util: file: introduce VIR_AUTOCLOSE macro to close fd of the file automatically

Signed-off-by: NShi Lei <shi_lei@massclouds.com>

src/util/virfile.h

@@ -54,6 +54,11 @@ int virFileClose(int *fdptr, virFileCloseFlags flags)
 int virFileFclose(FILE **file, bool preserve_errno) ATTRIBUTE_RETURN_CHECK;
 FILE *virFileFdopen(int *fdptr, const char *mode) ATTRIBUTE_RETURN_CHECK;
 
+static inline void virForceCloseHelper(int *fd)
+{
+    ignore_value(virFileClose(fd, VIR_FILE_CLOSE_PRESERVE_ERRNO));
+}
+
 /* For use on normal paths; caller must check return value,
    and failure sets errno per close. */
 # define VIR_CLOSE(FD) virFileClose(&(FD), 0)
@@ -64,8 +69,7 @@ FILE *virFileFdopen(int *fdptr, const char *mode) ATTRIBUTE_RETURN_CHECK;
 
 /* For use on cleanup paths; errno is unaffected by close,
    and no return value to worry about. */
-# define VIR_FORCE_CLOSE(FD) \
-    ignore_value(virFileClose(&(FD), VIR_FILE_CLOSE_PRESERVE_ERRNO))
+# define VIR_FORCE_CLOSE(FD) virForceCloseHelper(&(FD))
 # define VIR_FORCE_FCLOSE(FILE) ignore_value(virFileFclose(&(FILE), true))
 
 /* Similar VIR_FORCE_CLOSE() but ignores EBADF errors since they are expected
@@ -80,6 +84,16 @@ FILE *virFileFdopen(int *fdptr, const char *mode) ATTRIBUTE_RETURN_CHECK;
                  VIR_FILE_CLOSE_PRESERVE_ERRNO | \
                  VIR_FILE_CLOSE_DONT_LOG))
 
+/**
+ * VIR_AUTOCLOSE:
+ *
+ * Macro to automatically force close the fd by calling virForceCloseHelper
+ * when the fd goes out of scope. It's used to eliminate VIR_FORCE_CLOSE
+ * in cleanup sections.
+ */
+# define VIR_AUTOCLOSE __attribute__((cleanup(virForceCloseHelper))) int
+
+
 /* Opaque type for managing a wrapper around a fd.  */
 struct _virFileWrapperFd;