[Qemu-devel] [RFC][PATCH v4 07/18] virtagent: add getdmesg RPC

[Michael Roth]

Add RPC to view guest dmesg output.

Signed-off-by: Michael Roth <address@hidden>
---
 virtagent-daemon.c |   46 ++++++++++++++++++++++++++++++++++++++++++++++
 virtagent-daemon.h |    1 +
 2 files changed, 47 insertions(+), 0 deletions(-)

diff --git a/virtagent-daemon.c b/virtagent-daemon.c
index 44c0754..0dd72c0 100644
--- a/virtagent-daemon.c
+++ b/virtagent-daemon.c
@@ -81,6 +81,50 @@ EXIT_CLOSE_BAD:
     return result;
 }
 
+/* getdmesg(): return dmesg output
+ * rpc return values:
+ *   - dmesg output as a string
+ */
+static xmlrpc_value *getdmesg(xmlrpc_env *env,
+                              xmlrpc_value *param,
+                              void *user_data)
+{
+    char *dmesg_buf = NULL, cmd[256];
+    int ret;
+    xmlrpc_value *result = NULL;
+    FILE *pipe;
+
+    SLOG("getdmesg()");
+
+    dmesg_buf = qemu_mallocz(VA_DMESG_LEN + 2048);
+    sprintf(cmd, "dmesg -s %d", VA_DMESG_LEN);
+
+    pipe = popen(cmd, "r");
+    if (pipe == NULL) {
+        LOG("popen failed: %s", strerror(errno));
+        xmlrpc_faultf(env, "popen failed: %s", strerror(errno));
+        goto EXIT_NOCLOSE;
+    }
+
+    ret = fread(dmesg_buf, sizeof(char), VA_DMESG_LEN, pipe);
+    if (!ferror(pipe)) {
+        dmesg_buf[ret] = '\0';
+        TRACE("dmesg:\n%s", dmesg_buf);
+        result = xmlrpc_build_value(env, "s", dmesg_buf);
+    } else {
+        LOG("fread failed");
+        xmlrpc_faultf(env, "popen failed: %s", strerror(errno));
+    }
+
+    pclose(pipe);
+EXIT_NOCLOSE:
+    if (dmesg_buf) {
+        qemu_free(dmesg_buf);
+    }
+
+    return result;
+}
+
 static int va_accept(int listen_fd) {
     struct sockaddr_in saddr;
     struct sockaddr *addr;
@@ -110,6 +154,8 @@ typedef struct RPCFunction {
 static RPCFunction guest_functions[] = {
     { .func = getfile,
       .func_name = "getfile" },
+    { .func = getdmesg,
+      .func_name = "getdmesg" },
     { NULL, NULL }
 };
 static RPCFunction host_functions[] = {
diff --git a/virtagent-daemon.h b/virtagent-daemon.h
index 6c3436a..09b0097 100644
--- a/virtagent-daemon.h
+++ b/virtagent-daemon.h
@@ -18,5 +18,6 @@
 #define HOST_AGENT_PATH "/tmp/virtagent-host.sock"
 #define VA_GETFILE_MAX 1 << 30
 #define VA_FILEBUF_LEN 16384
+#define VA_DMESG_LEN 16384
 
 int va_server_init(VPDriver *vp_drv, bool is_host);
-- 
1.7.0.4