[PATCH 10/12] target-info: add -target and program-name selection

- Parse -target before TargetInfo is fixed; CLI overrides the program
  basename.
- Tokens are target_name or target_name-be / -le; -target help lists
  registered names in sorted order.
- When -target is omitted, infer the token from g_get_prgname(): strip
  .exe, take the longest dash-separated registered suffix, and retry
  without a trailing w for Windows GUI binaries.
- A basename that matches no registered token falls through to the
  unique default. Combined binaries with no suffix require -target
  when more than one default TargetInfo is registered.

Signed-off-by: Yonggang Luo <[email protected]>
---
 include/qemu/target-info-qom.h |  10 +-
 qemu-options.hx                |  13 +++
 system/vl.c                    |  28 ++++--
 target-info-qom.c              | 167 ++++++++++++++++++++++++++++++---
 tests/qtest/fuzz/fuzz.c        |   2 +-
 5 files changed, 197 insertions(+), 23 deletions(-)

diff --git a/include/qemu/target-info-qom.h b/include/qemu/target-info-qom.h
index 842cf241e0a..3b59cf82d65 100644
--- a/include/qemu/target-info-qom.h
+++ b/include/qemu/target-info-qom.h
@@ -40,7 +40,15 @@ typedef struct TargetInfoQomClass {
 
 OBJECT_DECLARE_TYPE(TargetInfoQom, TargetInfoQomClass, TARGET_INFO)
 
-void target_info_qom_set_target(void);
+/**
+ * target_info_qom_set_target:
+ * @name: -target token, or NULL/%empty to infer from the program
+ * basename or the unique default
+ *
+ * Tokens are target_name (arch default endian) or target_name-be /
+ * target_name-le. -target overrides the program basename.
+ */
+void target_info_qom_set_target(const char *name);
 
 /**
  * get_machine_types_available:
diff --git a/qemu-options.hx b/qemu-options.hx
index 34970fffc94..638b531aa49 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -223,6 +223,19 @@ SRST
     as -machine.
 ERST
 
+DEF("target", HAS_ARG, QEMU_OPTION_target,
+    "-target name    select target ('-target help' for list)\n", QEMU_ARCH_ALL)
+SRST
+``-target name``
+    Select the emulation target (``-target help`` for the list). The
+    default endian is the architecture default (``riscv64`` is little
+    endian). The other endian uses a ``-be`` or ``-le`` suffix
+    (``riscv64-be``, ``ppc64-le``). If omitted, a matching suffix of
+    the program basename is used (``qemu-system-riscv64-be``, and
+    ``qemu-system-aarch64w.exe`` on Windows). ``-target`` overrides
+    the program name.
+ERST
+
 DEF("cpu", HAS_ARG, QEMU_OPTION_cpu,
     "-cpu cpu        select CPU ('-cpu help' for list)\n", QEMU_ARCH_ALL)
 SRST
diff --git a/system/vl.c b/system/vl.c
index 83b9425de9b..405f434e036 100644
--- a/system/vl.c
+++ b/system/vl.c
@@ -166,6 +166,7 @@ typedef struct DeviceOption {
     QTAILQ_ENTRY(DeviceOption) next;
 } DeviceOption;
 
+static const char *target_option;
 static const char *cpu_option;
 static const char *mem_path;
 static const char *incoming;
@@ -2899,19 +2900,12 @@ void qemu_init(int argc, char **argv)
 
     os_setup_limits();
 
-    module_call_init(MODULE_INIT_TARGET_INFO);
-    target_info_qom_set_target();
-
-    module_init_info(qemu_modinfo);
-    module_allow_arch(target_name());
-
-    qemu_init_subsystems();
-
-    /* first pass of option parsing */
+    /*
+     * First pass: options needed before TargetInfo is fixed.
+     */
     optind = 1;
     while (optind < argc) {
         if (argv[optind][0] != '-') {
-            /* disk image */
             optind++;
         } else {
             const QEMUOption *popt;
@@ -2921,10 +2915,21 @@ void qemu_init(int argc, char **argv)
             case QEMU_OPTION_nouserconfig:
                 userconfig = false;
                 break;
+            case QEMU_OPTION_target:
+                target_option = optarg;
+                break;
             }
         }
     }
 
+    module_call_init(MODULE_INIT_TARGET_INFO);
+    target_info_qom_set_target(target_option);
+
+    module_init_info(qemu_modinfo);
+    module_allow_arch(target_name());
+
+    qemu_init_subsystems();
+
     machine_opts_dict = qdict_new();
     if (userconfig) {
         qemu_read_default_config_file(&error_fatal);
@@ -3687,6 +3692,9 @@ void qemu_init(int argc, char **argv)
             case QEMU_OPTION_nouserconfig:
                 /* Nothing to be parsed here. Especially, do not error out below. */
                 break;
+            case QEMU_OPTION_target:
+                /* Parsed before TargetInfo is selected. */
+                break;
 #if defined(CONFIG_POSIX) && !defined(EMSCRIPTEN)
             case QEMU_OPTION_daemonize:
                 os_set_daemonize(true);
diff --git a/target-info-qom.c b/target-info-qom.c
index 2c1c57b05fd..be03573a699 100644
--- a/target-info-qom.c
+++ b/target-info-qom.c
@@ -7,6 +7,7 @@
  */
 
 #include "qemu/osdep.h"
+#include "qemu/help_option.h"
 #include "qapi/error.h"
 #include "qom/object.h"
 #include "qemu/target-info-impl.h"
@@ -87,7 +88,139 @@ const TargetInfo *target_info(void)
     return target_info_ptr;
 }
 
-void target_info_qom_set_target(void)
+static const TargetInfo *target_info_from_class(ObjectClass *oc)
+{
+    return TARGET_INFO_CLASS(oc)->target_info;
+}
+
+/* Default token is target_name; the other endian is target_name-le or -be. */
+static char *target_info_option_name(const TargetInfo *ti)
+{
+    if (ti->is_default) {
+        return g_strdup(ti->target_name);
+    }
+    if (ti->endianness == ENDIAN_MODE_BIG) {
+        return g_strdup_printf("%s-be", ti->target_name);
+    }
+    return g_strdup_printf("%s-le", ti->target_name);
+}
+
+static gint target_info_token_name_cmp(gconstpointer a, gconstpointer b,
+                                       gpointer data)
+{
+    const TargetInfo *ta = target_info_from_class((ObjectClass *)a);
+    const TargetInfo *tb = target_info_from_class((ObjectClass *)b);
+    g_autofree char *na = target_info_option_name(ta);
+    g_autofree char *nb = target_info_option_name(tb);
+
+    return strcmp(na, nb);
+}
+
+static void G_NORETURN target_info_list_and_exit(GSList *targets)
+{
+    printf("Supported targets:\n");
+    for (GSList *l = targets; l; l = l->next) {
+        const TargetInfo *ti = target_info_from_class(l->data);
+        g_autofree char *opt_name = target_info_option_name(ti);
+
+        printf("  %s%s\n", opt_name, ti->is_default ? " (default)" : "");
+    }
+    exit(0);
+}
+
+static const TargetInfo *target_info_find_default(GSList *targets,
+                                                  size_t *num_default)
+{
+    const TargetInfo *chosen = NULL;
+
+    *num_default = 0;
+    for (GSList *l = targets; l; l = l->next) {
+        const TargetInfo *ti = target_info_from_class(l->data);
+
+        if (ti->is_default) {
+            (*num_default)++;
+            chosen = ti;
+        }
+    }
+    return chosen;
+}
+
+static const TargetInfo *target_info_find_token(GSList *targets,
+                                                const char *token)
+{
+    for (GSList *l = targets; l; l = l->next) {
+        const TargetInfo *ti = target_info_from_class(l->data);
+        g_autofree char *opt_name = target_info_option_name(ti);
+
+        if (!strcmp(opt_name, token)) {
+            return ti;
+        }
+    }
+    return NULL;
+}
+
+static bool target_info_base_match_token(const char *base, const char *token)
+{
+    size_t nlen = strlen(token);
+    size_t blen;
+
+    if (!base || !token[0] || !g_str_has_suffix(base, token)) {
+        return false;
+    }
+    blen = strlen(base);
+    return blen == nlen || base[blen - nlen - 1] == '-';
+}
+
+static const TargetInfo *target_info_find_prgname(GSList *targets,
+                                                  const char *base)
+{
+    const TargetInfo *chosen = NULL;
+    size_t best_len = 0;
+
+    if (!base || !base[0]) {
+        return NULL;
+    }
+
+    for (GSList *l = targets; l; l = l->next) {
+        const TargetInfo *ti = target_info_from_class(l->data);
+        g_autofree char *opt_name = target_info_option_name(ti);
+        size_t nlen = strlen(opt_name);
+
+        if (nlen > best_len &&
+            target_info_base_match_token(base, opt_name)) {
+            chosen = ti;
+            best_len = nlen;
+        }
+    }
+    return chosen;
+}
+
+static const TargetInfo *target_info_from_prgname(GSList *targets)
+{
+    const char *prg = g_get_prgname();
+    g_autofree char *base = NULL;
+    char *dot;
+    const TargetInfo *chosen;
+
+    if (!prg || !prg[0]) {
+        return NULL;
+    }
+
+    base = g_path_get_basename(prg);
+    dot = strrchr(base, '.');
+    if (dot && g_ascii_strcasecmp(dot, ".exe") == 0) {
+        *dot = '\0';
+    }
+
+    chosen = target_info_find_prgname(targets, base);
+    if (!chosen && strlen(base) > 1 && g_str_has_suffix(base, "w")) {
+        base[strlen(base) - 1] = '\0';
+        chosen = target_info_find_prgname(targets, base);
+    }
+    return chosen;
+}
+
+void target_info_qom_set_target(const char *name)
 {
     g_autoptr(GSList) targets = object_class_get_list(TYPE_TARGET_INFO, false);
     const TargetInfo *chosen = NULL;
@@ -98,25 +231,37 @@ void target_info_qom_set_target(void)
         error_setg(&error_fatal, "no target-info is available");
     }
 
-    if (num_found == 1) {
-        target_info_ptr = TARGET_INFO_CLASS(targets->data)->target_info;
+    if (name && is_help_option(name)) {
+        targets = g_slist_sort_with_data(targets, target_info_token_name_cmp,
+                                         NULL);
+        target_info_list_and_exit(targets);
+    }
+
+    if (name && name[0]) {
+        chosen = target_info_find_token(targets, name);
+        if (!chosen) {
+            error_setg(&error_fatal, "unknown target '%s'", name);
+        }
+        target_info_ptr = chosen;
         return;
     }
 
-    for (GSList *l = targets; l; l = l->next) {
-        const TargetInfo *ti = TARGET_INFO_CLASS(l->data)->target_info;
+    chosen = target_info_from_prgname(targets);
+    if (chosen) {
+        target_info_ptr = chosen;
+        return;
+    }
 
-        if (ti->is_default) {
-            num_default++;
-            chosen = ti;
-        }
+    if (num_found == 1) {
+        target_info_ptr = target_info_from_class(targets->data);
+        return;
     }
 
+    chosen = target_info_find_default(targets, &num_default);
     if (num_default != 1) {
         error_setg(&error_fatal, num_default == 0 ?
                                  "no default target-info is available" :
-                                 "more than one default target-info "
-                                 "is available");
+                                 "multiple default targets; use -target");
     }
 
     target_info_ptr = chosen;
diff --git a/tests/qtest/fuzz/fuzz.c b/tests/qtest/fuzz/fuzz.c
index a3a131c80f8..489c7138bb9 100644
--- a/tests/qtest/fuzz/fuzz.c
+++ b/tests/qtest/fuzz/fuzz.c
@@ -174,7 +174,7 @@ int LLVMFuzzerInitialize(int *argc, char ***argv, char ***envp)
     /* Initialize qgraph and modules */
     qos_graph_init();
     module_call_init(MODULE_INIT_TARGET_INFO);
-    target_info_qom_set_target();
+    target_info_qom_set_target(NULL);
     module_call_init(MODULE_INIT_FUZZ_TARGET);
     module_call_init(MODULE_INIT_QOM);
     module_call_init(MODULE_INIT_LIBQOS);
-- 
2.52.0.windows.1