* 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");
+ *
+ * Create an error and add additional explanation:
+ * error_setg(&err, "invalid quark");
+ * error_append_hint(&err, "Valid quarks are up, down, strange, "
+ * "charm, top, bottom.\n");
+ *
+ * Do *not* contract this to
+ * error_setg(&err, "invalid quark\n"
+ * "Valid quarks are up, down, strange, charm, top, bottom.");
+ *
+ * Report an error to the current monitor if we have one, else stderr:
+ * error_report_err(err);
+ * This frees the error object.
+ *
+ * Likewise, but with additional text prepended:
+ * error_reportf_err(err, "Could not frobnicate '%s': ", name);
+ *
+ * Report an error somewhere else:
+ * const char *msg = error_get_pretty(err);
+ * do with msg what needs to be done...
+ * error_free(err);
+ * Note that this loses hints added with error_append_hint().
+ *
+ * Handle an error without reporting it (just for completeness):
+ * error_free(err);
+ *
+ * Assert that an expected error occurred, but clean it up without
+ * reporting it (primarily useful in testsuites):
+ * error_free_or_abort(&err);
+ *
+ * Pass an existing error to the caller:
+ * error_propagate(errp, err);
+ * where Error **errp is a parameter, by convention the last one.
+ *
+ * Pass an existing error to the caller with the message modified:
+ * error_propagate(errp, err);
+ * error_prepend(errp, "Could not frobnicate '%s': ", name);
+ *
+ * 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);
+ *
+ * Call a function treating errors as fatal:
+ * foo(arg, &error_fatal);
+ *
+ * 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.
+ *
+ * Receive and accumulate multiple errors (first one wins):
+ * Error *err = NULL, *local_err = NULL;
+ * foo(arg, &err);
+ * bar(arg, &local_err);
+ * error_propagate(&err, local_err);
+ * if (err) {
+ * handle the error...
+ * }
+ *
+ * Do *not* "optimize" this to
+ * foo(arg, &err);
+ * bar(arg, &err); // WRONG!
+ * if (err) {
+ * handle the error...
+ * }
+ * because this may pass a non-null err to bar().
+ */
+
#ifndef ERROR_H
#define ERROR_H
-#include "qemu/compiler.h"
#include "qapi-types.h"
-#include <stdbool.h>
-/**
- * A class representing internal errors within QEMU. An error has a ErrorClass
- * code and a human message.
+/*
+ * Overall category of an error.
+ * Based on the qapi type QapiErrorClass, but reproduced here for nicer
+ * enum names.
*/
-typedef struct Error Error;
+typedef enum ErrorClass {
+ ERROR_CLASS_GENERIC_ERROR = QAPI_ERROR_CLASS_GENERICERROR,
+ ERROR_CLASS_COMMAND_NOT_FOUND = QAPI_ERROR_CLASS_COMMANDNOTFOUND,
+ ERROR_CLASS_DEVICE_ENCRYPTED = QAPI_ERROR_CLASS_DEVICEENCRYPTED,
+ ERROR_CLASS_DEVICE_NOT_ACTIVE = QAPI_ERROR_CLASS_DEVICENOTACTIVE,
+ ERROR_CLASS_DEVICE_NOT_FOUND = QAPI_ERROR_CLASS_DEVICENOTFOUND,
+ ERROR_CLASS_KVM_MISSING_CAP = QAPI_ERROR_CLASS_KVMMISSINGCAP,
+} ErrorClass;
-/**
- * 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 &error_fatal, print a suitable message and exit(1).
+ * 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, ...
+ * The resulting message should be a single phrase, with no newline or
+ * trailing punctuation.
+ * Please don't error_setg(&error_fatal, ...), use error_report() and
+ * exit(), because that's more obvious.
+ * Likewise, don't error_setg(&error_abort, ...), use assert().
*/
-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 is &error_fatal, print a suitable message and
+ * exit(1).
+ * 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.
+ * Please don't error_propagate(&error_fatal, ...), use
+ * error_report_err() and exit(), because that's more obvious.
*/
-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.
+ * Prepend some text to @errp's human-readable error message.
+ * The text is made by formatting @fmt, @ap like vprintf().
*/
-ErrorClass error_get_class(const Error *err);
+void error_vprepend(Error **errp, const char *fmt, va_list ap);
-/**
- * Returns an exact copy of the error passed as an argument.
+/*
+ * Prepend some text to @errp's human-readable error message.
+ * The text is made by formatting @fmt, ... like printf().
*/
-Error *error_copy(const Error *err);
+void error_prepend(Error **errp, const char *fmt, ...)
+ GCC_FMT_ATTR(2, 3);
-/**
- * Get a human readable representation of an error object.
+/*
+ * Append a printf-style human-readable explanation to an existing error.
+ * @errp may be NULL, but not &error_fatal or &error_abort.
+ * Trivially the case if you call it only after error_setg() or
+ * error_propagate().
+ * May be called multiple times. The resulting hint should end with a
+ * newline.
*/
-const char *error_get_pretty(Error *err);
+void error_append_hint(Error **errp, const char *fmt, ...)
+ GCC_FMT_ATTR(2, 3);
-/**
- * Convenience function to error_report() and free an error object.
+/*
+ * Convenience function to report open() failure.
*/
-void error_report_err(Error *);
+#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);
-/**
- * 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.
+/*
+ * Return an exact copy of @err.
*/
-void error_propagate(Error **dst_errp, Error *local_err);
+Error *error_copy(const Error *err);
-/**
- * Free an error object.
+/*
+ * Free @err.
+ * @err may be NULL.
*/
void error_free(Error *err);
-/**
- * If passed to error_set and friends, abort().
+/*
+ * Convenience function to assert that *@errp is set, then silently free it.
+ */
+void error_free_or_abort(Error **errp);
+
+/*
+ * Convenience function to error_report() and free @err.
*/
+void error_report_err(Error *err);
+/*
+ * Convenience function to error_prepend(), error_report() and free @err.
+ */
+void error_reportf_err(Error *err, const char *fmt, ...)
+ GCC_FMT_ATTR(2, 3);
+
+/*
+ * 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);
+
+/*
+ * Special error destination to abort on error.
+ * See error_setg() and error_propagate() for details.
+ */
extern Error *error_abort;
+/*
+ * Special error destination to exit(1) on error.
+ * See error_setg() and error_propagate() for details.
+ */
+extern Error *error_fatal;
+
#endif
Code Review / kvmfornfv.git / blobdiff