1 files changed, 30 insertions, 11 deletions

diff --git a/liblog/fake_log_device.c b/liblog/fake_log_device.c
index 8a8ece250..fcdb6c928 100644
--- a/liblog/fake_log_device.c
+++ b/liblog/fake_log_device.c
@@ -24,6 +24,7 @@
 #include <ctype.h>
 #include <errno.h>
 #include <fcntl.h>
+#include <signal.h>
 #include <stdlib.h>
 #include <string.h>
 
@@ -97,18 +98,33 @@ typedef struct LogState {
  */
 static pthread_mutex_t fakeLogDeviceLock = PTHREAD_MUTEX_INITIALIZER;
 
-static void lock()
+static void lock(sigset_t *sigflags)
 {
+    /*
+     * If we trigger a signal handler in the middle of locked activity and the
+     * signal handler logs a message, we could get into a deadlock state.
+     */
+    sigset_t all;
+
+    sigfillset(&all);
+    pthread_sigmask(SIG_BLOCK, &all, sigflags);
     pthread_mutex_lock(&fakeLogDeviceLock);
 }
 
-static void unlock()
+static void unlock(sigset_t *sigflags)
 {
     pthread_mutex_unlock(&fakeLogDeviceLock);
+    pthread_sigmask(SIG_UNBLOCK, sigflags, NULL);
 }
+
+#define DECLARE_SIGSET(name) sigset_t name
+
 #else   // !defined(_WIN32)
-#define lock() ((void)0)
-#define unlock() ((void)0)
+
+#define lock(sigflags) ((void)0)
+#define unlock(sigflags) ((void)0)
+#define DECLARE_SIGSET(name)
+
 #endif  // !defined(_WIN32)
 
 
@@ -154,8 +170,9 @@ static LogState *fdToLogState(int fd)
 static void deleteFakeFd(int fd)
 {
     LogState *ls;
+    DECLARE_SIGSET(sigflags);
 
-    lock();
+    lock(&sigflags);
 
     ls = fdToLogState(fd);
     if (ls != NULL) {
@@ -164,7 +181,7 @@ static void deleteFakeFd(int fd)
         free(ls);
     }
 
-    unlock();
+    unlock(&sigflags);
 }
 
 /*
@@ -548,12 +565,13 @@ static void showLog(LogState *state,
 static ssize_t logWritev(int fd, const struct iovec* vector, int count)
 {
     LogState* state;
+    DECLARE_SIGSET(sigflags);
 
     /* Make sure that no-one frees the LogState while we're using it.
      * Also guarantees that only one thread is in showLog() at a given
      * time (if it matters).
      */
-    lock();
+    lock(&sigflags);
 
     state = fdToLogState(fd);
     if (state == NULL) {
@@ -598,10 +616,10 @@ static ssize_t logWritev(int fd, const struct iovec* vector, int count)
     }
 
 bail:
-    unlock();
+    unlock(&sigflags);
     return vector[0].iov_len + vector[1].iov_len + vector[2].iov_len;
 error:
-    unlock();
+    unlock(&sigflags);
     return -1;
 }
 
@@ -621,8 +639,9 @@ static int logOpen(const char* pathName, int flags __unused)
 {
     LogState *logState;
     int fd = -1;
+    DECLARE_SIGSET(sigflags);
 
-    lock();
+    lock(&sigflags);
 
     logState = createLogState();
     if (logState != NULL) {
@@ -632,7 +651,7 @@ static int logOpen(const char* pathName, int flags __unused)
         errno = ENFILE;
     }
 
-    unlock();
+    unlock(&sigflags);
 
     return fd;
 }