Make __android_log_assert behave more like libc asserts.

If we don't output to stderr too, not only is it annoying to shell users (who
won't see anything), it prevents us from writing better gtests that actually
make assertions about the assert message.

Bug: http://b/23675822
Test: libutils tests still pass
Change-Id: I62b3144c385cba4dde485f0b0f9b42aeaef51e9a

1 files changed, 8 insertions, 0 deletions

diff --git a/liblog/logger_write.c b/liblog/logger_write.c
index 1a2d50612..43241254f 100644
--- a/liblog/logger_write.c
+++ b/liblog/logger_write.c
@@ -514,6 +514,14 @@ LIBLOG_ABI_PUBLIC void __android_log_assert(const char *cond, const char *tag,
             strcpy(buf, "Unspecified assertion failed");
     }
 
+    // Log assertion failures to stderr for the benefit of "adb shell" users
+    // and gtests (http://b/23675822).
+    struct iovec iov[2] = {
+        { buf, strlen(buf) },
+        { (char*) "\n", 1 },
+    };
+    TEMP_FAILURE_RETRY(writev(2, iov, 2));
+
     __android_log_write(ANDROID_LOG_FATAL, tag, buf);
     abort(); /* abort so we have a chance to debug the situation */
     /* NOTREACHED */