Allow applications to fork()

 - if fork() is called from an application, dlt is reset
   and user application needs to re-register application and
   contexts in child-process

Signed-off-by: Stefan Vacek <stefan.vacek@intel.com>

2 files changed, 53 insertions, 1 deletions

diff --git a/src/tests/CMakeLists.txt b/src/tests/CMakeLists.txt
index 557e403..d4ac21c 100644
--- a/src/tests/CMakeLists.txt
+++ b/src/tests/CMakeLists.txt
@@ -55,7 +55,12 @@ add_executable(dlt-test-filetransfer ${dlt_test_filetransfer_SRCS})
 target_link_libraries(dlt-test-filetransfer dlt)
 set_target_properties(dlt-test-filetransfer PROPERTIES LINKER_LANGUAGE C)
 
-install(TARGETS dlt-test-multi-process dlt-test-multi-process-client dlt-test-user dlt-test-client dlt-test-stress-user dlt-test-stress-client dlt-test-stress dlt-test-filetransfer
+set(dlt_test_fork_handler_SRCS dlt-test-fork-handler.c)
+add_executable(dlt-test-fork-handler ${dlt_test_fork_handler_SRCS})
+target_link_libraries(dlt-test-fork-handler dlt)
+set_target_properties(dlt-test-fork-handler PROPERTIES LINKER_LANGUAGE C)
+
+install(TARGETS dlt-test-multi-process dlt-test-multi-process-client dlt-test-user dlt-test-client dlt-test-stress-user dlt-test-stress-client dlt-test-stress dlt-test-filetransfer dlt-test-fork-handler
 	RUNTIME DESTINATION bin
 	COMPONENT base)
 
diff --git a/src/tests/dlt-test-fork-handler.c b/src/tests/dlt-test-fork-handler.c
new file mode 100644
index 0000000..d9c65e5
--- /dev/null
+++ b/src/tests/dlt-test-fork-handler.c
@@ -0,0 +1,47 @@
+/**
+ * Copyright (C) 2015 Intel Corporation
+ *
+ */
+
+#include <unistd.h> /* for fork() */
+
+#include "dlt.h"
+
+/**
+ * @brief sample code for using at_fork-handler
+ */
+int main()
+{
+  DltContext mainContext;
+
+  DLT_REGISTER_APP("PRNT", "Parent application");
+  DLT_REGISTER_CONTEXT(mainContext, "CTXP", "Parent context");
+  DLT_LOG(mainContext, DLT_LOG_WARN, DLT_STRING("First message before fork"));
+  usleep(200000);
+
+  pid_t pid = fork();
+  if (pid == 0) /* child process */
+  {
+    /* this message should not be visible */
+    /* DLT_LOG(mainContext, DLT_LOG_WARN, DLT_STRING("Child's first message after fork, pid: "), DLT_INT32(getpid())); */
+    /* unfortunately, this message does arrive, I assume because it still has (locally) valid data ... */
+
+    DLT_REGISTER_APP("CHLD", "Child application");
+    DLT_REGISTER_CONTEXT(mainContext, "CTXC", "Child context");
+    DLT_LOG(mainContext, DLT_LOG_WARN, DLT_STRING("Child's second message after fork, pid: "), DLT_INT32(getpid()));
+    usleep(400000);
+  }
+  else if (pid == -1) /* error in fork */
+  {
+    return -1;
+  }
+  else /* parent */
+  {
+    DLT_LOG(mainContext, DLT_LOG_WARN, DLT_STRING("Parent's first message after fork, pid: "), DLT_INT32(getpid()));
+    usleep(500000);
+  }
+
+  DLT_UNREGISTER_APP();
+
+  return 0;
+}