diff options
Diffstat (limited to 'qga/main.c')
| -rw-r--r-- | qga/main.c | 184 |
1 files changed, 184 insertions, 0 deletions
diff --git a/qga/main.c b/qga/main.c index ad751717fe..99346e15aa 100644 --- a/qga/main.c +++ b/qga/main.c @@ -15,6 +15,7 @@ #include <stdbool.h> #include <glib.h> #include <getopt.h> +#include <glib/gstdio.h> #ifndef _WIN32 #include <syslog.h> #include <sys/wait.h> @@ -30,6 +31,7 @@ #include "qapi/qmp/qerror.h" #include "qapi/qmp/dispatch.h" #include "qga/channel.h" +#include "qemu/bswap.h" #ifdef _WIN32 #include "qga/service-win32.h" #include <windows.h> @@ -53,6 +55,11 @@ #endif #define QGA_SENTINEL_BYTE 0xFF +typedef struct GAPersistentState { +#define QGA_PSTATE_DEFAULT_FD_COUNTER 1000 + int64_t fd_counter; +} GAPersistentState; + struct GAState { JSONMessageParser parser; GMainLoop *main_loop; @@ -76,6 +83,8 @@ struct GAState { #ifdef CONFIG_FSFREEZE const char *fsfreeze_hook; #endif + const gchar *pstate_filepath; + GAPersistentState pstate; }; struct GAState *ga_state; @@ -725,6 +734,171 @@ VOID WINAPI service_main(DWORD argc, TCHAR *argv[]) } #endif +static void set_persistent_state_defaults(GAPersistentState *pstate) +{ + g_assert(pstate); + pstate->fd_counter = QGA_PSTATE_DEFAULT_FD_COUNTER; +} + +static void persistent_state_from_keyfile(GAPersistentState *pstate, + GKeyFile *keyfile) +{ + g_assert(pstate); + g_assert(keyfile); + /* if any fields are missing, either because the file was tampered with + * by agents of chaos, or because the field wasn't present at the time the + * file was created, the best we can ever do is start over with the default + * values. so load them now, and ignore any errors in accessing key-value + * pairs + */ + set_persistent_state_defaults(pstate); + + if (g_key_file_has_key(keyfile, "global", "fd_counter", NULL)) { + pstate->fd_counter = + g_key_file_get_int64(keyfile, "global", "fd_counter", NULL); + } +} + +static void persistent_state_to_keyfile(const GAPersistentState *pstate, + GKeyFile *keyfile) +{ + g_assert(pstate); + g_assert(keyfile); + + g_key_file_set_int64(keyfile, "global", "fd_counter", pstate->fd_counter); +} + +static gboolean write_persistent_state(const GAPersistentState *pstate, + const gchar *path) +{ + GKeyFile *keyfile = g_key_file_new(); + GError *gerr = NULL; + gboolean ret = true; + gchar *data = NULL; + gsize data_len; + + g_assert(pstate); + + persistent_state_to_keyfile(pstate, keyfile); + data = g_key_file_to_data(keyfile, &data_len, &gerr); + if (gerr) { + g_critical("failed to convert persistent state to string: %s", + gerr->message); + ret = false; + goto out; + } + + g_file_set_contents(path, data, data_len, &gerr); + if (gerr) { + g_critical("failed to write persistent state to %s: %s", + path, gerr->message); + ret = false; + goto out; + } + +out: + if (gerr) { + g_error_free(gerr); + } + if (keyfile) { + g_key_file_free(keyfile); + } + g_free(data); + return ret; +} + +static gboolean read_persistent_state(GAPersistentState *pstate, + const gchar *path, gboolean frozen) +{ + GKeyFile *keyfile = NULL; + GError *gerr = NULL; + struct stat st; + gboolean ret = true; + + g_assert(pstate); + + if (stat(path, &st) == -1) { + /* it's okay if state file doesn't exist, but any other error + * indicates a permissions issue or some other misconfiguration + * that we likely won't be able to recover from. + */ + if (errno != ENOENT) { + g_critical("unable to access state file at path %s: %s", + path, strerror(errno)); + ret = false; + goto out; + } + + /* file doesn't exist. initialize state to default values and + * attempt to save now. (we could wait till later when we have + * modified state we need to commit, but if there's a problem, + * such as a missing parent directory, we want to catch it now) + * + * there is a potential scenario where someone either managed to + * update the agent from a version that didn't use a key store + * while qemu-ga thought the filesystem was frozen, or + * deleted the key store prior to issuing a fsfreeze, prior + * to restarting the agent. in this case we go ahead and defer + * initial creation till we actually have modified state to + * write, otherwise fail to recover from freeze. + */ + set_persistent_state_defaults(pstate); + if (!frozen) { + ret = write_persistent_state(pstate, path); + if (!ret) { + g_critical("unable to create state file at path %s", path); + ret = false; + goto out; + } + } + ret = true; + goto out; + } + + keyfile = g_key_file_new(); + g_key_file_load_from_file(keyfile, path, 0, &gerr); + if (gerr) { + g_critical("error loading persistent state from path: %s, %s", + path, gerr->message); + ret = false; + goto out; + } + + persistent_state_from_keyfile(pstate, keyfile); + +out: + if (keyfile) { + g_key_file_free(keyfile); + } + if (gerr) { + g_error_free(gerr); + } + + return ret; +} + +int64_t ga_get_fd_handle(GAState *s, Error **errp) +{ + int64_t handle; + + g_assert(s->pstate_filepath); + /* we blacklist commands and avoid operations that potentially require + * writing to disk when we're in a frozen state. this includes opening + * new files, so we should never get here in that situation + */ + g_assert(!ga_is_frozen(s)); + + handle = s->pstate.fd_counter++; + if (s->pstate.fd_counter < 0) { + s->pstate.fd_counter = 0; + } + if (!write_persistent_state(&s->pstate, s->pstate_filepath)) { + error_setg(errp, "failed to commit persistent state to disk"); + } + + return handle; +} + int main(int argc, char **argv) { const char *sopt = "hVvdm:p:l:f:F::b:s:t:"; @@ -854,7 +1028,9 @@ int main(int argc, char **argv) ga_enable_logging(s); s->state_filepath_isfrozen = g_strdup_printf("%s/qga.state.isfrozen", state_dir); + s->pstate_filepath = g_strdup_printf("%s/qga.state", state_dir); s->frozen = false; + #ifndef _WIN32 /* check if a previous instance of qemu-ga exited with filesystems' state * marked as frozen. this could be a stale value (a non-qemu-ga process @@ -911,6 +1087,14 @@ int main(int argc, char **argv) } } + /* load persistent state from disk */ + if (!read_persistent_state(&s->pstate, + s->pstate_filepath, + ga_is_frozen(s))) { + g_critical("failed to load persistent state"); + goto out_bad; + } + if (blacklist) { s->blacklist = blacklist; do { |