[Qemu-devel] [PATCH for-2.7 v2 2/3] vl: Table-based select_vgahw()

[Eduardo Habkost <ehabkost@redhat.com>]

Instead of implementing separate check functions for each vga
interface type, add a table enumerating the possible VGA
interfaces.

Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
---
Changes v1 -> v2:
* Keep assert(vga_interface_type == VGA_NONE) line
  Suggested-by: Eric Blake <eblake@redhat.com>
* Fix spacing on select_vgahw() definition
  Suggested-by: Eric Blake <eblake@redhat.com>
---
 include/sysemu/sysemu.h |   1 +
 vl.c                    | 115 ++++++++++++++++++++++++++----------------------
 2 files changed, 64 insertions(+), 52 deletions(-)

diff --git a/include/sysemu/sysemu.h b/include/sysemu/sysemu.h
index 38fb3ca..2033f8c 100644
--- a/include/sysemu/sysemu.h
+++ b/include/sysemu/sysemu.h
@@ -146,6 +146,7 @@ extern int autostart;
 typedef enum {
     VGA_NONE, VGA_STD, VGA_CIRRUS, VGA_VMWARE, VGA_XENFB, VGA_QXL,
     VGA_TCX, VGA_CG3, VGA_DEVICE, VGA_VIRTIO,
+    VGA_TYPE_MAX,
 } VGAInterfaceType;
 
 extern int vga_interface_type;
diff --git a/vl.c b/vl.c
index 3c565bb..b99f22f 100644
--- a/vl.c
+++ b/vl.c
@@ -2015,63 +2015,74 @@ static bool virtio_vga_available(void)
     return object_class_by_name("virtio-vga");
 }
 
-static void select_vgahw (const char *p)
+typedef struct VGAInterfaceInfo {
+    const char *opt_name;    /* option name */
+    const char *name;        /* human-readable name */
+    bool (*available)(void);
+} VGAInterfaceInfo;
+
+static VGAInterfaceInfo vga_interfaces[VGA_TYPE_MAX] = {
+    [VGA_NONE] = {
+        .opt_name = "none",
+    },
+    [VGA_STD] = {
+        .opt_name = "std",
+        .name = "standard VGA",
+        .available = vga_available,
+    },
+    [VGA_CIRRUS] = {
+        .opt_name = "cirrus",
+        .name = "Cirrus VGA",
+        .available = cirrus_vga_available,
+    },
+    [VGA_VMWARE] = {
+        .opt_name = "vmware",
+        .name = "VMWare SVGA",
+        .available = vmware_vga_available,
+    },
+    [VGA_VIRTIO] = {
+        .opt_name = "virtio",
+        .name = "Virtio VGA",
+        .available = virtio_vga_available,
+    },
+    [VGA_QXL] = {
+        .opt_name = "qxl",
+        .name = "QXL VGA",
+        .available = qxl_vga_available,
+    },
+    [VGA_TCX] = {
+        .opt_name = "tcx",
+        .name = "TCX framebuffer",
+        .available = tcx_vga_available,
+    },
+    [VGA_CG3] = {
+        .opt_name = "cg3",
+        .name = "CG3 framebuffer",
+        .available = cg3_vga_available,
+    },
+    [VGA_XENFB] = {
+        .opt_name = "xenfb",
+    },
+};
+
+static void select_vgahw(const char *p)
 {
     const char *opts;
+    int t;
 
     assert(vga_interface_type == VGA_NONE);
-    if (strstart(p, "std", &opts)) {
-        if (vga_available()) {
-            vga_interface_type = VGA_STD;
-        } else {
-            error_report("standard VGA not available");
-            exit(1);
-        }
-    } else if (strstart(p, "cirrus", &opts)) {
-        if (cirrus_vga_available()) {
-            vga_interface_type = VGA_CIRRUS;
-        } else {
-            error_report("Cirrus VGA not available");
-            exit(1);
-        }
-    } else if (strstart(p, "vmware", &opts)) {
-        if (vmware_vga_available()) {
-            vga_interface_type = VGA_VMWARE;
-        } else {
-            error_report("VMWare SVGA not available");
-            exit(1);
-        }
-    } else if (strstart(p, "virtio", &opts)) {
-        if (virtio_vga_available()) {
-            vga_interface_type = VGA_VIRTIO;
-        } else {
-            error_report("Virtio VGA not available");
-            exit(1);
-        }
-    } else if (strstart(p, "xenfb", &opts)) {
-        vga_interface_type = VGA_XENFB;
-    } else if (strstart(p, "qxl", &opts)) {
-        if (qxl_vga_available()) {
-            vga_interface_type = VGA_QXL;
-        } else {
-            error_report("QXL VGA not available");
-            exit(1);
-        }
-    } else if (strstart(p, "tcx", &opts)) {
-        if (tcx_vga_available()) {
-            vga_interface_type = VGA_TCX;
-        } else {
-            error_report("TCX framebuffer not available");
-            exit(1);
-        }
-    } else if (strstart(p, "cg3", &opts)) {
-        if (cg3_vga_available()) {
-            vga_interface_type = VGA_CG3;
-        } else {
-            error_report("CG3 framebuffer not available");
-            exit(1);
+    for (t = 0; t < VGA_TYPE_MAX; t++) {
+        VGAInterfaceInfo *ti = &vga_interfaces[t];
+        if (ti->opt_name && strstart(p, ti->opt_name, &opts)) {
+            if (ti->available && !ti->available()) {
+                error_report("%s not available", ti->name);
+                exit(1);
+            }
+            vga_interface_type = t;
+            break;
         }
-    } else if (!strstart(p, "none", &opts)) {
+    }
+    if (t == VGA_TYPE_MAX) {
     invalid_vga:
         error_report("unknown vga type: %s", p);
         exit(1);
-- 
2.1.0