xemu/include/glib-compat.h
Marc-André Lureau 6d593ab451 glib-compat: add g_unix_get_passwd_entry_qemu()
The glib function was introduced in 2.64. It's a safer version of
getpwnam, and also simpler to use than getpwnam_r.

Currently, it's only use by the next patch in qemu-ga, which doesn't
(well well...) need the thread safety guarantees. Since the fallback
version is still unsafe, I would rather keep the _qemu postfix, to make
sure it's not being misused by mistake. When/if necessary, we can
implement a safer fallback and drop the _qemu suffix.

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Michal Privoznik <mprivozn@redhat.com>
*fix checkpatch warnings about newlines before/after block comments
Signed-off-by: Michael Roth <michael.roth@amd.com>
2020-11-02 19:52:08 -06:00

106 lines
3.0 KiB
C

/*
* GLIB Compatibility Functions
*
* Copyright IBM, Corp. 2013
*
* Authors:
* Anthony Liguori <aliguori@us.ibm.com>
* Michael Tokarev <mjt@tls.msk.ru>
* Paolo Bonzini <pbonzini@redhat.com>
*
* This work is licensed under the terms of the GNU GPL, version 2 or later.
* See the COPYING file in the top-level directory.
*
*/
#ifndef QEMU_GLIB_COMPAT_H
#define QEMU_GLIB_COMPAT_H
/* Ask for warnings for anything that was marked deprecated in
* the defined version, or before. It is a candidate for rewrite.
*/
#define GLIB_VERSION_MIN_REQUIRED GLIB_VERSION_2_48
/* Ask for warnings if code tries to use function that did not
* exist in the defined version. These risk breaking builds
*/
#define GLIB_VERSION_MAX_ALLOWED GLIB_VERSION_2_48
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wdeprecated-declarations"
#include <glib.h>
#if defined(G_OS_UNIX)
#include <glib-unix.h>
#include <sys/types.h>
#include <pwd.h>
#endif
/*
* Note that because of the GLIB_VERSION_MAX_ALLOWED constant above, allowing
* use of functions from newer GLib via this compat header needs a little
* trickery to prevent warnings being emitted.
*
* Consider a function from newer glib-X.Y that we want to use
*
* int g_foo(const char *wibble)
*
* We must define a static inline function with the same signature that does
* what we need, but with a "_qemu" suffix e.g.
*
* static inline void g_foo_qemu(const char *wibble)
* {
* #if GLIB_CHECK_VERSION(X, Y, 0)
* g_foo(wibble)
* #else
* g_something_equivalent_in_older_glib(wibble);
* #endif
* }
*
* The #pragma at the top of this file turns off -Wdeprecated-declarations,
* ensuring this wrapper function impl doesn't trigger the compiler warning
* about using too new glib APIs. Finally we can do
*
* #define g_foo(a) g_foo_qemu(a)
*
* So now the code elsewhere in QEMU, which *does* have the
* -Wdeprecated-declarations warning active, can call g_foo(...) as normal,
* without generating warnings.
*/
#if defined(_WIN32) && !GLIB_CHECK_VERSION(2, 50, 0)
/*
* g_poll has a problem on Windows when using
* timeouts < 10ms, so use wrapper.
*/
#define g_poll(fds, nfds, timeout) g_poll_fixed(fds, nfds, timeout)
gint g_poll_fixed(GPollFD *fds, guint nfds, gint timeout);
#endif
#if defined(G_OS_UNIX)
/*
* Note: The fallback implementation is not MT-safe, and it returns a copy of
* the libc passwd (must be g_free() after use) but not the content. Because of
* these important differences the caller must be aware of, it's not #define for
* GLib API substitution.
*/
static inline struct passwd *
g_unix_get_passwd_entry_qemu(const gchar *user_name, GError **error)
{
#if GLIB_CHECK_VERSION(2, 64, 0)
return g_unix_get_passwd_entry(user_name, error);
#else
struct passwd *p = getpwnam(user_name);
if (!p) {
g_set_error_literal(error, G_UNIX_ERROR, 0, g_strerror(errno));
return NULL;
}
return (struct passwd *)g_memdup(p, sizeof(*p));
#endif
}
#endif /* G_OS_UNIX */
#pragma GCC diagnostic pop
#endif