[PATCH v2 01/31] Introduce string_printf

[Pedro Alves <palves@redhat.com>]

This introduces the string_printf function.  Like asprintf, but
returns a std::string.

gdb/ChangeLog:
yyyy-mm-yy  Pedro Alves  <palves@redhat.com>

	* common/common-utils.c (string_printf): New function.
	* common/common-utils.h: Include <string>.
	(string_printf): Declare.
---
 gdb/common/common-utils.c | 30 ++++++++++++++++++++++++++++++
 gdb/common/common-utils.h |  6 ++++++
 2 files changed, 36 insertions(+)

diff --git a/gdb/common/common-utils.c b/gdb/common/common-utils.c
index 5a346ec..05ba3aa 100644
--- a/gdb/common/common-utils.c
+++ b/gdb/common/common-utils.c
@@ -150,6 +150,36 @@ xsnprintf (char *str, size_t size, const char *format, ...)
   return ret;
 }
 
+/* See documentation in common-utils.h.  */
+
+std::string
+string_printf (const char* fmt, ...)
+{
+  std::string str;
+  va_list vp;
+
+  /* Start by assuming some reasonable size will be sufficient.  */
+  str.resize (1024);
+
+  while (1)
+    {
+      size_t size;
+      int result;
+
+      va_start (vp, fmt);
+      size = str.size ();
+      result = vsnprintf (&str[0], size, fmt, vp);
+      va_end (vp);
+
+      str.resize (result);
+
+      if (result < size)
+	break;
+    }
+
+  return str;
+}
+
 char *
 savestring (const char *ptr, size_t len)
 {
diff --git a/gdb/common/common-utils.h b/gdb/common/common-utils.h
index 47def11..a9053ff 100644
--- a/gdb/common/common-utils.h
+++ b/gdb/common/common-utils.h
@@ -20,6 +20,8 @@
 #ifndef COMMON_UTILS_H
 #define COMMON_UTILS_H
 
+#include <string>
+
 /* If possible, define FUNCTION_NAME, a macro containing the name of
    the function being defined.  Since this macro may not always be
    defined, all uses must be protected by appropriate macro definition
@@ -56,6 +58,10 @@ char *xstrvprintf (const char *format, va_list ap)
 int xsnprintf (char *str, size_t size, const char *format, ...)
      ATTRIBUTE_PRINTF (3, 4);
 
+/* Returns a std::string built from a printf-style format string.  */
+std::string string_printf (const char* fmt, ...)
+  ATTRIBUTE_PRINTF (1, 2);
+
 /* Make a copy of the string at PTR with LEN characters
    (and add a null character at the end in the copy).
    Uses malloc to get the space.  Returns the address of the copy.  */
-- 
2.5.5