Linking against `noderawfs.js` causes `ioctl_tiocgwinsz` to fail

[gudzpoz]

Version of emscripten/emsdk:

emcc (Emscripten gcc/clang-like replacement + linker emulating GNU ld) 3.1.61-git (67fa4c16496b157a7fc3377afd69ee0445e8a6e3)
clang version 19.0.0git (/startdir/llvm-project 7cfffe74eeb68fbb3fb9706ac7071f8caeeb6520)
Target: wasm32-unknown-emscripten
Thread model: posix
InstalledDir: /opt/emscripten-llvm/bin

Reproducing steps

1. Source file content:

   #include <stdio.h>
   #include <stdlib.h>
   #include <sys/ioctl.h>
   #include <err.h>
   #include <fcntl.h>
   #include <unistd.h>
   #include <termios.h>
   
   void ensure_noderawfs_init() {
       int c;
       FILE *file;
       file = fopen("/etc/hostname", "r");
       if (file) {
           while ((c = getc(file)) != EOF)
               putchar(c);
           fclose(file);
       }
   }
   
   void print_tty_size() {
       struct winsize ws;
       if(ioctl(STDIN_FILENO, TIOCGWINSZ, &ws) < 0) { // <--------------------
           err(EXIT_FAILURE, "/dev/stdin not a tty");
       }
       printf("TTY Size: %d x %d\n", ws.ws_row, ws.ws_col);
   }
   
   int main() {
       ensure_noderawfs_init();
       print_tty_size();
       return 0;
   }

2. Compile the code above and run it with node:

   $ emcc ioctl_test.c -lnodefs.js -lnoderawfs.js
   $ node ./a.out.js                      
   my-host-name      
   .../ledger/build/a.out.js:128
         throw ex;
         ^
   TypeError: Cannot read properties of undefined (reading 'ioctl_tiocgwinsz')
       at ___syscall_ioctl (.../ledger/build/a.out.js:4396:30)
      ...

Failing command line in full:

$ node ./a.out.js
my-host-name
.../ledger/build/a.out.js:128
      throw ex;
      ^

TypeError: Cannot read properties of undefined (reading 'ioctl_tiocgwinsz')
    at ___syscall_ioctl (.../ledger/build/a.out.js:4396:30)
    at wasm://wasm/0001a2fa:wasm-function[48]:0x13c2
    at wasm://wasm/0001a2fa:wasm-function[13]:0x4af
    at wasm://wasm/0001a2fa:wasm-function[14]:0x560
    at wasm://wasm/0001a2fa:wasm-function[15]:0x57d
    at .../ledger/build/a.out.js:641:12
    at callMain (.../ledger/build/a.out.js:4985:15)
    at doRun (.../ledger/build/a.out.js:5035:23)
    at run (.../ledger/build/a.out.js:5050:5)
    at runCaller (.../ledger/build/a.out.js:4970:19)

Node.js v20.12.2

Reproducing steps have been attached above.

Full link command and output with -v appended:

$ emcc ioctl_test.c -lnodefs.js -lnoderawfs.js -v
emcc ioctl_test.c -lnodefs.js -lnoderawfs.js -v 2>&1 | sed 's#/home/otaku/Workspaces/clones#...#g' | sed 's#/home/otaku/#$HOME/#g'
 /opt/emscripten-llvm/bin/clang -target wasm32-unknown-emscripten -fignore-exceptions -mllvm -combiner-global-alias-analysis=false -mllvm -enable-emscripten-sjlj -mllvm -disable-lsr --sysroot=$HOME/.emscripten_cache/sysroot -DEMSCRIPTEN -Werror=implicit-function-declaration -Xclang -iwithsysroot/include/fakesdl -Xclang -iwithsysroot/include/compat -v ioctl_test.c -c -o /tmp/emscripten_temp_e8xdm84r/ioctl_test_0.o
clang version 19.0.0git (/startdir/llvm-project 7cfffe74eeb68fbb3fb9706ac7071f8caeeb6520)
Target: wasm32-unknown-emscripten
Thread model: posix
InstalledDir: /opt/emscripten-llvm/bin
 (in-process)
 "/opt/emscripten-llvm/bin/clang-19" -cc1 -triple wasm32-unknown-emscripten -emit-obj -disable-free -clear-ast-before-backend -disable-llvm-verifier -discard-value-names -main-file-name ioctl_test.c -mrelocation-model static -mframe-pointer=none -ffp-contract=on -fno-rounding-math -mconstructor-aliases -target-cpu generic -fvisibility=hidden -debugger-tuning=gdb -fdebug-compilation-dir=.../ledger/build -v -fcoverage-compilation-dir=.../ledger/build -resource-dir /opt/emscripten-llvm/lib/clang/19 -D EMSCRIPTEN -isysroot $HOME/.emscripten_cache/sysroot -internal-isystem /opt/emscripten-llvm/lib/clang/19/include -internal-isystem $HOME/.emscripten_cache/sysroot/include/wasm32-emscripten -internal-isystem $HOME/.emscripten_cache/sysroot/include -Werror=implicit-function-declaration -ferror-limit 19 -fgnuc-version=4.2.1 -fskip-odr-check-in-gmf -fignore-exceptions -iwithsysroot/include/fakesdl -iwithsysroot/include/compat -mllvm -combiner-global-alias-analysis=false -mllvm -enable-emscripten-sjlj -mllvm -disable-lsr -o /tmp/emscripten_temp_e8xdm84r/ioctl_test_0.o -x c ioctl_test.c
clang -cc1 version 19.0.0git based upon LLVM 19.0.0git default target x86_64-unknown-linux-gnu
ignoring nonexistent directory "$HOME/.emscripten_cache/sysroot/include/wasm32-emscripten"
#include "..." search starts here:
#include <...> search starts here:
 $HOME/.emscripten_cache/sysroot/include/fakesdl
 $HOME/.emscripten_cache/sysroot/include/compat
 /opt/emscripten-llvm/lib/clang/19/include
 $HOME/.emscripten_cache/sysroot/include
End of search list.
 /opt/emscripten-llvm/bin/clang --version
 /opt/emscripten-llvm/bin/wasm-ld -o a.out.wasm /tmp/emscripten_temp_e8xdm84r/ioctl_test_0.o -L$HOME/.emscripten_cache/sysroot/lib/wasm32-emscripten -lGL-getprocaddr -lal -lhtml5 -lstubs-debug -lnoexit -lc-debug -ldlmalloc -lcompiler_rt -lc++-noexcept -lc++abi-debug-noexcept -lsockets -mllvm -combiner-global-alias-analysis=false -mllvm -enable-emscripten-sjlj -mllvm -disable-lsr /tmp/tmpa_r6uqttlibemscripten_js_symbols.so --strip-debug --export=emscripten_stack_get_end --export=emscripten_stack_get_free --export=emscripten_stack_get_base --export=emscripten_stack_get_current --export=emscripten_stack_init --export=_emscripten_stack_alloc --export=__get_temp_ret --export=__set_temp_ret --export=__wasm_call_ctors --export=_emscripten_stack_restore --export-if-defined=__start_em_asm --export-if-defined=__stop_em_asm --export-if-defined=__start_em_lib_deps --export-if-defined=__stop_em_lib_deps --export-if-defined=__start_em_js --export-if-defined=__stop_em_js --export-if-defined=main --export-if-defined=__main_argc_argv --export-if-defined=fflush --export-table -z stack-size=65536 --no-growable-memory --initial-heap=16777216 --no-entry --stack-first --table-base=1
 /opt/emscripten-llvm/bin/llvm-objcopy a.out.wasm a.out.wasm --remove-section=.debug* --remove-section=producers
 /usr/bin/wasm-emscripten-finalize --dyncalls-i64 --pass-arg=legalize-js-interface-exported-helpers a.out.wasm -o a.out.wasm --detect-features
 /usr/bin/node /usr/lib/emscripten/src/compiler.mjs /tmp/tmpek0bu9lr.json

Extra info

It seems to come from library_noderawfs.js setting stream.tty to true, while ioctl implementation in library_syscall.js expects a TTY object:

emscripten/src/library_noderawfs.js

Lines 47 to 52 in a1fe390

	createStandardStreams() {
	FS.createStream({ nfd: 0, position: 0, path: '', flags: 0, tty: true, seekable: false }, 0);
	for (var i = 1; i < 3; i++) {
	FS.createStream({ nfd: i, position: 0, path: '', flags: 577, tty: true, seekable: false }, i);
	}
	},

emscripten/src/library_syscall.js

Lines 279 to 285 in a1fe390

	if (!stream.tty) return -{{{ cDefs.ENOTTY }}};
	if (stream.tty.ops.ioctl_tiocgwinsz) {
	var winsize = stream.tty.ops.ioctl_tiocgwinsz(stream.tty);
	var argp = syscallGetVarargP();
	{{{ makeSetValue('argp', 0, 'winsize[0]', 'i16') }}};
	{{{ makeSetValue('argp', 2, 'winsize[1]', 'i16') }}};
	}

But I couldn't find any documentation on that tty field though.

[kleisauke]

I think (draft) PR #18163 will fix this.

[kleisauke]

I confirm PR #18163 fixes this. With that, I see:

$ emcc ioctl_test.c -lnodefs.js -lnoderawfs.js
$ node ./a.out.js
pc-kaw
TTY Size: 24 x 80

i.e. it just returns the hardcoded TTY size from here:

emscripten/src/library_tty.js

Lines 139 to 141 in 03fca01

	ioctl_tiocgwinsz(tty) {
	return [24, 80];
	}

[kleisauke]

Reopening due to the following unresolved issue:

emscripten/src/library_noderawfs.js

Line 58 in 73ae666

// FIXME: tty is set to true to appease isatty(), the underlying ioctl syscalls still needs to be implemented, see issue #22264.