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-rw-r--r--include/qapi/error.h210
-rw-r--r--qga/vss-win32.c6
-rw-r--r--qga/vss-win32/requester.cpp8
-rw-r--r--qga/vss-win32/requester.h13
-rw-r--r--util/error.c118
5 files changed, 233 insertions, 122 deletions
diff --git a/include/qapi/error.h b/include/qapi/error.h
index f44c451830..426d5eaceb 100644
--- a/include/qapi/error.h
+++ b/include/qapi/error.h
@@ -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.
+/*
+ * Get @err's human-readable error message.
*/
-void error_set(Error **errp, ErrorClass err_class, const char *fmt, ...)
- GCC_FMT_ATTR(3, 4);
+const char *error_get_pretty(Error *err);
-/**
- * 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.
+/*
+ * Get @err's error class.
+ * Note: use of error classes other than ERROR_CLASS_GENERIC_ERROR is
+ * strongly discouraged.
*/
-void error_set_errno(Error **errp, int os_error, ErrorClass err_class,
- const char *fmt, ...) GCC_FMT_ATTR(4, 5);
+ErrorClass error_get_class(const Error *err);
-#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.
+/*
+ * 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, ...
*/
-void error_set_win32(Error **errp, int win32_err, ErrorClass err_class,
- const char *fmt, ...) GCC_FMT_ATTR(4, 5);
-#endif
+#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);
-/**
- * Same as error_set(), but sets a generic error
+/*
+ * 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(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__)
+#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
-#define error_setg_win32(errp, win32_err, fmt, ...) \
- error_set_win32(errp, win32_err, ERROR_CLASS_GENERIC_ERROR, \
- fmt, ## __VA_ARGS__)
+/*
+ * 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
-/**
- * Helper for open() errors
+/*
+ * 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_setg_file_open(Error **errp, int os_errno, const char *filename);
+void error_propagate(Error **dst_errp, Error *local_err);
/*
- * Get the error class of an error object.
+ * Convenience function to report open() failure.
*/
-ErrorClass error_get_class(const Error *err);
+#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);
-/**
- * Returns an exact copy of the error passed as an argument.
+/*
+ * Return an exact copy of @err.
*/
Error *error_copy(const Error *err);
-/**
- * Get a human readable representation of an error object.
+/*
+ * Free @err.
+ * @err may be NULL.
*/
-const char *error_get_pretty(Error *err);
+void error_free(Error *err);
-/**
- * Convenience function to error_report() and free an error object.
+/*
+ * Convenience function to error_report() and free @err.
*/
void error_report_err(Error *);
-/**
- * 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.
- */
-void error_propagate(Error **dst_errp, Error *local_err);
-
-/**
- * Free an error object.
+/*
+ * 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.
*/
-void error_free(Error *err);
+#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);
-/**
- * If passed to error_set and friends, abort().
+/*
+ * Pass to error_setg() & friends to abort() on error.
*/
-
extern Error *error_abort;
#endif
diff --git a/qga/vss-win32.c b/qga/vss-win32.c
index 0e4095736e..2142b4964d 100644
--- a/qga/vss-win32.c
+++ b/qga/vss-win32.c
@@ -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",
diff --git a/qga/vss-win32/requester.cpp b/qga/vss-win32/requester.cpp
index 922e74ddfc..9b3e310971 100644
--- a/qga/vss-win32/requester.cpp
+++ b/qga/vss-win32/requester.cpp
@@ -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;
diff --git a/qga/vss-win32/requester.h b/qga/vss-win32/requester.h
index 374f9b8d16..c3093cf4b6 100644
--- a/qga/vss-win32/requester.h
+++ b/qga/vss-win32/requester.h
@@ -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);
diff --git a/util/error.c b/util/error.c
index 14f4351879..cdb726ce81 100644
--- a/util/error.c
+++ b/util/error.c
@@ -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, ...)
+{
+ 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, ...)
{
- Error *err;
- char *msg1;
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) {