[Qemu-devel] [RFC PATCH 1/2] -readconfig: use QemuOpts option format

[Eduardo Habkost <ehabkost@redhat.com>]

This changes -readconfig to use the name=value[,name=value] option
format.

It keeps "-readconfig filename" working by using the implied "path"
option name, but it changes the existing syntax a little, meaning that
files with "=" and "," in the filename have to be escaped.

I chose to break compatibility in those cases, instead of adding a new
option and keeping -readconfig as a legacy option. If you think adding a
new option is better, please let me know.

Cc: Ronnie Sahlberg <ronniesahlberg@gmail.com>
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
---
 qemu-config.c   |   70 +++++++++++++++++++++++++++++++++++++++++++++++++-----
 qemu-config.h   |    8 +++++-
 qemu-options.hx |    4 +-
 vl.c            |    6 ++--
 4 files changed, 75 insertions(+), 13 deletions(-)

diff --git a/qemu-config.c b/qemu-config.c
index be84a03..6b7b28b 100644
--- a/qemu-config.c
+++ b/qemu-config.c
@@ -816,21 +816,77 @@ out:
     return res;
 }
 
-int qemu_read_config_file(const char *filename)
+/* Not on vm_config_groups because this is not a global option setable by -set
+ * (QEMU_OPTION_set), just settings used to parse -readconfig argument.
+ */
+static QemuOptsList qemu_readconfig_opts = {
+    .name = "readconfig-opts",
+    .implied_opt_name = "path",
+    .head = QTAILQ_HEAD_INITIALIZER(qemu_readconfig_opts.head),
+    .desc = {
+        {
+            .name = "path",
+            .type = QEMU_OPT_STRING,
+        },
+        { /*End of list */ }
+    },
+};
+
+/* Read Qemu config file from open file
+ *
+ * The file will be closed before returning.
+ *
+ * Returns 0 on success, -errno on failure.
+ */
+static int qemu_read_config_file(FILE *f, const char *filename)
 {
-    FILE *f = fopen(filename, "r");
     int ret;
+    if (qemu_config_parse(f, vm_config_groups, filename) == 0) {
+        ret = 0;
+    } else {
+        ret = -EINVAL;
+    }
+    fclose(f);
+    return ret;
+}
 
+/* Read Qemu config file from 'filename'
+ *
+ * Returns 0 on success, -errno on failure.
+ */
+int qemu_read_config_filename(const char *filename)
+{
+    FILE *f = fopen(filename, "r");
     if (f == NULL) {
         return -errno;
     }
+    return qemu_read_config_file(f, filename);
+}
 
-    ret = qemu_config_parse(f, vm_config_groups, filename);
-    fclose(f);
+/* Read Qemu config file based on parsed QemuOpts object
+ *
+ * Returns 0 on success, -errno on failure.
+ */
+static int qemu_read_config_opts(QemuOpts *opts)
+{
+    const char *path = qemu_opt_get(opts, "path");
+    if (!path) {
+        return -EINVAL;
+    }
+    return qemu_read_config_filename(path);
+}
 
-    if (ret == 0) {
-        return 0;
-    } else {
+/* Read config file based on option arguments on 'arg'
+ *
+ * Returns 0 on success, -errno on failure.
+ */
+int qemu_read_config_arg(const char *arg)
+{
+    QemuOpts *opts = qemu_opts_parse(&qemu_readconfig_opts, arg, 1);
+    if (!opts) {
         return -EINVAL;
     }
+    int r = qemu_read_config_opts(opts);
+    qemu_opts_del(opts);
+    return r;
 }
diff --git a/qemu-config.h b/qemu-config.h
index 20d707f..0e6ac15 100644
--- a/qemu-config.h
+++ b/qemu-config.h
@@ -14,6 +14,12 @@ 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);
+/* Read config from filename
+ */
+int qemu_read_config_filename(const char *filename);
+
+/* Read config based on key=value options using QemuOpts syntax
+ */
+int qemu_read_config_arg(const char *arg);
 
 #endif /* QEMU_CONFIG_H */
diff --git a/qemu-options.hx b/qemu-options.hx
index daefce3..caa4fe1 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -2655,9 +2655,9 @@ Old param mode (ARM only).
 ETEXI
 
 DEF("readconfig", HAS_ARG, QEMU_OPTION_readconfig,
-    "-readconfig <file>\n", QEMU_ARCH_ALL)
+    "-readconfig [path=]<file>\n", QEMU_ARCH_ALL)
 STEXI
-@item -readconfig @var{file}
+@item -readconfig [type=]@var{file}
 @findex -readconfig
 Read device configuration from @var{file}.
 ETEXI
diff --git a/vl.c b/vl.c
index bd95539..c3e60fa 100644
--- a/vl.c
+++ b/vl.c
@@ -2351,12 +2351,12 @@ 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_filename(CONFIG_QEMU_CONFDIR "/qemu.conf");
         if (ret < 0 && ret != -ENOENT) {
             exit(1);
         }
 
-        ret = qemu_read_config_file(arch_config_name);
+        ret = qemu_read_config_filename(arch_config_name);
         if (ret < 0 && ret != -ENOENT) {
             exit(1);
         }
@@ -3144,7 +3144,7 @@ int main(int argc, char **argv, char **envp)
             }
             case QEMU_OPTION_readconfig:
                 {
-                    int ret = qemu_read_config_file(optarg);
+                    int ret = qemu_read_config_arg(optarg);
                     if (ret < 0) {
                         fprintf(stderr, "read config %s: %s\n", optarg,
                             strerror(-ret));
-- 
1.7.3.2