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
/work/armbru/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 <arm...@redhat.com>
---
include/qapi/error.h | 43 +++++++++++++++++++++++++++--------
qga/vss-win32.c | 2 +-
qga/vss-win32/requester.cpp | 5 +++--
qga/vss-win32/requester.h | 6 +++--
util/error.c | 55 ++++++++++++++++++++++++++++++++-------------
5 files changed, 81 insertions(+), 30 deletions(-)
diff --git a/include/qapi/error.h b/include/qapi/error.h
index 7d808e8..6285ade 100644
--- a/include/qapi/error.h
+++ b/include/qapi/error.h
@@ -104,16 +104,26 @@ ErrorClass error_get_class(const Error *err);
* The new error's class is ERROR_CLASS_GENERIC_ERROR, and its
* human-readable error message is made from printf-style @fmt, ...
*/
-void error_setg(Error **errp, const char *fmt, ...)
- GCC_FMT_ATTR(2, 3);
+#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.
*/
-void error_setg_errno(Error **errp, int os_error, const char *fmt, ...)
- GCC_FMT_ATTR(3, 4);
+#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
/*
@@ -121,8 +131,13 @@ void error_setg_errno(Error **errp, int os_error, const
char *fmt, ...)
* If @win32_error is non-zero, ": " + g_win32_error_message(win32_err)
* is appended to the human-readable error message.
*/
-void error_setg_win32(Error **errp, int win32_err, const char *fmt, ...)
- GCC_FMT_ATTR(3, 4);
+#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
/*
@@ -143,7 +158,12 @@ void error_propagate(Error **dst_errp, Error *local_err);
/*
* Convenience function to report open() failure.
*/
-void error_setg_file_open(Error **errp, int os_errno, const char *filename);
+#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.
@@ -166,8 +186,13 @@ void error_report_err(Error *);
* Note: use of error classes other than ERROR_CLASS_GENERIC_ERROR is
* strongly discouraged.
*/
-void error_set(Error **errp, ErrorClass err_class, const char *fmt, ...)
- GCC_FMT_ATTR(3, 4);
+#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.
diff --git a/qga/vss-win32.c b/qga/vss-win32.c
index d75d7bb..2142b49 100644
--- a/qga/vss-win32.c
+++ b/qga/vss-win32.c
@@ -150,7 +150,7 @@ 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_setg_win32 = error_setg_win32,
+ .error_setg_win32 = error_setg_win32_internal,
.errp = errp,
};
diff --git a/qga/vss-win32/requester.cpp b/qga/vss-win32/requester.cpp
index aae0d5f..bb8cc2c 100644
--- a/qga/vss-win32/requester.cpp
+++ b/qga/vss-win32/requester.cpp
@@ -23,8 +23,9 @@
/* Call QueryStatus every 10 ms while waiting for frozen event */
#define VSS_TIMEOUT_EVENT_MSEC 10
-#define err_set(e, err, fmt, ...) \
- ((e)->error_setg_win32((e)->errp, err, 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 */
diff --git a/qga/vss-win32/requester.h b/qga/vss-win32/requester.h
index 34be5c1..c3093cf 100644
--- a/qga/vss-win32/requester.h
+++ b/qga/vss-win32/requester.h
@@ -23,8 +23,10 @@ extern "C" {
struct Error;
/* Callback to set Error; used to avoid linking glib to the DLL */
-typedef void (*ErrorSetFunc)(struct Error **errp, int win32_err,
- const char *fmt, ...) GCC_FMT_ATTR(3, 4);
+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 */
diff --git a/util/error.c b/util/error.c
index b842f20..1dcea2b 100644
--- a/util/error.c
+++ b/util/error.c
@@ -18,12 +18,23 @@ struct Error
{
char *msg;
ErrorClass err_class;
+ const char *src, *func;
+ int line;
};
Error *error_abort;
-static void error_setv(Error **errp, ErrorClass err_class,
- const char *fmt, va_list ap)
+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;
int saved_errno = errno;
@@ -36,10 +47,12 @@ static void error_setv(Error **errp, ErrorClass err_class,
err = g_malloc0(sizeof(*err));
err->msg = g_strdup_vprintf(fmt, 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;
@@ -47,25 +60,31 @@ static void error_setv(Error **errp, ErrorClass err_class,
errno = saved_errno;
}
-void error_set(Error **errp, 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, err_class, fmt, ap);
+ error_setv(errp, src, line, func, err_class, fmt, ap);
va_end(ap);
}
-void error_setg(Error **errp, const char *fmt, ...)
+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, ERROR_CLASS_GENERIC_ERROR, fmt, ap);
+ error_setv(errp, src, line, func, ERROR_CLASS_GENERIC_ERROR, fmt, ap);
va_end(ap);
}
-void error_setg_errno(Error **errp, int os_errno, const char *fmt, ...)
+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;
@@ -76,7 +95,7 @@ void error_setg_errno(Error **errp, int os_errno, const char
*fmt, ...)
}
va_start(ap, fmt);
- error_setv(errp, ERROR_CLASS_GENERIC_ERROR, fmt, ap);
+ error_setv(errp, src, line, func, ERROR_CLASS_GENERIC_ERROR, fmt, ap);
va_end(ap);
if (os_errno != 0) {
@@ -88,14 +107,19 @@ void error_setg_errno(Error **errp, int os_errno, const
char *fmt, ...)
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_setg_win32(Error **errp, int win32_err, const char *fmt, ...)
+void error_setg_win32_internal(Error **errp,
+ const char *src, int line, const char *func,
+ int win32_err, const char *fmt, ...)
{
va_list ap;
char *msg1, *msg2;
@@ -105,7 +129,7 @@ void error_setg_win32(Error **errp, int win32_err, const
char *fmt, ...)
}
va_start(ap, fmt);
- error_setv(errp, ERROR_CLASS_GENERIC_ERROR, fmt, ap);
+ error_setv(errp, src, line, func, ERROR_CLASS_GENERIC_ERROR, fmt, ap);
va_end(ap);
if (win32_err != 0) {
@@ -158,8 +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) {
--
1.9.3
