[PATCH v4 14/25] gdbstub: Dynamically allocate target.xml buffer

[Akihiko Odaki]

There is no guarantee that target.xml fits in 1024 bytes, and the fixed
buffer length requires tedious buffer overflow check. Dynamically
allocate the target.xml buffer to resolve these problems.

Suggested-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Akihiko Odaki <akihiko.odaki@daynix.com>
---
 gdbstub/internals.h |  2 +-
 gdbstub/gdbstub.c   | 44 ++++++++++++++++++++++++--------------------
 gdbstub/softmmu.c   |  2 +-
 3 files changed, 26 insertions(+), 22 deletions(-)

diff --git a/gdbstub/internals.h b/gdbstub/internals.h
index f2b46cce41..4876ebd74f 100644
--- a/gdbstub/internals.h
+++ b/gdbstub/internals.h
@@ -33,7 +33,7 @@ typedef struct GDBProcess {
     uint32_t pid;
     bool attached;
 
-    char target_xml[1024];
+    char *target_xml;
 } GDBProcess;
 
 enum RSState {
diff --git a/gdbstub/gdbstub.c b/gdbstub/gdbstub.c
index c2ce970c98..452b5bf0ef 100644
--- a/gdbstub/gdbstub.c
+++ b/gdbstub/gdbstub.c
@@ -366,33 +366,37 @@ static const char *get_feature_xml(const char *p, const 
char **newp,
 
     name = NULL;
     if (strncmp(p, "target.xml", len) == 0) {
-        char *buf = process->target_xml;
-        const size_t buf_sz = sizeof(process->target_xml);
-
         /* Generate the XML description for this CPU.  */
-        if (!buf[0]) {
+        if (!process->target_xml) {
+            g_autoptr(GPtrArray) a = g_ptr_array_new_with_free_func(g_free);
             GDBRegisterState *r;
 
-            pstrcat(buf, buf_sz,
-                    "<?xml version=\"1.0\"?>"
-                    "<!DOCTYPE target SYSTEM \"gdb-target.dtd\">"
-                    "<target>");
+            g_ptr_array_add(
+                a,
+                g_strdup("<?xml version=\"1.0\"?>"
+                         "<!DOCTYPE target SYSTEM \"gdb-target.dtd\">"
+                         "<target>"));
             if (cc->gdb_arch_name) {
-                pstrcat(buf, buf_sz, "<architecture>");
-                pstrcat(buf, buf_sz, cc->gdb_arch_name(cpu));
-                pstrcat(buf, buf_sz, "</architecture>");
+                g_ptr_array_add(
+                    a,
+                    g_markup_printf_escaped("<architecture>%s</architecture>",
+                                            cc->gdb_arch_name(cpu)));
             }
-            pstrcat(buf, buf_sz, "<xi:include href=\"");
-            pstrcat(buf, buf_sz, cc->gdb_core_feature->xmlname);
-            pstrcat(buf, buf_sz, "\"/>");
+            g_ptr_array_add(
+                a,
+                g_markup_printf_escaped("<xi:include href=\"%s\"/>",
+                                        cc->gdb_core_feature->xmlname));
             for (r = cpu->gdb_regs; r; r = r->next) {
-                pstrcat(buf, buf_sz, "<xi:include href=\"");
-                pstrcat(buf, buf_sz, r->feature->xmlname);
-                pstrcat(buf, buf_sz, "\"/>");
+                g_ptr_array_add(
+                    a,
+                    g_markup_printf_escaped("<xi:include href=\"%s\"/>",
+                                            r->feature->xmlname));
             }
-            pstrcat(buf, buf_sz, "</target>");
+            g_ptr_array_add(a, g_strdup("</target>"));
+            g_ptr_array_add(a, NULL);
+            process->target_xml = g_strjoinv(NULL, (void *)a->pdata);
         }
-        return buf;
+        return process->target_xml;
     }
     if (cc->gdb_get_dynamic_xml) {
         char *xmlname = g_strndup(p, len);
@@ -2270,6 +2274,6 @@ void gdb_create_default_process(GDBState *s)
     process = &s->processes[s->process_num - 1];
     process->pid = pid;
     process->attached = false;
-    process->target_xml[0] = '\0';
+    process->target_xml = NULL;
 }
 
diff --git a/gdbstub/softmmu.c b/gdbstub/softmmu.c
index f509b7285d..5282324764 100644
--- a/gdbstub/softmmu.c
+++ b/gdbstub/softmmu.c
@@ -293,7 +293,7 @@ static int find_cpu_clusters(Object *child, void *opaque)
         assert(cluster->cluster_id != UINT32_MAX);
         process->pid = cluster->cluster_id + 1;
         process->attached = false;
-        process->target_xml[0] = '\0';
+        process->target_xml = NULL;
 
         return 0;
     }
-- 
2.41.0