libc: fix executable destruction support.
This change allows an executable to call its destructor functions
(declared with __attribute__((destructor))) to be properly called
when it normally exits.
Note that this is different from calling the destructors of a shared
library when it is unloaded with dlclose() or through program exit,
which are already supported.
Bug: 3106500
Change-Id: I1412ef5407f13b613fc6cb6103e0a691dbee4b1a
diff --git a/libc/bionic/libc_init_common.c b/libc/bionic/libc_init_common.c
index d78d673..f7579bd 100644
--- a/libc/bionic/libc_init_common.c
+++ b/libc/bionic/libc_init_common.c
@@ -84,3 +84,39 @@
/* setup system properties - requires environment */
__system_properties_init();
}
+
+/* This function will be called during normal program termination
+ * to run the destructors that are listed in the .fini_array section
+ * of the executable, if any.
+ *
+ * 'fini_array' points to a list of function addresses. The first
+ * entry in the list has value -1, the last one has value 0.
+ */
+void __libc_fini(void* array)
+{
+ int count;
+ void** fini_array = array;
+ const size_t minus1 = ~(size_t)0; /* ensure proper sign extension */
+
+ /* Sanity check - first entry must be -1 */
+ if (array == NULL || (size_t)fini_array[0] != minus1) {
+ return;
+ }
+
+ /* skip over it */
+ fini_array += 1;
+
+ /* Count the number of destructors. */
+ for (count = 0; fini_array[count] != NULL; count++);
+
+ /* Now call each destructor in reverse order. */
+ while (count > 0) {
+ void (*func)() = (void (*)) fini_array[--count];
+
+ /* Sanity check, any -1 in the list is ignored */
+ if ((size_t)func == minus1)
+ continue;
+
+ func();
+ }
+}