[RFA 01/12] Introduce string_vprintf

Tom Tromey
2017-09-28T19:50:20Z

This adds string_vprintf, a va_list variant of string_printf. This
will be used in later patches.

gdb/ChangeLog
2017-09-28 Tom Tromey <tom@tromey.com>

* common/common-utils.c (string_vprintf): New function.
* common/common-utils.h (string_vprintf): Declare.
---
gdb/ChangeLog | 5 +++++
gdb/common/common-utils.c | 21 +++++++++++++++++++++
gdb/common/common-utils.h | 4 ++++
3 files changed, 30 insertions(+)

diff --git a/gdb/common/common-utils.c b/gdb/common/common-utils.c
index 6b10d11..d8c546a 100644
--- a/gdb/common/common-utils.c
+++ b/gdb/common/common-utils.c
@@ -174,6 +174,27 @@ string_printf (const char* fmt, ...)
return str;
}

+/* See documentation in common-utils.h. */
+
+std::string
+string_vprintf (const char* fmt, va_list args)
+{
+ va_list vp;
+ size_t size;
+
+ va_copy (vp, args);
+ size = vsnprintf (NULL, 0, fmt, vp);
+ va_end (vp);
+
+ std::string str (size, '\0');
+
+ /* C++11 and later guarantee std::string uses contiguous memory and
+ always includes the terminating '\0'. */
+ vsprintf (&str[0], fmt, args);
+
+ 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 6475c28..19724f9 100644
--- a/gdb/common/common-utils.h
+++ b/gdb/common/common-utils.h
@@ -63,6 +63,10 @@ int xsnprintf (char *str, size_t size, const char *format, ...)
std::string string_printf (const char* fmt, ...)
ATTRIBUTE_PRINTF (1, 2);

+/* Like string_printf, but takes a va_list. */
+std::string string_vprintf (const char* fmt, va_list args)
+ ATTRIBUTE_PRINTF (1, 0);
+
/* 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. */
--
2.9.5