lib: daemon: Fix sem lock potential issue

sem_wait may return an error if a signal is received while waiting for
the lock,and therefore not take the lock before returning.
Changed to have a while loop.

Signed-off-by: Saya Sugiura <ssugiura@jp.adit-jv.com>

2 files changed, 11 insertions, 4 deletions

diff --git a/include/dlt/dlt_user.h b/include/dlt/dlt_user.h
index d736032..b885eaf 100644
--- a/include/dlt/dlt_user.h
+++ b/include/dlt/dlt_user.h
@@ -94,8 +94,11 @@ extern "C" {
 #   define DLT_USER_RESENDBUF_MAX_SIZE (DLT_USER_BUF_MAX_SIZE + 100)    /**< Size of resend buffer; Max DLT message size is 1390 bytes plus some extra header space  */
 
 /* Use a semaphore or mutex from your OS to prevent concurrent access to the DLT buffer. */
-#   define DLT_SEM_LOCK() { sem_wait(&dlt_mutex); }
-#   define DLT_SEM_FREE() { sem_post(&dlt_mutex); }
+#define DLT_SEM_LOCK() do{\
+    while ((sem_wait(&dlt_mutex) == -1) && (errno == EINTR)) \
+        continue;       /* Restart if interrupted */ \
+    } while(0)
+#define DLT_SEM_FREE() { sem_post(&dlt_mutex); }
 
 /**
  * This structure is used for every context used in an application.
diff --git a/src/daemon/dlt_daemon_common.h b/src/daemon/dlt_daemon_common.h
index 112cb92..be29bca 100644
--- a/src/daemon/dlt_daemon_common.h
+++ b/src/daemon/dlt_daemon_common.h
@@ -97,8 +97,12 @@ extern "C" {
 
 /* Use a semaphore or mutex from your OS to prevent concurrent access to the DLT buffer. */
 
-#   define DLT_DAEMON_SEM_LOCK() { sem_wait(&dlt_daemon_mutex); }
-#   define DLT_DAEMON_SEM_FREE() { sem_post(&dlt_daemon_mutex); }
+#define DLT_DAEMON_SEM_LOCK() do{\
+    while ((sem_wait(&dlt_daemon_mutex) == -1) && (errno == EINTR)) \
+        continue;       /* Restart if interrupted */ \
+    } while(0)
+
+#define DLT_DAEMON_SEM_FREE() { sem_post(&dlt_daemon_mutex); }
 extern sem_t dlt_daemon_mutex;
 
 /**