commit 0ea9b64d93ba1e677390d41ce23fdfcda0cba2b7
author Mark Salyzyn <salyzyn@google.com> Wed Jul 13 07:38:39 2016 -0700
committer Mark Salyzyn <salyzyn@google.com> Thu Jul 14 08:49:02 2016 -0700
tree eec155857513ee3b04f3b0dc42e86598d71e38aa
parent b7ce01d8c6ceee6b3873cd2b6b2ef96a24190127

liblog: reset pid and uid cache after a vfork()

(cherry pick from commit ec4f5c776d2bde026e2a74128218924be7b3f46a)

Bionic getuid() and getpid() calls cache to reduce the need to
perform a syscall, and also reset their own cache after a vfork().
No more need for liblog to be performing this flawed cache operation.

Bug: 30085794
Change-Id: I70feed8bff0ddd919c2885a348ba67b14ddc0e0d

liblog/logger.h

diff --git a/liblog/logger.h b/liblog/logger.h
index c727f29..0964756 100644
--- a/liblog/logger.h
+++ b/liblog/logger.h
@@ -146,11 +146,13 @@
 /* OS specific dribs and drabs */
 
 #if defined(_WIN32)
+#include <private/android_filesystem_config.h>
 typedef uint32_t uid_t;
+static inline uid_t __android_log_uid() { return AID_SYSTEM; }
+#else
+static inline uid_t __android_log_uid() { return getuid(); }
 #endif
 
-LIBLOG_HIDDEN uid_t __android_log_uid();
-LIBLOG_HIDDEN pid_t __android_log_pid();
 LIBLOG_HIDDEN void __android_log_lock();
 LIBLOG_HIDDEN int __android_log_trylock();
 LIBLOG_HIDDEN void __android_log_unlock();

liblog/logger_lock.c

diff --git a/liblog/logger_lock.c b/liblog/logger_lock.c
index ee979bd..14feee0 100644
--- a/liblog/logger_lock.c
+++ b/liblog/logger_lock.c
@@ -22,34 +22,8 @@
 #include <pthread.h>
 #endif
 
-#include <private/android_filesystem_config.h>
-
 #include "logger.h"
 
-LIBLOG_HIDDEN uid_t __android_log_uid()
-{
-#if defined(_WIN32)
-    return AID_SYSTEM;
-#else
-    static uid_t last_uid = AID_ROOT; /* logd *always* starts up as AID_ROOT */
-
-    if (last_uid == AID_ROOT) { /* have we called to get the UID yet? */
-        last_uid = getuid();
-    }
-    return last_uid;
-#endif
-}
-
-LIBLOG_HIDDEN pid_t __android_log_pid()
-{
-    static pid_t last_pid = (pid_t) -1;
-
-    if (last_pid == (pid_t) -1) {
-        last_pid = getpid();
-    }
-    return last_pid;
-}
-
 #if !defined(_WIN32)
 static pthread_mutex_t log_init_lock = PTHREAD_MUTEX_INITIALIZER;
 #endif

liblog/pmsg_writer.c

diff --git a/liblog/pmsg_writer.c b/liblog/pmsg_writer.c
index 2ba31fa..944feba 100644
--- a/liblog/pmsg_writer.c
+++ b/liblog/pmsg_writer.c
@@ -142,7 +142,7 @@
     pmsgHeader.magic = LOGGER_MAGIC;
     pmsgHeader.len = sizeof(pmsgHeader) + sizeof(header);
     pmsgHeader.uid = __android_log_uid();
-    pmsgHeader.pid = __android_log_pid();
+    pmsgHeader.pid = getpid();
 
     header.id = logId;
     header.tid = gettid();