2015-08-21 07:04:50 +00:00
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/*
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* QEMU Error Objects
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*
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* Copyright IBM, Corp. 2011
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2018-02-15 16:36:23 +00:00
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* Copyright (C) 2011-2015 Red Hat, Inc.
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2015-08-21 07:04:50 +00:00
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*
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* Authors:
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* Anthony Liguori <aliguori@us.ibm.com>
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2018-02-15 16:36:23 +00:00
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* Markus Armbruster <armbru@redhat.com>
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2015-08-21 07:04:50 +00:00
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*
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* This work is licensed under the terms of the GNU LGPL, version 2. See
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* the COPYING.LIB file in the top-level directory.
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*/
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2018-02-15 16:36:23 +00:00
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/*
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* Error reporting system loosely patterned after Glib's GError.
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*
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* Create an error:
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* error_setg(&err, "situation normal, all fouled up");
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*
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* Report an error to stderr:
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* error_report_err(err);
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* This frees the error object.
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*
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* Report an error somewhere else:
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* const char *msg = error_get_pretty(err);
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* do with msg what needs to be done...
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* error_free(err);
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*
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* Handle an error without reporting it (just for completeness):
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* error_free(err);
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*
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* Pass an existing error to the caller:
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* error_propagate(errp, err);
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* where Error **errp is a parameter, by convention the last one.
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*
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* Create a new error and pass it to the caller:
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* error_setg(errp, "situation normal, all fouled up");
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*
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* Call a function and receive an error from it:
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* Error *err = NULL;
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* foo(arg, &err);
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* if (err) {
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* handle the error...
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* }
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*
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* Call a function ignoring errors:
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* foo(arg, NULL);
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*
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* Call a function aborting on errors:
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* foo(arg, &error_abort);
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*
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* Receive an error and pass it on to the caller:
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* Error *err = NULL;
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* foo(arg, &err);
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* if (err) {
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* handle the error...
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* error_propagate(errp, err);
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* }
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* where Error **errp is a parameter, by convention the last one.
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*
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* Do *not* "optimize" this to
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* foo(arg, errp);
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* if (*errp) { // WRONG!
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* handle the error...
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* }
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* because errp may be NULL!
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*
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* But when all you do with the error is pass it on, please use
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* foo(arg, errp);
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* for readability.
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2018-02-18 01:49:03 +00:00
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*
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* Receive and accumulate multiple errors (first one wins):
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* Error *err = NULL, *local_err = NULL;
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* foo(arg, &err);
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* bar(arg, &local_err);
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* error_propagate(&err, local_err);
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* if (err) {
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* handle the error...
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* }
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*
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* Do *not* "optimize" this to
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* foo(arg, &err);
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* bar(arg, &err); // WRONG!
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* if (err) {
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* handle the error...
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* }
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* because this may pass a non-null err to bar().
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2018-02-15 16:36:23 +00:00
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*/
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2015-08-21 07:04:50 +00:00
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#ifndef ERROR_H
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#define ERROR_H
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#include "qemu/compiler.h"
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#include "qapi-types.h"
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2017-01-20 13:13:21 +00:00
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#include "unicorn/platform.h"
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2015-08-21 07:04:50 +00:00
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/**
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2018-02-15 16:36:23 +00:00
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* Opaque error object.
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2015-08-21 07:04:50 +00:00
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*/
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typedef struct Error Error;
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/**
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2018-02-15 16:36:23 +00:00
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* Get @err's human-readable error message.
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2015-08-21 07:04:50 +00:00
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*/
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2018-02-15 16:36:23 +00:00
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const char *error_get_pretty(Error *err);
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/*
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* Get @err's error class.
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* Note: use of error classes other than ERROR_CLASS_GENERIC_ERROR is
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* strongly discouraged.
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*/
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ErrorClass error_get_class(const Error *err);
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2015-08-21 07:04:50 +00:00
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/**
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* Set an indirect pointer to an error given a ErrorClass value and a
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* printf-style human message, followed by a strerror() string if
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* @os_error is not zero.
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*/
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void error_set_errno(Error **errp, int os_error, ErrorClass err_class,
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const char *fmt, ...) GCC_FMT_ATTR(4, 5);
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2018-02-15 16:36:23 +00:00
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/*
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* Create a new error object and assign it to *@errp.
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* If @errp is NULL, the error is ignored. Don't bother creating one
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* then.
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* If @errp is &error_abort, print a suitable message and abort().
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* If @errp is anything else, *@errp must be NULL.
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* The new error's class is ERROR_CLASS_GENERIC_ERROR, and its
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* human-readable error message is made from printf-style @fmt, ...
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2015-08-21 07:04:50 +00:00
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*/
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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__.
Backports commit 1e9b65bb1bad51735cab6c861c29b592dccabf0e from qemu
2018-02-15 16:40:27 +00:00
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#define error_setg(errp, fmt, ...) \
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error_setg_internal((errp), __FILE__, __LINE__, __func__, \
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(fmt), ## __VA_ARGS__)
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void error_setg_internal(Error **errp,
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const char *src, int line, const char *func,
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const char *fmt, ...)
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GCC_FMT_ATTR(5, 6);
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2015-08-21 07:04:50 +00:00
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/*
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2018-02-15 16:36:23 +00:00
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* Just like error_setg(), with @os_error info added to the message.
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* If @os_error is non-zero, ": " + strerror(os_error) is appended to
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* the human-readable error message.
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2015-08-21 07:04:50 +00:00
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*/
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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__.
Backports commit 1e9b65bb1bad51735cab6c861c29b592dccabf0e from qemu
2018-02-15 16:40:27 +00:00
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#define error_setg_errno(errp, os_error, fmt, ...) \
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error_setg_errno_internal((errp), __FILE__, __LINE__, __func__, \
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(os_error), (fmt), ## __VA_ARGS__)
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void error_setg_errno_internal(Error **errp,
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const char *fname, int line, const char *func,
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int os_error, const char *fmt, ...)
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GCC_FMT_ATTR(6, 7);
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2015-08-21 07:04:50 +00:00
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2018-02-15 16:36:23 +00:00
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/*
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* Propagate error object (if any) from @local_err to @dst_errp.
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* If @local_err is NULL, do nothing (because there's nothing to
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* propagate).
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* Else, if @dst_errp is NULL, errors are being ignored. Free the
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* error object.
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* Else, if @dst_errp is &error_abort, print a suitable message and
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* abort().
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* Else, if @dst_errp already contains an error, ignore this one: free
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* the error object.
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* Else, move the error object from @local_err to *@dst_errp.
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* On return, @local_err is invalid.
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2015-08-21 07:04:50 +00:00
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*/
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2018-02-15 16:36:23 +00:00
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void error_propagate(Error **dst_errp, Error *local_err);
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2015-08-21 07:04:50 +00:00
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/**
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2018-02-15 16:36:23 +00:00
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* Convenience function to report open() failure.
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2015-08-21 07:04:50 +00:00
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*/
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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__.
Backports commit 1e9b65bb1bad51735cab6c861c29b592dccabf0e from qemu
2018-02-15 16:40:27 +00:00
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#define error_setg_file_open(errp, os_errno, filename) \
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error_setg_file_open_internal((errp), __FILE__, __LINE__, __func__, \
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(os_errno), (filename))
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void error_setg_file_open_internal(Error **errp,
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const char *src, int line, const char *func,
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int os_errno, const char *filename);
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2015-08-21 07:04:50 +00:00
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/**
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2018-02-15 16:36:23 +00:00
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* Return an exact copy of @err.
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2015-08-21 07:04:50 +00:00
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*/
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2018-02-15 16:36:23 +00:00
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Error *error_copy(const Error *err);
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2015-08-21 07:04:50 +00:00
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/**
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2018-02-15 16:36:23 +00:00
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* Free @err.
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* @err may be NULL.
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2015-08-21 07:04:50 +00:00
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*/
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void error_free(Error *err);
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2018-02-15 16:36:23 +00:00
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/*
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* Just like error_setg(), except you get to specify the error class.
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* Note: use of error classes other than ERROR_CLASS_GENERIC_ERROR is
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* strongly discouraged.
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2015-08-21 07:04:50 +00:00
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*/
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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__.
Backports commit 1e9b65bb1bad51735cab6c861c29b592dccabf0e from qemu
2018-02-15 16:40:27 +00:00
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#define error_set(errp, err_class, fmt, ...) \
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error_set_internal((errp), __FILE__, __LINE__, __func__, \
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(err_class), (fmt), ## __VA_ARGS__)
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void error_set_internal(Error **errp,
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const char *src, int line, const char *func,
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ErrorClass err_class, const char *fmt, ...)
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GCC_FMT_ATTR(6, 7);
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2015-08-21 07:04:50 +00:00
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2018-02-15 16:36:23 +00:00
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/*
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* Pass to error_setg() & friends to abort() on error.
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*/
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2015-08-21 07:04:50 +00:00
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extern Error *error_abort;
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#endif
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