glib/glib/gstdio.h
Philip Withnall dfb0ea737b
gstdio: Move doc comment for g_clear_fd() to be next to the code
Nobody’s going to keep it up to date if it’s floating about in an
unrelated place, not next to the code.

Signed-off-by: Philip Withnall <pwithnall@gnome.org>
2024-10-01 14:29:31 +01:00

297 lines
8.0 KiB
C

/* gstdio.h - GFilename wrappers for C library functions
*
* Copyright 2004 Tor Lillqvist
*
* SPDX-License-Identifier: LGPL-2.1-or-later
*
* This library 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.
*
* This library 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 this library; if not, see <http://www.gnu.org/licenses/>.
*/
#ifndef __G_STDIO_H__
#define __G_STDIO_H__
#include <glib/gprintf.h>
#include <errno.h>
#include <sys/stat.h>
G_BEGIN_DECLS
#if (defined (__MINGW64_VERSION_MAJOR) || defined (_MSC_VER)) && !defined(_WIN64)
/* Make it clear that we mean the struct with 32-bit st_size and
* 32-bit st_*time fields as that is how the 32-bit GLib DLL normally
* has been compiled. If you get a compiler warning when calling
* g_stat(), do take it seriously and make sure that the type of
* struct stat the code in GLib fills in matches the struct the type
* of struct stat you pass to g_stat(). To avoid hassle, to get file
* attributes just use the GIO API instead which doesn't use struct
* stat.
*
* Sure, it would be nicer to use a struct with 64-bit st_size and
* 64-bit st_*time fields, but changing that now would break ABI. And
* in MinGW, a plain "struct stat" is the one with 32-bit st_size and
* st_*time fields.
*/
typedef struct _stat32 GStatBuf;
#elif defined(__MINGW64_VERSION_MAJOR) && defined(_WIN64)
typedef struct _stat64 GStatBuf;
#else
typedef struct stat GStatBuf;
#endif
#if defined(G_OS_UNIX) && !defined(G_STDIO_WRAP_ON_UNIX) && !defined(__GI_SCANNER__)
/* Just pass on to the system functions, so there's no potential for data
* format mismatches, especially with large file interfaces.
* A few functions can't be handled in this way, since they are not defined
* in a portable system header that we could include here.
*
* G_STDIO_WRAP_ON_UNIX is not public API and its behaviour is not guaranteed
* in future.
*/
#ifndef __GTK_DOC_IGNORE__
#define g_chmod chmod
#define g_open open
#define g_creat creat
#define g_rename rename
#define g_mkdir mkdir
#define g_stat stat
#define g_lstat lstat
#define g_remove remove
#define g_fopen fopen
#define g_freopen freopen
#define g_fsync fsync
#define g_utime utime
#endif
GLIB_AVAILABLE_IN_ALL
int g_access (const gchar *filename,
int mode);
GLIB_AVAILABLE_IN_ALL
int g_chdir (const gchar *path);
GLIB_AVAILABLE_IN_ALL
int g_unlink (const gchar *filename);
GLIB_AVAILABLE_IN_ALL
int g_rmdir (const gchar *filename);
#else /* ! G_OS_UNIX */
/* Wrappers for C library functions that take pathname arguments. On
* Unix, the pathname is a file name as it literally is in the file
* system. On well-maintained systems with consistent users who know
* what they are doing and no exchange of files with others this would
* be a well-defined encoding, preferably UTF-8. On Windows, the
* pathname is always in UTF-8, even if that is not the on-disk
* encoding, and not the encoding accepted by the C library or Win32
* API.
*/
GLIB_AVAILABLE_IN_ALL
int g_access (const gchar *filename,
int mode);
GLIB_AVAILABLE_IN_ALL
int g_chmod (const gchar *filename,
int mode);
GLIB_AVAILABLE_IN_ALL
int g_open (const gchar *filename,
int flags,
int mode);
GLIB_AVAILABLE_IN_ALL
int g_creat (const gchar *filename,
int mode);
GLIB_AVAILABLE_IN_ALL
int g_rename (const gchar *oldfilename,
const gchar *newfilename);
GLIB_AVAILABLE_IN_ALL
int g_mkdir (const gchar *filename,
int mode);
GLIB_AVAILABLE_IN_ALL
int g_chdir (const gchar *path);
GLIB_AVAILABLE_IN_ALL
int g_stat (const gchar *filename,
GStatBuf *buf);
GLIB_AVAILABLE_IN_ALL
int g_lstat (const gchar *filename,
GStatBuf *buf);
GLIB_AVAILABLE_IN_ALL
int g_unlink (const gchar *filename);
GLIB_AVAILABLE_IN_ALL
int g_remove (const gchar *filename);
GLIB_AVAILABLE_IN_ALL
int g_rmdir (const gchar *filename);
GLIB_AVAILABLE_IN_ALL
FILE *g_fopen (const gchar *filename,
const gchar *mode);
GLIB_AVAILABLE_IN_ALL
FILE *g_freopen (const gchar *filename,
const gchar *mode,
FILE *stream);
GLIB_AVAILABLE_IN_2_64
gint g_fsync (gint fd);
struct utimbuf; /* Don't need the real definition of struct utimbuf when just
* including this header.
*/
GLIB_AVAILABLE_IN_ALL
int g_utime (const gchar *filename,
struct utimbuf *utb);
#endif /* G_OS_UNIX */
GLIB_AVAILABLE_IN_2_36
gboolean g_close (gint fd,
GError **error);
/**
* g_clear_fd: (skip)
* @fd_ptr: (not optional) (inout) (transfer full): a pointer to a file descriptor
* @error: Used to return an error on failure
*
* If @fd_ptr points to a file descriptor, close it and return
* whether closing it was successful, like g_close().
* If @fd_ptr points to a negative number, return %TRUE without closing
* anything.
* In both cases, set @fd_ptr to `-1` before returning.
*
* Like g_close(), if closing the file descriptor fails, the error is
* stored in both %errno and @error. If this function succeeds,
* %errno is undefined.
*
* On POSIX platforms, this function is async-signal safe
* if @error is %NULL and @fd_ptr points to either a negative number or a
* valid open file descriptor.
* This makes it safe to call from a signal handler or a #GSpawnChildSetupFunc
* under those conditions.
* See [`signal(7)`](man:signal(7)) and
* [`signal-safety(7)`](man:signal-safety(7)) for more details.
*
* It is a programming error for @fd_ptr to point to a non-negative
* number that is not a valid file descriptor.
*
* A typical use of this function is to clean up a file descriptor at
* the end of its scope, whether it has been set successfully or not:
*
* |[
* gboolean
* operate_on_fd (GError **error)
* {
* gboolean ret = FALSE;
* int fd = -1;
*
* fd = open_a_fd (error);
*
* if (fd < 0)
* goto out;
*
* if (!do_something (fd, error))
* goto out;
*
* if (!g_clear_fd (&fd, error))
* goto out;
*
* ret = TRUE;
*
* out:
* // OK to call even if fd was never opened or was already closed
* g_clear_fd (&fd, NULL);
* return ret;
* }
* ]|
*
* This function is also useful in conjunction with #g_autofd.
*
* Returns: %TRUE on success
* Since: 2.76
*/
GLIB_AVAILABLE_STATIC_INLINE_IN_2_76
static inline gboolean g_clear_fd (int *fd_ptr,
GError **error);
GLIB_AVAILABLE_STATIC_INLINE_IN_2_76
static inline gboolean
g_clear_fd (int *fd_ptr,
GError **error)
{
int fd = *fd_ptr;
*fd_ptr = -1;
if (fd < 0)
return TRUE;
/* Suppress "Not available before" warning */
G_GNUC_BEGIN_IGNORE_DEPRECATIONS
return g_close (fd, error);
G_GNUC_END_IGNORE_DEPRECATIONS
}
/* g_autofd should be defined on the same compilers where g_autofree is
* This avoids duplicating the feature-detection here. */
#ifdef g_autofree
#ifndef __GTK_DOC_IGNORE__
/* Not public API */
static inline void
_g_clear_fd_ignore_error (int *fd_ptr)
{
/* Don't overwrite thread-local errno if closing the fd fails */
int errsv = errno;
/* Suppress "Not available before" warning */
G_GNUC_BEGIN_IGNORE_DEPRECATIONS
if (!g_clear_fd (fd_ptr, NULL))
{
/* Do nothing: we ignore all errors, except for EBADF which
* is a programming error, checked for by g_close(). */
}
G_GNUC_END_IGNORE_DEPRECATIONS
errno = errsv;
}
#endif
#define g_autofd _GLIB_CLEANUP(_g_clear_fd_ignore_error) GLIB_AVAILABLE_MACRO_IN_2_76
#endif
G_END_DECLS
#endif /* __G_STDIO_H__ */