BLI Path: add function `BLI_path_contains()`

Add function `BLI_path_contains(container, containee)` that returns true
if and only `container` contains `containee`.

Paths are normalised and converted to native path separators before
comparing. Relative paths are *not* made absolute, to simplify the
function call; if this is necessary the caller has to do this conversion
first.

1 files changed, 28 insertions, 0 deletions

diff --git a/source/blender/blenlib/intern/path_util.c b/source/blender/blenlib/intern/path_util.c
index 4d0678035ba..4fc59e6cffd 100644
--- a/source/blender/blenlib/intern/path_util.c
+++ b/source/blender/blenlib/intern/path_util.c
@@ -1935,6 +1935,34 @@ bool BLI_path_name_at_index(const char *__restrict path,
   return false;
 }
 
+bool BLI_path_contains(const char *container_path, const char *containee_path)
+{
+  char container_native[PATH_MAX];
+  char containee_native[PATH_MAX];
+
+  /* Keep space for a trailing slash. If the path is truncated by this, the containee path is
+   * longer than PATH_MAX and the result is ill-defined.  */
+  BLI_strncpy(container_native, container_path, PATH_MAX - 1);
+  BLI_strncpy(containee_native, containee_path, PATH_MAX);
+
+  BLI_path_slash_native(container_native);
+  BLI_path_slash_native(containee_native);
+
+  BLI_path_normalize(NULL, container_native);
+  BLI_path_normalize(NULL, containee_native);
+
+  if (STREQ(container_native, containee_native)) {
+    /* The paths are equal, they contain each other. */
+    return true;
+  }
+
+  /* Add a trailing slash to prevent same-prefix directories from matching.
+   * e.g. "/some/path" doesn't contain "/some/pathlib". */
+  BLI_path_slash_ensure(container_native);
+
+  return BLI_str_startswith(containee_native, container_native);
+}
+
 /**
  * Returns pointer to the leftmost path separator in string. Not actually used anywhere.
  */