Fix: IO::FileDescriptor#seek from current position #4558
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RX14
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Jun 13, 2017
src/io/file_descriptor.cr
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| seek_value = LibC.lseek(@fd, offset, whence) | ||
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| if whence.current? | ||
| seek_value = LibC.lseek(@fd, tell + offset, Seek::Set) |
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Would it not be acceptable simply to remove @in_buffer_rem.size from the offset here and not use Seek::Set?
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I guess. It would avoid a second lseek call.
Trying to seek from the current position failed because the system position of a buffered IO is different from the actual position in the stream.
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@ysbaddaden Good catch, thanks! |
mverzilli
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Trying to seek from the current position failed because the system position of a buffered IO is different from the actual position in Crystal land. For example reading 4 bytes from a File actually reads up to BUFFER_SIZE bytes. Seeking back 4 bytes should return to position
0, but since the system read more bytes, it ended up at an unexpected place.