WasmFS: Stop always including _wasmfs_read_file (#19516)

Instead, treat it like everything else. After recent fixes this now works ok,
and it helps a lot with code size: see the minimal metadce test, which
goes from 42,976 bytes to just 88 (which is basically us no longer linking
in all of WasmFS for a minimal program that doesn't do any I/O at all).

Author: kripken

emcc.py

@@ -2308,13 +2308,13 @@ def phase_linker_setup(options, state, newargs):
     settings.FILESYSTEM = 1
     settings.SYSCALLS_REQUIRE_FILESYSTEM = 0
     settings.JS_LIBRARIES.append((0, 'library_wasmfs.js'))
-    settings.REQUIRED_EXPORTS += ['_wasmfs_read_file']
     if settings.FORCE_FILESYSTEM:
       # Add exports for the JS API. Like the old JS FS, WasmFS by default
       # includes just what JS parts it actually needs, and FORCE_FILESYSTEM is
       # required to force all of it to be included if the user wants to use the
       # JS API directly.
       settings.REQUIRED_EXPORTS += [
+        '_wasmfs_read_file',
         '_wasmfs_write_file',
         '_wasmfs_open',
         '_wasmfs_close',

test/other/metadce/test_metadce_cxx_wasmfs.exports

@@ -2,7 +2,6 @@ __cxa_is_pointer_type
 __errno_location
 __indirect_function_table
 __wasm_call_ctors
-_wasmfs_read_file
 dynCall_iiiiiijj
 dynCall_iiiiij
 dynCall_iiiiijj

test/other/metadce/test_metadce_cxx_wasmfs.size

@@ -1 +1 @@
-163973
+159769

test/other/metadce/test_metadce_files_wasmfs.funcs

@@ -34,7 +34,6 @@ $__unlockfile
 $__wasi_fd_close
 $__wasi_fd_write
 $__wasm_call_ctors
-$close
 $decltype\28auto\29\20std::__2::__variant_detail::__visitation::__base::__dispatcher<1ul>::__dispatch\5babi:v160004\5d<std::__2::__variant_detail::__dtor<std::__2::__variant_detail::__traits<long\2c\20std::__2::shared_ptr<wasmfs::File>>\2c\20\28std::__2::__variant_detail::_Trait\291>::__destroy\5babi:v160004\5d\28\29::'lambda'\28auto&\29&&\2c\20std::__2::__variant_detail::__base<\28std::__2::__variant_detail::_Trait\291\2c\20long\2c\20std::__2::shared_ptr<wasmfs::File>>&>\28auto\2c\20std::__2::__variant_detail::__base<\28std::__2::__variant_detail::_Trait\291\2c\20long\2c\20std::__2::shared_ptr<wasmfs::File>>&\29
 $dlfree
 $dlmalloc
@@ -44,10 +43,8 @@ $is_equal\28std::type_info\20const*\2c\20std::type_info\20const*\2c\20bool\29
 $main
 $memcmp
 $memmove
-$open
 $operator\20new\28unsigned\20long\29
 $pthread_mutex_init
-$readAtOffset\28OffsetHandling\2c\20unsigned\20int\2c\20__wasi_iovec_t\20const*\2c\20unsigned\20long\2c\20unsigned\20long*\2c\20unsigned\20long\20long\29
 $sbrk
 $std::__2::__shared_ptr_emplace<wasmfs::MemoryDataFile\2c\20std::__2::allocator<wasmfs::MemoryDataFile>>::~__shared_ptr_emplace\28\29
 $std::__2::__shared_ptr_emplace<wasmfs::MemoryDataFile\2c\20std::__2::allocator<wasmfs::MemoryDataFile>>::~__shared_ptr_emplace\28\29.1
@@ -76,7 +73,6 @@ $std::__2::__shared_weak_count::lock\28\29
 $std::__2::__tree<std::__2::__value_type<std::__2::basic_string<char\2c\20std::__2::char_traits<char>\2c\20std::__2::allocator<char>>\2c\20wasmfs::Directory::DCacheEntry>\2c\20std::__2::__map_value_compare<std::__2::basic_string<char\2c\20std::__2::char_traits<char>\2c\20std::__2::allocator<char>>\2c\20std::__2::__value_type<std::__2::basic_string<char\2c\20std::__2::char_traits<char>\2c\20std::__2::allocator<char>>\2c\20wasmfs::Directory::DCacheEntry>\2c\20std::__2::less<std::__2::basic_string<char\2c\20std::__2::char_traits<char>\2c\20std::__2::allocator<char>>>\2c\20true>\2c\20std::__2::allocator<std::__2::__value_type<std::__2::basic_string<char\2c\20std::__2::char_traits<char>\2c\20std::__2::allocator<char>>\2c\20wasmfs::Directory::DCacheEntry>>>::destroy\28std::__2::__tree_node<std::__2::__value_type<std::__2::basic_string<char\2c\20std::__2::char_traits<char>\2c\20std::__2::allocator<char>>\2c\20wasmfs::Directory::DCacheEntry>\2c\20void*>*\29
 $std::__2::basic_string<char\2c\20std::__2::char_traits<char>\2c\20std::__2::allocator<char>>::__begin_lifetime\5babi:v160004\5d\28char*\2c\20unsigned\20long\29
 $std::__2::basic_string<char\2c\20std::__2::char_traits<char>\2c\20std::__2::allocator<char>>::__init_copy_ctor_external\28char\20const*\2c\20unsigned\20long\29
-$std::__2::shared_ptr<wasmfs::DataFile>::~shared_ptr\5babi:v160004\5d\28\29
 $std::__2::shared_ptr<wasmfs::SpecialFiles::\28anonymous\20namespace\29::RandomFile>\20std::__2::make_shared\5babi:v160004\5d<wasmfs::SpecialFiles::\28anonymous\20namespace\29::RandomFile\2c\20void>\28\29
 $std::__2::vector<unsigned\20char\2c\20std::__2::allocator<unsigned\20char>>::__append\28unsigned\20long\29
 $std::__2::vector<wasmfs::MemoryDirectory::ChildEntry\2c\20std::__2::allocator<wasmfs::MemoryDirectory::ChildEntry>>::erase\5babi:v160004\5d\28std::__2::__wrap_iter<wasmfs::MemoryDirectory::ChildEntry\20const*>\29
@@ -86,15 +82,12 @@ $wasmfs::DataFile::Handle::flush\28\29
 $wasmfs::DataFile::Handle::write\28unsigned\20char\20const*\2c\20unsigned\20long\2c\20long\20long\29
 $wasmfs::Directory::Handle::cacheChild\28std::__2::basic_string<char\2c\20std::__2::char_traits<char>\2c\20std::__2::allocator<char>>\20const&\2c\20std::__2::shared_ptr<wasmfs::File>\2c\20wasmfs::Directory::DCacheKind\29
 $wasmfs::Directory::Handle::getChild\28std::__2::basic_string<char\2c\20std::__2::char_traits<char>\2c\20std::__2::allocator<char>>\20const&\29
-$wasmfs::Directory::Handle::insertDataFile\28std::__2::basic_string<char\2c\20std::__2::char_traits<char>\2c\20std::__2::allocator<char>>\20const&\2c\20unsigned\20int\29
 $wasmfs::Directory::Handle::insertDirectory\28std::__2::basic_string<char\2c\20std::__2::char_traits<char>\2c\20std::__2::allocator<char>>\20const&\2c\20unsigned\20int\29
 $wasmfs::Directory::Handle::mountChild\28std::__2::basic_string<char\2c\20std::__2::char_traits<char>\2c\20std::__2::allocator<char>>\20const&\2c\20std::__2::shared_ptr<wasmfs::File>\29
 $wasmfs::Directory::getName\28std::__2::shared_ptr<wasmfs::File>\29
 $wasmfs::Directory::getSize\28\29
 $wasmfs::Directory::~Directory\28\29
-$wasmfs::File::Handle::~Handle\28\29
 $wasmfs::File::~File\28\29
-$wasmfs::FileTable::Handle::addEntry\28std::__2::shared_ptr<wasmfs::OpenFileState>\29
 $wasmfs::FileTable::Handle::getEntry\28unsigned\20int\29
 $wasmfs::FileTable::Handle::setEntry\28unsigned\20int\2c\20std::__2::shared_ptr<wasmfs::OpenFileState>\29
 $wasmfs::MemoryBackend::createDirectory\28unsigned\20int\29
@@ -145,5 +138,4 @@ $wasmfs::path::\28anonymous\20namespace\29::doParseFile\28std::__2::basic_string
 $wasmfs::path::\28anonymous\20namespace\29::doParseParent\28std::__2::basic_string_view<char\2c\20std::__2::char_traits<char>>\2c\20std::__2::shared_ptr<wasmfs::Directory>\2c\20unsigned\20long&\29
 $wasmfs::path::\28anonymous\20namespace\29::getBaseDir\28unsigned\20int\29
 $wasmfs::path::\28anonymous\20namespace\29::getChild\28std::__2::shared_ptr<wasmfs::Directory>\2c\20std::__2::basic_string_view<char\2c\20std::__2::char_traits<char>>\2c\20wasmfs::path::LinkBehavior\2c\20unsigned\20long&\29
-$wasmfs::path::parseFile\28std::__2::basic_string_view<char\2c\20std::__2::char_traits<char>>\2c\20unsigned\20int\2c\20wasmfs::path::LinkBehavior\29
 $wasmfs::path::parseParent\28std::__2::basic_string_view<char\2c\20std::__2::char_traits<char>>\2c\20unsigned\20int\29

test/other/metadce/test_metadce_files_wasmfs.size

@@ -1 +1 @@
-49396
+47462

test/other/metadce/test_metadce_hello_wasmfs.funcs

@@ -34,7 +34,6 @@ $__stdio_write
 $__time
 $__towrite
 $__unlockfile
-$__wasi_fd_close
 $__wasi_fd_write
 $__wasm_call_ctors
 $decltype\28auto\29\20std::__2::__variant_detail::__visitation::__base::__dispatcher<1ul>::__dispatch\5babi:v160004\5d<std::__2::__variant_detail::__dtor<std::__2::__variant_detail::__traits<long\2c\20std::__2::shared_ptr<wasmfs::File>>\2c\20\28std::__2::__variant_detail::_Trait\291>::__destroy\5babi:v160004\5d\28\29::'lambda'\28auto&\29&&\2c\20std::__2::__variant_detail::__base<\28std::__2::__variant_detail::_Trait\291\2c\20long\2c\20std::__2::shared_ptr<wasmfs::File>>&>\28auto\2c\20std::__2::__variant_detail::__base<\28std::__2::__variant_detail::_Trait\291\2c\20long\2c\20std::__2::shared_ptr<wasmfs::File>>&\29
@@ -92,7 +91,6 @@ $wasmfs::Directory::getSize\28\29
 $wasmfs::Directory::~Directory\28\29
 $wasmfs::File::~File\28\29
 $wasmfs::FileTable::Handle::getEntry\28unsigned\20int\29
-$wasmfs::FileTable::Handle::setEntry\28unsigned\20int\2c\20std::__2::shared_ptr<wasmfs::OpenFileState>\29
 $wasmfs::MemoryBackend::createDirectory\28unsigned\20int\29
 $wasmfs::MemoryBackend::createFile\28unsigned\20int\29
 $wasmfs::MemoryBackend::createSymlink\28std::__2::basic_string<char\2c\20std::__2::char_traits<char>\2c\20std::__2::allocator<char>>\29
@@ -141,5 +139,3 @@ $wasmfs::path::\28anonymous\20namespace\29::doParseFile\28std::__2::basic_string
 $wasmfs::path::\28anonymous\20namespace\29::doParseParent\28std::__2::basic_string_view<char\2c\20std::__2::char_traits<char>>\2c\20std::__2::shared_ptr<wasmfs::Directory>\2c\20unsigned\20long&\29
 $wasmfs::path::\28anonymous\20namespace\29::getBaseDir\28unsigned\20int\29
 $wasmfs::path::\28anonymous\20namespace\29::getChild\28std::__2::shared_ptr<wasmfs::Directory>\2c\20std::__2::basic_string_view<char\2c\20std::__2::char_traits<char>>\2c\20wasmfs::path::LinkBehavior\2c\20unsigned\20long&\29
-$wasmfs::path::parseFile\28std::__2::basic_string_view<char\2c\20std::__2::char_traits<char>>\2c\20unsigned\20int\2c\20wasmfs::path::LinkBehavior\29
-$wasmfs::path::parseParent\28std::__2::basic_string_view<char\2c\20std::__2::char_traits<char>>\2c\20unsigned\20int\29

test/other/metadce/test_metadce_hello_wasmfs.size

@@ -1 +1 @@
-45278
+44622

test/other/metadce/test_metadce_minimal_wasmfs.exports

@@ -1,4 +1,4 @@
-p
-q
-r
-s
+a
+b
+c
+d