storage: Add public Directory.exists() method

6 files changed, 35 insertions, 23 deletions

diff --git a/src/buildstream/buildelement.py b/src/buildstream/buildelement.py
index acb079a56..95b085eba 100644
--- a/src/buildstream/buildelement.py
+++ b/src/buildstream/buildelement.py
@@ -280,7 +280,7 @@ class BuildElement(Element):
             buildroot = self.get_variable("build-root")
             buildroot_vdir = vdir.descend(*buildroot.lstrip(os.sep).split(os.sep))
 
-            if buildroot_vdir._exists(marker_filename):
+            if buildroot_vdir.exists(marker_filename):
                 # Already prepared
                 return
 
diff --git a/src/buildstream/sandbox/_sandboxreapi.py b/src/buildstream/sandbox/_sandboxreapi.py
index c2b6cac48..26fe5f2b2 100644
--- a/src/buildstream/sandbox/_sandboxreapi.py
+++ b/src/buildstream/sandbox/_sandboxreapi.py
@@ -76,7 +76,7 @@ class SandboxREAPI(Sandbox):
 
                 # Ensure mount point exists in sandbox
                 mount_point_components = mount_point.split(os.path.sep)
-                if not vdir._exists(*mount_point_components):
+                if not vdir.exists(*mount_point_components):
                     if os.path.isdir(mount_source):
                         # Mounting a directory, mount point must be a directory
                         vdir.descend(*mount_point_components, create=True)
diff --git a/src/buildstream/sandbox/sandbox.py b/src/buildstream/sandbox/sandbox.py
index b82e2da59..6f6acc946 100644
--- a/src/buildstream/sandbox/sandbox.py
+++ b/src/buildstream/sandbox/sandbox.py
@@ -568,14 +568,14 @@ class Sandbox:
         vroot = self.get_virtual_directory()
         command_as_parts = command.lstrip(os.sep).split(os.sep)
         if os.path.isabs(command):
-            return vroot._exists(*command_as_parts, follow_symlinks=True)
+            return vroot.exists(*command_as_parts, follow_symlinks=True)
 
         if len(command_as_parts) > 1:
             return False
 
         for path in env.get("PATH").split(":"):
             path_as_parts = path.lstrip(os.sep).split(os.sep)
-            if vroot._exists(*path_as_parts, command, follow_symlinks=True):
+            if vroot.exists(*path_as_parts, command, follow_symlinks=True):
                 return True
 
         return False
diff --git a/src/buildstream/storage/_casbaseddirectory.py b/src/buildstream/storage/_casbaseddirectory.py
index e4b267a63..ffcf085bb 100644
--- a/src/buildstream/storage/_casbaseddirectory.py
+++ b/src/buildstream/storage/_casbaseddirectory.py
@@ -795,7 +795,7 @@ class CasBasedDirectory(Directory):
 
         return self.__digest
 
-    def _exists(self, *path, follow_symlinks=False):
+    def exists(self, *path, follow_symlinks=False):
         try:
             subdir = self.descend(*path[:-1], follow_symlinks=follow_symlinks)
             target = subdir.index.get(path[-1])
@@ -804,8 +804,8 @@ class CasBasedDirectory(Directory):
                     linklocation = target.target
                     newpath = linklocation.split(os.path.sep)
                     if os.path.isabs(linklocation):
-                        return subdir._find_root()._exists(*newpath, follow_symlinks=True)
-                    return subdir._exists(*newpath, follow_symlinks=True)
+                        return subdir._find_root().exists(*newpath, follow_symlinks=True)
+                    return subdir.exists(*newpath, follow_symlinks=True)
                 else:
                     return True
             return False
diff --git a/src/buildstream/storage/_filebaseddirectory.py b/src/buildstream/storage/_filebaseddirectory.py
index aafe33279..62fcc39c0 100644
--- a/src/buildstream/storage/_filebaseddirectory.py
+++ b/src/buildstream/storage/_filebaseddirectory.py
@@ -232,6 +232,22 @@ class FileBasedDirectory(Directory):
     def get_size(self):
         return utils._get_dir_size(self.external_directory)
 
+    def exists(self, *path, follow_symlinks=False):
+        try:
+            subdir = self.descend(*path[:-1], follow_symlinks=follow_symlinks)
+            newpath = os.path.join(subdir.external_directory, path[-1])
+            st = os.lstat(newpath)
+            if follow_symlinks and stat.S_ISLNK(st.st_mode):
+                linklocation = os.readlink(newpath)
+                newpath = linklocation.split(os.path.sep)
+                if os.path.isabs(linklocation):
+                    return subdir._find_root().exists(*newpath, follow_symlinks=True)
+                return subdir.exists(*newpath, follow_symlinks=True)
+            else:
+                return True
+        except (VirtualDirectoryError, FileNotFoundError):
+            return False
+
     def __str__(self):
         # This returns the whole path (since we don't know where the directory started)
         # which exposes the sandbox directory; we will have to assume for the time being
@@ -358,22 +374,6 @@ class FileBasedDirectory(Directory):
                     os.symlink(entry.target, dest_path)
                 result.files_written.append(relative_pathname)
 
-    def _exists(self, *path, follow_symlinks=False):
-        try:
-            subdir = self.descend(*path[:-1], follow_symlinks=follow_symlinks)
-            newpath = os.path.join(subdir.external_directory, path[-1])
-            st = os.lstat(newpath)
-            if follow_symlinks and stat.S_ISLNK(st.st_mode):
-                linklocation = os.readlink(newpath)
-                newpath = linklocation.split(os.path.sep)
-                if os.path.isabs(linklocation):
-                    return subdir._find_root()._exists(*newpath, follow_symlinks=True)
-                return subdir._exists(*newpath, follow_symlinks=True)
-            else:
-                return True
-        except (VirtualDirectoryError, FileNotFoundError):
-            return False
-
     def _create_empty_file(self, name):
         with open(os.path.join(self.external_directory, name), "w"):
             pass
diff --git a/src/buildstream/storage/directory.py b/src/buildstream/storage/directory.py
index 55cc717f2..a9249baee 100644
--- a/src/buildstream/storage/directory.py
+++ b/src/buildstream/storage/directory.py
@@ -196,6 +196,18 @@ class Directory:
         and effective space used may be lower than this number due to deduplication. """
         raise NotImplementedError()
 
+    def exists(self, *paths: str, follow_symlinks: bool = False) -> bool:
+        """ Check whether the specified path exists.
+
+        Args:
+          *paths: A list of strings which are all path components.
+          follow_symlinks: True to follow symlinks.
+
+        Returns:
+          True if the path exists, False otherwise.
+        """
+        raise NotImplementedError()
+
 
 # FileType:
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