Convert struct FromBytesWithNulError into enum
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tgross35
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@tgross35 I thought this proposal has already passed - see rust-lang/libs-team#493 |
## Description One of `CStr` constructors, `CStr::from_bytes_with_nul(bytes: &[u8])` handles 3 cases: 1. `bytes` has one NULL as the last value - creates CStr 2. `bytes` has no NULL - error 3. `bytes` has a NULL in some other position - error The 3rd case is error that may require lossy conversion, but the 2nd case can easily be handled by the user code. Unfortunately, this function returns an opaque `FromBytesWithNulError` error in both 2nd and 3rd case, so the user cannot detect just the 2nd case - having to re-implement the entire function and bring in the `memchr` dependency. ## Motivating examples or use cases In [this code](https://github.com/gquintard/varnish-rs/blob/f86d7a87683b08d2e634d63e77d9dc1d24ed4a13/varnish-sys/src/vcl/ws.rs#L158), my FFI code needs to copy user's `&[u8]` into a C-allocated memory blob in a NUL-terminated `CStr` format. My code must first validate if `&[u8]` has a trailing NUL (case 1), no NUL (adds one on the fly - case 2), or NUL in the middle (3rd case - error). I had to re-implement `from_bytes_with_nul` and add `memchr`dependency just to handle the 2nd case. ## Solution This PR renames the former `kind` enum from `FromBytesWithNulErrorKind` to `FromBytesWithNulError`, and removes the original struct.
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This PR renames the former
kindenum fromFromBytesWithNulErrorKindtoFromBytesWithNulError, and removes the original struct.See rust-lang/libs-team#493
Possible Changes - TBD
enum FromBytesWithNulErrorderiveCopy?Problem
One of
CStrconstructors,CStr::from_bytes_with_nul(bytes: &[u8])handles 3 cases:byteshas one NULL as the last value - creates CStrbyteshas no NULL - errorbyteshas a NULL in some other position - errorThe 3rd case is error that may require lossy conversion, but the 2nd case can easily be handled by the user code. Unfortunately, this function returns an opaque
FromBytesWithNulErrorerror in both 2nd and 3rd case, so the user cannot detect just the 2nd case - having to re-implement the entire function and bring in thememchrdependency.Motivating examples or use cases
In this code, my FFI code needs to copy user's
&[u8]into a C-allocated memory blob in a NUL-terminatedCStrformat. My code must first validate if&[u8]has a trailing NUL (case 1), no NUL (adds one on the fly - case 2), or NUL in the middle (3rd case - error). I had to re-implementfrom_bytes_with_nuland addmemchrdependency just to handle the 2nd case.r? @Amanieu