const char *value, uint8_t valuelen, prop_off_t *off)
{
- size_t region = n / PA_COUNT_MAX;
- prop_area *pa;
+ prop_off_t off_tmp;
+ prop_info *info = new_prop_obj(sizeof(prop_info), &off_tmp);
+ if (info) {
+ memcpy(info->name, name, namelen);
+ info->name[namelen] = '\0';
+ info->serial = (valuelen << 24);
+ memcpy(info->value, value, valuelen);
+ info->value[valuelen] = '\0';
+ ANDROID_MEMBAR_FULL();
+ *off = off_tmp;
+ }
- int err = map_prop_region(region);
- if (err < 0)
+ return info;
+}
+
+static void *to_prop_obj(prop_off_t off)
+{
+ size_t region = off / PA_DATA_SIZE;
+ size_t idx = off % PA_DATA_SIZE;
+
+ if (region > PA_REGION_COUNT)
return NULL;
- pa = __system_property_regions__[region];
- if((n % PA_COUNT_MAX) >= pa->count) {
- return 0;
- } else {
- return TOC_TO_INFO(pa, pa->toc[n]);
- }
+ if (map_prop_region(region) < 0)
+ return NULL;
+
+ return __system_property_regions__[region]->data + idx;
}
-const prop_info *__system_property_find(const char *name)
+static prop_bt *root_node()
{
- unsigned len = strlen(name);
- size_t region;
+ return to_prop_obj(0);
+}
- if (len >= PROP_NAME_MAX)
- return 0;
- if (len < 1)
- return 0;
+static int cmp_prop_name(const char *one, uint8_t one_len, const char *two,
+ uint8_t two_len)
+{
+ if (one_len < two_len)
+ return -1;
+ else if (one_len > two_len)
+ return 1;
+ else
+ return strncmp(one, two, one_len);
+}
- for (region = 0; region < PA_REGION_COUNT; region++) {
- prop_area *pa;
- unsigned count;
- unsigned *toc;
- prop_info *pi;
+static prop_bt *find_prop_bt(prop_bt *bt, const char *name, uint8_t namelen,
+ bool alloc_if_needed)
+{
+ while (true) {
+ int ret;
+ if (!bt)
+ return bt;
+ ret = cmp_prop_name(name, namelen, bt->name, bt->namelen);
+
+ if (ret == 0) {
+ return bt;
+ } else if (ret < 0) {
+ if (bt->left) {
+ bt = to_prop_obj(bt->left);
+ } else {
+ if (!alloc_if_needed)
+ return NULL;
+
+ bt = new_prop_bt(name, namelen, &bt->left);
+ }
+ } else {
+ if (bt->right) {
+ bt = to_prop_obj(bt->right);
+ } else {
+ if (!alloc_if_needed)
+ return NULL;
- int err = map_prop_region(region);
- if (err < 0)
- return 0;
- pa = __system_property_regions__[region];
- count = pa->count;
- toc = pa->toc;
+ bt = new_prop_bt(name, namelen, &bt->right);
+ }
+ }
+ }
+}
- while(count--) {
- unsigned entry = *toc++;
- if(TOC_NAME_LEN(entry) != len) continue;
+static const prop_info *find_property(prop_bt *trie, const char *name,
+ uint8_t namelen, const char *value, uint8_t valuelen,
+ bool alloc_if_needed)
+{
+ const char *remaining_name = name;
+
+ while (true) {
+ char *sep = strchr(remaining_name, '.');
+ bool want_subtree = (sep != NULL);
+ uint8_t substr_size;
+
+ prop_bt *root;
+
+ if (want_subtree) {
+ substr_size = sep - remaining_name;
+ } else {
+ substr_size = strlen(remaining_name);
+ }
- pi = TOC_TO_INFO(pa, entry);
- if(memcmp(name, pi->name, len)) continue;
+ if (!substr_size)
+ return NULL;
- return pi;
+ if (trie->children) {
+ root = to_prop_obj(trie->children);
+ } else if (alloc_if_needed) {
+ root = new_prop_bt(remaining_name, substr_size, &trie->children);
+ } else {
+ root = NULL;
}
+
+ if (!root)
+ return NULL;
+
+ trie = find_prop_bt(root, remaining_name, substr_size, alloc_if_needed);
+ if (!trie)
+ return NULL;
+
+ if (!want_subtree)
+ break;
+
+ remaining_name = sep + 1;
}
- return 0;
+ if (trie->prop) {
+ return to_prop_obj(trie->prop);
+ } else if (alloc_if_needed) {
+ return new_prop_info(name, namelen, value, valuelen, &trie->prop);
+ } else {
+ return NULL;
+ }
+}
+
+const prop_info *__system_property_find(const char *name)
+{
+ return find_property(root_node(), name, strlen(name), NULL, 0, false);
}
int __system_property_read(const prop_info *pi, char *name, char *value)
int __system_property_add(const char *name, unsigned int namelen,
const char *value, unsigned int valuelen)
{
- prop_area *pa;
- prop_info *pa_info_array;
- prop_info *pi;
- size_t region;
+ prop_area *pa = __system_property_regions__[0];
+ const prop_info *pi;
if (namelen >= PROP_NAME_MAX)
return -1;
if (namelen < 1)
return -1;
- for (region = 0; region < PA_REGION_COUNT; region++)
- {
- int err = map_prop_region_rw(region);
- if (err < 0)
- return -1;
-
- pa = __system_property_regions__[region];
-
- if (pa->count < PA_COUNT_MAX)
- break;
- }
-
- if (region == PA_REGION_COUNT)
+ pi = find_property(root_node(), name, namelen, value, valuelen, true);
+ if (!pi)
return -1;
- pa_info_array = (void*) (((char*) pa) + PA_INFO_START);
- pi = pa_info_array + pa->count;
- pi->serial = (valuelen << 24);
- memcpy(pi->name, name, namelen + 1);
- memcpy(pi->value, value, valuelen + 1);
-
- pa->toc[pa->count] = (namelen << 24) | (((unsigned) pi) - ((unsigned) pa));
- ANDROID_MEMBAR_FULL();
-
- pa->count++;
pa->serial++;
__futex_wake(&pa->serial, INT32_MAX);
-
return 0;
}
return pa->serial;
}
+
+struct find_nth_cookie {
+ unsigned count;
+ unsigned n;
+ const prop_info *pi;
+};
+
+static void find_nth_fn(const prop_info *pi, void *ptr)
+{
+ struct find_nth_cookie *cookie = ptr;
+
+ if (cookie->n == cookie->count)
+ cookie->pi = pi;
+
+ cookie->count++;
+}
+
+const prop_info *__system_property_find_nth(unsigned n)
+{
+ struct find_nth_cookie cookie;
+ int err;
+
+ memset(&cookie, 0, sizeof(cookie));
+ cookie.n = n;
+
+ err = __system_property_foreach(find_nth_fn, &cookie);
+ if (err < 0)
+ return NULL;
+
+ return cookie.pi;
+}
+
+static int foreach_property(prop_off_t off,
+ void (*propfn)(const prop_info *pi, void *cookie), void *cookie)
+{
+ prop_bt *trie = to_prop_obj(off);
+ if (!trie)
+ return -1;
+
+ if (trie->left) {
+ int err = foreach_property(trie->left, propfn, cookie);
+ if (err < 0)
+ return -1;
+ }
+ if (trie->prop) {
+ prop_info *info = to_prop_obj(trie->prop);
+ if (!info)
+ return -1;
+ propfn(info, cookie);
+ }
+ if (trie->children) {
+ int err = foreach_property(trie->children, propfn, cookie);
+ if (err < 0)
+ return -1;
+ }
+ if (trie->right) {
+ int err = foreach_property(trie->right, propfn, cookie);
+ if (err < 0)
+ return -1;
+ }
+
+ return 0;
+}
+
+int __system_property_foreach(void (*propfn)(const prop_info *pi, void *cookie),
+ void *cookie)
+{
+ return foreach_property(0, propfn, cookie);
+}
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