mirror of
https://github.com/jart/cosmopolitan.git
synced 2024-05-13 09:02:41 +00:00
a4b455185b
Renaming gc() to _gc() was a mistake since the better thing to do is put it behind the _COSMO_SOURCE macro. We need this change because I haven't wanted to use my amazing garbage collector ever since we renamed it. You now need to define _COSMO_SOURCE yourself when using amalgamation header and cosmocc users need to pass the -mcosmo flag to get the gc() function Some other issues relating to cancelation have been fixed along the way. We're also now putting cosmocc in a folder named `.cosmocc` so it can be more safely excluded by grep --exclude-dir=.cosmocc --exclude-dir=o etc.
76 lines
3.5 KiB
C
76 lines
3.5 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/stdio/stdio.h"
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#include "libc/temp.h"
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/**
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* Opens stream backed by anonymous file, e.g.
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*
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* FILE *f;
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* if (!(f = tmpfile())) {
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* perror("tmpfile");
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* exit(1);
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* }
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* // do stuff
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* fclose(f);
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*
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* This creates a secure temporary file inside $TMPDIR. If it isn't
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* defined, then /tmp is used on UNIX and GetTempPath() is used on the
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* New Technology. This resolution of $TMPDIR happens once in a ctor.
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*
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* Once fclose() is called, the returned file is guaranteed to be
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* deleted automatically. On UNIX the file is unlink()'d before this
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* function returns. On the New Technology it happens upon fclose().
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*
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* On newer Linux only (c. 2013) it's possible to turn the anonymous
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* returned file back into a real file, by doing this:
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*
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* linkat(AT_FDCWD, gc(xasprintf("/proc/self/fd/%d", fileno(f))),
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* AT_FDCWD, "real.txt", AT_SYMLINK_FOLLOW)
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*
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* On the New Technology, temporary files created by this function
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* should have better performance, because `kNtFileAttributeTemporary`
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* asks the kernel to more aggressively cache and reduce i/o ops.
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*
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* Favor tmpfd() or tmpfile() over `open(O_TMPFILE)` because the latter
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* is Linux-only and will cause open() failures on all other platforms.
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*
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* @see tmpfd() if you don't want to link stdio/malloc
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* @raise ECANCELED if thread was cancelled in masked mode
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* @raise EINTR if signal was delivered
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* @cancelationpoint
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* @asyncsignalsafe
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* @vforksafe
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*/
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FILE *tmpfile(void) {
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int fd;
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FILE *f;
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if ((fd = tmpfd()) != -1) {
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if ((f = fdopen(fd, "w+"))) {
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return f;
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} else {
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close(fd);
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return 0;
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}
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} else {
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return 0;
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}
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}
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