ch: Add config file support

Similar to the QEMU driver, the ch driver receives support for
configuration files that allows doing certain configuration on the
virtchd daemon.

The initial use case will be setting the verbosity of the cloud
hypervisor instances started by virtchd, but the implementation allows
for adding further options.

Signed-off-by: Stefan Kober <stefan.kober@cyberus-technology.de>
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Michal Privoznik <mprivozn@redhat.com>

src/ch/ch.conf

@@ -0,0 +1,3 @@
+# Master configuration file for the CH driver.
+# All settings described here are optional - if omitted, sensible
+# defaults are used.

src/ch/ch_conf.c

@@ -22,6 +22,7 @@
 
 #include "configmake.h"
 #include "vircommand.h"
+#include "virconf.h"
 #include "virfile.h"
 #include "virlog.h"
 #include "virobject.h"
@@ -81,6 +82,25 @@ virCaps *virCHDriverCapsInit(void)
     return g_steal_pointer(&caps);
 }
 
+int virCHDriverConfigLoadFile(virCHDriverConfig *cfg G_GNUC_UNUSED,
+                              const char *filename)
+{
+    g_autoptr(virConf) conf = NULL;
+
+    /* Just check the file is readable before opening it, otherwise
+     * libvirt emits an error.
+     */
+    if (access(filename, R_OK) == -1) {
+        VIR_INFO("Could not read ch config file %s", filename);
+        return 0;
+    }
+
+    if (!(conf = virConfReadFile(filename, 0)))
+        return -1;
+
+    return 0;
+}
+
 /**
  * virCHDriverGetCapabilities:
  *
@@ -149,6 +169,7 @@ virCHDriverConfigNew(bool privileged)
         cfg->logDir = g_strdup_printf("%s/log/libvirt/ch", LOCALSTATEDIR);
         cfg->stateDir = g_strdup_printf("%s/libvirt/ch", RUNSTATEDIR);
         cfg->saveDir = g_strdup_printf("%s/lib/libvirt/ch/save", LOCALSTATEDIR);
+        cfg->configDir = g_strdup_printf("%s/lib/libvirt/ch", LOCALSTATEDIR);
 
     } else {
         g_autofree char *rundir = NULL;
@@ -164,6 +185,7 @@ virCHDriverConfigNew(bool privileged)
 
         configbasedir = virGetUserConfigDirectory();
         cfg->saveDir = g_strdup_printf("%s/ch/save", configbasedir);
+        cfg->configDir = g_strdup_printf("%s/ch", configbasedir);
     }
 
     return cfg;

src/ch/ch_conf.h

@@ -38,6 +38,7 @@ struct _virCHDriverConfig {
     GObject parent;
 
     char *stateDir;
+    char *configDir;
     char *logDir;
     char *saveDir;
 
@@ -103,6 +104,8 @@ struct _CHSaveXMLHeader {
     uint32_t unused[11];
 };
 
+int virCHDriverConfigLoadFile(virCHDriverConfig *cfg,
+                                const char *filename);
 virCaps *virCHDriverCapsInit(void);
 virCaps *virCHDriverGetCapabilities(virCHDriver *driver,
                                       bool refresh);

src/ch/ch_driver.c

@@ -1411,6 +1411,7 @@ chStateInitialize(bool privileged,
                   virStateInhibitCallback callback G_GNUC_UNUSED,
                   void *opaque G_GNUC_UNUSED)
 {
+    g_autofree char *driverConf = NULL;
     int ret = VIR_DRV_STATE_INIT_ERROR;
     int rv;
 
@@ -1447,6 +1448,11 @@ chStateInitialize(bool privileged,
     if (!(ch_driver->config = virCHDriverConfigNew(privileged)))
         goto cleanup;
 
+    driverConf = g_strdup_printf("%s/ch.conf", ch_driver->config->configDir);
+
+    if (virCHDriverConfigLoadFile(ch_driver->config, driverConf) < 0)
+        goto cleanup;
+
     if (!(ch_driver->hostdevMgr = virHostdevManagerGetDefault()))
         goto cleanup;
 

src/ch/libvirtd_ch.aug

@@ -0,0 +1,40 @@
+(* /etc/libvirt/ch.conf *)
+
+module Libvirtd_ch =
+   autoload xfm
+
+   let eol   = del /[ \t]*\n/ "\n"
+   let value_sep   = del /[ \t]*=[ \t]*/  " = "
+   let indent = del /[ \t]*/ ""
+
+   let array_sep  = del /,[ \t\n]*/ ", "
+   let array_start = del /\[[ \t\n]*/ "[ "
+   let array_end = del /\]/ "]"
+
+   let str_val = del /\"/ "\"" . store /[^\"]*/ . del /\"/ "\""
+   let bool_val = store /0|1/
+   let int_val = store /[0-9]+/
+   let str_array_element = [ seq "el" . str_val ] . del /[ \t\n]*/ ""
+   let str_array_val = counter "el" . array_start . ( str_array_element . ( array_sep . str_array_element ) * ) ? . array_end
+
+   let str_entry       (kw:string) = [ key kw . value_sep . str_val ]
+   let bool_entry      (kw:string) = [ key kw . value_sep . bool_val ]
+   let int_entry       (kw:string) = [ key kw . value_sep . int_val ]
+   let str_array_entry (kw:string) = [ key kw . value_sep . str_array_val ]
+
+   (* Config entry grouped by function - same order as example config *)
+   let config_entry = bool_entry "placeholder"
+
+   (* Each entry in the config is one of the following three ... *)
+   let entry = config_entry
+   let comment = [ label "#comment" . del /#[ \t]*/ "# " .  store /([^ \t\n][^\n]*)?/ . del /\n/ "\n" ]
+   let empty = [ label "#empty" . eol ]
+
+   let record = indent . entry . eol
+
+   let lns = ( record | comment | empty ) *
+
+   let filter = incl "/etc/libvirt/ch.conf"
+              . Util.stdexcl
+
+   let xfm = transform lns filter