From 39097daf15c42243742667607d2cad2c9dc4f764 Mon Sep 17 00:00:00 2001 From: Michael Roth Date: Fri, 1 Mar 2013 11:40:27 -0600 Subject: qemu-ga: use key-value store to avoid recycling fd handles after restart Hosts hold on to handles provided by guest-file-open for periods that can span beyond the life of the qemu-ga process that issued them. Since these are issued starting from 0 on every restart, we run the risk of issuing duplicate handles after restarts/reboots. As a result, users with a stale copy of these handles may end up reading/writing corrupted data due to their existing handles effectively being re-assigned to an unexpected file or offset. We unfortunately do not issue handles as strings, but as integers, so a solution such as using UUIDs can't be implemented without introducing a new interface. As a workaround, we fix this by implementing a persistent key-value store that will be used to track the value of the last handle that was issued across restarts/reboots to avoid issuing duplicates. The store is automatically written to the same directory we currently set via --statedir to track fsfreeze state, and so should be applicable for stable releases where this flag is supported. A follow-up can use this same store for handling fsfreeze state, but that change is cosmetic and left out for now. Signed-off-by: Michael Roth Cc: qemu-stable@nongnu.org * fixed guest_file_handle_add() return value from uint64_t to int64_t --- qga/guest-agent-core.h | 1 + 1 file changed, 1 insertion(+) (limited to 'qga/guest-agent-core.h') diff --git a/qga/guest-agent-core.h b/qga/guest-agent-core.h index 3354598362..624a559d94 100644 --- a/qga/guest-agent-core.h +++ b/qga/guest-agent-core.h @@ -35,6 +35,7 @@ bool ga_is_frozen(GAState *s); void ga_set_frozen(GAState *s); void ga_unset_frozen(GAState *s); const char *ga_fsfreeze_hook(GAState *s); +int64_t ga_get_fd_handle(GAState *s, Error **errp); #ifndef _WIN32 void reopen_fd_to_null(int fd); -- cgit v1.2.1