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mpv/osdep/io.h
wm4 ef507ad50a osdep: add mkostemps() emulation
Supposed to follow the standard function.

The standard function is not standard, but a GNU extension. Adding some
ifdef mess is pointless too - it has no advantages other than having a
mess, and not spotting implementation bugs in the emulation due to
running it only on "obscure" platforms (like Windows, so most computers
actually, except the developer's platform).

There is mkstemp(), which at least is in POSIX 2008. But it's 100%
useless, except in some obscure cases: it doesn't set O_CLOEXEC, nor can
you pass it to it. Without O_CLOEXEC, we'd leak the temporary file to
all child processes. (The fact that the file, which is expected to reach
double or tripple digit GB sizes, will be deleted only once all
processes unreference the FD, makes this sort of a big deal. You could
ftruncate() it, but that doesn't fix all the other problems.)

Why did POSIX standardize mkstemp() and O_CLOEXEC apparently at the same
time, but provided no way to pass O_CLOEXEC to mkstemp()? With the
introduction of O_CLOEXEC, they acknowledged that there's a need to
atomically set the FD_CLOEXEC flag when creating file descriptors.
(FD_CLOEXEC was standard before that, but setting it with fcntl() is
racy.) You're much more likely to need a temp file that is CLOEXEC
rather than the opposite, and even if they were somehow opposed to
CLOEXEC by default (such as for compat. reasons), surely POSIX could
have standardized mkostemp() too or instead.

And then there's the fact that this whole O_CLOEXEC mess is stupid.
Surely there would have been a better way to handle this, instead of
requiring adding O_CLOEXEC to almost ALL instances of open() in all code
that has been written ever. The justification for this is that the
historic default was wrong, and you can't change it (e.g. this won't
work: changing the behavior of exec() and not inherit the FD to the
child process, unless a hypothetical O_KEEP_EXEC flag is set).

But on the other hand, surely you could have introduced an exec()
variant which does close all FDs, except a whitelist of FDs passed to
it. Let's call it execve2(). In fact, I'm going to argue that exec()
call sites are the most aware of whether (and which) FDs to inherit.
Some programs even tried to explicitly iterate over all opened FDs and
explicitly close "unwanted" FDs (which of course was problematic for
other reasons), and such an execve2() call would have been the ideal
solution.

Maybe this proposed solution would have had problems too. But surely
revisiting and reviewing every exec*() call would have been simpler than
reviewing every open() call. And more importantly, having to extend
every damn library function that either calls open() or creates FDs in
some other way, like mkstemp().

What argument are there going to be against this? That there will be
library code that can't keep working correctly with processes that use
the "old" exec? Well, what about all my legacy library code that uses
open() incorrectly, and that will break no matter what?

Well, I'm not going to claim that I can come up with better solutions
than POSIX (generally or in this case), but this situation is ABSOLUTELY
ATROCIOUS. It makes win32 programming look attractive compared to POSIX,
that standard pandering to dead people from the past. (Note: not trying
to insult dead people.)

I'm not sure what POSIX is even doing. Anything useful? Doesn't look
like it to me. Are they paid? Why? They didn't even fix the locale mess,
nor do they intend to. I bet they're proud of discussing compatibility
to 70ies code day in and day out iwtohut ever producing anything useful.
What a load of crap. They seriously got to do better than this.

Oh, and my wrapper is probably buggy. Fortunately that doesn't matter.
Also I'm dumping this into io.h. Originally, io.h was just supposed to
replace broken implementation of standard functions by MinGW (and then
by Android), but whatever, just give a dumping ground for shit code.
2019-09-19 20:37:05 +02:00

213 lines
5.4 KiB
C

/*
* unicode/utf-8 I/O helpers and wrappers for Windows
*
* This file is part of mpv.
*
* mpv is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* mpv is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with mpv. If not, see <http://www.gnu.org/licenses/>.
*/
#ifndef MPLAYER_OSDEP_IO
#define MPLAYER_OSDEP_IO
#include "config.h"
#include <stdbool.h>
#include <stdint.h>
#include <limits.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <locale.h>
#if HAVE_GLOB_POSIX
#include <glob.h>
#endif
#if HAVE_ANDROID
# include <unistd.h>
# include <stdio.h>
// replace lseek with the 64bit variant
#ifdef lseek
# undef lseek
#endif
#define lseek(f,p,w) lseek64((f), (p), (w))
// replace possible fseeko with a
// lseek64 based solution.
#ifdef fseeko
# undef fseeko
#endif
static inline int mp_fseeko(FILE* fp, off64_t offset, int whence) {
int ret = -1;
if ((ret = fflush(fp)) != 0) {
return ret;
}
return lseek64(fileno(fp), offset, whence) >= 0 ? 0 : -1;
}
#define fseeko(f,p,w) mp_fseeko((f), (p), (w))
#endif // HAVE_ANDROID
#ifndef O_BINARY
#define O_BINARY 0
#endif
// This is in POSIX.1-2008, but support outside of Linux is scarce.
#ifndef O_CLOEXEC
#define O_CLOEXEC 0
#endif
#ifndef FD_CLOEXEC
#define FD_CLOEXEC 0
#endif
bool mp_set_cloexec(int fd);
int mp_make_cloexec_pipe(int pipes[2]);
int mp_make_wakeup_pipe(int pipes[2]);
void mp_flush_wakeup_pipe(int pipe_end);
#ifdef _WIN32
#include <wchar.h>
wchar_t *mp_from_utf8(void *talloc_ctx, const char *s);
char *mp_to_utf8(void *talloc_ctx, const wchar_t *s);
#endif
#ifdef __CYGWIN__
#include <io.h>
#endif
#ifdef __MINGW32__
#include <stdio.h>
#include <dirent.h>
#include <sys/stat.h>
#include <fcntl.h>
int mp_printf(const char *format, ...);
int mp_fprintf(FILE *stream, const char *format, ...);
int mp_open(const char *filename, int oflag, ...);
int mp_creat(const char *filename, int mode);
FILE *mp_fopen(const char *filename, const char *mode);
DIR *mp_opendir(const char *path);
struct dirent *mp_readdir(DIR *dir);
int mp_closedir(DIR *dir);
int mp_mkdir(const char *path, int mode);
char *mp_win32_getcwd(char *buf, size_t size);
FILE *mp_tmpfile(void);
char *mp_getenv(const char *name);
off_t mp_lseek(int fd, off_t offset, int whence);
// mp_stat types. MSVCRT's dev_t and ino_t are way too short to be unique.
typedef uint64_t mp_dev_t_;
#ifdef _WIN64
typedef unsigned __int128 mp_ino_t_;
#else
// 32-bit Windows doesn't have a __int128-type, which means ReFS file IDs will
// be truncated and might collide. This is probably not a problem because ReFS
// is not available in consumer versions of Windows.
typedef uint64_t mp_ino_t_;
#endif
#define dev_t mp_dev_t_
#define ino_t mp_ino_t_
// mp_stat uses a different structure to MSVCRT, with 64-bit inodes
struct mp_stat {
dev_t st_dev;
ino_t st_ino;
unsigned short st_mode;
unsigned int st_nlink;
short st_uid;
short st_gid;
dev_t st_rdev;
int64_t st_size;
time_t st_atime;
time_t st_mtime;
time_t st_ctime;
};
int mp_stat(const char *path, struct mp_stat *buf);
int mp_fstat(int fd, struct mp_stat *buf);
typedef struct {
size_t gl_pathc;
char **gl_pathv;
size_t gl_offs;
void *ctx;
} mp_glob_t;
// glob-win.c
int mp_glob(const char *restrict pattern, int flags,
int (*errfunc)(const char*, int), mp_glob_t *restrict pglob);
void mp_globfree(mp_glob_t *pglob);
#define printf(...) mp_printf(__VA_ARGS__)
#define fprintf(...) mp_fprintf(__VA_ARGS__)
#define open(...) mp_open(__VA_ARGS__)
#define creat(...) mp_creat(__VA_ARGS__)
#define fopen(...) mp_fopen(__VA_ARGS__)
#define opendir(...) mp_opendir(__VA_ARGS__)
#define readdir(...) mp_readdir(__VA_ARGS__)
#define closedir(...) mp_closedir(__VA_ARGS__)
#define mkdir(...) mp_mkdir(__VA_ARGS__)
#define getcwd(...) mp_win32_getcwd(__VA_ARGS__)
#define tmpfile(...) mp_tmpfile(__VA_ARGS__)
#define getenv(...) mp_getenv(__VA_ARGS__)
#undef lseek
#define lseek(...) mp_lseek(__VA_ARGS__)
// Affects both "stat()" and "struct stat".
#undef stat
#define stat mp_stat
#undef fstat
#define fstat(...) mp_fstat(__VA_ARGS__)
void *mmap(void *addr, size_t length, int prot, int flags, int fd, off_t offset);
int munmap(void *addr, size_t length);
int msync(void *addr, size_t length, int flags);
#define PROT_READ 1
#define PROT_WRITE 2
#define MAP_SHARED 1
#define MAP_FAILED ((void *)-1)
#define MS_ASYNC 1
#define MS_SYNC 2
#define MS_INVALIDATE 4
#ifndef GLOB_NOMATCH
#define GLOB_NOMATCH 3
#endif
#define glob_t mp_glob_t
#define glob(...) mp_glob(__VA_ARGS__)
#define globfree(...) mp_globfree(__VA_ARGS__)
// These are stubs since there is not anything that helps with this on Windows.
#define locale_t int
#define LC_ALL_MASK 0
#define LC_CTYPE_MASK 0
locale_t newlocale(int, const char *, locale_t);
locale_t uselocale(locale_t);
void freelocale(locale_t);
#else /* __MINGW32__ */
#include <sys/mman.h>
#endif /* __MINGW32__ */
int mp_mkostemps(char *template, int suffixlen, int flags);
#endif