gdbstub: Introduce GDBFeatureBuilder

GDBFeatureBuilder unifies the logic to generate dynamic GDBFeature.

Signed-off-by: Akihiko Odaki <akihiko.odaki@daynix.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20231025093128.33116-4-akihiko.odaki@daynix.com>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20231106185112.2755262-11-alex.bennee@linaro.org>

gdbstub/gdbstub.c

@@ -422,6 +422,71 @@ static const char *get_feature_xml(const char *p, const char **newp,
     return NULL;
 }
 
+void gdb_feature_builder_init(GDBFeatureBuilder *builder, GDBFeature *feature,
+                              const char *name, const char *xmlname,
+                              int base_reg)
+{
+    char *header = g_markup_printf_escaped(
+        "<?xml version=\"1.0\"?>"
+        "<!DOCTYPE feature SYSTEM \"gdb-target.dtd\">"
+        "<feature name=\"%s\">",
+        name);
+
+    builder->feature = feature;
+    builder->xml = g_ptr_array_new();
+    g_ptr_array_add(builder->xml, header);
+    builder->base_reg = base_reg;
+    feature->xmlname = xmlname;
+    feature->num_regs = 0;
+}
+
+void gdb_feature_builder_append_tag(const GDBFeatureBuilder *builder,
+                                    const char *format, ...)
+{
+    va_list ap;
+    va_start(ap, format);
+    g_ptr_array_add(builder->xml, g_markup_vprintf_escaped(format, ap));
+    va_end(ap);
+}
+
+void gdb_feature_builder_append_reg(const GDBFeatureBuilder *builder,
+                                    const char *name,
+                                    int bitsize,
+                                    int regnum,
+                                    const char *type,
+                                    const char *group)
+{
+    if (builder->feature->num_regs < regnum) {
+        builder->feature->num_regs = regnum;
+    }
+
+    if (group) {
+        gdb_feature_builder_append_tag(
+            builder,
+            "<reg name=\"%s\" bitsize=\"%d\" regnum=\"%d\" type=\"%s\" group=\"%s\"/>",
+            name, bitsize, builder->base_reg + regnum, type, group);
+    } else {
+        gdb_feature_builder_append_tag(
+            builder,
+            "<reg name=\"%s\" bitsize=\"%d\" regnum=\"%d\" type=\"%s\"/>",
+            name, bitsize, builder->base_reg + regnum, type);
+    }
+}
+
+void gdb_feature_builder_end(const GDBFeatureBuilder *builder)
+{
+    g_ptr_array_add(builder->xml, (void *)"</feature>");
+    g_ptr_array_add(builder->xml, NULL);
+
+    builder->feature->xml = g_strjoinv(NULL, (void *)builder->xml->pdata);
+
+    for (guint i = 0; i < builder->xml->len - 2; i++) {
+        g_free(g_ptr_array_index(builder->xml, i));
+    }
+
+    g_ptr_array_free(builder->xml, TRUE);
+}
+
 const GDBFeature *gdb_find_static_feature(const char *xmlname)
 {
     const GDBFeature *feature;

include/exec/gdbstub.h

@@ -16,6 +16,12 @@ typedef struct GDBFeature {
     int num_regs;
 } GDBFeature;
 
+typedef struct GDBFeatureBuilder {
+    GDBFeature *feature;
+    GPtrArray *xml;
+    int base_reg;
+} GDBFeatureBuilder;
+
 
 /* Get or set a register.  Returns the size of the register.  */
 typedef int (*gdb_get_reg_cb)(CPUArchState *env, GByteArray *buf, int reg);
@@ -44,6 +50,50 @@ void gdb_register_coprocessor(CPUState *cpu,
  */
 int gdbserver_start(const char *port_or_device);
 
+/**
+ * gdb_feature_builder_init() - Initialize GDBFeatureBuilder.
+ * @builder: The builder to be initialized.
+ * @feature: The feature to be filled.
+ * @name: The name of the feature.
+ * @xmlname: The name of the XML.
+ * @base_reg: The base number of the register ID.
+ */
+void gdb_feature_builder_init(GDBFeatureBuilder *builder, GDBFeature *feature,
+                              const char *name, const char *xmlname,
+                              int base_reg);
+
+/**
+ * gdb_feature_builder_append_tag() - Append a tag.
+ * @builder: The builder.
+ * @format: The format of the tag.
+ * @...: The values to be formatted.
+ */
+void G_GNUC_PRINTF(2, 3)
+gdb_feature_builder_append_tag(const GDBFeatureBuilder *builder,
+                               const char *format, ...);
+
+/**
+ * gdb_feature_builder_append_reg() - Append a register.
+ * @builder: The builder.
+ * @name: The register's name; it must be unique within a CPU.
+ * @bitsize: The register's size, in bits.
+ * @regnum: The offset of the register's number in the feature.
+ * @type: The type of the register.
+ * @group: The register group to which this register belongs; it can be NULL.
+ */
+void gdb_feature_builder_append_reg(const GDBFeatureBuilder *builder,
+                                    const char *name,
+                                    int bitsize,
+                                    int regnum,
+                                    const char *type,
+                                    const char *group);
+
+/**
+ * gdb_feature_builder_end() - End building GDBFeature.
+ * @builder: The builder.
+ */
+void gdb_feature_builder_end(const GDBFeatureBuilder *builder);
+
 /**
  * gdb_find_static_feature() - Find a static feature.
  * @xmlname: The name of the XML.