[RFC 2/7] Add libiberty/concat styled concat_path function

Philipp Rudo
2017-01-12T11:32:33Z

This commit adds concat_path function to concatenate an arbitrary number of
path elements. The function automatically adds an directory separator between
two elements as needed.

gdb/ChangeLog:

* common/common-utils (startswith): Convert to C++.
(endswith): New function.
* utils.c (_concat_path, approx_path_length): New function.
* utils.h (_concat_path): New export.
(concat_path): New define.
---
gdb/common/common-utils.h | 16 +++++++++++++---
gdb/utils.c | 46 ++++++++++++++++++++++++++++++++++++++++++++++
gdb/utils.h | 17 +++++++++++++++++
3 files changed, 76 insertions(+), 3 deletions(-)

diff --git a/gdb/common/common-utils.h b/gdb/common/common-utils.h
index 618d266..be3c106 100644
--- a/gdb/common/common-utils.h
+++ b/gdb/common/common-utils.h
@@ -74,13 +74,23 @@ char *savestring (const char *ptr, size_t len);

extern char *safe_strerror (int);

-/* Return non-zero if the start of STRING matches PATTERN, zero
+/* Return non-zero if the start of STR matches PATTERN, zero
otherwise. */

static inline int
-startswith (const char *string, const char *pattern)
+startswith (std::string str, std::string pattern)
{
- return strncmp (string, pattern, strlen (pattern)) == 0;
+ return (str.find (pattern) == 0);
+}
+
+/* Return non-zero if the end of STR matches PATTERN, zero
+ otherwise. */
+
+static inline int
+endswith (std::string str, std::string pattern)
+{
+ return (str.rfind (pattern) != std::string::npos
+ && str.rfind (pattern) == (str.length () - pattern.length ()));
}

ULONGEST strtoulst (const char *num, const char **trailer, int base);
diff --git a/gdb/utils.c b/gdb/utils.c
index ee37e49..e924b2c 100644
--- a/gdb/utils.c
+++ b/gdb/utils.c
@@ -3193,6 +3193,52 @@ substitute_path_component (std::string &str, const std::string &from,
}
}

+/* Approximate length of final path. Helper for concat_path. */
+
+static inline unsigned long
+approx_path_length (std::initializer_list<std::string> args,
+ std::string dir_separator)
+{
+ size_t length = 0;
+
+ for (std::string arg: args)
+ length += arg.length () + dir_separator.length ();
+
+ return length;
+}
+
+/* See utils.h. */
+
+std::string
+_concat_path (std::initializer_list<std::string> args,
+ std::string dir_separator)
+{
+ std::string dst;
+ dst.reserve (approx_path_length (args, dir_separator));
+
+ for (std::string arg: args)
+ {
+ if (arg.empty ())
+ continue;
+
+ if (startswith (arg, dir_separator)
+ && endswith (dst, dir_separator))
+ dst.erase (dst.length () - dir_separator.length (),
+ dir_separator.length ());
+
+ else if (!dst.empty ()
+ && !startswith (arg, dir_separator)
+ && !endswith (dst, dir_separator)
+ && dst != TARGET_SYSROOT_PREFIX)
+ dst += dir_separator;
+
+ dst += arg;
+ }
+
+ dst.shrink_to_fit ();
+ return dst;
+}
+
#ifdef HAVE_WAITPID

#ifdef SIGALRM
diff --git a/gdb/utils.h b/gdb/utils.h
index 674f672..5d68a18 100644
--- a/gdb/utils.h
+++ b/gdb/utils.h
@@ -24,6 +24,7 @@
#include "exceptions.h"
#include "common/scoped_restore.h"
#include <chrono>
+#include <string>

extern void initialize_utils (void);

@@ -143,6 +144,22 @@ extern void substitute_path_component (std::string &str,
const std::string &from,
const std::string &to);

+/* Concatenate an arbitrary number of path elements. Adds and removes
+ directory separators as needed.
+
+ concat_path (/first, second) => /first/second
+ concat_path (first, second) => first/second
+ concat_path (first/, second) => first/second
+ concat_path (first, /second) => first/second
+ concat_path (first/, /second) => first/second
+ concat_path (target:, second) => target:second
+ */
+
+extern std::string _concat_path (std::initializer_list<std::string> args,
+ std::string dir_separator);
+
+#define concat_path(...) _concat_path ({__VA_ARGS__}, SLASH_STRING)
+
char *ldirname (const char *filename);

extern int count_path_elements (const char *path);
--
2.8.4