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Add ref to buffer during fs.write and fs.read

There was the possibility the buffer could be GCed while the eio_req was
pending.  Still needs test coverage for the fs.read() problem.

See:
http://groups.google.com/group/nodejs/browse_thread/thread/c11f8b683f37cef
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1 parent ba5ac87 commit 44fa89cda815e749cda9493ea313ef3679689a61 @ry ry committed Nov 17, 2010
Showing with 61 additions and 0 deletions.
  1. +11 −0 src/node_file.cc
  2. +50 −0 test/simple/test-fs-sir-writes-alot.js
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@@ -31,6 +31,7 @@ using namespace v8;
ThrowException(Exception::TypeError(String::New("Bad argument")))
static Persistent<String> encoding_symbol;
static Persistent<String> errno_symbol;
+static Persistent<String> buf_symbol;
// Buffer for readlink() and other misc callers; keep this scoped at
// file-level rather than method-level to avoid excess stack usage.
@@ -636,6 +637,10 @@ static Handle<Value> Write(const Arguments& args) {
Local<Value> cb = args[5];
if (cb->IsFunction()) {
+ // Grab a reference to buffer so it isn't GCed
+ Local<Object> cb_obj = cb->ToObject();
+ cb_obj->Set(buf_symbol, buffer->handle_);
+
ASYNC_CALL(write, cb, fd, buf, len, pos)
} else {
ssize_t written = pos < 0 ? write(fd, buf, len) : pwrite(fd, buf, len, pos);
@@ -698,6 +703,11 @@ static Handle<Value> Read(const Arguments& args) {
cb = args[5];
if (cb->IsFunction()) {
+ // Grab a reference to buffer so it isn't GCed
+ // TODO: need test coverage
+ Local<Object> cb_obj = cb->ToObject();
+ cb_obj->Set(buf_symbol, buffer->handle_);
+
ASYNC_CALL(read, cb, fd, buf, len, pos);
} else {
// SYNC
@@ -788,6 +798,7 @@ void File::Initialize(Handle<Object> target) {
errno_symbol = NODE_PSYMBOL("errno");
encoding_symbol = NODE_PSYMBOL("node:encoding");
+ buf_symbol = NODE_PSYMBOL("__buf");
}
void InitFs(Handle<Object> target) {
@@ -0,0 +1,50 @@
+var common = require('../common');
+var fs = require("fs");
+var assert = require("assert");
+var join = require('path').join;
+
+var filename = join(common.tmpDir, 'out.txt');
+
+try {
+ fs.unlinkSync(filename);
+} catch (e) {
+ // might not exist, that's okay.
+}
+
+var fd = fs.openSync(filename, "w");
+
+var line = "aaaaaaaaaaaaaaaaaaaaaaaaaaaa\n";
+
+var N = 10240, complete = 0;
+for (var i = 0; i < N; i ++) {
+ // Create a new buffer for each write. Before the write is actually
+ // executed by the thread pool, the buffer will be collected.
+ var buffer = new Buffer(line);
+ fs.write(fd, buffer, 0, buffer.length, null, function (er, written) {
+ complete++;
+ if (complete === N) {
+ fs.closeSync(fd);
+ var s = fs.createReadStream(filename);
+ s.on("data", testBuffer);
+ }
+ });
+}
+
+var bytesChecked = 0;
+
+function testBuffer (b) {
+ for (var i = 0; i < b.length; i++) {
+ bytesChecked++;
+ if (b[i] !== 'a'.charCodeAt(0) && b[i] !== '\n'.charCodeAt(0)) {
+ throw new Error("invalid char "+i+","+b[i]);
+ }
+ }
+}
+
+process.on('exit', function () {
+ // Probably some of the writes are going to overlap, so we can't assume
+ // that we get (N * line.length). Let's just make sure we've checked a
+ // few...
+ assert.ok(bytesChecked > 1000);
+});
+

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