Log update outputs in order

Although stdout and stderr are both redirected to log file with no
buffering, we are seeing some outputs are mixed in random order.
This is because ui_print commands from the updater are passed to the
recovery binary via a pipe, which may interleave with other outputs
that go to stderr directly.

In recovery, adding ui::PrintOnScreenOnly() function to handle
ui_print command, which skips printing to stdout. Meanwhile, updater
prints the contents to stderr in addition to piping them to recovery.

Change-Id: Idda93ea940d2e23a0276bb8ead4aa70a3cb97700

1 files changed, 3 insertions, 1 deletions

diff --git a/ui.h b/ui.h
index 4dcaa0f..ca72911 100644
--- a/ui.h
+++ b/ui.h
@@ -62,8 +62,10 @@ class RecoveryUI {
     virtual bool WasTextEverVisible() = 0;
 
     // Write a message to the on-screen log (shown if the user has
-    // toggled on the text display).
+    // toggled on the text display). Print() will also dump the message
+    // to stdout / log file, while PrintOnScreenOnly() not.
     virtual void Print(const char* fmt, ...) __printflike(2, 3) = 0;
+    virtual void PrintOnScreenOnly(const char* fmt, ...) __printflike(2, 3) = 0;
 
     virtual void ShowFile(const char* filename) = 0;