pfelf: fix and optimize mmapped section reading#526
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fabled merged 2 commits intoopen-telemetry:mainfrom Jun 16, 2025
Merged
pfelf: fix and optimize mmapped section reading#526fabled merged 2 commits intoopen-telemetry:mainfrom
fabled merged 2 commits intoopen-telemetry:mainfrom
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The Section reader elfReader was assigned the SectionReader, not the backing pfelf.File's elfReader. This caused the dynamic cast to mmap.ReaderAt always fail in Section.Data(). Fix the assignment to pass the backing elfReader, for the cast to work correctly. And while at it, remove the SectionReader as it causes GC pressure and implement the ReadAt() function on the struct directly. This also fixes the Section to implement io.ReaderAt itnerface which commit 9788d39 accidentally removed by removing the embedded io.ReaderAt interface. Add also interace contract tests in the file.
florianl
approved these changes
Jun 13, 2025
rockdaboot
approved these changes
Jun 13, 2025
christos68k
approved these changes
Jun 13, 2025
| return 0, io.EOF | ||
| } | ||
| if uint64(off)+uint64(len(p)) > sh.FileSize { | ||
| p = p[:sh.FileSize-uint64(off)] |
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Should we explicitly also return EOF here? The following ReadAt will not do that for this case (as it doesn't know anything about sh.FileSize).
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Yes. Per io.ReaderAt contract an error needs to be returned if read is short. I've added this.
This was referenced Jul 8, 2025
This was referenced Aug 14, 2025
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The Section reader elfReader was assigned the SectionReader, not the backing pfelf.File's elfReader. This caused the dynamic cast to mmap.ReaderAt always fail in Section.Data().
Fix the assignment to pass the backing elfReader, for the cast to work correctly. And while at it, remove the SectionReader as it causes GC pressure and implement the ReadAt() function on the struct directly. This also fixes the Section to implement io.ReaderAt itnerface which commit 9788d39 accidentally removed by removing the embedded io.ReaderAt interface. Add also interace contract tests in the file.