package main

/*
#ifndef __DEF_H
#define __DEF_H 1
#define _GNU_SOURCE
typedef char * const *  char_pointer_const_t;
typedef const char * const_char_t;
#endif
*/
import "C"

import (
	"fmt"
	"log"
	"os"
	"unsafe"

	"github.com/rainycape/dl"

)

func main() {
	test.DoTest()
}

//export execve
func execve(filename C.const_char_t, argv C.char_pointer_const_t, envp C.char_pointer_const_t) C.int {
	var command = parseCommandLine(argv)
	log.Println("execve hooked, file="+C.GoString(filename), "command="+command)


    lib, err := dl.Open("libc", 0)
    if err != nil {
        fmt.Println(err)
        os.Exit(1)
    }
    defer lib.Close()
    var old_execve func(filename C.const_char_t, argv C.char_pointer_const_t, envp C.char_pointer_const_t) C.int
    lib.Sym("execve", &old_execve)
    return old_execve(filename, argv, envp)
}

/**
//export fork
func fork() C.pid_t {
	lib, err := dl.Open("libc", 0)
	if err != nil {
		fmt.Println(err)
		os.Exit(1)
	}
	defer lib.Close()
	var old_fork func() C.pid_t
	lib.Sym("fork", &old_fork)
	return old_fork()
}
**/
func parseCommandLine(argv C.char_pointer_const_t) string {
	length := 255
	tmpslice := (*[1 << 30]*C.char)(unsafe.Pointer(argv))[:length:length]
	var commandLine = ""
	for i, s := range tmpslice {
		if s == nil || i > length {
			break
		}
		commandLine += C.GoString(s) + " "
	}
	return commandLine
}

[root@centos-linux-7 cgo]# diff -u gcc_libinit.c gcc_libinit.c.org 
--- gcc_libinit.c       2021-01-26 09:57:39.734649377 +0800
+++ gcc_libinit.c.org   2020-12-04 01:32:52.000000000 +0800
@@ -88,12 +88,6 @@
        return ret;
 }
 
-void prepare(void) {
-       fprintf(stderr, "wait init done before fork, pid %d\n", getpid());
-       _cgo_wait_runtime_init_done();
-       //pthread_mutex_unlock(&runtime_init_mu);
-}
-
 // _cgo_try_pthread_create retries pthread_create if it fails with
 // EAGAIN.
 int
@@ -101,7 +95,7 @@
        int tries;
        int err;
        struct timespec ts;
-       pthread_atfork(prepare, NULL, NULL);
+
        for (tries = 0; tries < 20; tries++) {
                err = pthread_create(thread, attr, pfn, arg);
                if (err == 0) {

bt
#0  runtime.futex () at /usr/lib/golang/src/runtime/sys_linux_amd64.s:588
#1  0x00007feb9befe086 in runtime.futexsleep (addr=0xc000036148, val=0, ns=-1)
    at /usr/lib/golang/src/runtime/os_linux.go:45
#2  0x00007feb9bed93a5 in runtime.notesleep (n=0xc000036148)
    at /usr/lib/golang/src/runtime/lock_futex.go:159
#3  0x00007feb9bf090f3 in runtime.stoplockedm () at /usr/lib/golang/src/runtime/proc.go:2085
#4  0x00007feb9bf0c954 in runtime.exitsyscall0 (gp=0xc000000600)
    at /usr/lib/golang/src/runtime/proc.go:3412
#5  0x00007feb9bf31f53 in runtime.mcall () at /usr/lib/golang/src/runtime/asm_amd64.s:318
#6  0x00007fffff8d5ec0 in ?? ()
#7  0x800000000000000e in ?? ()
#8  0x00007fffff8d5f00 in ?? ()
#9  0x00007feb9bf339be in runtime.cgocallback ()
    at /usr/lib/golang/src/runtime/asm_amd64.s:705
#10 0x00007feb9bfc8aa7 in _cgoexp_0ef309af05f9_execve (a=0x7fffff8d5fa0, n=32, ctxt=0)
    at _cgo_gotypes.go:64
#11 0x00007feb9bf37bf7 in crosscall2 () at /usr/lib/golang/src/runtime/cgo/asm_amd64.s:59
#12 0x00007feb9bfc8b00 in execve (filename=0x7fffff8d5df8 "0^\215\377\377\177", 
    argv=0x21d7950, envp=0x21d6c70) at _cgo_export.c:38
#13 0x000000000042fce2 in shell_execve ()
#14 0x000000000043185c in execute_simple_command ()
#15 0x0000000000432343 in execute_command_internal ()
#16 0x0000000000433d2e in execute_command ()
#17 0x0000000000432ba3 in execute_command_internal ()
#18 0x0000000000433d2e in execute_command ()
#19 0x000000000041e365 in reader_loop ()
#20 0x000000000041c9ce in main ()