Fix the C library runtime initialization order.
This allows libc.so to run the C runtime initializer as soon as the
dynamic linker loads the shared library, i.e. before any other initializers
(e.g. static C++ constructors in other shared libraries the executable depends
on).
This also removes the bug where the initializers from the executable itself
were run twice: once by the dynamic linker, and another time by __libc_init
as defined by libc_init_dynamic.c
diff --git a/libc/bionic/libc_init_common.c b/libc/bionic/libc_init_common.c
index de4919d..c77c162 100644
--- a/libc/bionic/libc_init_common.c
+++ b/libc/bionic/libc_init_common.c
@@ -39,23 +39,6 @@
#include <bionic_tls.h>
#include <errno.h>
-extern void _init(void);
-extern void _fini(void);
-
-static void call_array(void(**list)())
-{
- // First element is -1, list is null-terminated
- while (*++list) {
- (*list)();
- }
-}
-
-static void __bionic_do_global_dtors(structors_array_t const * const p)
-{
- call_array(p->fini_array);
- //_fini();
-}
-
extern unsigned __get_sp(void);
extern pid_t gettid(void);
@@ -69,23 +52,23 @@
int __system_properties_init(void);
-void __libc_init_common(uintptr_t *elfdata,
- void (*onexit)(void),
- int (*slingshot)(int, char**, char**),
- structors_array_t const * const structors,
- void (*pre_ctor_hook)())
-{
- pthread_internal_t thread;
- pthread_attr_t thread_attr;
- void *tls_area[BIONIC_TLS_SLOTS];
- int argc;
- char **argv, **envp, **envend;
- struct auxentry *auxentry;
- unsigned int page_size = 0, page_shift = 0;
+#ifdef MALLOCK_LEAK_CHECK
+void malloc_debug_init(void);
+#endif
- /* The main thread's stack has empirically shown to be 84k */
+void __libc_init_common(uintptr_t *elfdata)
+{
+ int argc = *elfdata;
+ char** argv = (char**)(elfdata + 1);
+ char** envp = argv + argc + 1;
+
+ pthread_attr_t thread_attr;
+ static pthread_internal_t thread;
+ static void* tls_area[BIONIC_TLS_SLOTS];
+
+ /* setup pthread runtime and maint thread descriptor */
unsigned stacktop = (__get_sp() & ~(PAGE_SIZE - 1)) + PAGE_SIZE;
- unsigned stacksize = 128 * 1024; //84 * 1024;
+ unsigned stacksize = 128 * 1024;
unsigned stackbottom = stacktop - stacksize;
pthread_attr_init(&thread_attr);
@@ -93,30 +76,20 @@
_init_thread(&thread, gettid(), &thread_attr, (void*)stackbottom);
__init_tls(tls_area, &thread);
- argc = (int) *elfdata++;
- argv = (char**) elfdata;
- envp = argv+(argc+1);
- environ = envp;
-
- __progname = argv[0] ? argv[0] : "<unknown>";
-
+ /* clear errno - requires TLS area */
errno = 0;
+ /* set program name */
+ __progname = argv[0] ? argv[0] : "<unknown>";
+
+ /* setup environment pointer */
+ environ = envp;
+
+ /* setup system properties - requires environment */
__system_properties_init();
- if (pre_ctor_hook) pre_ctor_hook();
-
- // XXX: we should execute the .fini_array upon exit
-
- // pre-init array.
- // XXX: I'm not sure what's the different with the init array.
- call_array(structors->preinit_array);
-
- // for compatibility with non-eabi binary, call the .ctors section
- call_array(structors->ctors_array);
-
- // call static constructors
- call_array(structors->init_array);
-
- exit(slingshot(argc, argv, envp));
+ /* setup malloc leak checker, requires system properties */
+#if MALLOC_LEAK_CHECK
+ malloc_debug_init();
+#endif
}
diff --git a/libc/bionic/libc_init_common.h b/libc/bionic/libc_init_common.h
index bbc82e4..8663c61 100644
--- a/libc/bionic/libc_init_common.h
+++ b/libc/bionic/libc_init_common.h
@@ -38,10 +38,6 @@
void (**ctors_array)(void);
} structors_array_t;
-extern __noreturn void __libc_init_common(uintptr_t *elfdata,
- void (*onexit)(void),
- int (*slingshot)(int, char**, char**),
- structors_array_t const * const structors,
- void (*pre_ctor_hook)());
+extern void __libc_init_common(uintptr_t *elfdata);
#endif
diff --git a/libc/bionic/libc_init_dynamic.c b/libc/bionic/libc_init_dynamic.c
index 8cf24b4..b8e1078 100644
--- a/libc/bionic/libc_init_dynamic.c
+++ b/libc/bionic/libc_init_dynamic.c
@@ -26,41 +26,74 @@
* SUCH DAMAGE.
*/
/*
- * libc_init_static.c
+ * libc_init_dynamic.c
*
- * This function takes the raw data block set up by the ELF loader
- * in the kernel and parses it. It is invoked by crt0.S which makes
- * any necessary adjustments and passes calls this function using
- * the standard C calling convention.
+ * This source files provides two important functions for dynamic
+ * executables:
*
- * The arguments are:
- * uintptr_t *elfdata -- The ELF loader data block; usually from the stack.
- * Basically a pointer to argc.
- * void (*onexit)(void) -- Function to install into onexit
+ * - a C runtime initializer (__libc_preinit), which is called by
+ * the dynamic linker when libc.so is loaded. This happens before
+ * any other initializer (e.g. static C++ constructors in other
+ * shared libraries the program depends on).
+ *
+ * - a program launch function (__libc_init), which is called after
+ * all dynamic linking has been performed. Technically, it is called
+ * from arch-$ARCH/bionic/crtbegin_dynamic.S which is itself called
+ * by the dynamic linker after all libraries have been loaded and
+ * initialized.
*/
-/*
- * Several Linux ABIs don't pass the onexit pointer, and the ones that
- * do never use it. Therefore, unless USE_ONEXIT is defined, we just
- * ignore the onexit pointer.
- */
-/* #define USE_ONEXIT */
-
#include <stddef.h>
#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <elf.h>
-#include "pthread_internal.h"
#include "atexit.h"
#include "libc_init_common.h"
+#include <bionic_tls.h>
extern void malloc_debug_init();
+/* We flag the __libc_preinit function as a constructor to ensure
+ * that its address is listed in libc.so's .init_array section.
+ * This ensures that the function is called by the dynamic linker
+ * as soon as the shared library is loaded.
+ */
+void __attribute__((constructor)) __libc_prenit(void);
+
+void __libc_prenit(void)
+{
+ /* Read the ELF data pointer form a special slot of the
+ * TLS area, then call __libc_init_common with it.
+ *
+ * Note that:
+ * - we clear the slot so no other initializer sees its value.
+ * - __libc_init_common() will change the TLS area so the old one
+ * won't be accessible anyway.
+ */
+ void** tls_area = (void**)__get_tls();
+ unsigned* elfdata = tls_area[TLS_SLOT_BIONIC_PREINIT];
+
+ tls_area[TLS_SLOT_BIONIC_PREINIT] = NULL;
+
+ __libc_init_common(elfdata);
+}
+
__noreturn void __libc_init(uintptr_t *elfdata,
void (*onexit)(void),
int (*slingshot)(int, char**, char**),
structors_array_t const * const structors)
{
- __libc_init_common(elfdata, onexit, slingshot, structors, malloc_debug_init);
+ /* When we reach this point, all initializers have been already
+ * run by the dynamic linker, so ignore 'structors'.
+ */
+ int argc = (int)*elfdata;
+ char** argv = (char**)(elfdata + 1);
+ char** envp = argv + argc + 1;
+
+ /* Several Linux ABIs don't pass the onexit pointer, and the ones that
+ * do never use it. Therefore, we ignore it.
+ */
+
+ exit(slingshot(argc, argv, envp));
}
diff --git a/libc/bionic/libc_init_static.c b/libc/bionic/libc_init_static.c
index ec463f7..d097b6b 100644
--- a/libc/bionic/libc_init_static.c
+++ b/libc/bionic/libc_init_static.c
@@ -28,24 +28,15 @@
/*
* libc_init_static.c
*
- * This function takes the raw data block set up by the ELF loader
- * in the kernel and parses it. It is invoked by crt0.S which makes
- * any necessary adjustments and passes calls this function using
- * the standard C calling convention.
+ * The program startup function __libc_init() defined here is
+ * used for static executables only (i.e. those that don't depend
+ * on shared libraries). It is called from arch-$ARCH/bionic/crtbegin_static.S
+ * which is directly invoked by the kernel when the program is launched.
*
- * The arguments are:
- * uintptr_t *elfdata -- The ELF loader data block; usually from the stack.
- * Basically a pointer to argc.
- * void (*onexit)(void) -- Function to install into onexit
+ * The 'structors' parameter contains pointers to various initializer
+ * arrays that must be run before the program's 'main' routine is launched.
*/
-/*
- * Several Linux ABIs don't pass the onexit pointer, and the ones that
- * do never use it. Therefore, unless USE_ONEXIT is defined, we just
- * ignore the onexit pointer.
- */
-/* #define USE_ONEXIT */
-
#include <stddef.h>
#include <stdio.h>
#include <stdlib.h>
@@ -58,19 +49,41 @@
#include <bionic_tls.h>
#include <errno.h>
+static void call_array(void(**list)())
+{
+ // First element is -1, list is null-terminated
+ while (*++list) {
+ (*list)();
+ }
+}
+
__noreturn void __libc_init(uintptr_t *elfdata,
void (*onexit)(void),
int (*slingshot)(int, char**, char**),
structors_array_t const * const structors)
{
-/*
- * To enable malloc checks for statically linked programs, add
- * "WITH_MALLOC_CHECK_LIBC_A := true" in device/buildspec.mk
- */
-#ifdef MALLOC_LEAK_CHECK
- extern void malloc_debug_init();
- __libc_init_common(elfdata, onexit, slingshot, structors, malloc_debug_init);
-#else
- __libc_init_common(elfdata, onexit, slingshot, structors, NULL);
-#endif
+ int argc;
+ char **argv, **envp;
+
+ /* Initialize the C runtime environment */
+ __libc_init_common(elfdata);
+
+ /* Several Linux ABIs don't pass the onexit pointer, and the ones that
+ * do never use it. Therefore, we ignore it.
+ */
+
+ /* pre-init array. */
+ call_array(structors->preinit_array);
+
+ /* .ctors section initializers, for non-arm-eabi ABIs */
+ call_array(structors->ctors_array);
+
+ // call static constructors
+ call_array(structors->init_array);
+
+ argc = (int) *elfdata;
+ argv = (char**)(elfdata + 1);
+ envp = argv + argc + 1;
+
+ exit(slingshot(argc, argv, envp));
}