Add support for varargs length in utf8 printf

renderdoc/common/formatting.h

@@ -38,8 +38,9 @@ struct Args
   virtual unsigned int get_uint() = 0;
   virtual double get_double() = 0;
   virtual void *get_ptr() = 0;
+  virtual const char *get_str() = 0;
   virtual uint64_t get_uint64() = 0;
-  virtual size_t get_size() = 0;
+  size_t get_size() { return sizeof(size_t) == 8 ? (size_t)get_uint64() : get_uint(); }
 };
 
 rdcstr Fmt(const char *format, ...);

renderdoc/driver/vulkan/vk_shader_feedback.cpp

@@ -145,6 +145,11 @@ public:
     m_Idx++;
     return NULL;
   }
+  const char *get_str() override
+  {
+    m_Idx++;
+    return NULL;
+  }
   uint64_t get_uint64() override
   {
     uint64_t ret = *(uint64_t *)m_Cur;
@@ -153,7 +158,6 @@ public:
     return ret;
   }
 
-  size_t get_size() override { return sizeof(size_t) == 8 ? (size_t)get_uint64() : get_uint(); }
   rdcstr get_error() { return m_Error; }
 private:
   const uint32_t *m_Cur;

renderdoc/strings/utf8printf.cpp

@@ -157,9 +157,12 @@ struct FormatterParams
   int Precision;
   LengthModifier Length;
 
-  static const int NoWidth = -1;    // can't set negative width, so -1 indicates no width specified
-  static const int NoPrecision =
-      -1;    // can't set negative precision, so -1 indicates no precision specified
+  // can't set negative width, so -1 indicates no width specified
+  static const int NoWidth = -1;
+  // can't set negative precision, so -1 indicates no precision specified
+  static const int NoPrecision = -1;
+  // VarArgs precision - for %.*s strings
+  static const int VarPrecision = -2;
 };
 
 ///////////////////////////////////////////////////////////////////////////////
@@ -1447,6 +1450,11 @@ inline void *custom_arg_getter::get_next<void *>()
   return formatter.get_ptr();
 }
 template <>
+inline const char *custom_arg_getter::get_next<const char *>()
+{
+  return formatter.get_str();
+}
+template <>
 inline uint64_t custom_arg_getter::get_next<uint64_t>()
 {
   return formatter.get_uint64();
@@ -1589,10 +1597,10 @@ int utf8print_template(char *buf, size_t bufsize, const char *fmt, arg_getter ar
       {
         iter++;
 
-        // note standard printf supports * here to read precision from a vararg
         if(*iter == '*')
         {
-          RDCDUMPMSG("Unexpected character * expecting precision");
+          formatter.Precision = FormatterParams::VarPrecision;
+          iter++;
         }
         // if there's no value for the precision, it is 0
         else if(*iter < '0' || *iter > '9')
@@ -1676,11 +1684,19 @@ int utf8print_template(char *buf, size_t bufsize, const char *fmt, arg_getter ar
       int *i = (int *)arg;
       *i = args.template get_next<int>();
     }
-    else if(type == 's' || type == 'p')
+    else if(type == 'p')
     {
       void **p = (void **)arg;
       *p = args.template get_next<void *>();
     }
+    else if(type == 's')
+    {
+      if(formatter.Precision == FormatterParams::VarPrecision)
+        formatter.Precision = (int)args.template get_next<unsigned int>();
+
+      const char **p = (const char **)arg;
+      *p = args.template get_next<const char *>();
+    }
     else if(type == 'e' || type == 'E' || type == 'f' || type == 'F' || type == 'g' ||
             type == 'G' || type == 'a' || type == 'A')
     {
@@ -2006,6 +2022,12 @@ TEST_CASE("utf8printf standard string formatters", "[utf8printf]")
     // these string constants take 2 bytes for each code point in UTF-8, so it's 8 bytes for 4 chars
     CHECK(StringFormat::Fmt("%.4s", s.c_str()) == s.substr(0, 8));
     CHECK(StringFormat::Fmt("%.4ls", ws.c_str()) == s.substr(0, 8));
+
+    CHECK(StringFormat::Fmt("%.*s", 4, "foobar") == "foob");
+    CHECK(StringFormat::Fmt("%.*ls", 4, L"foobar") == "foob");
+
+    CHECK(StringFormat::Fmt("%10.*s", 4, "foobar") == "      foob");
+    CHECK(StringFormat::Fmt("%-10.*s", 4, "foobar") == "foob      ");
   };
 };