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fs: add positioned file writing feature to fs.WriteStream

Patterned on same feature in ReadStream; a small bit of new code added
plus two refactorings of previous code; added two test files.

Fixes #1645.
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1 parent e4ebeb6 commit e58c036c27f460873695d7b7c0a7b00da0bdf962 @tshinnic tshinnic committed with koichik Sep 11, 2011
Showing with 335 additions and 16 deletions.
  1. +5 −0 doc/api/fs.markdown
  2. +26 −16 lib/fs.js
  3. +98 −0 test/simple/test-file-write-stream2.js
  4. +206 −0 test/simple/test-file-write-stream3.js
View
5 doc/api/fs.markdown
@@ -496,3 +496,8 @@ Returns a new WriteStream object (See `Writable Stream`).
{ flags: 'w',
encoding: null,
mode: 0666 }
+
+`options` may also include a `start` option to allow writing data at
+some position past the beginning of the file. Modifying a file rather
+than replacing it may require a `flags` mode of `r+` rather than the
+default mode `w`.
View
42 lib/fs.js
@@ -1112,6 +1112,14 @@ var WriteStream = fs.WriteStream = function(path, options) {
this[key] = options[key];
}
+ if (this.start !== undefined) {
+ if (this.start < 0) {
+ throw new Error('start must be >= zero');
+ }
+
+ this.pos = this.start;
+ }
+
this.busy = false;
this._queue = [];
@@ -1153,26 +1161,25 @@ WriteStream.prototype.flush = function() {
if (method == fs.write) {
self.bytesWritten += arguments[1];
- }
+ if (cb) {
+ // write callback
+ cb(null, arguments[1]);
+ }
- // stop flushing after close
- if (method === fs.close) {
+ } else if (method === fs.open) {
+ // save reference for file pointer
+ self.fd = arguments[1];
+ self.emit('open', self.fd);
+
+ } else if (method === fs.close) {
+ // stop flushing after close
if (cb) {
cb(null);
}
self.emit('close');
return;
}
- // save reference for file pointer
- if (method === fs.open) {
- self.fd = arguments[1];
- self.emit('open', self.fd);
- } else if (cb) {
- // write callback
- cb(null, arguments[1]);
- }
-
self.flush();
});
@@ -1197,14 +1204,17 @@ WriteStream.prototype.write = function(data) {
cb = arguments[arguments.length - 1];
}
- if (Buffer.isBuffer(data)) {
- this._queue.push([fs.write, data, 0, data.length, null, cb]);
- } else {
+ if (!Buffer.isBuffer(data)) {
var encoding = 'utf8';
if (typeof(arguments[1]) == 'string') encoding = arguments[1];
- this._queue.push([fs.write, data, undefined, encoding, cb]);
+ data = new Buffer('' + data, encoding);
}
+ this._queue.push([fs.write, data, 0, data.length, this.pos, cb]);
+
+ if (this.pos !== undefined) {
+ this.pos += data.length;
+ }
this.flush();
View
98 test/simple/test-file-write-stream2.js
@@ -0,0 +1,98 @@
+// Copyright Joyent, Inc. and other Node contributors.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a
+// copy of this software and associated documentation files (the
+// "Software"), to deal in the Software without restriction, including
+// without limitation the rights to use, copy, modify, merge, publish,
+// distribute, sublicense, and/or sell copies of the Software, and to permit
+// persons to whom the Software is furnished to do so, subject to the
+// following conditions:
+//
+// The above copyright notice and this permission notice shall be included
+// in all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+// OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN
+// NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
+// DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
+// OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
+// USE OR OTHER DEALINGS IN THE SOFTWARE.
+
+var common = require('../common');
+var assert = require('assert');
+
+var path = require('path'),
+ fs = require('fs'),
+ util = require('util');
+
+
+var filepath = path.join(common.tmpDir, 'write.txt'),
+ file;
+
+var EXPECTED = '012345678910';
+
+var cb_expected = 'write open drain write drain close error ',
+ cb_occurred = '';
+
+var countDrains = 0;
+
+
+process.on('exit', function() {
+ removeTestFile();
+ if ( cb_occurred !== cb_expected) {
+ console.log(' Test callback events missing or out of order:');
+ console.log(' expected: %j', cb_expected);
+ console.log(' occurred: %j', cb_occurred);
+ assert.strictEqual(cb_occurred, cb_expected,
+ 'events missing or out of order: "' +
+ cb_occurred + '" !== "' + cb_expected + '"');
+ }
+});
+
+function removeTestFile() {
+ try {
+ fs.unlinkSync(filepath);
+ } catch (e) {}
+}
+
+
+removeTestFile();
+
+file = fs.createWriteStream(filepath);
+
+file.on('open', function(fd) {
+ cb_occurred += 'open ';
+ assert.equal(typeof fd, 'number');
+});
+
+file.on('drain', function() {
+ cb_occurred += 'drain ';
+ ++countDrains;
+ if (countDrains === 1) {
+ assert.equal(fs.readFileSync(filepath), EXPECTED);
+ file.write(EXPECTED);
+ cb_occurred += 'write ';
+ } else if (countDrains == 2) {
+ assert.equal(fs.readFileSync(filepath), EXPECTED + EXPECTED);
+ file.end();
+ }
+});
+
+file.on('close', function() {
+ cb_occurred += 'close ';
+ assert.strictEqual(file.bytesWritten, EXPECTED.length * 2);
+ file.write('should not work anymore');
+});
+
+
+file.on('error', function(err) {
+ cb_occurred += 'error ';
+ assert.ok(err.message.indexOf('not writable') >= 0);
+});
+
+
+for (var i = 0; i < 11; i++) {
+ assert.strictEqual(file.write(i), false);
+}
+cb_occurred += 'write ';
View
206 test/simple/test-file-write-stream3.js
@@ -0,0 +1,206 @@
+// Copyright Joyent, Inc. and other Node contributors.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a
+// copy of this software and associated documentation files (the
+// "Software"), to deal in the Software without restriction, including
+// without limitation the rights to use, copy, modify, merge, publish,
+// distribute, sublicense, and/or sell copies of the Software, and to permit
+// persons to whom the Software is furnished to do so, subject to the
+// following conditions:
+//
+// The above copyright notice and this permission notice shall be included
+// in all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+// OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN
+// NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
+// DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
+// OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
+// USE OR OTHER DEALINGS IN THE SOFTWARE.
+
+var common = require('../common');
+var assert = require('assert');
+
+var path = require('path'),
+ fs = require('fs'),
+ util = require('util');
+
+
+var filepath = path.join(common.tmpDir, 'write_pos.txt');
+
+
+var cb_expected = 'write open close write open close write open close ',
+ cb_occurred = '';
+
+var fileDataInitial = 'abcdefghijklmnopqrstuvwxyz';
+
+var fileDataExpected_1 = 'abcdefghijklmnopqrstuvwxyz';
+var fileDataExpected_2 = 'abcdefghij123456qrstuvwxyz';
+var fileDataExpected_3 = 'abcdefghij\u2026\u2026qrstuvwxyz';
+
+
+process.on('exit', function() {
+ removeTestFile();
+ if ( cb_occurred !== cb_expected) {
+ console.log(' Test callback events missing or out of order:');
+ console.log(' expected: %j', cb_expected);
+ console.log(' occurred: %j', cb_occurred);
+ assert.strictEqual(cb_occurred, cb_expected,
+ 'events missing or out of order: "' +
+ cb_occurred + '" !== "' + cb_expected + '"');
+ }
+});
+
+function removeTestFile() {
+ try {
+ fs.unlinkSync(filepath);
+ } catch (ex) { }
+}
+
+
+removeTestFile();
+
+
+function run_test_1() {
+ var file, buffer, options;
+
+ options = {};
+ file = fs.createWriteStream(filepath, options);
+ console.log(' (debug: start ', file.start);
+ console.log(' (debug: pos ', file.pos);
+
+ file.on('open', function(fd) {
+ cb_occurred += 'open ';
+ });
+
+ file.on('close', function() {
+ cb_occurred += 'close ';
+ console.log(' (debug: bytesWritten ', file.bytesWritten);
+ console.log(' (debug: start ', file.start);
+ console.log(' (debug: pos ', file.pos);
+ assert.strictEqual(file.bytesWritten, buffer.length);
+ var fileData = fs.readFileSync(filepath, 'utf8');
+ console.log(' (debug: file data ', fileData);
+ console.log(' (debug: expected ', fileDataExpected_1);
+ assert.equal(fileData, fileDataExpected_1);
+
+ run_test_2();
+ });
+
+ file.on('error', function(err) {
+ cb_occurred += 'error ';
+ console.log(' (debug: err event ', err);
+ throw err;
+ });
+
+ buffer = new Buffer(fileDataInitial);
+ file.write(buffer);
+ cb_occurred += 'write ';
+
+ file.end();
+}
+
+
+function run_test_2() {
+ var file, buffer, options;
+
+ buffer = new Buffer('123456');
+
+ options = { start: 10,
+ flags: 'r+' };
+ file = fs.createWriteStream(filepath, options);
+ console.log(' (debug: start ', file.start);
+ console.log(' (debug: pos ', file.pos);
+
+ file.on('open', function(fd) {
+ cb_occurred += 'open ';
+ });
+
+ file.on('close', function() {
+ cb_occurred += 'close ';
+ console.log(' (debug: bytesWritten ', file.bytesWritten);
+ console.log(' (debug: start ', file.start);
+ console.log(' (debug: pos ', file.pos);
+ assert.strictEqual(file.bytesWritten, buffer.length);
+ var fileData = fs.readFileSync(filepath, 'utf8');
+ console.log(' (debug: file data ', fileData);
+ console.log(' (debug: expected ', fileDataExpected_2);
+ assert.equal(fileData, fileDataExpected_2);
+
+ run_test_3();
+ });
+
+ file.on('error', function(err) {
+ cb_occurred += 'error ';
+ console.log(' (debug: err event ', err);
+ throw err;
+ });
+
+ file.write(buffer);
+ cb_occurred += 'write ';
+
+ file.end();
+}
+
+
+function run_test_3() {
+ var file, buffer, options;
+
+ var data = '\u2026\u2026', // 3 bytes * 2 = 6 bytes in UTF-8
+ fileData;
+
+ options = { start: 10,
+ flags: 'r+' };
+ file = fs.createWriteStream(filepath, options);
+ console.log(' (debug: start ', file.start);
+ console.log(' (debug: pos ', file.pos);
+
+ file.on('open', function(fd) {
+ cb_occurred += 'open ';
+ });
+
+ file.on('close', function() {
+ cb_occurred += 'close ';
+ console.log(' (debug: bytesWritten ', file.bytesWritten);
+ console.log(' (debug: start ', file.start);
+ console.log(' (debug: pos ', file.pos);
+ assert.strictEqual(file.bytesWritten, data.length * 3);
+ fileData = fs.readFileSync(filepath, 'utf8');
+ console.log(' (debug: file data ', fileData);
+ console.log(' (debug: expected ', fileDataExpected_3);
+ assert.equal(fileData, fileDataExpected_3);
+
+ run_test_4();
+ });
+
+ file.on('error', function(err) {
+ cb_occurred += 'error ';
+ console.log(' (debug: err event ', err);
+ throw err;
+ });
+
+ file.write(data, 'utf8');
+ cb_occurred += 'write ';
+
+ file.end();
+}
+
+
+function run_test_4() {
+ var file, options;
+
+ options = { start: -5,
+ flags: 'r+' };
+
+ // Error: start must be >= zero
+ assert.throws(
+ function() {
+ file = fs.createWriteStream(filepath, options);
+ },
+ /start must be/
+ );
+
+}
+
+run_test_1();

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