[PATCH 1/2] Introduce string_appendf/string_vappendf (Re: [RFA 4/6] Simple cleanup removals in remote.c)
Pedro Alves
palves@redhat.com
Mon Oct 16 23:34:00 GMT 2017
On 10/17/2017 12:00 AM, Tom Tromey wrote:
>>>>>> "Pedro" == Pedro Alves <palves@redhat.com> writes:
>
> Pedro> This suggests to me that we're missing a string_printf variant
> Pedro> that appends to a preexisting string:
> Pedro> void string_appendf (std::string &dest, const char* fmt, ...);
> Pedro> See (untested) patch below.
>
> Seems like a good idea FWIW.
Alright, here's a version with unit tests, then.
>From 7d51020e1f1f77d9bfc3a4a06be19d1cbb889500 Mon Sep 17 00:00:00 2001
From: Pedro Alves <palves@redhat.com>
Date: Mon, 16 Oct 2017 23:22:27 +0100
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:
yyyy-mm-dd Pedro Alves <palves@redhat.com>
* common/common-utils.c (string_appendf, string_vappendf): New
functions.
* common/common-utils.h (string_appendf, string_vappendf): New
declarations.
* remote.c (remote_set_syscall_catchpoint): Use string_append.
* 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 | 44 +++++++++++++++++++++++++++++++
gdb/common/common-utils.h | 9 +++++++
gdb/unittests/common-utils-selftests.c | 47 ++++++++++++++++++++++++++++++++++
3 files changed, 100 insertions(+)
diff --git a/gdb/common/common-utils.c b/gdb/common/common-utils.c
index d8c546a..942aebb 100644
--- a/gdb/common/common-utils.c
+++ b/gdb/common/common-utils.c
@@ -195,6 +195,50 @@ 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;
+ int grow_size;
+
+ va_start (vp, fmt);
+ 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'. */
+ va_start (vp, fmt);
+ vsprintf (&str[curr_size], 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. */
diff --git a/gdb/unittests/common-utils-selftests.c b/gdb/unittests/common-utils-selftests.c
index cf65513..9825845 100644
--- a/gdb/unittests/common-utils-selftests.c
+++ b/gdb/unittests/common-utils-selftests.c
@@ -76,6 +76,51 @@ 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, ...);
+
+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
+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
@@ -83,4 +128,6 @@ _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);
}
--
2.5.5
More information about the Gdb-patches
mailing list