qemu-char: Print strerror message on failure

The only way for chardev drivers to communicate an error was to return a NULL
pointer, which resulted in an error message that said _that_ something went
wrong, but not _why_.

This patch changes the interface to return 0/-errno and updates
qemu_chr_open_opts to use strerror to display a more helpful error message.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>

1 files changed, 5 insertions, 3 deletions

diff --git a/console.c b/console.c
index acd8ca162c..242086cf42 100644
--- a/console.c
+++ b/console.c
@@ -1514,7 +1514,7 @@ static void text_console_do_init(CharDriverState *chr, DisplayState *ds)
         chr->init(chr);
 }
 
-CharDriverState *text_console_init(QemuOpts *opts)
+int text_console_init(QemuOpts *opts, CharDriverState **_chr)
 {
     CharDriverState *chr;
     TextConsole *s;
@@ -1546,7 +1546,7 @@ CharDriverState *text_console_init(QemuOpts *opts)
 
     if (!s) {
         free(chr);
-        return NULL;
+        return -EBUSY;
     }
 
     s->chr = chr;
@@ -1554,7 +1554,9 @@ CharDriverState *text_console_init(QemuOpts *opts)
     s->g_height = height;
     chr->opaque = s;
     chr->chr_set_echo = text_console_set_echo;
-    return chr;
+
+    *_chr = chr;
+    return 0;
 }
 
 void text_consoles_set_display(DisplayState *ds)