qemu-io: add command completion

Autocomplete qemu-io commands at the interactive prompt.

Note this only completes command names and not their options.
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

include/qemu-io.h

@@ -42,5 +42,8 @@ bool qemuio_command(BlockDriverState *bs, const char *cmd);
 
 void qemuio_add_command(const cmdinfo_t *ci);
 int qemuio_command_usage(const cmdinfo_t *ci);
+void qemuio_complete_command(const char *input,
+                             void (*fn)(const char *cmd, void *opaque),
+                             void *opaque);
 
 #endif /* QEMU_IO_H */

qemu-io-cmds.c

@@ -94,6 +94,21 @@ static const cmdinfo_t *find_command(const char *cmd)
     return NULL;
 }
 
+/* Invoke fn() for commands with a matching prefix */
+void qemuio_complete_command(const char *input,
+                             void (*fn)(const char *cmd, void *opaque),
+                             void *opaque)
+{
+    cmdinfo_t *ct;
+    size_t input_len = strlen(input);
+
+    for (ct = cmdtab; ct < &cmdtab[ncmds]; ct++) {
+        if (strncmp(input, ct->name, input_len) == 0) {
+            fn(ct->name, opaque);
+        }
+    }
+}
+
 static char **breakline(char *input, int *count)
 {
     int c = 0;

qemu-io.c

@@ -236,9 +236,15 @@ static void readline_func(void *opaque, const char *str, void *readline_opaque)
     *line = g_strdup(str);
 }
 
+static void completion_match(const char *cmd, void *opaque)
+{
+    readline_add_completion(readline_state, cmd);
+}
+
 static void readline_completion_func(void *opaque, const char *str)
 {
-    /* No command or argument completion implemented yet */
+    readline_set_completion_index(readline_state, strlen(str));
+    qemuio_complete_command(str, completion_match, NULL);
 }
 
 static char *fetchline_readline(void)