[RFC v4 2/9] Add libiberty/concat styled concat_path function

Philipp Rudo
2017-06-12T17:08:44Z

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.h (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 | 11 +++++++++++
gdb/utils.c | 46 ++++++++++++++++++++++++++++++++++++++++++++++
gdb/utils.h | 17 +++++++++++++++++
3 files changed, 74 insertions(+)

diff --git a/gdb/common/common-utils.h b/gdb/common/common-utils.h
index 787bac9a03..465e1342af 100644
--- a/gdb/common/common-utils.h
+++ b/gdb/common/common-utils.h
@@ -84,6 +84,17 @@ startswith (const char *string, const char *pattern)
return strncmp (string, pattern, strlen (pattern)) == 0;
}

+/* Return non-zero if the end of STRING matches PATTERN, zero
+ otherwise. */
+
+static inline int
+endswith (const char *string, const char *pattern)
+{
+ return (strlen (string) > strlen (pattern)
+ && strncmp (string + strlen (string) - strlen (pattern), pattern,
+ strlen (pattern)) == 0);
+}
+
ULONGEST strtoulst (const char *num, const char **trailer, int base);

/* Skip leading whitespace characters in INP, returning an updated
diff --git a/gdb/utils.c b/gdb/utils.c
index 2a7d39801e..53123f7a06 100644
--- a/gdb/utils.c
+++ b/gdb/utils.c
@@ -3126,6 +3126,52 @@ 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 (const 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 (const std::string &arg : args)
+ {
+ if (arg.empty ())
+ continue;
+
+ if (startswith (arg.c_str (), dir_separator.c_str ())
+ && endswith (dst.c_str (), dir_separator.c_str ()))
+ dst.erase (dst.length () - dir_separator.length (),
+ dir_separator.length ());
+
+ else if (!dst.empty ()
+ && !startswith (arg.c_str (), dir_separator.c_str ())
+ && !endswith (dst.c_str (), dir_separator.c_str ())
+ && 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 9726025c12..506e178d85 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);

@@ -140,6 +141,22 @@ 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)
+
std::string ldirname (const char *filename);

extern int count_path_elements (const char *path);
--
2.11.2