mirror of
https://github.com/jart/cosmopolitan.git
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94 lines
4.3 KiB
C
94 lines
4.3 KiB
C
/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
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│ vi: set et ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi │
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╞══════════════════════════════════════════════════════════════════════════════╡
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│ Copyright 2020 Justine Alexandra Roberts Tunney │
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│ │
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│ Permission to use, copy, modify, and/or distribute this software for │
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│ any purpose with or without fee is hereby granted, provided that the │
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│ above copyright notice and this permission notice appear in all copies. │
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│ │
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│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL │
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│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED │
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│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE │
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│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL │
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│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR │
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│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER │
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│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR │
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│ PERFORMANCE OF THIS SOFTWARE. │
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╚─────────────────────────────────────────────────────────────────────────────*/
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#include "libc/calls/calls.h"
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#include "libc/calls/internal.h"
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#include "libc/calls/syscall-sysv.internal.h"
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#include "libc/cosmo.h"
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#include "libc/dce.h"
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#include "libc/errno.h"
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#include "libc/fmt/itoa.h"
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#include "libc/intrin/describeflags.h"
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#include "libc/intrin/strace.h"
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#include "libc/mem/alloca.h"
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#include "libc/str/str.h"
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#include "libc/sysv/errfuns.h"
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static struct Splice {
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_Atomic(uint32_t) once;
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bool ok;
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} g_splice;
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static bool HasSplice(void) {
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int e;
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bool ok;
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e = errno;
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if (IsLinux()) {
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// Our testing indicates splice() doesn't work as documneted on
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// RHEL5 and RHEL7 so let's require a modern kernel to be safe.
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// We choose close_range() for this since it's listed by pledge
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ok = sys_close_range(-1, -2, 0) == -1 && errno == EINVAL;
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} else {
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ok = false;
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}
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errno = e;
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return ok;
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}
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static void splice_init(void) {
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g_splice.ok = HasSplice();
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}
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/**
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* Transfers data to/from pipe.
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*
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* @param flags can have SPLICE_F_{MOVE,NONBLOCK,MORE,GIFT}
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* @param opt_in_out_inoffset may be specified if `infd` isn't a pipe and is
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* used as both an input and output parameter for pread() behavior
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* @param opt_in_out_outoffset may be specified if `outfd` isn't a pipe and is
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* used as both an input and output parameter for pwrite() behavior
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* @return number of bytes transferred, 0 on input end, or -1 w/ errno
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* @raise EBADF if `infd` or `outfd` aren't open files or append-only
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* @raise ENOTSUP if `infd` or `outfd` is a zip file descriptor
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* @raise ESPIPE if an offset arg was specified for a pipe fd
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* @raise EINVAL if offset was given for non-seekable device
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* @raise EINVAL if file system doesn't support splice()
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* @raise EFAULT if one of the pointers memory is bad
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* @raise EINVAL if `flags` is invalid
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* @raise ENOSYS if not Linux 5.9+
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* @see copy_file_range() for file ↔ file
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* @see sendfile() for seekable → socket
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*/
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ssize_t splice(int infd, int64_t *opt_in_out_inoffset, int outfd,
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int64_t *opt_in_out_outoffset, size_t uptobytes,
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uint32_t flags) {
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ssize_t rc;
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cosmo_once(&g_splice.once, splice_init);
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if (!g_splice.ok) {
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rc = enosys();
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} else if (__isfdkind(infd, kFdZip) || __isfdkind(outfd, kFdZip)) {
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rc = enotsup();
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} else {
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rc = sys_splice(infd, opt_in_out_inoffset, outfd, opt_in_out_outoffset,
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uptobytes, flags);
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}
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STRACE("splice(%d, %s, %d, %s, %'zu, %#x) → %'ld% m", infd,
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DescribeInOutInt64(rc, opt_in_out_inoffset), outfd,
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DescribeInOutInt64(rc, opt_in_out_outoffset), uptobytes, flags);
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return rc;
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}
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