Protect against stray EOFs #44
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Unfortunately: 1. Read can read bytes and return an EOF at the same time (could cause us to fail to parse something that's actually correct). 2. ReadByte is not allowed to do this (fixed in PeekByte). 3. Returning EOF on _actual_ error cases can cause the error to be silently dropped somewhere up the stack (where the EOF may be interpreted as "I'm done"). I've replaced EOF with ErrUnexpectedEOF where appropriate. This crap really shouldn't be necessary, but such is life.
ZenGround0
approved these changes
Mar 3, 2021
| @@ -74,6 +76,10 @@ func ScanForLinks(br io.Reader, cb func(cid.Cid)) error { | |||
| } | |||
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Without knowing this code it is hard to know which functions are safe from returning io.EOFs, for example CborReadHeaderBuf above does not check for EOFs but from the names and arguments it seems like it could return them. I don't know if this is actually what we should do but here and in discard it would help me be more sure EOF handling is correct if we did error escalation in a defer statement.
MarcoPolo
reviewed
Feb 10, 2022
| @@ -172,7 +174,7 @@ func (d *Deferred) UnmarshalCBOR(br io.Reader) error { | |||
| // Copy the bytes | |||
| limitedReader.N = int64(extra) | |||
| buf.Grow(int(extra)) | |||
| if n, err := buf.ReadFrom(&limitedReader); err != nil { | |||
| if n, err := buf.ReadFrom(&limitedReader); err != nil && err != io.EOF { | |||
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buf.ReadFrom doesn't return io.EOF: https://pkg.go.dev/bytes@go1.17.6#Buffer.ReadFrom
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Unfortunately:
This crap really shouldn't be necessary, but such is life.