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error: On abort, report where the error was created 

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Merge remote-tracking branch 'remotes/armbru/tags/pull-error-2015-09-10' into staging

error: On abort, report where the error was created

# gpg: Signature made Thu 10 Sep 2015 13:01:39 BST using RSA key ID EB918653
# gpg: Good signature from "Markus Armbruster <armbru@redhat.com>"
# gpg:                 aka "Markus Armbruster <armbru@pond.sub.org>"

* remotes/armbru/tags/pull-error-2015-09-10:
  error: On abort, report where the error was created
  error: Revamp interface documentation
  error: error_set_errno() is unused, drop
  qga/vss-win32: Document the DLL requires non-null errp
  qga: Clean up unnecessarily dirty casts
  error: Make error_setg() a function
  error: De-duplicate code creating Error objects

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
This commit is contained in:
Peter Maydell 2015-09-10 14:51:35 +01:00
parent fbf054cb0a 1e9b65bb1b
commit fe556410cf
5 changed files with 245 additions and 134 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

234
include/qapi/error.h
View File

@ -2,13 +2,75 @@
* QEMU Error Objects
*
* Copyright IBM, Corp. 2011
* Copyright (C) 2011-2015 Red Hat, Inc.
*
* Authors:
* Anthony Liguori <aliguori@us.ibm.com>
* Markus Armbruster <armbru@redhat.com>
*
* This work is licensed under the terms of the GNU LGPL, version 2. See
* the COPYING.LIB file in the top-level directory.
*/
/*
* Error reporting system loosely patterned after Glib's GError.
*
* Create an error:
* error_setg(&err, "situation normal, all fouled up");
*
* Report an error to stderr:
* error_report_err(err);
* This frees the error object.
*
* Report an error somewhere else:
* const char *msg = error_get_pretty(err);
* do with msg what needs to be done...
* error_free(err);
*
* Handle an error without reporting it (just for completeness):
* error_free(err);
*
* Pass an existing error to the caller:
* error_propagate(errp, err);
* where Error **errp is a parameter, by convention the last one.
*
* Create a new error and pass it to the caller:
* error_setg(errp, "situation normal, all fouled up");
*
* Call a function and receive an error from it:
* Error *err = NULL;
* foo(arg, &err);
* if (err) {
* handle the error...
* }
*
* Call a function ignoring errors:
* foo(arg, NULL);
*
* Call a function aborting on errors:
* foo(arg, &error_abort);
*
* Receive an error and pass it on to the caller:
* Error *err = NULL;
* foo(arg, &err);
* if (err) {
* handle the error...
* error_propagate(errp, err);
* }
* where Error **errp is a parameter, by convention the last one.
*
* Do *not* "optimize" this to
* foo(arg, errp);
* if (*errp) { // WRONG!
* handle the error...
* }
* because errp may be NULL!
*
* But when all you do with the error is pass it on, please use
* foo(arg, errp);
* for readability.
*/
#ifndef ERROR_H
#define ERROR_H
@ -16,93 +78,125 @@
#include "qapi-types.h"
#include <stdbool.h>
/**
* A class representing internal errors within QEMU. An error has a ErrorClass
* code and a human message.
/*
* Opaque error object.
*/
typedef struct Error Error;
/**
* Set an indirect pointer to an error given a ErrorClass value and a
* printf-style human message. This function is not meant to be used outside
* of QEMU.
*/
void error_set(Error **errp, ErrorClass err_class, const char *fmt, ...)
GCC_FMT_ATTR(3, 4);
/**
* Set an indirect pointer to an error given a ErrorClass value and a
* printf-style human message, followed by a strerror() string if
* @os_error is not zero.
*/
void error_set_errno(Error **errp, int os_error, ErrorClass err_class,
const char *fmt, ...) GCC_FMT_ATTR(4, 5);
#ifdef _WIN32
/**
* Set an indirect pointer to an error given a ErrorClass value and a
* printf-style human message, followed by a g_win32_error_message() string if
* @win32_err is not zero.
*/
void error_set_win32(Error **errp, int win32_err, ErrorClass err_class,
const char *fmt, ...) GCC_FMT_ATTR(4, 5);
#endif
/**
* Same as error_set(), but sets a generic error
*/
#define error_setg(errp, fmt, ...) \
error_set(errp, ERROR_CLASS_GENERIC_ERROR, fmt, ## __VA_ARGS__)
#define error_setg_errno(errp, os_error, fmt, ...) \
error_set_errno(errp, os_error, ERROR_CLASS_GENERIC_ERROR, \
fmt, ## __VA_ARGS__)
#ifdef _WIN32
#define error_setg_win32(errp, win32_err, fmt, ...) \
error_set_win32(errp, win32_err, ERROR_CLASS_GENERIC_ERROR, \
fmt, ## __VA_ARGS__)
#endif
/**
* Helper for open() errors
*/
void error_setg_file_open(Error **errp, int os_errno, const char *filename);
/*
* Get the error class of an error object.
*/
ErrorClass error_get_class(const Error *err);
/**
* Returns an exact copy of the error passed as an argument.
*/
Error *error_copy(const Error *err);
/**
* Get a human readable representation of an error object.
* Get @err's human-readable error message.
*/
const char *error_get_pretty(Error *err);
/**
* Convenience function to error_report() and free an error object.
/*
* Get @err's error class.
* Note: use of error classes other than ERROR_CLASS_GENERIC_ERROR is
* strongly discouraged.
*/
void error_report_err(Error *);
ErrorClass error_get_class(const Error *err);
/**
* Propagate an error to an indirect pointer to an error. This function will
* always transfer ownership of the error reference and handles the case where
* dst_err is NULL correctly. Errors after the first are discarded.
/*
* Create a new error object and assign it to *@errp.
* If @errp is NULL, the error is ignored. Don't bother creating one
* then.
* If @errp is &error_abort, print a suitable message and abort().
* If @errp is anything else, *@errp must be NULL.
* The new error's class is ERROR_CLASS_GENERIC_ERROR, and its
* human-readable error message is made from printf-style @fmt, ...
*/
#define error_setg(errp, fmt, ...) \
error_setg_internal((errp), __FILE__, __LINE__, __func__, \
(fmt), ## __VA_ARGS__)
void error_setg_internal(Error **errp,
const char *src, int line, const char *func,
const char *fmt, ...)
GCC_FMT_ATTR(5, 6);
/*
* Just like error_setg(), with @os_error info added to the message.
* If @os_error is non-zero, ": " + strerror(os_error) is appended to
* the human-readable error message.
*/
#define error_setg_errno(errp, os_error, fmt, ...) \
error_setg_errno_internal((errp), __FILE__, __LINE__, __func__, \
(os_error), (fmt), ## __VA_ARGS__)
void error_setg_errno_internal(Error **errp,
const char *fname, int line, const char *func,
int os_error, const char *fmt, ...)
GCC_FMT_ATTR(6, 7);
#ifdef _WIN32
/*
* Just like error_setg(), with @win32_error info added to the message.
* If @win32_error is non-zero, ": " + g_win32_error_message(win32_err)
* is appended to the human-readable error message.
*/
#define error_setg_win32(errp, win32_err, fmt, ...) \
error_setg_win32_internal((errp), __FILE__, __LINE__, __func__, \
(win32_err), (fmt), ## __VA_ARGS__)
void error_setg_win32_internal(Error **errp,
const char *src, int line, const char *func,
int win32_err, const char *fmt, ...)
GCC_FMT_ATTR(6, 7);
#endif
/*
* Propagate error object (if any) from @local_err to @dst_errp.
* If @local_err is NULL, do nothing (because there's nothing to
* propagate).
* Else, if @dst_errp is NULL, errors are being ignored. Free the
* error object.
* Else, if @dst_errp is &error_abort, print a suitable message and
* abort().
* Else, if @dst_errp already contains an error, ignore this one: free
* the error object.
* Else, move the error object from @local_err to *@dst_errp.
* On return, @local_err is invalid.
*/
void error_propagate(Error **dst_errp, Error *local_err);
/**
* Free an error object.
/*
* Convenience function to report open() failure.
*/
#define error_setg_file_open(errp, os_errno, filename) \
error_setg_file_open_internal((errp), __FILE__, __LINE__, __func__, \
(os_errno), (filename))
void error_setg_file_open_internal(Error **errp,
const char *src, int line, const char *func,
int os_errno, const char *filename);
/*
* Return an exact copy of @err.
*/
Error *error_copy(const Error *err);
/*
* Free @err.
* @err may be NULL.
*/
void error_free(Error *err);
/**
* If passed to error_set and friends, abort().
/*
* Convenience function to error_report() and free @err.
*/
void error_report_err(Error *);
/*
* Just like error_setg(), except you get to specify the error class.
* Note: use of error classes other than ERROR_CLASS_GENERIC_ERROR is
* strongly discouraged.
*/
#define error_set(errp, err_class, fmt, ...) \
error_set_internal((errp), __FILE__, __LINE__, __func__, \
(err_class), (fmt), ## __VA_ARGS__)
void error_set_internal(Error **errp,
const char *src, int line, const char *func,
ErrorClass err_class, const char *fmt, ...)
GCC_FMT_ATTR(6, 7);
/*
* Pass to error_setg() & friends to abort() on error.
*/
extern Error *error_abort;
#endif

6
qga/vss-win32.c
View File

@ -150,11 +150,11 @@ void qga_vss_fsfreeze(int *nr_volume, Error **errp, bool freeze)
const char *func_name = freeze ? "requester_freeze" : "requester_thaw";
QGAVSSRequesterFunc func;
ErrorSet errset = {
.error_set = (ErrorSetFunc)error_set_win32,
.errp = (void **)errp,
.err_class = ERROR_CLASS_GENERIC_ERROR
.error_setg_win32 = error_setg_win32_internal,
.errp = errp,
};
g_assert(errp); /* requester.cpp requires it */
func = (QGAVSSRequesterFunc)GetProcAddress(provider_lib, func_name);
if (!func) {
error_setg_win32(errp, GetLastError(), "failed to load %s from %s",

8
qga/vss-win32/requester.cpp
View File

@ -23,10 +23,12 @@
/* Call QueryStatus every 10 ms while waiting for frozen event */
#define VSS_TIMEOUT_EVENT_MSEC 10
#define err_set(e, err, fmt, ...) \
((e)->error_set((e)->errp, err, (e)->err_class, fmt, ## __VA_ARGS__))
#define err_set(e, err, fmt, ...) \
((e)->error_setg_win32((e)->errp, __FILE__, __LINE__, __func__, \
err, fmt, ## __VA_ARGS__))
/* Bad idea, works only when (e)->errp != NULL: */
#define err_is_set(e) ((e)->errp && *(e)->errp)
/* To lift this restriction, error_propagate(), like we do in QEMU code */
/* Handle to VSSAPI.DLL */
static HMODULE hLib;

13
qga/vss-win32/requester.h
View File

@ -20,13 +20,16 @@
extern "C" {
#endif
struct Error;
/* Callback to set Error; used to avoid linking glib to the DLL */
typedef void (*ErrorSetFunc)(void **errp, int win32_err, int err_class,
const char *fmt, ...) GCC_FMT_ATTR(4, 5);
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_set;
void **errp;
int err_class;
ErrorSetFunc error_setg_win32;
struct Error **errp; /* restriction: must not be null */
} ErrorSet;
STDAPI requester_init(void);

118
util/error.c
View File

@ -18,14 +18,25 @@ struct Error
{
char *msg;
ErrorClass err_class;
const char *src, *func;
int line;
};
Error *error_abort;
void error_set(Error **errp, ErrorClass err_class, const char *fmt, ...)
static void error_do_abort(Error *err)
{
fprintf(stderr, "Unexpected error in %s() at %s:%d:\n",
err->func, err->src, err->line);
error_report_err(err);
abort();
}
static void error_setv(Error **errp,
const char *src, int line, const char *func,
ErrorClass err_class, const char *fmt, va_list ap)
{
Error *err;
va_list ap;
int saved_errno = errno;
if (errp == NULL) {
@ -34,15 +45,14 @@ void error_set(Error **errp, ErrorClass err_class, const char *fmt, ...)
assert(*errp == NULL);
err = g_malloc0(sizeof(*err));
va_start(ap, fmt);
err->msg = g_strdup_vprintf(fmt, ap);
va_end(ap);
err->err_class = err_class;
err->src = src;
err->line = line;
err->func = func;
if (errp == &error_abort) {
error_report_err(err);
abort();
error_do_abort(err);
}
*errp = err;
@ -50,83 +60,86 @@ void error_set(Error **errp, ErrorClass err_class, const char *fmt, ...)
errno = saved_errno;
}
void error_set_errno(Error **errp, int os_errno, ErrorClass err_class,
const char *fmt, ...)
void error_set_internal(Error **errp,
const char *src, int line, const char *func,
ErrorClass err_class, const char *fmt, ...)
{
Error *err;
char *msg1;
va_list ap;
va_start(ap, fmt);
error_setv(errp, src, line, func, err_class, fmt, ap);
va_end(ap);
}
void error_setg_internal(Error **errp,
const char *src, int line, const char *func,
const char *fmt, ...)
{
va_list ap;
va_start(ap, fmt);
error_setv(errp, src, line, func, ERROR_CLASS_GENERIC_ERROR, fmt, ap);
va_end(ap);
}
void error_setg_errno_internal(Error **errp,
const char *src, int line, const char *func,
int os_errno, const char *fmt, ...)
{
va_list ap;
char *msg;
int saved_errno = errno;
if (errp == NULL) {
return;
}
assert(*errp == NULL);
err = g_malloc0(sizeof(*err));
va_start(ap, fmt);
msg1 = g_strdup_vprintf(fmt, ap);
if (os_errno != 0) {
err->msg = g_strdup_printf("%s: %s", msg1, strerror(os_errno));
g_free(msg1);
} else {
err->msg = msg1;
}
error_setv(errp, src, line, func, ERROR_CLASS_GENERIC_ERROR, fmt, ap);
va_end(ap);
err->err_class = err_class;
if (errp == &error_abort) {
error_report_err(err);
abort();
if (os_errno != 0) {
msg = (*errp)->msg;
(*errp)->msg = g_strdup_printf("%s: %s", msg, strerror(os_errno));
g_free(msg);
}
*errp = err;
errno = saved_errno;
}
void error_setg_file_open(Error **errp, int os_errno, const char *filename)
void error_setg_file_open_internal(Error **errp,
const char *src, int line, const char *func,
int os_errno, const char *filename)
{
error_setg_errno(errp, os_errno, "Could not open '%s'", filename);
error_setg_errno_internal(errp, src, line, func, os_errno,
"Could not open '%s'", filename);
}
#ifdef _WIN32
void error_set_win32(Error **errp, int win32_err, ErrorClass err_class,
const char *fmt, ...)
void error_setg_win32_internal(Error **errp,
const char *src, int line, const char *func,
int win32_err, const char *fmt, ...)
{
Error *err;
char *msg1;
va_list ap;
char *msg1, *msg2;
if (errp == NULL) {
return;
}
assert(*errp == NULL);
err = g_malloc0(sizeof(*err));
va_start(ap, fmt);
msg1 = g_strdup_vprintf(fmt, ap);
error_setv(errp, src, line, func, ERROR_CLASS_GENERIC_ERROR, fmt, ap);
va_end(ap);
if (win32_err != 0) {
char *msg2 = g_win32_error_message(win32_err);
err->msg = g_strdup_printf("%s: %s (error: %x)", msg1, msg2,
(unsigned)win32_err);
msg1 = (*errp)->msg;
msg2 = g_win32_error_message(win32_err);
(*errp)->msg = g_strdup_printf("%s: %s (error: %x)", msg1, msg2,
(unsigned)win32_err);
g_free(msg2);
g_free(msg1);
} else {
err->msg = msg1;
}
va_end(ap);
err->err_class = err_class;
if (errp == &error_abort) {
error_report_err(err);
abort();
}
*errp = err;
}
#endif
@ -169,8 +182,7 @@ void error_free(Error *err)
void error_propagate(Error **dst_errp, Error *local_err)
{
if (local_err && dst_errp == &error_abort) {
error_report_err(local_err);
abort();
error_do_abort(local_err);
} else if (dst_errp && !*dst_errp) {
*dst_errp = local_err;
} else if (local_err) {