Add EINTR handling for std.stdio and std.process#11007
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thewilsonator merged 4 commits intodlang:masterfrom May 6, 2026
Merged
Add EINTR handling for std.stdio and std.process#11007thewilsonator merged 4 commits intodlang:masterfrom
thewilsonator merged 4 commits intodlang:masterfrom
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Introduces a new package(std) module providing two composable retry primitives for interrupted system calls: - retryOnEINTR: loops while a one-shot syscall returns an error sentinel and errno == EINTR; propagates the final result to the caller. - retryShortIO: drives a partial-progress I/O loop (à la fwrite/posix.write) until all bytes are transferred or a non-transient error occurs; accepts an optional onEINTR hook (clearerr discipline for stdio call sites). Replaces the nested retryInterrupted template in std.process and provides the primitive for fixing std.stdio's EINTR-prone write paths. Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
The byte-array fast path of LockingTextWriter.put throws ErrnoException when fwrite reports a short write, matching the writer's documented contract. The per-character fall-through path discarded the return values of fputc/fputwc, so write errors (closed/broken pipe, full disk, EBADF, etc.) corrupted output silently. Wrap the underlying calls in putcChecked / putwcChecked so the per-character path raises the same ErrnoException as the byte-array path. Demonstrated by the new /dev/full test. dlang#11005
…rites A signal whose handler does not carry SA_RESTART can interrupt fwrite(3) mid-write, causing it to return a short count with errno == EINTR and the stream's error indicator set. Three write paths in std.stdio treated this as fatal: LockingTextWriter.put (byte-array fast path and per-character paths), File.rawWrite, and BinaryWriterImpl.rawWrite. Programs would crash on the next writeln after a signal landed mid-flush. Wrap the underlying fwrite/fputc/fputwc calls in std.internal.retry's retryShortIO and retryOnEINTR so EINTR is transparently retried until the buffer is fully written or a non-transient error occurs. dlang#11006
Removes the local nested retryInterrupted template in spawnProcessPosix and switches its three call sites to the shared retryOnEINTR helper. Pure refactor — semantics are identical.
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ping when this is no longer draft
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@thewilsonator Thanks, was waiting for CI. Ready for review. |
thewilsonator
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May 6, 2026
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Fixes #11006. As a bonus, also fixes #11005 (bug was noticed during implementation).