Introduce a new utils_resolve_relative function

This function aims to resolve relative path such as './' and
'../' in the middle of 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@gmail.com>

diff --git a/src/common/utils.c b/src/common/utils.c
index da4c036b9630a3ecddebd9aa74d419609705379d..4ccf36a6c781bc09bbcb6a1108af8354d275e9b6 100644 (file)
--- a/src/common/utils.c
+++ b/src/common/utils.c
@@ -35,6 +35,74 @@
 #include "utils.h"
 #include "defaults.h"
 
+/*
+ * Resolve the './' and '../' strings in the middle of a path using
+ * our very own way to do it, so that it works even if the directory
+ * does not exist
+ */
+LTTNG_HIDDEN
+char *utils_resolve_relative(const char *path)
+{
+       char *next, *previous, *slash, *start_path, *absolute_path = NULL;
+
+       /* Safety net */
+       if (path == NULL) {
+               goto error;
+       }
+
+       /* Allocate memory for the absolute path */
+       absolute_path = zmalloc(PATH_MAX);
+       if (absolute_path == NULL) {
+               PERROR("zmalloc expand path");
+               goto error;
+       }
+
+       /* Copy the path in the absolute path */
+       strncpy(absolute_path, path, PATH_MAX);
+
+       /* As long as we find '/./' in the path string */
+       while ((next = strstr(absolute_path, "/./"))) {
+
+               /* We prepare the start_path not containing it */
+               start_path = strndup(absolute_path, next - absolute_path);
+
+               /* And we concatenate it with the part after this string */
+               snprintf(absolute_path, PATH_MAX, "%s%s", start_path, next + 2);
+
+               free(start_path);
+       }
+
+       /* As long as we find '/../' in the path string */
+       while ((next = strstr(absolute_path, "/../"))) {
+               /* If the path starts with '/../', there's a problem */
+               if (next == absolute_path) {
+                       ERR("%s: Path cannot be resolved", path);
+                       goto error;
+               }
+
+               /* We find the last level of directory */
+               previous = absolute_path;
+               while ((slash = strpbrk(previous + 1, "/")) && slash != next) {
+                       previous = slash;
+               }
+
+               /* Then we prepare the start_path not containing it */
+               start_path = strndup(absolute_path, previous - absolute_path);
+
+               /* And we concatenate it with the part after the '/../' */
+               snprintf(absolute_path, PATH_MAX, "%s%s", start_path, next + 3);
+
+               free(start_path);
+       }
+
+       return absolute_path;
+
+error:
+       free(absolute_path);
+       return NULL;
+}
+
+
 /*
  * 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

diff --git a/src/common/utils.h b/src/common/utils.h
index 52f2798d116764cf01a783f64eb14d64751b5e8d..c56942f56a770bdef81af1fd5d03b8cbb05b0e14 100644 (file)
--- a/src/common/utils.h
+++ b/src/common/utils.h
@@ -26,6 +26,7 @@
 #define MEBI_LOG2 20
 #define GIBI_LOG2 30
 
+char *utils_resolve_relative(const char *path);
 char *utils_expand_path(const char *path);
 int utils_create_pipe(int *dst);
 int utils_create_pipe_cloexec(int *dst);