mirror of
https://github.com/jart/cosmopolitan.git
synced 2025-01-31 19:43:32 +00:00
3f0bcdc3ef
- Exhaustively document cancellation points - Rename SIGCANCEL to SIGTHR just like BSDs - Further improve POSIX thread cancellations - Ensure asynchronous cancellations work correctly - Elevate the quality of getrandom() and getentropy() - Make futexes cancel correctly on OpenBSD 6.x and 7.x - Add reboot.com and shutdown.com to examples directory - Remove underscore prefix from awesome timespec_*() APIs - Create assertions that help verify our cancellation points - Remove bad timespec APIs (cmp generalizes eq/ne/gt/gte/lt/lte)
115 lines
4.5 KiB
C
115 lines
4.5 KiB
C
/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
|
|
│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi│
|
|
╞══════════════════════════════════════════════════════════════════════════════╡
|
|
│ Copyright 2020 Justine Alexandra Roberts Tunney │
|
|
│ │
|
|
│ Permission to use, copy, modify, and/or distribute this software for │
|
|
│ any purpose with or without fee is hereby granted, provided that the │
|
|
│ above copyright notice and this permission notice appear in all copies. │
|
|
│ │
|
|
│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL │
|
|
│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED │
|
|
│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE │
|
|
│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL │
|
|
│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR │
|
|
│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER │
|
|
│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR │
|
|
│ PERFORMANCE OF THIS SOFTWARE. │
|
|
╚─────────────────────────────────────────────────────────────────────────────*/
|
|
#include "libc/calls/calls.h"
|
|
#include "libc/dce.h"
|
|
#include "libc/errno.h"
|
|
#include "libc/runtime/runtime.h"
|
|
#include "libc/stdio/rand.h"
|
|
#include "libc/stdio/temp.h"
|
|
#include "libc/str/str.h"
|
|
#include "libc/sysv/consts/o.h"
|
|
|
|
#define _O_TMPFILE 000020200000
|
|
|
|
/**
|
|
* Returns file descriptor of open anonymous file, e.g.
|
|
*
|
|
* int fd;
|
|
* if ((fd = tmpfd()) == -1) {
|
|
* perror("tmpfd");
|
|
* exit(1);
|
|
* }
|
|
* // do stuff
|
|
* close(f);
|
|
*
|
|
* This creates a secure temporary file inside $TMPDIR. If it isn't
|
|
* defined, then /tmp is used on UNIX and GetTempPath() is used on the
|
|
* New Technology. This resolution of $TMPDIR happens once in a ctor,
|
|
* which is copied to the `kTmpDir` global.
|
|
*
|
|
* Once close() is called, the returned file is guaranteed to be deleted
|
|
* automatically. On UNIX the file is unlink()'d before this function
|
|
* returns. On the New Technology it happens upon close().
|
|
*
|
|
* On newer Linux only (c. 2013) it's possible to turn the anonymous
|
|
* returned file back into a real file, by doing this:
|
|
*
|
|
* linkat(AT_FDCWD, _gc(xasprintf("/proc/self/fd/%d", fd)),
|
|
* AT_FDCWD, "real.txt", AT_SYMLINK_FOLLOW)
|
|
*
|
|
* On the New Technology, temporary files created by this function
|
|
* should have better performance, because `kNtFileAttributeTemporary`
|
|
* asks the kernel to more aggressively cache and reduce i/o ops.
|
|
*
|
|
* The tmpfd() function should be favored over `open(O_TMPFILE)` because
|
|
* the latter only works on Linux, and will cause open() failures on all
|
|
* other platforms.
|
|
*
|
|
* @return file descriptor on success, or -1 w/ errno
|
|
* @raise ECANCELED if thread was cancelled in masked mode
|
|
* @raise EINTR if signal was delivered
|
|
* @see tmpfile() for stdio version
|
|
* @cancellationpoint
|
|
* @asyncsignalsafe
|
|
* @threadsafe
|
|
* @vforksafe
|
|
*/
|
|
int tmpfd(void) {
|
|
FILE *f;
|
|
unsigned x;
|
|
int fd, i, j, e;
|
|
char path[PATH_MAX], *p;
|
|
e = errno;
|
|
if (IsLinux() && (fd = open(kTmpPath, O_RDWR | _O_TMPFILE, 0600)) != -1) {
|
|
return fd;
|
|
}
|
|
errno = e;
|
|
p = path;
|
|
p = stpcpy(p, kTmpPath);
|
|
p = stpcpy(p, "tmp.");
|
|
if (program_invocation_short_name &&
|
|
strlen(program_invocation_short_name) < 128) {
|
|
p = stpcpy(p, program_invocation_short_name);
|
|
*p++ = '.';
|
|
}
|
|
for (i = 0; i < 10; ++i) {
|
|
x = _rand64();
|
|
for (j = 0; j < 6; ++j) {
|
|
p[j] = "0123456789abcdefghijklmnopqrstuvwxyz"[x % 36];
|
|
x /= 36;
|
|
}
|
|
p[j] = 0;
|
|
e = errno;
|
|
if ((fd = open(path,
|
|
O_RDWR | O_CREAT | O_EXCL | (IsWindows() ? _O_TMPFILE : 0),
|
|
0600)) != -1) {
|
|
if (!IsWindows()) {
|
|
if (unlink(path)) {
|
|
notpossible;
|
|
}
|
|
}
|
|
return fd;
|
|
} else if (errno == EEXIST) {
|
|
errno = e;
|
|
} else {
|
|
break;
|
|
}
|
|
}
|
|
return -1;
|
|
}
|