DataFlash: add O_CLOEXEC in places missing it

By opening with O_CLOEXEC we make sure we don't leak the file descriptor
when we are exec'ing or calling out subprograms. Right now we currently
don't do it so there's no harm, but it's good practice in Linux to have
it.

libraries/DataFlash/DataFlash_File.cpp

@@ -154,7 +154,7 @@ void DataFlash_File::Init()
 bool DataFlash_File::file_exists(const char *filename) const
 {
 #if DATAFLASH_FILE_MINIMAL
-    int fd = open(filename, O_RDONLY);
+    int fd = open(filename, O_RDONLY|O_CLOEXEC);
     if (fd == -1) {
         return false;
     }
@@ -536,7 +536,7 @@ uint16_t DataFlash_File::find_last_log()
     if (fname == nullptr) {
         return ret;
     }
-    int fd = open(fname, O_RDONLY);
+    int fd = open(fname, O_RDONLY|O_CLOEXEC);
     free(fname);
     if (fd != -1) {
         char buf[10];
@@ -651,7 +651,7 @@ int16_t DataFlash_File::get_log_data(const uint16_t list_entry, const uint16_t p
             return -1;
         }
         stop_logging();
-        _read_fd = ::open(fname, O_RDONLY);
+        _read_fd = ::open(fname, O_RDONLY|O_CLOEXEC);
         if (_read_fd == -1) {
             _open_error = true;
             int saved_errno = errno;
@@ -804,7 +804,7 @@ uint16_t DataFlash_File::start_new_log(void)
     if (fname == nullptr) {
         return 0xFFFF;
     }
-    _write_fd = ::open(fname, O_WRONLY|O_CREAT|O_TRUNC, 0666);
+    _write_fd = ::open(fname, O_WRONLY|O_CREAT|O_TRUNC|O_CLOEXEC, 0666);
     _cached_oldest_log = 0;
 
     if (_write_fd == -1) {
@@ -828,7 +828,7 @@ uint16_t DataFlash_File::start_new_log(void)
 
     // we avoid fopen()/fprintf() here as it is not available on as many
     // systems as open/write (specifically the QURT RTOS)
-    int fd = open(fname, O_WRONLY|O_CREAT, 0644);
+    int fd = open(fname, O_WRONLY|O_CREAT|O_CLOEXEC, 0644);
     free(fname);
     if (fd == -1) {
         return 0xFFFF;
@@ -873,7 +873,7 @@ void DataFlash_File::LogReadProcess(const uint16_t list_entry,
     if (fname == nullptr) {
         return;
     }
-    _read_fd = ::open(fname, O_RDONLY);
+    _read_fd = ::open(fname, O_RDONLY|O_CLOEXEC);
     free(fname);
     if (_read_fd == -1) {
         return;

libraries/DataFlash/DataFlash_SITL.cpp

@@ -31,11 +31,11 @@ void DataFlash_SITL::Init()
 {
     DataFlash_Backend::Init();
 	if (flash_fd == 0) {
-		flash_fd = open("dataflash.bin", O_RDWR, 0777);
+		flash_fd = open("dataflash.bin", O_RDWR|O_CLOEXEC, 0777);
 		if (flash_fd == -1) {
 			uint8_t *fill;
 			fill = (uint8_t *)malloc(DF_PAGE_SIZE*DF_NUM_PAGES);
-			flash_fd = open("dataflash.bin", O_RDWR | O_CREAT, 0777);
+			flash_fd = open("dataflash.bin", O_RDWR | O_CREAT | O_CLOEXEC, 0777);
 			memset(fill, 0xFF, DF_PAGE_SIZE*DF_NUM_PAGES);
 			write(flash_fd, fill, DF_PAGE_SIZE*DF_NUM_PAGES);
 			free(fill);