# Reader.peekDelimiterInclusive: Fix handling of \`stream\` implementations that return 0 · gitcafe/zig

[View on GitCafe](https://git.cafe/gitcafe/zig/commit/acd6ffdf69332d61b51f64f4707b472c147b7034)

Repository: [gitcafe/zig](https://git.cafe/gitcafe/zig)

Visibility: public

Requested revision: acd6ffdf69332d61b51f64f4707b472c147b7034

Requested commit: acd6ffdf69332d61b51f64f4707b472c147b7034

Commit: acd6ffdf69332d61b51f64f4707b472c147b7034

Tree: f7a797f21a4d70962014bbf7b6669a9178e4a626

Author: Ryan Liptak

Committer: Andrew Kelley

## Message

```
Reader.peekDelimiterInclusive: Fix handling of `stream` implementations that return 0

Previously, the logic in peekDelimiterInclusive (when the delimiter was not found in the existing buffer) used the `n` returned from `r.vtable.stream` as the length of the slice to check, but it's valid for `vtable.stream` implementations to return 0 if they wrote to the buffer instead of `w`. In that scenario, the `indexOfScalarPos` would be given a 0-length slice so it would never be able to find the delimiter.

This commit changes the logic to assume that `r.vtable.stream` can both:
- return 0, and
- modify seek/end (i.e. it's also valid for a `vtable.stream` implementation to rebase)

Also introduces `std.testing.ReaderIndirect` which helps in being able to test against Reader implementations that return 0 from `stream`/`readVec`

Fixes #25428

```

## Parents

- [ff16a7c3fa29c95edefc8496114d577b4037fe6f](https://git.cafe/gitcafe/zig/commit/ff16a7c3fa29c95edefc8496114d577b4037fe6f?format=markdown)

[Source at this commit](https://git.cafe/gitcafe/zig/tree/acd6ffdf69332d61b51f64f4707b472c147b7034?format=markdown)