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LibC: Shared libraries shouldn't have an entry point

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The _start() function attempts to call main() which is a
problem when trying to build a shared library with --no-undefined:

  $ echo > t.c
  $ gcc -shared -Wl,--no-undefined -o t.so t.c
  /usr/local/lib/gcc/i686-pc-serenity/10.2.0/../../../../i686-pc-serenity/bin/ld:
  /usr/lib/crt0_shared.o: in function `_start':
  ./Build/i686/../../Userland/Libraries/LibC/crt0_shared.cpp:56: undefined reference to `main'
  collect2: error: ld returned 1 exit status

Also, unless explicitly requested by the user shared libraries
should not have an entry point (e.g. _start) at all.
This commit is contained in:
Gunnar Beutner 2021-04-15 17:03:21 +02:00 committed by Andreas Kling
parent d719e745fb
commit 67516fa555
1 changed files with 0 additions and 32 deletions
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32
Userland/Libraries/LibC/crt0_shared.cpp
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@ -31,36 +31,4 @@
#include <sys/internals.h>
#include <unistd.h>
extern "C" {
extern u32 __stack_chk_guard;
int main(int, char**, char**);
extern void __libc_init();
extern void _init();
extern char** environ;
extern bool __environ_is_malloced;
int _start(int argc, char** argv, char** env);
int _start(int argc, char** argv, char** env)
{
u32 original_stack_chk = __stack_chk_guard;
arc4random_buf(&__stack_chk_guard, sizeof(__stack_chk_guard));
if (__stack_chk_guard == 0)
__stack_chk_guard = original_stack_chk;
_init();
int status = main(argc, argv, env);
// Restore the stack guard to the value we entered _start with,
// so we don't trigger the stack canary check on the way out.
__stack_chk_guard = original_stack_chk;
return status;
}
}
void* __dso_handle __attribute__((__weak__));