[Qemu-devel] [PATCH 4/4] cpu model corrections/updates: add verbose config file handling

[john cooper <john.cooper@redhat.com>]

Failure by qemu to open a default config file isn't cause to
error exit -- it just quietly continues on.   After puzzling
issues with otherwise opaque config file locations and
startup handling numerous times, some help from qemu seemed
justified.

The prior version of this patch overloaded "-readconfig ?"
to enable verbose handling.  Here we add a global "-config"
flag which takes [verbose][,nodefault] as options modifying
config file handling.  Note "-nodefconfig" has been removed
and functionally replaced here by the "nodefault" flag option.

Signed-off-by: john cooper <john.cooper@redhat.com>
---

diff --git a/qemu-config.c b/qemu-config.c
index 52f18be..1b871d6 100644
--- a/qemu-config.c
+++ b/qemu-config.c
@@ -630,21 +630,31 @@ out:
     return res;
 }
 
-int qemu_read_config_file(const char *filename)
+/* attempt to open and parse config file, report problems if vflag
+ */
+int qemu_read_config_file(const char *filename, int vflag)
 {
     FILE *f = fopen(filename, "r");
-    int ret;
+    int rv = 0;
+    const char *err;
 
     if (f == NULL) {
-        return -errno;
+        rv = -errno;
+        err = "open";
     }
-
-    ret = qemu_config_parse(f, vm_config_groups, filename);
-    fclose(f);
-
-    if (ret == 0) {
-        return 0;
-    } else {
-        return -EINVAL;
+    else if (qemu_config_parse(f, vm_config_groups, filename) != 0) {
+        rv = -EINVAL;
+        err = "parse";
+    }
+    else if (vflag) {
+        fprintf(stderr, "parsed config file %s\n", filename);
+    }
+    if (f) {
+        fclose(f);
+    }
+    if (rv && vflag) {
+        fprintf(stderr, "can't %s config file %s: %s\n",
+                err, filename, strerror(-rv));
     }
+    return rv;
 }
diff --git a/qemu-config.h b/qemu-config.h
index 20d707f..b90a7cc 100644
--- a/qemu-config.h
+++ b/qemu-config.h
@@ -14,6 +14,6 @@ void qemu_add_globals(void);
 void qemu_config_write(FILE *fp);
 int qemu_config_parse(FILE *fp, QemuOptsList **lists, const char *fname);
 
-int qemu_read_config_file(const char *filename);
+int qemu_read_config_file(const char *filename, int vflag);
 
 #endif /* QEMU_CONFIG_H */
diff --git a/qemu-options.hx b/qemu-options.hx
index 4d99a58..00c0845 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -2290,16 +2290,19 @@ STEXI
 @findex -writeconfig
 Write device configuration to @var{file}.
 ETEXI
-DEF("nodefconfig", 0, QEMU_OPTION_nodefconfig,
-    "-nodefconfig\n"
-    "                do not load default config files at startup\n",
+DEF("config", HAS_ARG, QEMU_OPTION_config,
+    "-config [nodefault][,verbose]\n"
+    "                set global config file options.\n",
     QEMU_ARCH_ALL)
 STEXI
-@item -nodefconfig
-@findex -nodefconfig
-Normally QEMU loads a configuration file from @var{sysconfdir}/qemu.conf and
-@var{sysconfdir}/target-@var{ARCH}.conf on startup.  The @code{-nodefconfig}
-option will prevent QEMU from loading these configuration files at startup.
+@item -config
+@findex -config
+By default QEMU loads a configuration file from @var{sysconfdir}/qemu.conf and
+@var{sysconfdir}/target-@var{ARCH}.conf on startup.
+The @code{-config nodefault} option will prevent QEMU from loading these
+configuration files at startup.
+Additionally @code{-config verbose} will provide detail to the user of
+all config file handling.
 ETEXI
 #ifdef CONFIG_SIMPLE_TRACE
 DEF("trace", HAS_ARG, QEMU_OPTION_trace,
diff --git a/vl.c b/vl.c
index 805e11f..160f14b 100644
--- a/vl.c
+++ b/vl.c
@@ -1806,6 +1806,7 @@ int main(int argc, char **argv, char **envp)
     const char *incoming = NULL;
     int show_vnc_port = 0;
     int defconfig = 1;
+    int defconfig_verbose = 0;
 
 #ifdef CONFIG_SIMPLE_TRACE
     const char *trace_file = NULL;
@@ -1854,8 +1855,25 @@ int main(int argc, char **argv, char **envp)
 
             popt = lookup_opt(argc, argv, &optarg, &optind);
             switch (popt->index) {
-            case QEMU_OPTION_nodefconfig:
-                defconfig=0;
+            case QEMU_OPTION_config:
+                {
+                char *p, *q, *r;
+
+                for (r = p = strdup(optarg); (q = strtok(r, ",")); r = NULL)
+                    if (!strcmp(q, "nodefault")) {
+                        defconfig = 0;
+                    } else if (!strcmp(q, "verbose")) {
+                        defconfig_verbose = 1;
+                    } else {
+                        fprintf(stderr, "unknown option \"%s\"\n", q);
+                        exit(1);
+                    }
+                free(p);
+                break;
+                }
+            case QEMU_OPTION_readconfig:
+                if (qemu_read_config_file(optarg, defconfig_verbose) < 0)
+                    exit(1);
                 break;
             }
         }
@@ -1864,12 +1882,13 @@ int main(int argc, char **argv, char **envp)
     if (defconfig) {
         int ret;
 
-        ret = qemu_read_config_file(CONFIG_QEMU_CONFDIR "/qemu.conf");
+        ret = qemu_read_config_file(CONFIG_QEMU_CONFDIR "/qemu.conf",
+                                    defconfig_verbose);
         if (ret < 0 && ret != -ENOENT) {
             exit(1);
         }
 
-        ret = qemu_read_config_file(arch_config_name);
+        ret = qemu_read_config_file(arch_config_name, defconfig_verbose);
         if (ret < 0 && ret != -ENOENT) {
             exit(1);
         }
@@ -2577,16 +2596,6 @@ int main(int argc, char **argv, char **envp)
                 }
                 break;
 #endif
-            case QEMU_OPTION_readconfig:
-                {
-                    int ret = qemu_read_config_file(optarg);
-                    if (ret < 0) {
-                        fprintf(stderr, "read config %s: %s\n", optarg,
-                            strerror(-ret));
-                        exit(1);
-                    }
-                    break;
-                }
             case QEMU_OPTION_spice:
                 olist = qemu_find_opts("spice");
                 if (!olist) {
-- 
john.cooper@redhat.com