From 6a03abcfd23f31d1df06eb0059830e22621282bb Mon Sep 17 00:00:00 2001
From: Elliott Hughes <enh@google.com>
Date: Mon, 3 Nov 2014 12:32:17 -0800
Subject: [PATCH] Ensure we initialize stdin/stdout/stderr's recursive mutexes.

Bug: 18208568
Change-Id: I9da16ce0f9375bc363d1d02be706d73fd3b1e150
---
 libc/Android.mk                                    |  2 +-
 .../{upstream-openbsd/lib/libc => }/stdio/findfp.c | 28 +++++++++++++++-------
 tests/stdio_test.cpp                               | 17 +++++++++++++
 3 files changed, 37 insertions(+), 10 deletions(-)
 rename libc/{upstream-openbsd/lib/libc => }/stdio/findfp.c (89%)

diff --git a/libc/Android.mk b/libc/Android.mk
index 037febf3c..694c64228 100644
--- a/libc/Android.mk
+++ b/libc/Android.mk
@@ -58,6 +58,7 @@ libc_common_src_files := \
     bionic/siginterrupt.c \
     bionic/sigsetmask.c \
     bionic/system_properties_compat.c \
+    stdio/findfp.c \
     stdio/snprintf.c\
     stdio/sprintf.c \
     stdio/stdio_ext.cpp \
@@ -399,7 +400,6 @@ libc_upstream_openbsd_src_files := \
     upstream-openbsd/lib/libc/stdio/fgetwc.c \
     upstream-openbsd/lib/libc/stdio/fgetws.c \
     upstream-openbsd/lib/libc/stdio/fileno.c \
-    upstream-openbsd/lib/libc/stdio/findfp.c \
     upstream-openbsd/lib/libc/stdio/flags.c \
     upstream-openbsd/lib/libc/stdio/fmemopen.c \
     upstream-openbsd/lib/libc/stdio/fopen.c \
diff --git a/libc/upstream-openbsd/lib/libc/stdio/findfp.c b/libc/stdio/findfp.c
similarity index 89%
rename from libc/upstream-openbsd/lib/libc/stdio/findfp.c
rename to libc/stdio/findfp.c
index 3594369bf..35d028e14 100644
--- a/libc/upstream-openbsd/lib/libc/stdio/findfp.c
+++ b/libc/stdio/findfp.c
@@ -39,7 +39,10 @@
 #include <string.h>
 #include "local.h"
 #include "glue.h"
-#include "thread_private.h"
+#include "private/thread_private.h"
+
+#define ALIGNBYTES (sizeof(uintptr_t) - 1)
+#define ALIGN(p) (((uintptr_t)(p) + ALIGNBYTES) &~ ALIGNBYTES)
 
 int	__sdidinit;
 
@@ -47,9 +50,7 @@ int	__sdidinit;
 
 #define	std(flags, file) \
 	{0,0,0,flags,file,{0},0,__sF+file,__sclose,__sread,__sseek,__swrite, \
-	 {(unsigned char *)(__sFext+file), 0}}
-/*	 p r w flags file _bf z  cookie      close    read    seek    write 
-	 ext */
+	    {(unsigned char *)(__sFext+file), 0},NULL,0,{0},{0},{0},0,0}
 
 				/* the usual - (stdin + stdout + stderr) */
 static FILE usual[FOPEN_MAX - 3];
@@ -162,17 +163,26 @@ void
 __sinit(void)
 {
 	_THREAD_PRIVATE_MUTEX(__sinit_mutex);
-	int i;
 
 	_THREAD_PRIVATE_MUTEX_LOCK(__sinit_mutex);
-	if (__sdidinit)
-		goto out;	/* bail out if caller lost the race */
-	for (i = 0; i < FOPEN_MAX - 3; i++) {
+	if (__sdidinit) {
+		/* bail out if caller lost the race */
+		_THREAD_PRIVATE_MUTEX_UNLOCK(__sinit_mutex);
+		return;
+	}
+
+	/* Initialize stdin/stdout/stderr (for the recursive mutex). http://b/18208568. */
+	for (size_t i = 0; i < 3; ++i) {
+		_FILEEXT_SETUP(__sF+i, __sFext+i);
+	}
+	/* Initialize the pre-allocated (but initially unused) streams. */
+	for (size_t i = 0; i < FOPEN_MAX - 3; ++i) {
 		_FILEEXT_SETUP(usual+i, usualext+i);
 	}
+
 	/* make sure we clean up on exit */
 	__atexit_register_cleanup(_cleanup); /* conservative */
 	__sdidinit = 1;
-out: 
+
 	_THREAD_PRIVATE_MUTEX_UNLOCK(__sinit_mutex);
 }
diff --git a/tests/stdio_test.cpp b/tests/stdio_test.cpp
index 6a653b4dd..549792efb 100644
--- a/tests/stdio_test.cpp
+++ b/tests/stdio_test.cpp
@@ -29,6 +29,23 @@
 
 #include "TemporaryFile.h"
 
+TEST(stdio, flockfile_18208568_stderr) {
+  // Check that we have a _recursive_ mutex for flockfile.
+  flockfile(stderr);
+  feof(stderr); // We don't care about the result, but this needs to take the lock.
+  funlockfile(stderr);
+}
+
+TEST(stdio, flockfile_18208568_regular) {
+  // We never had a bug for streams other than stdin/stdout/stderr, but test anyway.
+  FILE* fp = fopen("/dev/null", "w");
+  ASSERT_TRUE(fp != NULL);
+  flockfile(fp);
+  feof(fp);
+  funlockfile(fp);
+  fclose(fp);
+}
+
 TEST(stdio, tmpfile_fileno_fprintf_rewind_fgets) {
   FILE* fp = tmpfile();
   ASSERT_TRUE(fp != NULL);
-- 
2.11.0