fix: handle negative offset in sysread tied READ method#388
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fix: handle negative offset in sysread tied READ method#388Koan-Bot wants to merge 1 commit intocpan-authors:mainfrom
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The READ method did not normalize negative offsets before using them, unlike the WRITE method which converts negative offsets to positive and validates bounds. When sysread was called with a negative offset exceeding the buffer length (e.g., sysread($fh, $buf, 10, -100) on a 2-byte buffer), Perl's substr would die instead of producing the proper "Offset outside string" warning with EINVAL. Now matches WRITE behavior: negative offsets are converted to positive (offset = buf_len + offset), and out-of-bounds negatives get a clean warning + EINVAL return. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
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What
Handle negative offsets in the tied
READmethod, matching the existingWRITEbehavior.Why
sysread($fh, $buf, $len, -N)with a negative offset exceeding the buffer length would crash with Perl's substr error instead of producing the proper "Offset outside string" warning withEINVAL— unlikesyswritewhich already handled this correctly.How
Normalize negative offsets to positive (like WRITE already does):
offset = buf_len + offset. If still negative after normalization, warn and returnundefwithEINVAL.Testing
3 new test subtests in
t/sysreadwrite_edge_cases.t:All existing sysread/syswrite tests continue to pass.
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