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error: On abort, report where the error was created

Browse source 
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__.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Acked-by: Laszlo Ersek <lersek@redhat.com>
This commit is contained in:
Markus Armbruster 2015-06-19 19:21:59 +02:00
parent edf6f3b335
commit 1e9b65bb1b
5 changed files with 81 additions and 30 deletions
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55
util/error.c
View file

@ -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) {