LibC: Run constructors on process startup.

Cooperate with the compiler to generate and execute the _init_array list
of constructor functions on userspace program statup. This took two days
to get working, my goodness. :^)

LibC/.gitignore

@@ -1,4 +1,5 @@
 *.o
 *.no
+*.ao
 *.d
 libc.a

LibC/Makefile

@@ -40,17 +40,16 @@ LIBC_OBJS = \
        poll.o \
        locale.o \
        arpa/inet.o \
-       netdb.o \
-       crt0.o
+       netdb.o
 
-ASM_OBJS = setjmp.no
+ASM_OBJS = setjmp.no crti.ao crtn.ao
 
 CPP_OBJS = $(AK_OBJS) $(WIDGETS_OBJS) $(LIBC_OBJS)
 
 LIBRARY = libc.a
 STANDARD_FLAGS = -std=c++17
 WARNING_FLAGS = -Wextra -Wall -Wundef -Wcast-qual -Wwrite-strings -Wimplicit-fallthrough
-FLAVOR_FLAGS = -fno-exceptions -fno-rtti
+FLAVOR_FLAGS = -fno-exceptions -fno-rtti -fno-sized-deallocation
 OPTIMIZATION_FLAGS = -Os
 INCLUDE_FLAGS = -I.. -I.
 
@@ -60,8 +59,14 @@ CXXFLAGS = -MMD -MP $(WARNING_FLAGS) $(OPTIMIZATION_FLAGS) $(FLAVOR_FLAGS) $(STA
 CXX = i686-pc-serenity-g++
 LD = i686-pc-serenity-ld
 AR = i686-pc-serenity-ar
+AS = i686-pc-serenity-as
 
-all: $(LIBRARY)
+all: $(LIBRARY) startfiles
+
+startfiles:
+	@echo "CXX $<"; $(CXX) $(CXXFLAGS) -o crt0.o -c crt0.cpp
+	cp crti.ao crti.o
+	cp crtn.ao crtn.o
 
 $(LIBRARY): $(CPP_OBJS) $(ASM_OBJS)
 	@echo "LIB $@"; $(AR) rcs $@ $(CPP_OBJS) $(ASM_OBJS)
@@ -72,6 +77,9 @@ $(LIBRARY): $(CPP_OBJS) $(ASM_OBJS)
 %.no: %.asm
 	@echo "NASM $@"; nasm -f elf -o $@ $<
 
+%.ao: %.S
+	@echo "AS $@"; $(AS) -o $@ $<
+
 -include $(OBJS:%.o=%.d)
 
 clean:

LibC/SharedBuffer.cpp

@@ -1,6 +1,7 @@
 #include <LibC/SharedBuffer.h>
 #include <unistd.h>
 #include <stdio.h>
+#include <AK/kmalloc.h>
 
 RetainPtr<SharedBuffer> SharedBuffer::create(pid_t peer, int size)
 {

LibC/crt0.cpp

@@ -10,17 +10,31 @@ int errno;
 char** environ;
 //bool __environ_is_malloced;
 
-void __malloc_init();
-void __stdio_init();
+void __libc_init()
+{
+    void __malloc_init();
+    __malloc_init();
+
+    void __stdio_init();
+    __stdio_init();
+}
 
 int _start(int argc, char** argv, char** env)
 {
-    errno = 0;
     environ = env;
     //__environ_is_malloced = false;
 
-    __stdio_init();
-    __malloc_init();
+    __libc_init();
+
+    extern void _init();
+    _init();
+
+    extern void (*__init_array_start[])(int, char**, char**) __attribute__((visibility("hidden")));
+    extern void (*__init_array_end[])(int, char**, char**) __attribute__((visibility("hidden")));
+
+    const size_t size = __init_array_end - __init_array_start;
+    for (size_t i = 0; i < size; i++)
+        (*__init_array_start[i])(argc, argv, env);
 
     int status = main(argc, argv);
 
@@ -37,4 +51,8 @@ int _start(int argc, char** argv, char** env)
     assert(false);
 }
 
+void __cxa_atexit()
+{
+}
+
 }

LibC/crti.S

@@ -0,0 +1,9 @@
+.global _init
+.section .init
+_init:
+    push %ebp
+
+.global _fini
+.section .fini
+_fini:
+    push %ebp

LibC/crtn.S

@@ -0,0 +1,7 @@
+.section .init
+    pop %ebp
+    ret
+
+.section .fini
+    pop %ebp
+    ret

LibC/install.sh

@@ -10,3 +10,5 @@ cp arpa/*.h ../Root/usr/include/arpa/
 cp netinet/*.h ../Root/usr/include/netinet/
 cp libc.a ../Root/usr/lib/
 cp crt0.o ../Root/usr/lib/
+cp crti.ao ../Root/usr/lib/crti.o
+cp crtn.ao ../Root/usr/lib/crtn.o