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fix(dav): reject negative seeks in assembly streams #65399

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fix(dav): reject negative seeks in assembly streams #65399

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f112ffe
fix(dav): reject negative assembly stream seeks
joshtrichards Oct 11, 2026
8280f92
test(dav): cover AssemblyStream seek and read edge cases
joshtrichards Oct 11, 2026
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8 changes: 4 additions & 4 deletions apps/dav/lib/Upload/AssemblyStream.php
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Original file line number Diff line number Diff line change
Expand Up @@ -78,12 +78,12 @@ public function stream_seek($offset, $whence = SEEK_SET) {
$offset = $this->size + $offset;
}

if ($offset === $this->pos) {
return true;
if ($offset < 0 || $offset > $this->size) {
return false;
}

if ($offset > $this->size) {
return false;
if ($offset === $this->pos) {
return true;
}

$nodeIndex = 0;
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96 changes: 96 additions & 0 deletions apps/dav/tests/unit/Upload/AssemblyStreamTest.php
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Original file line number Diff line number Diff line change
Expand Up @@ -63,6 +63,102 @@ public function testSeek(string $expected, array $nodeData): void {
$this->assertEquals(substr($expected, $offset), $content);
}

public function testSeekModesAndBoundaries(): void {
$stream = AssemblyStream::wrap([
$this->buildNode('0', 'abc'),
$this->buildNode('1', 'def'),
]);

$this->assertSame(0, fseek($stream, 3, SEEK_SET));
$this->assertSame(3, ftell($stream));
$this->assertSame(0, fseek($stream, 3, SEEK_SET));
$this->assertSame(3, ftell($stream));
$this->assertSame('def', stream_get_contents($stream));

$this->assertSame(0, fseek($stream, 0, SEEK_SET));
$this->assertSame('ab', fread($stream, 2));
$this->assertSame(2, ftell($stream));
$this->assertSame(0, fseek($stream, 1, SEEK_CUR));
$this->assertSame('def', stream_get_contents($stream));

$this->assertSame(0, fseek($stream, -2, SEEK_END));
$this->assertSame('ef', stream_get_contents($stream));

$this->assertSame(0, fseek($stream, 6, SEEK_SET));
$this->assertSame('', fread($stream, 1));
$this->assertSame(-1, fseek($stream, 7, SEEK_SET));
$this->assertSame(6, ftell($stream));
}

public function testNegativeSeekIsRejectedWithoutChangingPosition(): void {
$stream = AssemblyStream::wrap([
$this->buildNode('0', 'abcdef'),
]);
$this->assertSame('a', fread($stream, 1));

foreach ([
[-1, SEEK_SET],
[-2, SEEK_CUR],
[-7, SEEK_END],
] as [$offset, $whence]) {
$this->assertSame(-1, fseek($stream, $offset, $whence));
$this->assertSame(1, ftell($stream));
}
}

public function testEmptyAssemblyAndNegativeSeek(): void {
$stream = AssemblyStream::wrap([]);

$this->assertSame('', stream_get_contents($stream));
$this->assertSame(0, fseek($stream, 0, SEEK_SET));
$this->assertSame(-1, fseek($stream, -1, SEEK_SET));
$this->assertSame(0, ftell($stream));
}

public function testReadsFromResourceBackedNode(): void {
$data = 'resource-backed chunk';
$source = fopen('php://temp', 'w+');
fwrite($source, $data);
rewind($source);

$node = $this->getMockBuilder(File::class)
->onlyMethods(['getName', 'get', 'getSize'])
->getMock();
$node->method('getName')->willReturn('0');
$node->method('get')->willReturn($source);
$node->method('getSize')->willReturn(strlen($data));

$stream = AssemblyStream::wrap([$node]);
$this->assertSame($data, stream_get_contents($stream));
}

public function testThrowsWhenNodeStreamIsShorterThanReportedSize(): void {
$node = $this->getMockBuilder(File::class)
->onlyMethods(['getName', 'get', 'getSize'])
->getMock();
$node->method('getName')->willReturn('0');
$node->method('get')->willReturn('abc');
$node->method('getSize')->willReturn(5);

$stream = AssemblyStream::wrap([$node]);

$this->expectException(\Exception::class);
$this->expectExceptionMessage('Stream from assembly node shorter than expected');
stream_get_contents($stream);
}

public function testTellAndStatReportStreamPositionAndSize(): void {
$stream = AssemblyStream::wrap([
$this->buildNode('0', 'abc'),
$this->buildNode('1', 'def'),
]);

$this->assertSame(0, ftell($stream));
$this->assertSame(6, fstat($stream)['size']);
$this->assertSame('ab', fread($stream, 2));
$this->assertSame(2, ftell($stream));
}

public static function providesNodes(): array {
$data8k = self::makeData(8192);
$dataLess8k = self::makeData(8191);
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