fs: improve readFileSync with file descriptors

PR-URL: #49691
Reviewed-By: Stephen Belanger <admin@stephenbelanger.com>

Author: anonrig

benchmark/fs/readFileSync.js

@@ -6,12 +6,21 @@ const fs = require('fs');
 constbench=common.createBenchmark(main,{
 encoding: ['undefined','utf8'],
 path: ['existing','non-existing'],
-n: [60e1],
+hasFileDescriptor: ['true','false'],
+n: [1e4],
 });
 
-functionmain({ n, encoding, path }){
+functionmain({ n, encoding, path, hasFileDescriptor}){
 constenc=encoding==='undefined' ? undefined : encoding;
-constfile=path==='existing' ? __filename : '/tmp/not-found';
+letfile;
+letshouldClose=false;
+
+if(hasFileDescriptor==='true'){
+shouldClose=path==='existing';
+file=path==='existing' ? fs.openSync(__filename) : -1;
+}else{
+file=path==='existing' ? __filename : '/tmp/not-found';
+}
 bench.start();
 for(leti=0;i<n;++i){
 try{
@@ -21,4 +30,7 @@ function main({ n, encoding, path }) {
 }
 }
 bench.end(n);
+if(shouldClose){
+fs.closeSync(file);
+}
 }

lib/fs.js

@@ -437,13 +437,11 @@ function tryReadSync(fd, isUserFd, buffer, pos, len) {
 functionreadFileSync(path,options){
 options=getOptions(options,{flag: 'r'});
 
-constisUserFd=isFd(path);// File descriptor ownership
-
-// TODO(@anonrig): Do not handle file descriptor ownership for now.
-if(!isUserFd&&(options.encoding==='utf8'||options.encoding==='utf-8')){
+if(options.encoding==='utf8'||options.encoding==='utf-8'){
 returnsyncFs.readFileUtf8(path,options.flag);
 }
 
+constisUserFd=isFd(path);// File descriptor ownership
 constfd=isUserFd ? path : fs.openSync(path,options.flag,0o666);
 
 conststats=tryStatSync(fd,isUserFd);

lib/internal/fs/sync.js

@@ -9,7 +9,7 @@ const {
  getStatFsFromBinding,
  getValidatedFd,
 }=require('internal/fs/utils');
-const{ parseFileMode }=require('internal/validators');
+const{ parseFileMode, isInt32}=require('internal/validators');
 
 constbinding=internalBinding('fs');
 
@@ -19,7 +19,9 @@ const binding = internalBinding('fs');
  * @return {string}
  */
 functionreadFileUtf8(path,flag){
-path=pathModule.toNamespacedPath(getValidatedPath(path));
+if(!isInt32(path)){
+path=pathModule.toNamespacedPath(getValidatedPath(path));
+}
 returnbinding.readFileUtf8(path,stringToFlags(flag));
 }
 

src/node_file.cc

@@ -2190,7 +2190,7 @@ static void OpenSync(const FunctionCallbackInfo<Value>& args) {
 uv_fs_t req;
 auto make = OnScopeLeave([&req]() { uv_fs_req_cleanup(&req); });
 FS_SYNC_TRACE_BEGIN(open);
-int err = uv_fs_open(nullptr, &req, *path, flags, mode, nullptr);
+auto err = uv_fs_open(nullptr, &req, *path, flags, mode, nullptr);
 FS_SYNC_TRACE_END(open);
 if (err < 0) {
 return env->ThrowUVException(err, "open", nullptr, path.out());
@@ -2581,30 +2581,41 @@ static void ReadFileUtf8(const FunctionCallbackInfo<Value>& args) {
 
 CHECK_GE(args.Length(), 2);
 
- BufferValue path(env->isolate(), args[0]);
-CHECK_NOT_NULL(*path);
-
 CHECK(args[1]->IsInt32());
 constint flags = args[1].As<Int32>()->Value();
 
-if (CheckOpenPermissions(env, path, flags).IsNothing()) return;
-
+ uv_file file;
 uv_fs_t req;
-auto defer_req_cleanup = OnScopeLeave([&req]() { uv_fs_req_cleanup(&req); });
 
-FS_SYNC_TRACE_BEGIN(open);
- uv_file file = uv_fs_open(nullptr, &req, *path, flags, 438, nullptr);
-FS_SYNC_TRACE_END(open);
-if (req.result < 0) {
-// req will be cleaned up by scope leave.
-return env->ThrowUVException(req.result, "open", nullptr, path.out());
+bool is_fd = args[0]->IsInt32();
+
+// Check for file descriptor
+if (is_fd) {
+ file = args[0].As<Int32>()->Value();
+ } else {
+ BufferValue path(env->isolate(), args[0]);
+CHECK_NOT_NULL(*path);
+if (CheckOpenPermissions(env, path, flags).IsNothing()) return;
+
+FS_SYNC_TRACE_BEGIN(open);
+ file = uv_fs_open(nullptr, &req, *path, flags, O_RDONLY, nullptr);
+FS_SYNC_TRACE_END(open);
+if (req.result < 0) {
+uv_fs_req_cleanup(&req);
+// req will be cleaned up by scope leave.
+return env->ThrowUVException(req.result, "open", nullptr, path.out());
+ }
  }
 
-auto defer_close = OnScopeLeave([file]() {
-uv_fs_t close_req;
-CHECK_EQ(0, uv_fs_close(nullptr, &close_req, file, nullptr));
-uv_fs_req_cleanup(&close_req);
+auto defer_close = OnScopeLeave([file, is_fd, &req]() {
+if (!is_fd) {
+FS_SYNC_TRACE_BEGIN(close);
+CHECK_EQ(0, uv_fs_close(nullptr, &req, file, nullptr));
+FS_SYNC_TRACE_END(close);
+ }
+uv_fs_req_cleanup(&req);
  });
+
  std::string result{};
 char buffer[8192];
 uv_buf_t buf = uv_buf_init(buffer, sizeof(buffer));
@@ -2615,7 +2626,7 @@ static void ReadFileUtf8(const FunctionCallbackInfo<Value>& args) {
 if (req.result < 0) {
 FS_SYNC_TRACE_END(read);
 // req will be cleaned up by scope leave.
-return env->ThrowUVException(req.result, "read", nullptr, path.out());
+return env->ThrowUVException(req.result, "read", nullptr);
  }
 if (r <= 0) {
 break;