96 lines
2.9 KiB
Diff
96 lines
2.9 KiB
Diff
From 4cde9d78c4293e294f80376266cfce420f15a6ff Mon Sep 17 00:00:00 2001
|
|
From: "Richard W.M. Jones" <rjones@redhat.com>
|
|
Date: Tue, 23 Jul 2024 15:28:06 +0100
|
|
Subject: [PATCH] server: Take a thread-local copy of the last call to
|
|
nbdkit_error
|
|
|
|
nbdkit_error has traditionally been a "fancy wrapper around fprintf"
|
|
(kind of, don't take that literally). It is encouraged that plugins
|
|
and filters do something like:
|
|
|
|
if (error) {
|
|
nbdkit_error ("oops, a bad thing happened");
|
|
return -1;
|
|
}
|
|
|
|
but we don't enforce this. Plugins might call nbdkit_error more than
|
|
once or not at all.
|
|
|
|
The point where we get to sending an error back over the wire to the
|
|
NBD client is long after the plugin returned above, and after
|
|
nbdkit_error was called.
|
|
|
|
Therefore in order to send errors back to the NBD client, we must keep
|
|
the last error message around.
|
|
|
|
This change simply modifies nbdkit_error to make a best-effort attempt
|
|
to save the last error message in thread-local storage.
|
|
|
|
We also clear the last error when a new request starts, to ensure that
|
|
we don't leak errors across different callbacks or connections.
|
|
|
|
(cherry picked from commit bfa6d4064cb74f429149d14ab4025b258fc95ec4)
|
|
---
|
|
server/log.c | 21 +++++++++++++++++++++
|
|
server/protocol.c | 5 +++++
|
|
2 files changed, 26 insertions(+)
|
|
|
|
diff --git a/server/log.c b/server/log.c
|
|
index 9c1f667a..acf14d57 100644
|
|
--- a/server/log.c
|
|
+++ b/server/log.c
|
|
@@ -40,6 +40,25 @@
|
|
|
|
#include "internal.h"
|
|
|
|
+/* Copy the error message to threadlocal. This is sent to callers
|
|
+ * which are using structured replies, but is for extra information
|
|
+ * only so don't fail if we are unable to copy it.
|
|
+ */
|
|
+static void
|
|
+copy_error_to_threadlocal (int orig_errno, const char *fs, va_list args)
|
|
+{
|
|
+ va_list args_copy;
|
|
+ char *msg;
|
|
+ int r;
|
|
+
|
|
+ va_copy (args_copy, args);
|
|
+ errno = orig_errno; /* must restore in case fs contains %m */
|
|
+ r = vasprintf (&msg, fs, args_copy);
|
|
+ va_end (args_copy);
|
|
+ if (r != -1 && msg)
|
|
+ threadlocal_set_last_error (msg); /* ownership passed to threadlocal */
|
|
+}
|
|
+
|
|
/* Call the right log_*_verror function depending on log_sink.
|
|
* Note: preserves the previous value of errno.
|
|
*/
|
|
@@ -48,6 +67,8 @@ log_verror (const char *fs, va_list args)
|
|
{
|
|
int orig_errno = errno;
|
|
|
|
+ copy_error_to_threadlocal (orig_errno, fs, args);
|
|
+
|
|
switch (log_to) {
|
|
case LOG_TO_DEFAULT:
|
|
if (forked_into_background)
|
|
diff --git a/server/protocol.c b/server/protocol.c
|
|
index 677da05c..d428bfc8 100644
|
|
--- a/server/protocol.c
|
|
+++ b/server/protocol.c
|
|
@@ -239,6 +239,11 @@ handle_request (uint16_t cmd, uint16_t flags, uint64_t offset, uint32_t count,
|
|
*/
|
|
threadlocal_set_errno (0);
|
|
|
|
+ /* Also clear the last error in this thread so we will only save
|
|
+ * nbdkit_error() from this request.
|
|
+ */
|
|
+ threadlocal_clear_last_error ();
|
|
+
|
|
switch (cmd) {
|
|
case NBD_CMD_READ:
|
|
if (backend_pread (c, buf, count, offset, 0, &err) == -1)
|
|
--
|
|
2.43.0
|
|
|