1 files changed, 121 insertions, 0 deletions
diff --git a/lib/cleanup.c b/lib/cleanup.c
new file mode 100644
index 0000000..c16f1bc
--- /dev/null
+++ b/lib/cleanup.c
@@ -0,0 +1,121 @@
+/*
+ * SPDX-FileCopyrightText: 2008 - 2011, Nicolas François
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#include <config.h>
+
+#include <assert.h>
+#include <stdio.h>
+
+#include "prototypes.h"
+
+/*
+ * The cleanup_functions stack.
+ */
+#define CLEANUP_FUNCTIONS 10
+
+typedef /*@null@*/void * parg_t;
+
+static cleanup_function cleanup_functions[CLEANUP_FUNCTIONS];
+static parg_t cleanup_function_args[CLEANUP_FUNCTIONS];
+static pid_t cleanup_pid = 0;
+
+/*
+ * - Cleanup functions shall not fail.
+ * - You should register do_cleanups with atexit.
+ * - You should add cleanup functions to the stack with add_cleanup when
+ *   an operation is expected to be executed later, and remove it from the
+ *   stack with del_cleanup when it has been executed.
+ *
+ **/
+
+/*
+ * do_cleanups - perform the actions stored in the cleanup_functions stack.
+ *
+ * Cleanup action are not executed on exit of the processes started by the
+ * parent (first caller of add_cleanup).
+ *
+ * It is intended to be used as:
+ *     atexit (do_cleanups);
+ */
+void do_cleanups (void)
+{
+	unsigned int i;
+
+	/* Make sure there were no overflow */
+	assert (NULL == cleanup_functions[CLEANUP_FUNCTIONS-1]);
+
+	if (getpid () != cleanup_pid) {
+		return;
+	}
+
+	i = CLEANUP_FUNCTIONS;
+	do {
+		i--;
+		if (cleanup_functions[i] != NULL) {
+			cleanup_functions[i] (cleanup_function_args[i]);
+		}
+	} while (i>0);
+}
+
+/*
+ * add_cleanup - Add a cleanup_function to the cleanup_functions stack.
+ */
+void add_cleanup (/*@notnull@*/cleanup_function pcf, /*@null@*/void *arg)
+{
+	unsigned int i;
+	assert (NULL != pcf);
+
+	assert (NULL == cleanup_functions[CLEANUP_FUNCTIONS-2]);
+
+	if (0 == cleanup_pid) {
+		cleanup_pid = getpid ();
+	}
+
+	/* Add the cleanup_function at the end of the stack */
+	for (i=0; NULL != cleanup_functions[i]; i++);
+	cleanup_functions[i] = pcf;
+	cleanup_function_args[i] = arg;
+}
+
+/*
+ * del_cleanup - Remove a cleanup_function from the cleanup_functions stack.
+ */
+void del_cleanup (/*@notnull@*/cleanup_function pcf)
+{
+	unsigned int i;
+	assert (NULL != pcf);
+
+	/* Find the pcf cleanup function */
+	for (i=0; i<CLEANUP_FUNCTIONS; i++) {
+		if (cleanup_functions[i] == pcf) {
+			break;
+		}
+	}
+
+	/* Make sure the cleanup function was found */
+	assert (i<CLEANUP_FUNCTIONS);
+
+	/* Move the rest of the cleanup functions */
+	for (; i<CLEANUP_FUNCTIONS; i++) {
+		/* Make sure the cleanup function was specified only once */
+		assert (   (i == (CLEANUP_FUNCTIONS -1))
+		        || (cleanup_functions[i+1] != pcf));
+
+		if (i == (CLEANUP_FUNCTIONS -1)) {
+			cleanup_functions[i] = NULL;
+			cleanup_function_args[i] = NULL;
+		} else {
+			cleanup_functions[i] = cleanup_functions[i+1];
+			cleanup_function_args[i] = cleanup_function_args[i+1];
+		}
+
+		/* A NULL indicates the end of the stack */
+		if (NULL == cleanup_functions[i]) {
+			break;
+		}
+	}
+}
+