xemu/qga/vss-win32/requester.h
Markus Armbruster 1e9b65bb1b error: On abort, report where the error was created
This is particularly useful when we abort in error_propagate(),
because there the stack backtrace doesn't lead to where the error was
created.  Looks like this:

    Unexpected error in parse_block_error_action() at .../qemu/blockdev.c:322:
    qemu-system-x86_64: -drive if=none,werror=foo: 'foo' invalid write error action
    Aborted (core dumped)

Note: to get this example output, I monkey-patched drive_new() to pass
&error_abort to blockdev_init().

To keep the error handling boiler plate from growing even more, all
error_setFOO() become macros expanding into error_setFOO_internal()
with additional __FILE__, __LINE__, __func__ arguments.  Not exactly
pretty, but it works.

The macro trickery breaks down when you take the address of an
error_setFOO().  Fortunately, we do that in just one place: qemu-ga's
Windows VSS provider and requester DLL wants to call
error_setg_win32() through a function pointer "to avoid linking glib
to the DLL".  Use error_setg_win32_internal() there.  The use of the
function pointer is already wrapped in a macro, so the churn isn't
bad.

Code size increases by some 35KiB for me (0.7%).  Tolerable.  Could be
less if we passed relative rather than absolute source file names to
the compiler, or forwent reporting __func__.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Acked-by: Laszlo Ersek <lersek@redhat.com>
2015-09-10 13:48:06 +02:00

47 lines
1.1 KiB
C

/*
* QEMU Guest Agent VSS requester declarations
*
* Copyright Hitachi Data Systems Corp. 2013
*
* Authors:
* Tomoki Sekiyama <tomoki.sekiyama@hds.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 VSS_WIN32_REQUESTER_H
#define VSS_WIN32_REQUESTER_H
#include <basetyps.h> /* STDAPI */
#include "qemu/compiler.h"
#ifdef __cplusplus
extern "C" {
#endif
struct Error;
/* Callback to set Error; used to avoid linking glib to the DLL */
typedef void (*ErrorSetFunc)(struct Error **errp,
const char *src, int line, const char *func,
int win32_err, const char *fmt, ...)
GCC_FMT_ATTR(6, 7);
typedef struct ErrorSet {
ErrorSetFunc error_setg_win32;
struct Error **errp; /* restriction: must not be null */
} ErrorSet;
STDAPI requester_init(void);
STDAPI requester_deinit(void);
typedef void (*QGAVSSRequesterFunc)(int *, ErrorSet *);
void requester_freeze(int *num_vols, ErrorSet *errset);
void requester_thaw(int *num_vols, ErrorSet *errset);
#ifdef __cplusplus
}
#endif
#endif