[lttng-dev] [lttng-tools PATCH 1/2] Introduce a new utils_resolve_relative function

[Raphaël Beamonte]

This functions allows to resolve relative path such as './'
and '../' inside a path string. This allows to use paths such
as '~/../test' that are received as '/home/x/../test' for
instance.

Signed-off-by: Raphaël Beamonte <raphael.beamonte at gmail.com>
---
 src/common/utils.c |   48 ++++++++++++++++++++++++++++++++++++++++++++++++
 src/common/utils.h |    1 +
 2 files changed, 49 insertions(+)

diff --git a/src/common/utils.c b/src/common/utils.c
index da4c036..7b52760 100644
--- a/src/common/utils.c
+++ b/src/common/utils.c
@@ -36,6 +36,54 @@
 #include "defaults.h"
 
 /*
+ * Resolve the './' and '../' strings inside a path using our
+ * very own way to do it, so that it works even if the directory
+ * does not exist
+ */
+LTTNG_HIDDEN
+int utils_resolve_relative(char *path)
+{
+	char *next, *previous, *slash, *start_path;
+
+	/* As long as we find '/./' in the path string */
+	while ((next = strstr(path, "/./"))) {
+
+		/* We prepare the start_path not containing it */
+		start_path = strndup(path, next - path);
+
+		/* And we concatenate it with the part after this string */
+		snprintf(path, PATH_MAX, "%s%s", start_path, next + 2);
+
+		free(start_path);
+	}
+
+	while ((next = strstr(path, "/../"))) {
+		/* If the path starts with '/../', there's a problem */
+		if (next == path) {
+			ERR("%s: Path cannot be resolved", path);
+			return 1;
+		}
+
+		/* We find the last level of directory */
+		previous = path;
+		while ((slash = strpbrk(previous + 1, "/")) && slash != next) {
+			previous = slash;
+		}
+
+		/* Then we prepare the start_path not containing it */
+		start_path = strndup(path, previous - path);
+
+		/* And we concatenate it with the part after the '/../' */
+		snprintf(path, PATH_MAX, "%s%s", start_path, next + 3);
+
+		free(start_path);
+	}
+
+	return 0;
+}
+
+
+/*
  * Return the realpath(3) of the path even if the last directory token does not
  * exist. For example, with /tmp/test1/test2, if test2/ does not exist but the
  * /tmp/test1 does, the real path is returned. In normal time, realpath(3)
diff --git a/src/common/utils.h b/src/common/utils.h
index 52f2798..ced3584 100644
--- a/src/common/utils.h
+++ b/src/common/utils.h
@@ -26,6 +26,7 @@
 #define MEBI_LOG2 20
 #define GIBI_LOG2 30
 
+int utils_resolve_relative(char *path);
 char *utils_expand_path(const char *path);
 int utils_create_pipe(int *dst);
 int utils_create_pipe_cloexec(int *dst);
-- 
1.7.10.4