[Qemu-devel] [PATCH 32/38] char: use a static array for backends

[Marc-André Lureau]

Number and kinds of backends is known at compile-time, use a fixed-sized
static array to simplify iterations & lookups.

Signed-off-by: Marc-André Lureau <address@hidden>
---
 backends/baum.c       |   2 +-
 backends/msmouse.c    |   2 +-
 backends/testdev.c    |   2 +-
 qemu-char.c           | 117 +++++++++++++++++++++++++++-----------------------
 spice-qemu-char.c     |   4 +-
 ui/console.c          |   2 +-
 include/sysemu/char.h |   2 +-
 7 files changed, 70 insertions(+), 61 deletions(-)

diff --git a/backends/baum.c b/backends/baum.c
index 4fe11de..0a65c99 100644
--- a/backends/baum.c
+++ b/backends/baum.c
@@ -644,7 +644,7 @@ fail_handle:
 static void register_types(void)
 {
     static const CharDriver driver = {
-        "braille", CHARDEV_BACKEND_KIND_BRAILLE, NULL, chr_baum_init
+        { "braille" }, CHARDEV_BACKEND_KIND_BRAILLE, NULL, chr_baum_init
     };
 
     register_char_driver(&driver);
diff --git a/backends/msmouse.c b/backends/msmouse.c
index d6ab4ca..3367d67 100644
--- a/backends/msmouse.c
+++ b/backends/msmouse.c
@@ -180,7 +180,7 @@ static CharDriverState *qemu_chr_open_msmouse(const char 
*id,
 static void register_types(void)
 {
     static const CharDriver driver = {
-        "msmouse", CHARDEV_BACKEND_KIND_MSMOUSE, NULL, qemu_chr_open_msmouse
+        { "msmouse" }, CHARDEV_BACKEND_KIND_MSMOUSE, NULL, 
qemu_chr_open_msmouse
     };
     register_char_driver(&driver);
 }
diff --git a/backends/testdev.c b/backends/testdev.c
index 5936189..d41352a 100644
--- a/backends/testdev.c
+++ b/backends/testdev.c
@@ -131,7 +131,7 @@ static CharDriverState *chr_testdev_init(const char *id,
 static void register_types(void)
 {
     static const CharDriver driver = {
-        "testdev", CHARDEV_BACKEND_KIND_TESTDEV, NULL, chr_testdev_init
+        { "testdev" }, CHARDEV_BACKEND_KIND_TESTDEV, NULL, chr_testdev_init
     };
     register_char_driver(&driver);
 }
diff --git a/qemu-char.c b/qemu-char.c
index 594e795..7348cb0 100644
--- a/qemu-char.c
+++ b/qemu-char.c
@@ -4042,20 +4042,20 @@ static void qemu_chr_parse_udp(QemuOpts *opts, 
ChardevBackend *backend,
     }
 }
 
-static GSList *backends;
+static const CharDriver *backends[CHARDEV_BACKEND_KIND__MAX];
 
 void register_char_driver(const CharDriver *driver)
 {
-    backends = g_slist_append(backends, (void *)driver);
+    backends[driver->kind] = driver;
 }
 
 CharDriverState *qemu_chr_new_from_opts(QemuOpts *opts,
                                         Error **errp)
 {
     Error *local_err = NULL;
-    CharDriver *cd;
+    const CharDriver *cd;
     CharDriverState *chr;
-    GSList *i;
+    int i;
     ChardevReturn *ret = NULL;
     ChardevBackend *backend;
     const char *id = qemu_opts_id(opts);
@@ -4069,9 +4069,14 @@ CharDriverState *qemu_chr_new_from_opts(QemuOpts *opts,
 
     if (is_help_option(qemu_opt_get(opts, "backend"))) {
         fprintf(stderr, "Available chardev backend types:\n");
-        for (i = backends; i; i = i->next) {
-            cd = i->data;
-            fprintf(stderr, "%s\n", cd->name);
+        for (i = 0; i < ARRAY_SIZE(backends); i++) {
+            cd = backends[i];
+            if (cd) {
+                fprintf(stderr, "%s\n", cd->name[0]);
+                if (cd->name[1]) {
+                    fprintf(stderr, "%s\n", cd->name[1]);
+                }
+            }
         }
         exit(!is_help_option(qemu_opt_get(opts, "backend")));
     }
@@ -4081,14 +4086,17 @@ CharDriverState *qemu_chr_new_from_opts(QemuOpts *opts,
         goto err;
     }
 
-    for (i = backends; i; i = i->next) {
-        cd = i->data;
+    cd = NULL;
+    for (i = 0; i < ARRAY_SIZE(backends); i++) {
+        const char *name = qemu_opt_get(opts, "backend");
+        cd = backends[i];
 
-        if (strcmp(cd->name, qemu_opt_get(opts, "backend")) == 0) {
+        if (cd && (g_str_equal(cd->name[0], name) ||
+                   (cd->name[1] && g_str_equal(cd->name[1], name)))) {
             break;
         }
     }
-    if (i == NULL) {
+    if (cd == NULL) {
         error_setg(errp, "chardev: backend \"%s\" not found",
                    qemu_opt_get(opts, "backend"));
         goto err;
@@ -4293,20 +4301,32 @@ ChardevInfoList *qmp_query_chardev(Error **errp)
     return chr_list;
 }
 
+static ChardevBackendInfoList *
+qmp_prepend_backend(ChardevBackendInfoList *list, const CharDriver *c,
+                    const char *name)
+{
+    ChardevBackendInfoList *info = g_malloc0(sizeof(*info));
+    info->value = g_malloc0(sizeof(*info->value));
+    info->value->name = g_strdup(name);
+    info->next = list;
+    return info;
+
+}
+
 ChardevBackendInfoList *qmp_query_chardev_backends(Error **errp)
 {
     ChardevBackendInfoList *backend_list = NULL;
-    CharDriver *c = NULL;
-    GSList *i = NULL;
-
-    for (i = backends; i; i = i->next) {
-        ChardevBackendInfoList *info = g_malloc0(sizeof(*info));
-        c = i->data;
-        info->value = g_malloc0(sizeof(*info->value));
-        info->value->name = g_strdup(c->name);
+    const CharDriver *c;
+    int i;
 
-        info->next = backend_list;
-        backend_list = info;
+    for (i = 0; i < ARRAY_SIZE(backends); i++) {
+        c = backends[i];
+        if (c) {
+            backend_list = qmp_prepend_backend(backend_list, c, c->name[0]);
+            if (c->name[1]) {
+                backend_list = qmp_prepend_backend(backend_list, c, 
c->name[1]);
+            }
+        }
     }
 
     return backend_list;
@@ -4746,9 +4766,8 @@ ChardevReturn *qmp_chardev_add(const char *id, 
ChardevBackend *backend,
 {
     ChardevReturn *ret = g_new0(ChardevReturn, 1);
     CharDriverState *chr = NULL;
+    const CharDriver *cd;
     Error *local_err = NULL;
-    GSList *i;
-    CharDriver *cd;
     bool be_opened = true;
 
     chr = qemu_chr_find(id);
@@ -4757,22 +4776,16 @@ ChardevReturn *qmp_chardev_add(const char *id, 
ChardevBackend *backend,
         goto out_error;
     }
 
-    for (i = backends; i; i = i->next) {
-        cd = i->data;
-
-        if (cd->kind == backend->type) {
-            chr = cd->create(id, backend, ret, &be_opened, &local_err);
-            if (local_err) {
-                error_propagate(errp, local_err);
-                goto out_error;
-            }
-            break;
-        }
+    cd = (int)backend->type >= 0 && backend->type < ARRAY_SIZE(backends) ?
+        backends[backend->type] : NULL;
+    if (cd == NULL) {
+        error_setg(errp, "chardev backend not available");
+        goto out_error;
     }
 
-    if (chr == NULL) {
-        assert(!i);
-        error_setg(errp, "chardev backend not available");
+    chr = cd->create(id, backend, ret, &be_opened, &local_err);
+    if (local_err) {
+        error_propagate(errp, local_err);
         goto out_error;
     }
 
@@ -4825,42 +4838,38 @@ static void register_types(void)
 {
     int i;
     static const CharDriver drivers[] = {
-        { "null", CHARDEV_BACKEND_KIND_NULL, NULL, qemu_chr_open_null },
-        { "socket", CHARDEV_BACKEND_KIND_SOCKET,
+        { { "null" }, CHARDEV_BACKEND_KIND_NULL, NULL, qemu_chr_open_null },
+        { { "socket" }, CHARDEV_BACKEND_KIND_SOCKET,
           qemu_chr_parse_socket, qmp_chardev_open_socket },
-        { "udp", CHARDEV_BACKEND_KIND_UDP, qemu_chr_parse_udp,
+        { { "udp" }, CHARDEV_BACKEND_KIND_UDP, qemu_chr_parse_udp,
           qmp_chardev_open_udp },
-        { "ringbuf", CHARDEV_BACKEND_KIND_RINGBUF,
+        { { "ringbuf" }, CHARDEV_BACKEND_KIND_RINGBUF,
           qemu_chr_parse_ringbuf, qemu_chr_open_ringbuf },
-        { "file", CHARDEV_BACKEND_KIND_FILE,
+        { { "file" }, CHARDEV_BACKEND_KIND_FILE,
           qemu_chr_parse_file_out, qmp_chardev_open_file },
-        { "stdio", CHARDEV_BACKEND_KIND_STDIO,
+        { { "stdio" }, CHARDEV_BACKEND_KIND_STDIO,
           qemu_chr_parse_stdio, qemu_chr_open_stdio },
 #if defined HAVE_CHARDEV_SERIAL
-        { "serial", CHARDEV_BACKEND_KIND_SERIAL,
-          qemu_chr_parse_serial, qmp_chardev_open_serial },
-        { "tty", CHARDEV_BACKEND_KIND_SERIAL,
+        { { "serial", "tty" }, CHARDEV_BACKEND_KIND_SERIAL,
           qemu_chr_parse_serial, qmp_chardev_open_serial },
 #endif
 #ifdef HAVE_CHARDEV_PARPORT
-        { "parallel", CHARDEV_BACKEND_KIND_PARALLEL,
-          qemu_chr_parse_parallel, qmp_chardev_open_parallel },
-        { "parport", CHARDEV_BACKEND_KIND_PARALLEL,
+        { { "parallel", "parport" }, CHARDEV_BACKEND_KIND_PARALLEL,
           qemu_chr_parse_parallel, qmp_chardev_open_parallel },
 #endif
 #ifdef HAVE_CHARDEV_PTY
-        { "pty", CHARDEV_BACKEND_KIND_PTY, NULL, qemu_chr_open_pty },
+        { { "pty" }, CHARDEV_BACKEND_KIND_PTY, NULL, qemu_chr_open_pty },
 #endif
 #ifdef _WIN32
-        { "console", CHARDEV_BACKEND_KIND_CONSOLE, NULL,
+        { { "console" }, CHARDEV_BACKEND_KIND_CONSOLE, NULL,
           qemu_chr_open_win_con },
 #endif
-        { "pipe", CHARDEV_BACKEND_KIND_PIPE,
+        { { "pipe" }, CHARDEV_BACKEND_KIND_PIPE,
           qemu_chr_parse_pipe, qemu_chr_open_pipe },
-        { "mux", CHARDEV_BACKEND_KIND_MUX, qemu_chr_parse_mux,
+        { { "mux" }, CHARDEV_BACKEND_KIND_MUX, qemu_chr_parse_mux,
           qemu_chr_open_mux },
         /* Bug-compatibility: */
-        { "memory", CHARDEV_BACKEND_KIND_MEMORY,
+        { { "memory" }, CHARDEV_BACKEND_KIND_MEMORY,
           qemu_chr_parse_ringbuf, qemu_chr_open_ringbuf },
     };
 
diff --git a/spice-qemu-char.c b/spice-qemu-char.c
index 7ce8527..3172461 100644
--- a/spice-qemu-char.c
+++ b/spice-qemu-char.c
@@ -390,11 +390,11 @@ static void qemu_chr_parse_spice_port(QemuOpts *opts, 
ChardevBackend *backend,
 static void register_types(void)
 {
     static const CharDriver vmc_driver = {
-        "spicevmc", CHARDEV_BACKEND_KIND_SPICEVMC,
+        { "spicevmc" }, CHARDEV_BACKEND_KIND_SPICEVMC,
         qemu_chr_parse_spice_vmc, qemu_chr_open_spice_vmc
     };
     static const CharDriver port_driver = {
-        "spiceport", CHARDEV_BACKEND_KIND_SPICEPORT,
+        { "spiceport" }, CHARDEV_BACKEND_KIND_SPICEPORT,
         qemu_chr_parse_spice_port, qemu_chr_open_spice_port
     };
     register_char_driver(&vmc_driver);
diff --git a/ui/console.c b/ui/console.c
index a65223a..4e31cf2 100644
--- a/ui/console.c
+++ b/ui/console.c
@@ -2183,7 +2183,7 @@ static const TypeInfo qemu_console_info = {
 static void register_types(void)
 {
     static const CharDriver vc_driver = {
-        "vc", CHARDEV_BACKEND_KIND_VC, qemu_chr_parse_vc, vc_init
+        { "vc" }, CHARDEV_BACKEND_KIND_VC, qemu_chr_parse_vc, vc_init
     };
 
     type_register_static(&qemu_console_info);
diff --git a/include/sysemu/char.h b/include/sysemu/char.h
index 6a4b3ef..ee5618b 100644
--- a/include/sysemu/char.h
+++ b/include/sysemu/char.h
@@ -474,7 +474,7 @@ void qemu_chr_set_feature(CharDriverState *chr,
 QemuOpts *qemu_chr_parse_compat(const char *label, const char *filename);
 
 typedef struct CharDriver {
-    const char *name;
+    const char *name[2]; /* name & opt alias */
     ChardevBackendKind kind;
     void (*parse)(QemuOpts *opts, ChardevBackend *backend, Error **errp);
     CharDriverState *(*create)(const char *id,
-- 
2.10.0