Resetprop small refactor

native/jni/resetprop/resetprop.cpp

@@ -2,52 +2,6 @@
  *
  * Copyright 2016 nkk71     <nkk71x@gmail.com>
  * Copyright 2016 topjohnwu <topjohnwu@gmail.com>
- *
- * Info:
- *
- * all changes are in
- *
- * bionic/libc/bionic/system_properties.cpp
- *
- * Functions that need to be patched/added in system_properties.cpp
- *
- * int __system_properties_init2()
- *     on android 7, first tear down the everything then let it initialize again:
- *         if (initialized) {
- *             //list_foreach(contexts, [](context_node* l) { l->reset_access(); });
- *             //return 0;
- *             free_and_unmap_contexts();
- *             initialized = false;
- *         }
- *
- *
- * static prop_area* map_prop_area(const char* filename, bool is_legacy)
- *     we dont want this read only so change: 'O_RDONLY' to 'O_RDWR'
- *
- * static prop_area* map_fd_ro(const int fd)
- *     we dont want this read only so change: 'PROT_READ' to 'PROT_READ | PROT_WRITE'
- *
- *
- * Copy the code of prop_info *prop_area::find_property, and modify to delete props
- * const prop_info *prop_area::find_property_and_del(prop_bt *const trie, const char *name)
- * {
- *    ...
- *    ...  Do not alloc a new prop_bt here, remove all code involve alloc_if_needed
- *    ...
- *
- *     if (prop_offset != 0) {
- *         atomic_store_explicit(&current->prop, 0, memory_order_release); // Add this line to nullify the prop entry
- *         return to_prop_info(&current->prop);
- *     } else {
- *
- *    ....
- * }
- *
- *
- * by patching just those functions directly, all other functions should be ok
- * as is.
- *
- *
  */
 
 #include <stdio.h>

native/jni/resetprop/system_properties.cpp

@@ -153,7 +153,7 @@ class prop_area {
   }
 
   const prop_info* find(const char* name);
-  bool del(const char *name);               // resetprop add
+  bool del(const char *name);  /* resetprop add */
   bool add(const char* name, unsigned int namelen, const char* value, unsigned int valuelen);
 
   bool foreach (void (*propfn)(const prop_info* pi, void* cookie), void* cookie);
@@ -184,7 +184,7 @@ class prop_area {
   const prop_info* find_property(prop_bt* const trie, const char* name, uint32_t namelen,
                                  const char* value, uint32_t valuelen, bool alloc_if_needed);
 
-  bool find_property_and_del(prop_bt *const trie, const char *name);    // resetprop add
+  bool find_property_and_del(prop_bt *const trie, const char *name);  /* resetprop add */
 
   bool foreach_property(prop_bt* const trie, void (*propfn)(const prop_info* pi, void* cookie),
                         void* cookie);
@@ -283,7 +283,8 @@ static prop_area* map_prop_area_rw(const char* filename, const char* context,
   return pa;
 }
 
-static prop_area* map_fd_ro(const int fd) {
+// resetprop: map the memory as rw
+static prop_area* map_fd_rw(const int fd) {
   struct stat fd_stat;
   if (fstat(fd, &fd_stat) < 0) {
     return nullptr;
@@ -298,7 +299,7 @@ static prop_area* map_fd_ro(const int fd) {
   pa_size = fd_stat.st_size;
   pa_data_size = pa_size - sizeof(prop_area);
 
-  void* const map_result = mmap(nullptr, pa_size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);  // resetprop: add PROT_WRITE
+  void* const map_result = mmap(nullptr, pa_size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);  /* resetprop: add PROT_WRITE */
   if (map_result == MAP_FAILED) {
     return nullptr;
   }
@@ -313,10 +314,10 @@ static prop_area* map_fd_ro(const int fd) {
 }
 
 static prop_area* map_prop_area(const char* filename) {
-  int fd = open(filename, O_CLOEXEC | O_NOFOLLOW | O_RDWR);       // resetprop: O_RDONLY -> O_RDWR
+  int fd = open(filename, O_CLOEXEC | O_NOFOLLOW | O_RDWR);  /* resetprop: O_RDONLY -> O_RDWR */
   if (fd == -1) return nullptr;
 
-  prop_area* map_result = map_fd_ro(fd);
+  prop_area* map_result = map_fd_rw(fd);
   close(fd);
 
   return map_result;
@@ -530,7 +531,7 @@ bool prop_area::find_property_and_del(prop_bt* const trie, const char* name) {
 
   uint_least32_t prop_offset = atomic_load_explicit(&current->prop, memory_order_relaxed);
   if (prop_offset != 0) {
-    atomic_store_explicit(&current->prop, 0, memory_order_release);     // resetprop: nullify the offset to delete the prop
+    atomic_store_explicit(&current->prop, 0, memory_order_release);
     return true;
   } else {
     return false;
@@ -1116,17 +1117,16 @@ static bool initialize_properties() {
     if (!initialize_properties_from_file("/system/etc/selinux/plat_property_contexts")) {
       return false;
     }
-    if (!initialize_properties_from_file("/vendor/etc/selinux/nonplat_property_contexts")
+    // Don't check for failure here, so we always have a sane list of properties.
-            && !initialize_properties_from_file("/vendor/etc/selinux/vendor_property_contexts")) {
+    // E.g. In case of recovery, the vendor partition will not have mounted and we
-      return false;
+    // still need the system / platform properties to function.
-    }
+    initialize_properties_from_file("/vendor/etc/selinux/nonplat_property_contexts") ||
+            initialize_properties_from_file("/vendor/etc/selinux/vendor_property_contexts");
   } else {
     if (!initialize_properties_from_file("/plat_property_contexts")) {
       return false;
     }
-    if (!initialize_properties_from_file("/nonplat_property_contexts")) {
+    initialize_properties_from_file("/nonplat_property_contexts");
-      return false;
-    }
   }
 
   return true;