liblog: add __android_log_is_loggable()

- Add new liblog API __android_log_is_loggable(prio, tag, def)
- future plan to integrate this into the runtime checks and into
  the logd daemon for filtration. Inert for now.

Bug: 17760225
Change-Id: I16395b4d42acc08f0209f55a1cbf87b0b2112898

4 files changed, 80 insertions, 1 deletions

diff --git a/liblog/Android.mk b/liblog/Android.mk
index a4e5f5e..5756c54 100644
--- a/liblog/Android.mk
+++ b/liblog/Android.mk
@@ -46,7 +46,7 @@ else
 endif
 
 liblog_host_sources := $(liblog_sources) fake_log_device.c
-liblog_target_sources := $(liblog_sources) log_time.cpp
+liblog_target_sources := $(liblog_sources) log_time.cpp log_is_loggable.c
 ifneq ($(TARGET_USES_LOGD),false)
 liblog_target_sources += log_read.c
 else
diff --git a/liblog/fake_log_device.c b/liblog/fake_log_device.c
index cf3dc50..8a8ece2 100644
--- a/liblog/fake_log_device.c
+++ b/liblog/fake_log_device.c
@@ -689,3 +689,9 @@ ssize_t fakeLogWritev(int fd, const struct iovec* vector, int count)
     /* Assume that open() was called first. */
     return redirectWritev(fd, vector, count);
 }
+
+int __android_log_is_loggable(int prio, const char *tag __unused, int def)
+{
+    int logLevel = def;
+    return logLevel >= 0 && prio >= logLevel;
+}
diff --git a/liblog/log_is_loggable.c b/liblog/log_is_loggable.c
new file mode 100644
index 0000000..df67123
--- /dev/null
+++ b/liblog/log_is_loggable.c
@@ -0,0 +1,69 @@
+/*
+** Copyright 2014, The Android Open Source Project
+**
+** Licensed under the Apache License, Version 2.0 (the "License");
+** you may not use this file except in compliance with the License.
+** You may obtain a copy of the License at
+**
+**     http://www.apache.org/licenses/LICENSE-2.0
+**
+** Unless required by applicable law or agreed to in writing, software
+** distributed under the License is distributed on an "AS IS" BASIS,
+** WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+** See the License for the specific language governing permissions and
+** limitations under the License.
+*/
+
+#include <ctype.h>
+#include <string.h>
+#include <sys/system_properties.h>
+
+#include <android/log.h>
+
+static int __android_log_level(const char *tag, int def)
+{
+    char buf[PROP_VALUE_MAX];
+
+    if (!tag || !*tag) {
+        return def;
+    }
+    {
+        static const char log_namespace[] = "log.tag.";
+        char key[sizeof(log_namespace) + strlen(tag)];
+
+        strcpy(key, log_namespace);
+        strcpy(key + sizeof(log_namespace) - 1, tag);
+
+        if (__system_property_get(key + 8, buf) <= 0) {
+            buf[0] = '\0';
+        }
+    }
+    switch (toupper(buf[0])) {
+        case 'V': return ANDROID_LOG_VERBOSE;
+        case 'D': return ANDROID_LOG_DEBUG;
+        case 'I': return ANDROID_LOG_INFO;
+        case 'W': return ANDROID_LOG_WARN;
+        case 'E': return ANDROID_LOG_ERROR;
+        case 'F': /* FALLTHRU */ /* Not officially supported */
+        case 'A': return ANDROID_LOG_FATAL;
+        case 'S': return -1; /* ANDROID_LOG_SUPPRESS */
+    }
+    return def;
+}
+
+int __android_log_is_loggable(int prio, const char *tag, int def)
+{
+    static char user;
+    int logLevel;
+
+    if (user == 0) {
+        char buf[PROP_VALUE_MAX];
+        if (__system_property_get("ro.build.type", buf) <= 0) {
+            buf[0] = '\0';
+        }
+        user = strcmp(buf, "user") ? -1 : 1;
+    }
+
+    logLevel = (user == 1) ? def : __android_log_level(tag, def);
+    return logLevel >= 0 && prio >= logLevel;
+}
diff --git a/liblog/log_read.c b/liblog/log_read.c
index 2f21a5d..dbed886 100644
--- a/liblog/log_read.c
+++ b/liblog/log_read.c
@@ -34,7 +34,11 @@
 /* branchless on many architectures. */
 #define min(x,y) ((y) ^ (((x) ^ (y)) & -((x) < (y))))
 
+#if (defined(USE_MINGW) || defined(HAVE_WINSOCK))
+#define WEAK static
+#else
 #define WEAK __attribute__((weak))
+#endif
 #ifndef __unused
 #define __unused __attribute__((unused))
 #endif