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alexcrichton opened this issue Nov 11, 2013 · 3 comments · Fixed by #12204
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Seek needs finalization of its API #10432

alexcrichton opened this issue Nov 11, 2013 · 3 comments · Fixed by #12204
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1.0

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@alexcrichton
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There is currently an XXX on the seek trait asking a question about what to do about seeks out of bounds of the current file. Additionally, this leads to the fail!()-ing implementations of Seek on MemReader, BufReader, and BufWriter. MemWriter currently has an implementation that fills with 0s when you seek beyond the end and then perform a write.

In my opinion, the semantics should be defined as:

  • If you seek to a negative offset, return an error immediately (from the call to seek).
  • If you seek within "the file", we're all good
  • If you seek beyond the end of "the file", then it's a valid operation and it's left up to the implementation to decide what to do afterwards. For example, a writer may decide to fill the intermediate gap with 0s. On the other hand, a reader would return an EndOfFile error on the next read (etc.).

This behavior follows what lseek + read + write appear to do. Regardless, we need to decide on this for 1.0. Nominating.
@alexcrichton
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Additionally, tell can fail right now, but it would be super awesome if it didn't have to. Do we actually prevent all of the error cases?

@pnkfelix
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Accepted for P-backcompat-libs

@emberian
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Someone in IRC also pointed out that seek/tell should be split into their own traits, with Seek probably inheriting from Tell. I don't remember the exact argument.

@alexcrichton alexcrichton mentioned this issue Feb 12, 2014
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bors added a commit that referenced this issue Feb 12, 2014
@bors
auto merge of #12204 : alexcrichton/rust/seek, r=pcwalton
1d5c52d 
This adopts the rules posted in #10432:

1. If a seek position is negative, then an error is generated
2. Seeks beyond the end-of-file are allowed. Future writes will fill the gap
   with data and future reads will return errors.
3. Seeks within the bounds of a file are fine.

Closes #10432
bors added a commit to rust-lang-ci/rust that referenced this issue Jul 25, 2022
@bors
Auto merge of rust-lang#12063 - iDawer:ide.signature_help, r=Veykril
23e47e1 
fix: Fall back to parameter definitions on error types in signature help

Fixes  rust-lang#10432
flip1995 pushed a commit to flip1995/rust that referenced this issue May 5, 2023
@bors
Auto merge of rust-lang#10432 - samueltardieu:issue-10430, r=Manishearth
7a870ae 
New lint: detect `if` expressions with simple boolean assignments to the same target

Closes rust-lang#10430

changelog: [`needless_bool_assign`] new lint to detect simple boolean assignment to the same target in `if` branches
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Finalize the Seek API alexcrichton/rust
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@alexcrichton @pnkfelix @emberian