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fs: fix corruption in writeFile and writeFileSync

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1. writeFileSync bumps position incorrectly, causing it to drift in
iteration three and onwards.

2. Append mode files will get corrupted in the middle if writeFile or
writeFileSync iterates multiple times, unless running on Linux. position
starts out as null so first write is OK, but then position will refer to
a location inside an existing file, corrupting that data. Linux ignores
position for append mode files so it doesn't happen there.

This commit fixes these two related issues by bumping position correctly
and by always using null as the position argument to write/writeSync for
append mode files.

PR-URL: https://github.com/iojs/io.js/pull/1063
Reviewed-By: Bert Belder <bertbelder@gmail.com>
This commit is contained in:
Olov Lassus 2015-03-05 01:03:34 +01:00 committed by Bert Belder
parent 4e9bf93e9c
commit c9207f7fc2
1 changed files with 11 additions and 5 deletions
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16
lib/fs.js
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@ -1099,7 +1099,9 @@ function writeAll(fd, buffer, offset, length, position, callback) {
} else {
offset += written;
length -= written;
position += written;
if (position !== null) {
position += written;
}
writeAll(fd, buffer, offset, length, position, callback);
}
}
@ -1148,13 +1150,17 @@ fs.writeFileSync = function(path, data, options) {
if (!(data instanceof Buffer)) {
data = new Buffer('' + data, options.encoding || 'utf8');
}
var written = 0;
var offset = 0;
var length = data.length;
var position = /a/.test(flag) ? null : 0;
try {
while (written < length) {
written += fs.writeSync(fd, data, written, length - written, position);
position += written;
while (length > 0) {
var written = fs.writeSync(fd, data, offset, length, position);
offset += written;
length -= written;
if (position !== null) {
position += written;
}
}
} finally {
fs.closeSync(fd);