From 31b833b3eab69d91df67edc3e9a21792abc3f93e Mon Sep 17 00:00:00 2001 From: Pedro Alves Date: Mon, 30 Oct 2017 11:41:34 +0000 Subject: Introduce string_appendf/string_vappendf string_appendf is like string_printf, but instead of allocating a new string, it appends to an existing string. This allows reusing a std::string's memory buffer across several calls, for example. gdb/ChangeLog: 2017-10-30 Pedro Alves * common/common-utils.c (string_appendf, string_vappendf): New functions. * common/common-utils.h (string_appendf, string_vappendf): New declarations. * unittests/common-utils-selftests.c (string_appendf_func) (test_appendf_func, string_vappendf_wrapper, string_appendf_tests) (string_vappendf_tests): New functions. (_initialize_common_utils_selftests): Register "string_appendf" and "string_vappendf tests". --- gdb/common/common-utils.c | 34 ++++++++++++++++++++++++++++++++++ gdb/common/common-utils.h | 9 +++++++++ 2 files changed, 43 insertions(+) (limited to 'gdb/common') diff --git a/gdb/common/common-utils.c b/gdb/common/common-utils.c index d8c546a..7139302 100644 --- a/gdb/common/common-utils.c +++ b/gdb/common/common-utils.c @@ -195,6 +195,40 @@ string_vprintf (const char* fmt, va_list args) return str; } + +/* See documentation in common-utils.h. */ + +void +string_appendf (std::string &str, const char *fmt, ...) +{ + va_list vp; + + va_start (vp, fmt); + string_vappendf (str, fmt, vp); + va_end (vp); +} + + +/* See documentation in common-utils.h. */ + +void +string_vappendf (std::string &str, const char *fmt, va_list args) +{ + va_list vp; + int grow_size; + + va_copy (vp, args); + grow_size = vsnprintf (NULL, 0, fmt, vp); + va_end (vp); + + size_t curr_size = str.size (); + str.resize (curr_size + grow_size); + + /* C++11 and later guarantee std::string uses contiguous memory and + always includes the terminating '\0'. */ + vsprintf (&str[curr_size], fmt, args); +} + char * savestring (const char *ptr, size_t len) { diff --git a/gdb/common/common-utils.h b/gdb/common/common-utils.h index 19724f9..a32863c 100644 --- a/gdb/common/common-utils.h +++ b/gdb/common/common-utils.h @@ -67,6 +67,15 @@ std::string string_printf (const char* fmt, ...) std::string string_vprintf (const char* fmt, va_list args) ATTRIBUTE_PRINTF (1, 0); +/* Like string_printf, but appends to DEST instead of returning a new + std::string. */ +void string_appendf (std::string &dest, const char* fmt, ...) + ATTRIBUTE_PRINTF (2, 3); + +/* Like string_appendf, but takes a va_list. */ +void string_vappendf (std::string &dest, const char* fmt, va_list args) + ATTRIBUTE_PRINTF (2, 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. */ -- cgit v1.1