mirrors/cosmopolitan
1
0
Fork 0
mirror of https://github.com/jart/cosmopolitan.git synced 2025-02-07 06:53:33 +00:00
Code Issues Projects Releases Packages Wiki Activity Actions

Fix some bugs

Browse source
This commit is contained in:
Justine Tunney 2022-08-14 13:28:07 -07:00
parent 5584f6adcf
commit 6c0bbfac4a
15 changed files with 289 additions and 136 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

1
libc/calls/calls.h
View file

@ -184,6 +184,7 @@ int sys_ptrace(int, ...);
int sysctl(const int *, unsigned, void *, size_t *, void *, size_t);
int tgkill(int, int, int);
int tkill(int, int);
int tmpfd(void);
int touch(const char *, uint32_t);
int truncate(const char *, uint64_t);
int ttyname_r(int, char *, size_t);

9
libc/calls/pledge-linux.c
View file

@ -1939,12 +1939,9 @@ privileged int sys_pledge_linux(unsigned long ipromises, int mode) {
} else {
// non-trapping mode
//
// 1. our sigsys error message handler can't be inherited across
// execve() boundaries so if you've pledged exec then that'll
// mean no error messages for you.
//
// 2. we do not trap pledge("", 0) because that would go against
// its documented purpose of only permitted exit().
// our sigsys error message handler can't be inherited across
// execve() boundaries so if you've pledged exec then that'll
// likely cause a SIGSYS in your child after the exec happens
switch (mode & PLEDGE_PENALTY_MASK) {
case PLEDGE_PENALTY_KILL_THREAD:
sf[0].k = SECCOMP_RET_KILL_THREAD;

0
libc/runtime/program_invocation_short_name.S → libc/calls/program_invocation_short_name.S
View file

113
libc/calls/tmpfd.c Normal file
View file

@ -0,0 +1,113 @@
/*-*- 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
* @see tmpfile() for stdio version
* @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)) {
asm("hlt");
unreachable;
}
}
return fd;
} else if (errno == EEXIST) {
errno = e;
} else {
break;
}
}
return -1;
}

4
libc/intrin/kopenflags.S
View file

@ -40,10 +40,10 @@ kOpenFlags:
.e O_TRUNC,"TRUNC" //
.e O_CLOEXEC,"CLOEXEC" //
.e O_NONBLOCK,"NONBLOCK" //
.e O_DIRECTORY,"DIRECTORY" //
.e O_TMPFILE,"TMPFILE" // linux, windows
.e O_DIRECTORY,"DIRECTORY" // order matters
.e O_DIRECT,"DIRECT" // no-op on xnu/openbsd
.e O_APPEND,"APPEND" // weird on nt
.e O_TMPFILE,"TMPFILE" // linux, windows
.e O_NOFOLLOW,"NOFOLLOW" // unix
.e O_SYNC,"SYNC" // unix
.e O_ASYNC,"ASYNC" // unix

81
libc/stdio/tmpfile.c
View file

@ -17,59 +17,58 @@
│ PERFORMANCE OF THIS SOFTWARE. │
╚─────────────────────────────────────────────────────────────────────────────*/
#include "libc/calls/calls.h"
#include "libc/errno.h"
#include "libc/stdio/rand.h"
#include "libc/runtime/runtime.h"
#include "libc/stdio/stdio.h"
#include "libc/stdio/temp.h"
#include "libc/str/str.h"
#include "libc/sysv/consts/o.h"
/**
* Opens stream backed by anonymous file.
* Opens stream backed by anonymous file, e.g.
*
* We use $TMPDIR or /tmp to create a temporary file securely, which
* will be unlink()'d before this function returns. The file content
* will be released from disk once fclose() is called.
* FILE *f;
* if (!(f = tmpfile())) {
* perror("tmpfile");
* exit(1);
* }
* // do stuff
* fclose(f);
*
* @see mkostempsm(), kTmpPath
* 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 fclose() 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 fclose().
*
* 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", fileno(f))),
* 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.
*
* Favor tmpfd() or tmpfile() over `open(O_TMPFILE)` because the latter
* is Linux-only and will cause open() failures on all other platforms.
*
* @see tmpfd() if you don't want to link stdio/malloc
* @asyncsignalsafe
* @threadsafe
* @vforksafe
*/
FILE *tmpfile(void) {
int fd;
FILE *f;
unsigned x;
int fd, i, j, e;
char path[PATH_MAX], *p;
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, 0600)) != -1) {
unlink(path);
if ((f = fdopen(fd, "w+"))) {
return f;
} else {
close(fd);
return 0;
}
} else if (errno == EEXIST) {
errno = e;
if ((fd = tmpfd()) != -1) {
if ((f = fdopen(fd, "w+"))) {
return f;
} else {
break;
close(fd);
return 0;
}
} else {
return 0;
}
return 0;
}

2
libc/sysv/consts.sh
View file

@ -196,7 +196,7 @@ syscon open O_SEQUENTIAL 0 0 0 0 0 0x40000000 # kNtFileFlagSequen
syscon open O_COMPRESSED 0 0 0 0 0 0x20000000 # kNtFileAttributeCompressed [SYNC libc/calls/open-nt.c]
syscon open O_INDEXED 0 0 0 0 0 0x10000000 # !kNtFileAttributeNotContentIndexed [SYNC libc/calls/open-nt.c]
syscon open O_CLOEXEC 0x00080000 0x01000000 0x00100000 0x00010000 0x00400000 0x00080000 # NT faked as Linux [SYNC libc/calls/open-nt.c]
syscon open O_TMPFILE 0x00410000 0 0 0 0 0x00410000 # Linux 3.11+ (c. 2013) __O_TMPFILE | O_DIRECTORY; kNtFileAttributeTemporary|kNtFileFlagDeleteOnClose [SYNC libc/calls/open-nt.c]
syscon open O_TMPFILE 0x00410000 0xffffffff 0xffffffff 0xffffffff 0xffffffff 0xffffffff # please use tmpfd(); Linux 3.11+ (c. 2013) __O_TMPFILE | O_DIRECTORY; kNtFileAttributeTemporary|kNtFileFlagDeleteOnClose [SYNC libc/calls/open-nt.c]
syscon open O_SPARSE 0 0 0 0 0 0 # wut
syscon open O_NONBLOCK 0x00000800 0x00000004 0x00000004 0x00000004 0x00000004 0x00000800 # bsd consensus
syscon open O_ASYNC 0x00002000 0x00000040 0x00000040 0x00000040 0x00000040 0 # bsd consensus

2
libc/sysv/consts/O_TMPFILE.S
View file

@ -1,2 +1,2 @@
#include "libc/sysv/consts/syscon.internal.h"
.syscon open,O_TMPFILE,0x00410000,0,0,0,0,0x00410000
.syscon open,O_TMPFILE,0x00410000,0xffffffff,0xffffffff,0xffffffff,0xffffffff,0xffffffff

67
test/libc/stdio/tmpfile_test.c
View file

@ -16,15 +16,78 @@
│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR │
│ PERFORMANCE OF THIS SOFTWARE. │
╚─────────────────────────────────────────────────────────────────────────────*/
#include "libc/calls/calls.h"
#include "libc/calls/struct/dirent.h"
#include "libc/calls/struct/stat.h"
#include "libc/calls/syscall_support-sysv.internal.h"
#include "libc/dce.h"
#include "libc/intrin/kprintf.h"
#include "libc/runtime/gc.internal.h"
#include "libc/runtime/runtime.h"
#include "libc/stdio/stdio.h"
#include "libc/stdio/temp.h"
#include "libc/str/str.h"
#include "libc/sysv/consts/at.h"
#include "libc/testlib/testlib.h"
#include "libc/x/x.h"
char testlib_enable_tmp_setup_teardown;
char oldtmpdir[PATH_MAX];
bool IsDirectoryEmpty(const char *path) {
DIR *d;
bool res = true;
struct dirent *e;
ASSERT_NE(NULL, (d = opendir(path)));
while ((e = readdir(d))) {
if (!strcmp(e->d_name, ".")) continue;
if (!strcmp(e->d_name, "..")) continue;
res = false;
}
closedir(d);
return res;
}
void SetUp(void) {
strcpy(oldtmpdir, kTmpPath);
strcpy(kTmpPath, ".");
}
void TearDown(void) {
strcpy(kTmpPath, oldtmpdir);
}
TEST(tmpfile, test) {
FILE *f = tmpfile();
FILE *f;
struct stat st;
EXPECT_TRUE(IsDirectoryEmpty(kTmpPath));
f = tmpfile();
if (IsWindows()) {
EXPECT_FALSE(IsDirectoryEmpty(kTmpPath));
} else {
EXPECT_TRUE(IsDirectoryEmpty(kTmpPath));
}
EXPECT_SYS(0, 0, fstat(fileno(f), &st));
EXPECT_NE(010600, st.st_mode);
EXPECT_NE(-1, fputc('t', f));
EXPECT_NE(-1, fflush(f));
rewind(f);
EXPECT_EQ('t', fgetc(f));
EXPECT_NE(-1, fclose(f));
EXPECT_EQ(0, fclose(f));
EXPECT_TRUE(IsDirectoryEmpty(kTmpPath));
}
TEST(tmpfile, renameToRealFile) {
if (!IsLinux() || !__is_linux_2_6_23()) return;
FILE *f;
f = tmpfile();
ASSERT_EQ(2, fputs("hi", f));
ASSERT_SYS(0, 0,
linkat(AT_FDCWD, gc(xasprintf("/proc/self/fd/%d", fileno(f))),
AT_FDCWD, "real", AT_SYMLINK_FOLLOW));
ASSERT_EQ(0, fclose(f));
ASSERT_NE(NULL, (f = fopen("real", "r")));
ASSERT_EQ('h', fgetc(f));
ASSERT_EQ('i', fgetc(f));
ASSERT_EQ(0, fclose(f));
}

10
third_party/dlmalloc/dlmalloc.c vendored
View file

@ -1,17 +1,17 @@
#include "libc/assert.h"
#include "libc/intrin/likely.h"
#include "libc/intrin/weaken.h"
#include "libc/calls/calls.h"
#include "libc/dce.h"
#include "libc/errno.h"
#include "libc/intrin/kprintf.h"
#include "libc/intrin/likely.h"
#include "libc/intrin/weaken.h"
#include "libc/macros.internal.h"
#include "libc/mem/mem.h"
#include "libc/nexgen32e/bsr.h"
#include "libc/nexgen32e/rdtsc.h"
#include "libc/stdio/rand.h"
#include "libc/runtime/runtime.h"
#include "libc/runtime/sysconf.h"
#include "libc/stdio/rand.h"
#include "libc/stdio/stdio.h"
#include "libc/str/str.h"
#include "libc/sysv/consts/map.h"
@ -342,8 +342,8 @@ static int sys_trim(mstate m, size_t pad) {
size_t newsize = sp->size - extra;
(void)newsize; /* placate people compiling -Wunused-variable */
/* Prefer mremap, fall back to munmap */
if ((CALL_MREMAP(sp->base, sp->size, newsize, 0) != MFAIL) ||
(CALL_MUNMAP(sp->base + newsize, extra) == 0)) {
if (CALL_MREMAP(sp->base, sp->size, newsize, 0) != MFAIL ||
(!extra || !CALL_MUNMAP(sp->base + newsize, extra))) {
released = extra;
}
}

9
third_party/lua/lunix.c vendored
View file

@ -948,6 +948,14 @@ static int LuaUnixOpen(lua_State *L) {
luaL_optinteger(L, 2, O_RDONLY), luaL_optinteger(L, 3, 0)));
}
// unix.tmpfd()
// ├─→ fd:int
// └─→ nil, unix.Errno
static int LuaUnixTmpfd(lua_State *L) {
int olderr = errno;
return SysretInteger(L, "tmpfd", olderr, tmpfd());
}
// unix.close(fd:int)
// ├─→ true
// └─→ nil, unix.Errno
@ -2640,6 +2648,7 @@ static const luaL_Reg kLuaUnix[] = {
{"sync", LuaUnixSync}, // flushes files and disks
{"syslog", LuaUnixSyslog}, // logs to system log
{"tiocgwinsz", LuaUnixTiocgwinsz}, // pseudoteletypewriter dimensions
{"tmpfd", LuaUnixTmpfd}, // create anonymous file
{"truncate", LuaUnixTruncate}, // shrink or extend file medium
{"umask", LuaUnixUmask}, // set default file mask
{"unlink", LuaUnixUnlink}, // remove file

37
third_party/make/job.c vendored
View file

@ -1753,7 +1753,7 @@ unveil_variable (const struct variable *var)
char *val, *tok, *state, *start;
if (!var) return 0;
start = val = xstrdup (variable_expand (var->value));
while (tok = strtok_r (start, " \t\r\n", &state))
while ((tok = strtok_r (start, " \t\r\n", &state)))
{
RETURN_ON_ERROR (Unveil (tok, "r"));
start = 0;
@ -1808,15 +1808,6 @@ child_execute_job (struct childbase *child, int good_stdin, char **argv)
if (stack_limit.rlim_cur)
setrlimit (RLIMIT_STACK, &stack_limit);
/* For any redirected FD, dup2() it to the standard FD.
They are all marked close-on-exec already. */
if (fdin >= 0 && fdin != FD_STDIN)
EINTRLOOP (r, dup2 (fdin, FD_STDIN));
if (fdout != FD_STDOUT)
EINTRLOOP (r, dup2 (fdout, FD_STDOUT));
if (fderr != FD_STDERR)
EINTRLOOP (r, dup2 (fderr, FD_STDERR));
g_strict = Vartoi (lookup_variable (STRING_SIZE_TUPLE (".STRICT")));
intptr_t loc = (intptr_t)child; /* we can cast if it's on the heap ;_; */
@ -1846,7 +1837,7 @@ child_execute_job (struct childbase *child, int good_stdin, char **argv)
{
OSS (error, NILF, "%s: command not found on $PATH: %s",
argv[0], strerror (errno));
return -1;
_Exit (127);
}
}
@ -1955,7 +1946,7 @@ child_execute_job (struct childbase *child, int good_stdin, char **argv)
{
OSS (error, NILF, "%s: touch target failed %s",
c->file->name, strerror (errno));
return -1;
_Exit (127);
}
DB (DB_JOBS, (_("Unveiling %s with permissions %s\n"),
c->file->name, "rwx"));
@ -1963,7 +1954,7 @@ child_execute_job (struct childbase *child, int good_stdin, char **argv)
{
OSS (error, NILF, "%s: unveil target failed %s",
c->file->name, strerror (errno));
return -1;
_Exit (127);
}
}
@ -2001,16 +1992,20 @@ child_execute_job (struct childbase *child, int good_stdin, char **argv)
}
}
/* For any redirected FD, dup2() it to the standard FD.
They are all marked close-on-exec already. */
if (fdin >= 0 && fdin != FD_STDIN)
EINTRLOOP (r, dup2 (fdin, FD_STDIN));
if (fdout != FD_STDOUT)
EINTRLOOP (r, dup2 (fdout, FD_STDOUT));
if (fderr != FD_STDERR)
EINTRLOOP (r, dup2 (fderr, FD_STDERR));
/* Run the command. */
exec_command (argv, child->environment);
if (pid < 0)
OSS (error, NILF, "%s: exec_command failed: %s",
argv[0], strerror (r));
return pid;
OnError:
return -1;
_Exit (127);
}
@ -2029,7 +2024,7 @@ exec_command (char **argv, char **envp)
if(errno == ENOENT)
OSS (error, NILF, "%s: command doesn't exist: %s",
argv[0], strerror (errno));
else if(!g_strict && errno == ENOEXEC)
else if(errno == ENOEXEC)
{
/* The file was not a program. Try it as a shell script. */
const char *shell;
@ -2063,7 +2058,7 @@ exec_command (char **argv, char **envp)
OSS (error, NILF, "%s: execv failed: %s",
argv[0], strerror (errno));
_exit (127);
_Exit (127);
}

14
third_party/python/python.mk vendored
View file

@ -2082,6 +2082,20 @@ o/$(MODE)/third_party/python/pythontester.com.dbg: \
$(APE_NO_MODIFY_SELF)
@$(APELINK)
# if these files exist, then python will try to open them
o/$(MODE)/third_party/python/Lib/test/test_robotparser.py.runs \
o/$(MODE)/third_party/python/Lib/test/test_wsgiref.py.runs: private \
.UNVEIL += \
/etc/mime.types \
/etc/httpd/mime.types \
/etc/httpd/conf/mime.types \
/etc/apache/mime.types \
/etc/apache2/mime.types \
/usr/local/etc/httpd/conf/mime.types \
/usr/local/lib/netscape/mime.types \
/usr/local/etc/httpd/conf/mime.types \
/usr/local/etc/mime.types
o/$(MODE)/third_party/python/Lib/test/test_grammar.py.runs: \
o/$(MODE)/third_party/python/pythontester.com
@$(COMPILE) -ACHECK -wtT$@ $(PYHARNESSARGS) $< -m test.test_grammar $(PYTESTARGS)

56
third_party/unzip/unix.c vendored
View file

@ -133,62 +133,6 @@ static ZCONST char CannotSetTimestamps[] =
#ifndef SFX
#ifdef NO_DIR /* for AT&T 3B1 */
#define _opendir(path) fopen(path,"r")
#define _closedir(dir) fclose(dir)
typedef FILE DIR;
typedef struct zdir {
FILE *dirhandle;
struct dirent *entry;
} DIR
DIR *opendir OF((ZCONST char *dirspec));
void closedir OF((DIR *dirp));
struct dirent *readdir OF((DIR *dirp));
DIR *opendir(dirspec)
ZCONST char *dirspec;
{
DIR *dirp;
if ((dirp = malloc(sizeof(DIR)) != NULL) {
if ((dirp->dirhandle = fopen(dirspec, "r")) == NULL) {
free(dirp);
dirp = NULL;
}
}
return dirp;
}
void closedir(dirp)
DIR *dirp;
{
fclose(dirp->dirhandle);
free(dirp);
}
/*
* Apparently originally by Rich Salz.
* Cleaned up and modified by James W. Birdsall.
*/
struct dirent *readdir(dirp)
DIR *dirp;
{
if (dirp == NULL)
return NULL;
for (;;)
if (fread(&(dirp->entry), sizeof (struct dirent), 1,
dirp->dirhandle) == 0)
return (struct dirent *)NULL;
else if ((dirp->entry).d_ino)
return &(dirp->entry);
} /* end function readdir() */
#endif /* NO_DIR */
/**********************/
/* Function do_wild() */ /* for porting: dir separator; match(ignore_case) */

20
tool/net/help.txt
View file

@ -2361,7 +2361,6 @@ UNIX MODULE
- `O_NONBLOCK` asks read/write to fail with EAGAIN rather than block
- `O_DIRECT` it's complicated (not supported on Apple and OpenBSD)
- `O_DIRECTORY` useful for stat'ing (hint on UNIX but required on NT)
- `O_TMPFILE` try to make temp more secure (Linux and Windows only)
- `O_NOFOLLOW` fail if it's a symlink (zero on Windows)
- `O_DSYNC` it's complicated (zero on non-Linux/Apple)
- `O_RSYNC` it's complicated (zero on non-Linux/Apple)
@ -4201,6 +4200,25 @@ UNIX MODULE
Returns cellular dimensions of pseudoteletypewriter display.
unix.tmpfd()
├─→ fd:int
└─→ nil, unix.Errno
Returns file descriptor of open anonymous file.
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 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.
────────────────────────────────────────────────────────────────────────────────
UNIX DIR OBJECT