From 31b833b3eab69d91df67edc3e9a21792abc3f93e Mon Sep 17 00:00:00 2001 From: Pedro Alves Date: Mon, 30 Oct 2017 11:41:34 +0000 Subject: [PATCH] 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/ChangeLog | 12 +++++++ gdb/common/common-utils.c | 34 ++++++++++++++++++ gdb/common/common-utils.h | 9 +++++ gdb/unittests/common-utils-selftests.c | 49 ++++++++++++++++++++++++++ 4 files changed, 104 insertions(+) diff --git a/gdb/ChangeLog b/gdb/ChangeLog index 20d78baa83c..f3abf16fac9 100644 --- a/gdb/ChangeLog +++ b/gdb/ChangeLog @@ -1,3 +1,15 @@ +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". + 2017-10-30 Pedro Alves * unittests/common-utils-selftests.c (format_func): New typedef. diff --git a/gdb/common/common-utils.c b/gdb/common/common-utils.c index d8c546a3d93..71393027f7d 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 19724f9782c..a32863c02fe 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. */ diff --git a/gdb/unittests/common-utils-selftests.c b/gdb/unittests/common-utils-selftests.c index 596406e84ea..0e1d2c6ff78 100644 --- a/gdb/unittests/common-utils-selftests.c +++ b/gdb/unittests/common-utils-selftests.c @@ -77,6 +77,52 @@ string_vprintf_tests () test_format_func (format); } +/* Type of both 'string_appendf' and the 'string_vappendf_wrapper' + function below. Used to run the same tests against both + string_appendf and string_vappendf. */ +typedef void (string_appendf_func) (std::string &str, const char *fmt, ...) + ATTRIBUTE_PRINTF (2, 3); + +static void +test_appendf_func (string_appendf_func *func) +{ + std::string str; + + func (str, "%s", ""); + SELF_CHECK (str == ""); + + func (str, "%s", "test"); + SELF_CHECK (str == "test"); + + func (str, "%d", 23); + SELF_CHECK (str == "test23"); + + func (str, "%s %d %s", "foo", 45, "bar"); + SELF_CHECK (str == "test23foo 45 bar"); +} + +static void ATTRIBUTE_PRINTF (2, 3) +string_vappendf_wrapper (std::string &str, const char *fmt, ...) +{ + va_list vp; + + va_start (vp, fmt); + string_vappendf (str, fmt, vp); + va_end (vp); +} + +static void +string_appendf_tests () +{ + test_appendf_func (string_appendf); +} + +static void +string_vappendf_tests () +{ + test_appendf_func (string_vappendf_wrapper); +} + } /* namespace selftests */ void @@ -84,4 +130,7 @@ _initialize_common_utils_selftests () { selftests::register_test ("string_printf", selftests::string_printf_tests); selftests::register_test ("string_vprintf", selftests::string_vprintf_tests); + selftests::register_test ("string_appendf", selftests::string_appendf_tests); + selftests::register_test ("string_vappendf", + selftests::string_vappendf_tests); } -- 2.30.2