* fix: report short S3 ReaderAt reads
Problem: S3BackendStorageFile.ReadAt returned a short buffer with a nil error, hiding truncated remote data.
Root cause: Every terminal io.EOF was cleared regardless of how many bytes were read.
Fix: Clear io.EOF only when the requested buffer was completely filled.
Validation: go test ./weed/storage/backend/...
Co-authored-by: Codex <noreply@openai.com>
* fix: validate S3 ReaderAt requests
Co-authored-by: Codex <noreply@openai.com>
* s3 ReadAt: simplify negative offset error
* s3 ReadAt: stop reading once the buffer is full
Skips the extra Read that only collected the terminal EOF, and bounds
the loop if the server ignores the Range header and returns more data
than requested, where Read on an empty slice can spin forever.
* s3 ReadAt: cover full reads that arrive with io.EOF
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Co-authored-by: Codex <noreply@openai.com>
Co-authored-by: Chris Lu <chris.lu@gmail.com>
