Move some properties users to __system_property_read_callback()

This is needed if they will ever handle ro. properties that have
values longer than 92 characters.

Bug: 23102347
Bug: 34954705
Test: read and write properties with value length > 92 characters
Change-Id: I44aa135c97ec010f12162c30f743387810ae2c5d

base/properties.cpp

@@ -36,13 +36,18 @@ std::string GetProperty(const std::string& key, const std::string& default_value
   const prop_info* pi = __system_property_find(key.c_str());
   if (pi == nullptr) return default_value;
 
-  char buf[PROP_VALUE_MAX];
-  if (__system_property_read(pi, nullptr, buf) > 0) return buf;
+  std::string property_value;
+  __system_property_read_callback(pi,
+                                  [](void* cookie, const char*, const char* value, unsigned) {
+                                    auto property_value = reinterpret_cast<std::string*>(cookie);
+                                    *property_value = value;
+                                  },
+                                  &property_value);
 
   // If the property exists but is empty, also return the default value.
   // Since we can't remove system properties, "empty" is traditionally
   // the same as "missing" (this was true for cutils' property_get).
-  return default_value;
+  return property_value.empty() ? default_value : property_value;
 }
 
 bool GetBoolProperty(const std::string& key, bool default_value) {

debuggerd/libdebuggerd/tombstone.cpp

@@ -35,12 +35,12 @@
 #include <string>
 
 #include <android-base/file.h>
+#include <android-base/properties.h>
 #include <android-base/stringprintf.h>
 #include <android-base/unique_fd.h>
 #include <android/log.h>
 #include <backtrace/Backtrace.h>
 #include <backtrace/BacktraceMap.h>
-#include <cutils/properties.h>
 #include <log/log.h>
 #include <log/logprint.h>
 #include <private/android_filesystem_config.h>
@@ -53,6 +53,8 @@
 #include "libdebuggerd/machine.h"
 #include "libdebuggerd/open_files_list.h"
 
+using android::base::GetBoolProperty;
+using android::base::GetProperty;
 using android::base::StringPrintf;
 
 #define STACK_WORDS 16
@@ -206,14 +208,11 @@ static const char* get_sigcode(int signo, int code) {
 }
 
 static void dump_header_info(log_t* log) {
-  char fingerprint[PROPERTY_VALUE_MAX];
-  char revision[PROPERTY_VALUE_MAX];
+  auto fingerprint = GetProperty("ro.build.fingerprint", "unknown");
+  auto revision = GetProperty("ro.revision", "unknown");
 
-  property_get("ro.build.fingerprint", fingerprint, "unknown");
-  property_get("ro.revision", revision, "unknown");
-
-  _LOG(log, logtype::HEADER, "Build fingerprint: '%s'\n", fingerprint);
-  _LOG(log, logtype::HEADER, "Revision: '%s'\n", revision);
+  _LOG(log, logtype::HEADER, "Build fingerprint: '%s'\n", fingerprint.c_str());
+  _LOG(log, logtype::HEADER, "Revision: '%s'\n", revision.c_str());
   _LOG(log, logtype::HEADER, "ABI: '%s'\n", ABI_STRING);
 }
 
@@ -722,9 +721,7 @@ static void dump_crash(log_t* log, BacktraceMap* map, BacktraceMap* map_new,
                        const std::string& process_name, const std::map<pid_t, std::string>& threads,
                        uintptr_t abort_msg_address) {
   // don't copy log messages to tombstone unless this is a dev device
-  char value[PROPERTY_VALUE_MAX];
-  property_get("ro.debuggable", value, "0");
-  bool want_logs = (value[0] == '1');
+  bool want_logs = GetBoolProperty("ro.debuggable", false);
 
   _LOG(log, logtype::HEADER,
        "*** *** *** *** *** *** *** *** *** *** *** *** *** *** *** ***\n");

fs_mgr/Android.bp

@@ -55,12 +55,22 @@ cc_library_static {
         "liblogwrap",
         "libfstab",
     ],
+    cppflags: [
+        "-DALLOW_SKIP_SECURE_CHECK=0",
+        "-DALLOW_ADBD_DISABLE_VERITY=0",
+    ],
     product_variables: {
         debuggable: {
-            cppflags: ["-DALLOW_ADBD_DISABLE_VERITY=1"],
+            cppflags: [
+                "-UALLOW_ADBD_DISABLE_VERITY",
+                "-DALLOW_ADBD_DISABLE_VERITY=1",
+            ],
         },
         eng: {
-            cppflags: ["-DALLOW_SKIP_SECURE_CHECK=1"],
+            cppflags: [
+                "-UALLOW_SKIP_SECURE_CHECK",
+                "-DALLOW_SKIP_SECURE_CHECK=1",
+            ],
         },
     },
 }

fs_mgr/fs_mgr.cpp

@@ -543,15 +543,6 @@ static int fs_match(const char *in1, const char *in2)
     return ret;
 }
 
-static int device_is_force_encrypted() {
-    int ret = -1;
-    char value[PROP_VALUE_MAX];
-    ret = __system_property_get("ro.vold.forceencryption", value);
-    if (ret < 0)
-        return 0;
-    return strcmp(value, "1") ? 0 : 1;
-}
-
 /*
  * Tries to mount any of the consecutive fstab entries that match
  * the mountpoint of the one given by fstab->recs[start_idx].
@@ -726,7 +717,9 @@ out:
 
 static bool needs_block_encryption(const struct fstab_rec* rec)
 {
-    if (device_is_force_encrypted() && fs_mgr_is_encryptable(rec)) return true;
+    if (android::base::GetBoolProperty("ro.vold.forceencryption", false) &&
+        fs_mgr_is_encryptable(rec))
+        return true;
     if (rec->fs_mgr_flags & MF_FORCECRYPT) return true;
     if (rec->fs_mgr_flags & MF_CRYPT) {
         /* Check for existence of convert_fde breadcrumb file */
@@ -769,20 +762,7 @@ static int handle_encryptable(const struct fstab_rec* rec)
 }
 
 bool is_device_secure() {
-    int ret = -1;
-    char value[PROP_VALUE_MAX];
-    ret = __system_property_get("ro.secure", value);
-    if (ret == 0) {
-#ifdef ALLOW_SKIP_SECURE_CHECK
-        // Allow eng builds to skip this check if the property
-        // is not readable (happens during early mount)
-        return false;
-#else
-        // If error and not an 'eng' build, we want to fail secure.
-        return true;
-#endif
-    }
-    return strcmp(value, "0") ? true : false;
+    return android::base::GetBoolProperty("ro.secure", ALLOW_SKIP_SECURE_CHECK ? false : true);
 }
 
 /* When multiple fstab records share the same mount_point, it will