WasmFS: Can't create a file when using fetch + icase backends

[kd935]

Version of emscripten/emsdk:

emcc (Emscripten gcc/clang-like replacement + linker emulating GNU ld) 3.1.25-git (29f65fa7babef81cc00dfe9ce8d36de482247a70)
clang version 16.0.0 (https://github.com/llvm/llvm-project effd75bda4b1a9b26e554c1cda3e3b4c72fa0aa8)
Target: wasm32-unknown-emscripten
Thread model: posix
InstalledDir: C:\Users\kdots\emsdk\3.1.24\upstream\bin

Failing command line in full:

#include <errno.h>
#include <cassert>
#include <stdio.h>
#include <emscripten/wasmfs.h>
#include <string.h>

using namespace std;

const char* url = "http://localhost:8000/files/";
backend_t create_fetch_backend(void* arg)
{
	return wasmfs_create_fetch_backend(url);
}

int main()
{
  backend_t backend = wasmfs_create_icase_backend(create_fetch_backend, NULL);
  assert(backend);

  const char *mountPath = "/fetch/";
  int result = wasmfs_create_directory(mountPath, S_IRUGO | S_IWUGO, backend);
  assert(result == 0);

  const char *filePath = "/fetch/test.txt";
  int fd = wasmfs_create_file(filePath, S_IRUGO | S_IWUGO, backend);
  printf("%d, %s\n", fd, strerror(errno));
  assert(fd > 0);
}

Full link command and output with -v appended:

C:\Users\kdots>em++ -std=c++17 C:/build/test.cpp -o C:/build/test.html -s FORCE_FILESYSTEM=1 -s EXIT_RUNTIME=1 -s WASMFS=1 -s USE_PTHREADS=1 -s PTHREAD_POOL_SIZE=4 -v
 "C:/Users/kdots/emsdk/3.1.24/upstream/bin\clang.exe" --version
 "C:/Users/kdots/emsdk/3.1.24/upstream/bin\clang++.exe" -target wasm32-unknown-emscripten -fignore-exceptions -fvisibility=default -mllvm -combiner-global-alias-analysis=false -mllvm -enable-emscripten-sjlj -mllvm -disable-lsr -D__EMSCRIPTEN_SHARED_MEMORY__=1 -DEMSCRIPTEN -IC:\Users\kdots\emsdk\3.1.24\upstream\emscripten\cache\sysroot\include\SDL --sysroot=C:\Users\kdots\emsdk\3.1.24\upstream\emscripten\cache\sysroot -Xclang -iwithsysroot/include\compat -std=c++17 -v -pthread C:/build/test.cpp -c -o C:\Users\kdots\AppData\Local\Temp\emscripten_temp_8rir65ub\test_0.o
clang version 16.0.0 (https://github.com/llvm/llvm-project effd75bda4b1a9b26e554c1cda3e3b4c72fa0aa8)
Target: wasm32-unknown-emscripten
Thread model: posix
InstalledDir: C:\Users\kdots\emsdk\3.1.24\upstream\bin
 (in-process)
 "C:\\Users\\kdots\\emsdk\\3.1.24\\upstream\\bin\\clang++.exe" -cc1 -triple wasm32-unknown-emscripten -emit-obj -mrelax-all --mrelax-relocations -disable-free -clear-ast-before-backend -main-file-name test.cpp -mrelocation-model static -mframe-pointer=none -ffp-contract=on -fno-rounding-math -mconstructor-aliases -target-feature +atomics -target-feature +bulk-memory -target-feature +mutable-globals -target-feature +sign-ext -target-cpu generic -mllvm -treat-scalable-fixed-error-as-warning -debugger-tuning=gdb -v "-fcoverage-compilation-dir=C:\\Users\\kdots" -resource-dir "C:\\Users\\kdots\\emsdk\\3.1.24\\upstream\\lib\\clang\\16.0.0" -D __EMSCRIPTEN_SHARED_MEMORY__=1 -D EMSCRIPTEN -I "C:\\Users\\kdots\\emsdk\\3.1.24\\upstream\\emscripten\\cache\\sysroot\\include\\SDL" -isysroot "C:\\Users\\kdots\\emsdk\\3.1.24\\upstream\\emscripten\\cache\\sysroot" -internal-isystem "C:\\Users\\kdots\\emsdk\\3.1.24\\upstream\\emscripten\\cache\\sysroot/include/wasm32-emscripten/c++/v1" -internal-isystem "C:\\Users\\kdots\\emsdk\\3.1.24\\upstream\\emscripten\\cache\\sysroot/include/c++/v1" -internal-isystem "C:\\Users\\kdots\\emsdk\\3.1.24\\upstream\\lib\\clang\\16.0.0\\include" -internal-isystem "C:\\Users\\kdots\\emsdk\\3.1.24\\upstream\\emscripten\\cache\\sysroot/include/wasm32-emscripten" -internal-isystem "C:\\Users\\kdots\\emsdk\\3.1.24\\upstream\\emscripten\\cache\\sysroot/include" -std=c++17 -fdeprecated-macro "-fdebug-compilation-dir=C:\\Users\\kdots" -ferror-limit 19 -fmessage-length=172 -fvisibility=default -pthread -fgnuc-version=4.2.1 -fcxx-exceptions -fignore-exceptions -fexceptions -fcolor-diagnostics "-iwithsysroot/include\\compat" -mllvm -combiner-global-alias-analysis=false -mllvm -enable-emscripten-sjlj -mllvm -disable-lsr -o "C:\\Users\\kdots\\AppData\\Local\\Temp\\emscripten_temp_8rir65ub\\test_0.o" -x c++ C:/build/test.cpp
clang -cc1 version 16.0.0 based upon LLVM 16.0.0git default target x86_64-pc-windows-msvc
ignoring nonexistent directory "C:\Users\kdots\emsdk\3.1.24\upstream\emscripten\cache\sysroot/include/wasm32-emscripten/c++/v1"
ignoring nonexistent directory "C:\Users\kdots\emsdk\3.1.24\upstream\emscripten\cache\sysroot/include/wasm32-emscripten"
#include "..." search starts here:
#include <...> search starts here:
 C:\Users\kdots\emsdk\3.1.24\upstream\emscripten\cache\sysroot\include\SDL
 C:\Users\kdots\emsdk\3.1.24\upstream\emscripten\cache\sysroot/include\compat
 C:\Users\kdots\emsdk\3.1.24\upstream\emscripten\cache\sysroot/include/c++/v1
 C:\Users\kdots\emsdk\3.1.24\upstream\lib\clang\16.0.0\include
 C:\Users\kdots\emsdk\3.1.24\upstream\emscripten\cache\sysroot/include
End of search list.
 "C:/Users/kdots/emsdk/3.1.24/upstream/bin\wasm-ld.exe" -o C:/build/test.wasm C:\Users\kdots\AppData\Local\Temp\emscripten_temp_8rir65ub\test_0.o -LC:\Users\kdots\emsdk\3.1.24\upstream\emscripten\cache\sysroot\lib\wasm32-emscripten C:\Users\kdots\emsdk\3.1.24\upstream\emscripten\cache\sysroot\lib\wasm32-emscripten\crtbegin.o --whole-archive -lwasmfs-mt-debug --no-whole-archive -lGL-mt -lal -lhtml5 -lstubs-debug -lc-mt-debug -ldlmalloc-mt -lcompiler_rt-mt -lc++-mt-noexcept -lc++abi-debug-mt-noexcept -lsockets-mt -mllvm -combiner-global-alias-analysis=false -mllvm -enable-emscripten-sjlj -mllvm -disable-lsr --import-undefined --import-memory --shared-memory --strip-debug --export-if-defined=main --export-if-defined=_emscripten_thread_init --export-if-defined=_emscripten_thread_exit --export-if-defined=_emscripten_thread_crashed --export-if-defined=_emscripten_tls_init --export-if-defined=pthread_self --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_argc_argv --export-if-defined=fflush --export=emscripten_stack_get_end --export=emscripten_stack_get_free --export=emscripten_stack_get_base --export=emscripten_stack_init --export=_wasmfs_read_file --export=_wasmfs_write_file --export=_wasmfs_mkdir --export=_wasmfs_chdir --export=_wasmfs_symlink --export=_wasmfs_chmod --export=_wasmfs_identify --export=_wasmfs_readdir_start --export=_wasmfs_readdir_get --export=_wasmfs_readdir_finish --export=stackSave --export=stackRestore --export=stackAlloc --export=__wasm_call_ctors --export=__errno_location --export=emscripten_dispatch_to_thread_ --export=_emscripten_thread_free_data --export=emscripten_main_browser_thread_id --export=emscripten_main_thread_process_queued_calls --export=emscripten_run_in_main_runtime_thread_js --export=emscripten_stack_set_limits --export=emscripten_proxy_finish --export=emscripten_proxy_execute_queue --export=__get_temp_ret --export=__set_temp_ret --export=__funcs_on_exit --export=malloc --export=free --export-table -z stack-size=5242880 --initial-memory=16777216 --no-entry --max-memory=16777216 --global-base=1024
 "C:/Users/kdots/emsdk/3.1.24/upstream\bin\wasm-emscripten-finalize" --dyncalls-i64 --pass-arg=legalize-js-interface-exported-helpers C:/build/test.wasm -o C:/build/test.wasm --detect-features
 "C:/Users/kdots/emsdk/3.1.24/node/14.18.2_64bit/bin/node.exe" C:\Users\kdots\emsdk\3.1.24\upstream\emscripten\src\compiler.js C:\Users\kdots\AppData\Local\Temp\tmphso1n93o.json
 "C:/Users/kdots/emsdk/3.1.24/upstream/bin\llvm-objcopy.exe" C:/build/test.wasm C:/build/test.wasm --remove-section=.debug* --remove-section=producers
 "C:/Users/kdots/emsdk/3.1.24/node/14.18.2_64bit/bin/node.exe" C:\Users\kdots\emsdk\3.1.24\upstream\emscripten\tools\preprocessor.js C:\Users\kdots\AppData\Local\Temp\emscripten_temp_8rir65ub\settings.js worker.js --expandMacros
 "C:/Users/kdots/emsdk/3.1.24/node/14.18.2_64bit/bin/node.exe" C:\Users\kdots\emsdk\3.1.24\upstream\emscripten\tools\preprocessor.js C:\Users\kdots\AppData\Local\Temp\emscripten_temp_8rir65ub\settings.js shell.html

Output:

-29, No error information
test.js:1085 Aborted(Assertion failed: fd > 0, at: C:/build/test.cpp,29,main)

[shashank-mishra14]

Assign this is issue to me I can work on it.