Revert "bionic: reimplement property area as hybrid trie/binary tree"
This reverts commit 6ac8e6a46d71a51bec16938efa89f275fa89cf7d.
diff --git a/libc/bionic/system_properties.c b/libc/bionic/system_properties.c
index 126fea5..b12879e 100644
--- a/libc/bionic/system_properties.c
+++ b/libc/bionic/system_properties.c
@@ -34,7 +34,6 @@
#include <poll.h>
#include <fcntl.h>
#include <stdbool.h>
-#include <string.h>
#include <sys/mman.h>
@@ -52,15 +51,12 @@
#include <sys/atomics.h>
#include <bionic_atomic_inline.h>
-#define ALIGN(x, a) (((x) + (a - 1)) & ~(a - 1))
-
struct prop_area {
- unsigned bytes_used;
+ unsigned volatile count;
unsigned volatile serial;
unsigned magic;
unsigned version;
- unsigned reserved[28];
- char data[0];
+ unsigned toc[1];
};
typedef struct prop_area prop_area;
@@ -73,46 +69,11 @@
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");
@@ -159,11 +120,6 @@
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;
@@ -269,183 +225,83 @@
return map_prop_region(0);
}
-static void *new_prop_obj(size_t size, prop_off_t *off)
+int __system_property_foreach(
+ void (*propfn)(const prop_info *pi, void *cookie),
+ void *cookie)
{
+ size_t region;
+
+ for (region = 0; region < PA_REGION_COUNT; region++) {
+ prop_area *pa;
+ unsigned i;
+
+ int err = map_prop_region(region);
+ if (err < 0)
+ 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);
+ }
+ }
+
+ return 0;
+}
+
+const prop_info *__system_property_find_nth(unsigned n)
+{
+ size_t region = n / PA_COUNT_MAX;
prop_area *pa;
- size_t i, idx;
- size = ALIGN(size, sizeof(uint32_t));
- for (i = 0; i < PA_REGION_COUNT; i++) {
- int err = map_prop_region_rw(i);
- if (err < 0) {
- return NULL;
- }
-
- pa = __system_property_regions__[i];
- if (pa->bytes_used + size <= PA_DATA_SIZE)
- break;
- }
-
- if (i == PA_REGION_COUNT)
+ int err = map_prop_region(region);
+ if (err < 0)
return NULL;
+ pa = __system_property_regions__[region];
- 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 bt;
-}
-
-static prop_info *new_prop_info(const char *name, uint8_t namelen,
- const char *value, uint8_t valuelen, prop_off_t *off)
-{
- 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;
- }
-
- 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;
-
- if (map_prop_region(region) < 0)
- return NULL;
-
- return __system_property_regions__[region]->data + idx;
-}
-
-static prop_bt *root_node()
-{
- return to_prop_obj(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);
-}
-
-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;
-
- bt = new_prop_bt(name, namelen, &bt->right);
- }
- }
- }
-}
-
-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);
- }
-
- if (!substr_size)
- return NULL;
-
- 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;
- }
-
- if (trie->prop) {
- return to_prop_obj(trie->prop);
- } else if (alloc_if_needed) {
- return new_prop_info(name, namelen, value, valuelen, &trie->prop);
+ if((n % PA_COUNT_MAX) >= pa->count) {
+ return 0;
} else {
- return NULL;
+ return TOC_TO_INFO(pa, pa->toc[n]);
}
}
const prop_info *__system_property_find(const char *name)
{
- return find_property(root_node(), name, strlen(name), NULL, 0, false);
+ unsigned len = strlen(name);
+ size_t region;
+
+ if (len >= PROP_NAME_MAX)
+ return 0;
+ if (len < 1)
+ return 0;
+
+ for (region = 0; region < PA_REGION_COUNT; region++) {
+ prop_area *pa;
+ unsigned count;
+ unsigned *toc;
+ prop_info *pi;
+
+ int err = map_prop_region(region);
+ if (err < 0)
+ return 0;
+ pa = __system_property_regions__[region];
+ count = pa->count;
+ toc = pa->toc;
+
+ while(count--) {
+ unsigned entry = *toc++;
+ if(TOC_NAME_LEN(entry) != len) continue;
+
+ pi = TOC_TO_INFO(pa, entry);
+ if(memcmp(name, pi->name, len)) continue;
+
+ return pi;
+ }
+ }
+
+ return 0;
}
int __system_property_read(const prop_info *pi, char *name, char *value)
@@ -607,8 +463,10 @@
int __system_property_add(const char *name, unsigned int namelen,
const char *value, unsigned int valuelen)
{
- prop_area *pa = __system_property_regions__[0];
- const prop_info *pi;
+ prop_area *pa;
+ prop_info *pa_info_array;
+ prop_info *pi;
+ size_t region;
if (namelen >= PROP_NAME_MAX)
return -1;
@@ -617,12 +475,34 @@
if (namelen < 1)
return -1;
- pi = find_property(root_node(), name, namelen, value, valuelen, true);
- if (!pi)
+ 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)
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;
}
@@ -641,72 +521,3 @@
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);
-}
diff --git a/libc/include/sys/_system_properties.h b/libc/include/sys/_system_properties.h
index 9c48e1b..4971a4c 100644
--- a/libc/include/sys/_system_properties.h
+++ b/libc/include/sys/_system_properties.h
@@ -37,7 +37,7 @@
typedef struct prop_msg prop_msg;
#define PROP_AREA_MAGIC 0x504f5250
-#define PROP_AREA_VERSION 0xfc6ed0ab
+#define PROP_AREA_VERSION 0x45434f76
#define PROP_SERVICE_NAME "property_service"
#define PROP_FILENAME "/dev/__properties__"
@@ -45,9 +45,14 @@
/* (4 header words + 28 toc words) = 128 bytes */
/* 128 bytes header and toc + 28 prop_infos @ 128 bytes = 3712 bytes */
+#define PA_COUNT_MAX 28
#define PA_REGION_COUNT 128
+#define PA_INFO_START 128
#define PA_SIZE 4096
+#define TOC_NAME_LEN(toc) ((toc) >> 24)
+#define TOC_TO_INFO(area, toc) ((prop_info*) (((char*) area) + ((toc) & 0xFFFFFF)))
+
#define SERIAL_VALUE_LEN(serial) ((serial) >> 24)
#define SERIAL_DIRTY(serial) ((serial) & 1)
@@ -79,6 +84,11 @@
** 1. pi->serial = pi->serial | 1
** 2. memcpy(pi->value, local_value, value_len)
** 3. pi->serial = (value_len << 24) | ((pi->serial + 1) & 0xffffff)
+**
+** Improvements:
+** - maintain the toc sorted by pi->name to allow lookup
+** by binary search
+**
*/
#define PROP_PATH_RAMDISK_DEFAULT "/default.prop"