[Qemu-devel] [PATCH] char: don't exit on hmp 'chardev-add help'

[Anton Nefedov <anton.nefedov@virtuozzo.com>]

qemu_chr_new_from_opts() is used from both vl.c and hmp,
and it is quite confusing to see qemu suddenly exit after receiving a help
option in hmp.

Create a separate function for printing help and let different callers
react accordingly.

Signed-off-by: Anton Nefedov <anton.nefedov@virtuozzo.com>
---
 include/chardev/char.h |  9 +++++++++
 chardev/char.c         | 27 +++++++++++++++++++--------
 vl.c                   |  4 ++++
 3 files changed, 32 insertions(+), 8 deletions(-)

diff --git a/include/chardev/char.h b/include/chardev/char.h
index 1604ea9..461962b 100644
--- a/include/chardev/char.h
+++ b/include/chardev/char.h
@@ -59,6 +59,15 @@ struct Chardev {
 };
 
 /**
+ * @qemu_chr_help:
+ *
+ * Print available chardevice backends if 'asked for help' in @opts
+ *
+ * Returns: true if there was a help option
+ */
+bool qemu_chr_help(QemuOpts *opts);
+
+/**
  * @qemu_chr_new_from_opts:
  *
  * Create a new character backend from a QemuOpts list.
diff --git a/chardev/char.c b/chardev/char.c
index c34b44a..19833fe 100644
--- a/chardev/char.c
+++ b/chardev/char.c
@@ -604,14 +604,9 @@ ChardevBackend *qemu_chr_parse_opts(QemuOpts *opts, Error **errp)
     return backend;
 }
 
-Chardev *qemu_chr_new_from_opts(QemuOpts *opts, Error **errp)
+bool qemu_chr_help(QemuOpts *opts)
 {
-    const ChardevClass *cc;
-    Chardev *chr = NULL;
-    ChardevBackend *backend = NULL;
-    const char *name = chardev_alias_translate(qemu_opt_get(opts, "backend"));
-    const char *id = qemu_opts_id(opts);
-    char *bid = NULL;
+    const char *name = qemu_opt_get(opts, "backend");
 
     if (name && is_help_option(name)) {
         GString *str = g_string_new("");
@@ -620,7 +615,23 @@ Chardev *qemu_chr_new_from_opts(QemuOpts *opts, Error **errp)
 
         error_report("Available chardev backend types: %s", str->str);
         g_string_free(str, true);
-        exit(0);
+        return true;
+    }
+
+    return false;
+}
+
+Chardev *qemu_chr_new_from_opts(QemuOpts *opts, Error **errp)
+{
+    const ChardevClass *cc;
+    Chardev *chr = NULL;
+    ChardevBackend *backend = NULL;
+    const char *name = chardev_alias_translate(qemu_opt_get(opts, "backend"));
+    const char *id = qemu_opts_id(opts);
+    char *bid = NULL;
+
+    if (qemu_chr_help(opts)) {
+        return NULL;
     }
 
     if (id == NULL) {
diff --git a/vl.c b/vl.c
index fb6b2ef..7cad539 100644
--- a/vl.c
+++ b/vl.c
@@ -2344,6 +2344,10 @@ static int chardev_init_func(void *opaque, QemuOpts *opts, Error **errp)
 {
     Error *local_err = NULL;
 
+    if (qemu_chr_help(opts)) {
+        exit(0);
+    }
+
     qemu_chr_new_from_opts(opts, &local_err);
     if (local_err) {
         error_report_err(local_err);
-- 
2.7.4