a1c965da1e
Sixty-five headers sat side by side in include/, so `#include "irq.h"` said nothing about where irq.h was or what it belonged to, and errno.h, stat.h and fcntl.h at the top shadowed the system's for any host tool built with -I./include. They are in folders now -- arch/ core/ fs/ dev/ gfx/ net/ uapi/ (and ldls/ for the Linux driver layer) -- and every include names the folder, as Linux's do: "core/proc.h". Done mechanically and checked the hard way: the kernel built from this tree disassembles identically to the one built from the tree before it. The full image boots, and userland is the same set of programs. Paths in docs and comments follow; docs/guides/layout.md has a table of what is where, and tools/fix-includes.py rewrites old-style includes from the folders in the tree, for code written before this. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01S1giNvrHTrPMPw7V6x1kQ4
59 lines
1.5 KiB
C
59 lines
1.5 KiB
C
// reflink -- copy a file by sharing its blocks instead of duplicating them.
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//
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// reflink <src> <dst>
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//
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// The copy is instant and free whatever the file's size: only metadata is
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// written. Both files are ordinary and writable afterwards; the first write to
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// either copies just the run it touches. `df` before and after is the check
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// that it really shared rather than quietly copying.
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//
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// Uses FICLONE, which is Linux's ioctl for exactly this, so the same call works
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// against any filesystem that supports cloning.
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#include "core/types.h"
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#include "uapi/user.h"
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#include "uapi/fcntl.h"
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#define FICLONE 0x40049409
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static void
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puts_(const char *s)
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{
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int n = 0;
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while (s[n]) n++;
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write(2, (void *)s, n);
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}
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int
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main(int argc, char *argv[])
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{
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if (argc != 3) {
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puts_("usage: reflink <src> <dst>\n");
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exit();
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}
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int src = open(argv[1], O_RDONLY);
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if (src < 0) {
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puts_("reflink: cannot open "); puts_(argv[1]); puts_("\n");
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exit();
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}
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// O_TRUNC matters: FICLONE replaces the destination's contents entirely,
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// and creating it non-empty would leave blocks to release mid-clone.
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int dst = open(argv[2], O_CREATE | O_WRONLY | O_TRUNC);
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if (dst < 0) {
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puts_("reflink: cannot create "); puts_(argv[2]); puts_("\n");
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close(src);
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exit();
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}
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if (ioctl(dst, FICLONE, (void *)(long)src) < 0) {
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puts_("reflink: FICLONE failed\n");
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close(src); close(dst);
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exit();
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}
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close(src);
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close(dst);
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exit();
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}
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