6f3175d8a5
There were none: fcntl answered F_SETLK with EINVAL and flock was not a system call. Alpine's apk, which runs unmodified on SchOS through Alpine's own musl, locks its database before reading it and stopped there. kernel/fs/lock.c keeps one table of advisory locks keyed by (dev, inum): flock() for the whole file, owned by the open file description; F_SETLK/F_SETLKW/F_GETLK for byte ranges, owned by the process and released when it closes any descriptor on the file or exits; and the F_OFD_* forms, ranges owned by the description. flock and record locks do not see each other, as on Linux. Waiters sleep until any release and are interrupted by a signal. cmd/locktest checks each between a parent and a child, including range splitting, F_GETLK's report, and a blocked waiter being woken. shell.nix gains pkg-config, meson, ninja, m4, bison, flex and xz, for the X ports. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01S1giNvrHTrPMPw7V6x1kQ4
50 lines
2.1 KiB
C
50 lines
2.1 KiB
C
#pragma once
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// open(2) flags.
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//
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// These are the *Linux x86-64* values, and they have to be: every program in
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// the userland is built against a libc that sends Linux flag values, and the
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// kernel reads them with these constants. They disagreed for a long time, with
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// results that looked like filesystem corruption rather than like a mistake --
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// Linux O_APPEND (0x400) landed on SchOS's O_TRUNC, so `cmd >> file`
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// truncated the file it was meant to extend, and Linux O_TRUNC (0x200) landed
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// on O_CREATE, so `cmd > file` left whatever was past the new end in place.
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// Neither failure pointed anywhere near a header.
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//
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// Do not tidy these into a neat sequence. They are an external interface.
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#define O_RDONLY 0x000000
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#define O_WRONLY 0x000001
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#define O_RDWR 0x000002
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#define O_ACCMODE 0x000003
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#define O_CREATE 0x000040 /* Linux O_CREAT (0100) */
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#define O_CREAT O_CREATE /* the spelling every program uses */
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#define O_EXCL 0x000080 /* Linux O_EXCL (0200) */
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#define O_NOCTTY 0x000100 /* Linux O_NOCTTY (0400) */
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#define O_TRUNC 0x000200 /* Linux O_TRUNC (01000) */
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#define O_APPEND 0x000400 /* Linux O_APPEND (02000) */
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#define O_NONBLOCK 0x000800 /* Linux O_NONBLOCK (04000); no-op here */
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#define O_DIRECTORY 0x010000 /* Linux O_DIRECTORY (0200000) */
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#define O_NOFOLLOW 0x020000 /* Linux O_NOFOLLOW (0400000) */
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#define O_CLOEXEC 0x080000 /* Linux O_CLOEXEC (02000000) */
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// SchOS-only, placed above every flag Linux defines so it can never be
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// mistaken for one. 0x40000 was used before and collides with Linux O_NOATIME.
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#define O_EXTENT 0x8000000 /* sparse-extent hint */
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#define F_DUPFD 0
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#define F_GETFD 1
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#define F_SETFD 2
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#define F_GETFL 3
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#define F_SETFL 4
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#define F_DUPFD_CLOEXEC 1030 // Linux value
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// Record locks; see kernel/fs/lock.c.
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#define F_GETLK 5
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#define F_SETLK 6
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#define F_SETLKW 7
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#define F_OFD_GETLK 36
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#define F_OFD_SETLK 37
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#define F_OFD_SETLKW 38
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#define FD_CLOEXEC 1
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