How to :-s STANDALONE_WASM and provide my own mmap/munamp

[yowl]

These symbols are in libstandalonewasm.a :

llvm-nm E:\GitHub\emsdk\upstream\emscripten\cache\wasm\libstandalonewasm.a

standalone.o:
00000000 d .L.str
0000000b d .L.str.1
00000017 d .L.str.2
00000001 T _Exit
0000016c T __cxa_allocate_exception
00000162 T __cxa_throw
000000a1 T __map_file
         U __stack_pointer
000000ab T __syscall192
000000f7 T __syscall221
000000b0 T __syscall5
000000f2 T __syscall54
000000a6 T __syscall91

syscall192 and syscall91, and they are just stubs

emscripten/system/lib/standalone/standalone.c

Lines 66 to 73 in 38485ce

	long __syscall91(int x, int y) { // munmap
	return -ENOSYS;
	}
	// mmap2()
	long __syscall192(long addr, long len, long prot, long flags, long fd, long off) {
	return -ENOSYS;
	}

I want to provide my own implementation of these. Is that possible? Currently when mine are linked in wasm-ld fails with duplicate symbol errors and ld's --allow-multiple-definition is not supported:

wasm-ld: error: duplicate symbol: __syscall91
>>> defined in wasi.o
>>> defined in E:\GitHub\emsdk\upstream\emscripten\cache\wasm\libstandalonewasm.a(standalone.o)

wasm-ld: error: duplicate symbol: __syscall192
>>> defined in wasi.o
>>> defined in E:\GitHub\emsdk\upstream\emscripten\cache\wasm\libstandalonewasm.a(standalone.o)

[yowl]

As a workaround, I've edited standalone.c and that is working.

[bryanmcquade]

Yowl would you be willing to share your edits to standalone.c to add mmap / munmap support?

[yowl]

For mmap the most recent version I have is simply:

long mmap(long addr, long len, long prot, long flags, long fd, long long off) {
	
	void* alignedAddress;

	if (addr == 0)
	{
		// alignment must match OS_PAGE_SIZE or GCToOSInterface::Initialize will fail
		if (posix_memalign(&alignedAddress, len, 65536) != 0)
		{
			return -1; // failed
		}
	}

	memset(alignedAddress, 0, len);
	return (long)alignedAddress;
}

For munmap, I just returned 0

Originally, I don't know if something changed in emscripten, I had these as syscalls, that might still be the way to go. You see in the example above it's called mmap not __syscall192 . See what the current emscripten does.

long __syscall91(int x, int y) { // munmap
  return 0;
}

// mmap2()
long __syscall192(long addr, long len, long prot, long flags, long fd, long off) {