Merge pull request github#14114 from yoff/python/allow-namespace-packages

Python: Allow namespace packages

Author: yoff

python/ql/lib/change-notes/2023-09-29-allow-namespace-packages.md

@@ -0,0 +1,4 @@
+---
+category: minorAnalysis
+---
+* Namespace packages in the form of regular packages with missing `__init__.py`-files are now allowed. This enables the analysis to resolve modules and functions inside such packages.

python/ql/lib/semmle/python/Module.qll

@@ -179,21 +179,6 @@ private predicate legalDottedName(string name) {
 bindingset[name]
 private predicate legalShortName(string name) { name.regexpMatch("(\\p{L}|_)(\\p{L}|\\d|_)*") }
 
-/**
- * Holds if `f` is potentially a source package.
- * Does it have an __init__.py file (or --respect-init=False for Python 2) and is it within the source archive?
- */
-private predicate isPotentialSourcePackage(Folder f) {
-  f.getRelativePath() != "" and
-  isPotentialPackage(f)
-}
-
-private predicate isPotentialPackage(Folder f) {
-  exists(f.getFile("__init__.py"))
-  or
-  py_flags_versioned("options.respect_init", "False", _) and major_version() = 2 and exists(f)
-}
-
 private string moduleNameFromBase(Container file) {
   // We used to also require `isPotentialPackage(f)` to hold in this case,
   // but we saw modules not getting resolved because their folder did not
@@ -236,31 +221,114 @@ private predicate transitively_imported_from_entry_point(File file) {
   )
 }
 
+/**
+ * Holds if the folder `f` is a regular Python package,
+ * containing an `__init__.py` file.
+ */
+private predicate isRegularPackage(Folder f, string name) {
+  legalShortName(name) and
+  name = f.getStem() and
+  exists(f.getFile("__init__.py"))
+}
+
+/** Gets the name of a module imported in package `c`. */
+private string moduleImportedInPackage(Container c) {
+  legalShortName(result) and
+  // it has to be imported in this folder
+  result =
+    any(ImportExpr i | i.getLocation().getFile().getParent() = c)
+        .getName()
+        // strip everything after the first `.`
+        .regexpReplaceAll("\\..*", "") and
+  result != ""
+}
+
+/** Holds if the file `f` could be resolved to a module named `name`. */
+private predicate isPotentialModuleFile(File file, string name) {
+  legalShortName(name) and
+  name = file.getStem() and
+  file.getExtension() = ["py", "pyc", "so", "pyd"] and
+  // it has to be imported in this folder
+  name = moduleImportedInPackage(file.getParent())
+}
+
+/**
+ * Holds if the folder `f` is a namespace package named `name`.
+ *
+ * See https://peps.python.org/pep-0420/#specification
+ * for details on namespace packages.
+ */
+private predicate isNameSpacePackage(Folder f, string name) {
+  legalShortName(name) and
+  name = f.getStem() and
+  not isRegularPackage(f, name) and
+  // it has to be imported in a file
+  // either in this folder or next to this folder
+  name = moduleImportedInPackage([f, f.getParent()]) and
+  // no sibling regular package
+  // and no sibling module
+  not exists(Folder sibling | sibling.getParent() = f.getParent() |
+    isRegularPackage(sibling.getFolder(name), name)
+    or
+    isPotentialModuleFile(sibling.getAFile(), name)
+  )
+}
+
+/**
+ * Holds if the folder `f` is a package (either a regular package
+ * or a namespace package) named `name`.
+ */
+private predicate isPackage(Folder f, string name) {
+  isRegularPackage(f, name)
+  or
+  isNameSpacePackage(f, name)
+}
+
+/**
+ * Holds if the file `f` is a module named `name`.
+ */
+private predicate isModuleFile(File file, string name) {
+  isPotentialModuleFile(file, name) and
+  not isPackage(file.getParent(), _)
+}
+
+/**
+ * Holds if the folder `f` is a package named `name`
+ * and does reside inside another package.
+ */
+private predicate isOutermostPackage(Folder f, string name) {
+  isPackage(f, name) and
+  not isPackage(f.getParent(), _)
+}
+
+/** Gets the name of the module that `c` resolves to, if any. */
 cached
-string moduleNameFromFile(Container file) {
+string moduleNameFromFile(Container c) {
+  // package
+  isOutermostPackage(c, result)
+  or
+  // module
+  isModuleFile(c, result)
+  or
   Stages::AST::ref() and
   exists(string basename |
-    basename = moduleNameFromBase(file) and
+    basename = moduleNameFromBase(c) and
     legalShortName(basename)
   |
-    result = moduleNameFromFile(file.getParent()) + "." + basename
+    // recursive case
+    result = moduleNameFromFile(c.getParent()) + "." + basename
     or
     // If `file` is a transitive import of a file that's executed directly, we allow references
     // to it by its `basename`.
-    transitively_imported_from_entry_point(file) and
+    transitively_imported_from_entry_point(c) and
     result = basename
   )
   or
-  isPotentialSourcePackage(file) and
-  result = file.getStem() and
-  (
-    not isPotentialSourcePackage(file.getParent()) or
-    not legalShortName(file.getParent().getBaseName())
-  )
-  or
-  result = file.getStem() and file.getParent() = file.getImportRoot()
+  //
+  // standard library
+  result = c.getStem() and c.getParent() = c.getImportRoot()
   or
-  result = file.getStem() and isStubRoot(file.getParent())
+  result = c.getStem() and isStubRoot(c.getParent())
 }
 
 private predicate isStubRoot(Folder f) {

python/ql/lib/semmle/python/dataflow/new/internal/DataFlowPublic.qll

@@ -400,7 +400,7 @@ class ModuleVariableNode extends Node, TModuleVariableNode {
   override Scope getScope() { result = mod }
 
   override string toString() {
-    result = "ModuleVariableNode in " + mod.toString() + " for " + var.getId()
+    result = "ModuleVariableNode in " + concat( | | mod.toString(), ",") + " for " + var.getId()
   }
 
   /** Gets the module in which this variable appears. */

python/ql/test/2/library-tests/six/pointsto.expected

@@ -5,5 +5,4 @@
 | six.moves.range | builtin-class xrange |
 | six.moves.urllib | Package six.moves.urllib |
 | six.moves.urllib.parse | Module six.moves.urllib_parse |
-| six.moves.urllib.parse.urlsplit | Function urlsplit |
 | six.moves.zip | Builtin-function zip |

python/ql/test/3/library-tests/modules/entry_point/modules.expected

@@ -1,5 +1,14 @@
 | module | hash_bang/module.py:0:0:0:0 | Module module |
 | module | name_main/module.py:0:0:0:0 | Module module |
+| namespace_package | hash_bang/namespace_package:0:0:0:0 | Package namespace_package |
+| namespace_package | name_main/namespace_package:0:0:0:0 | Package namespace_package |
+| namespace_package | no_py_extension/namespace_package:0:0:0:0 | Package namespace_package |
+| namespace_package.namespace_package_main | hash_bang/namespace_package/namespace_package_main.py:0:0:0:0 | Module namespace_package.namespace_package_main |
+| namespace_package.namespace_package_main | name_main/namespace_package/namespace_package_main.py:0:0:0:0 | Module namespace_package.namespace_package_main |
+| namespace_package.namespace_package_main | no_py_extension/namespace_package/namespace_package_main.py:0:0:0:0 | Module namespace_package.namespace_package_main |
+| namespace_package.namespace_package_module | hash_bang/namespace_package/namespace_package_module.py:0:0:0:0 | Module namespace_package.namespace_package_module |
+| namespace_package.namespace_package_module | name_main/namespace_package/namespace_package_module.py:0:0:0:0 | Module namespace_package.namespace_package_module |
+| namespace_package.namespace_package_module | no_py_extension/namespace_package/namespace_package_module.py:0:0:0:0 | Module namespace_package.namespace_package_module |
 | package | hash_bang/package:0:0:0:0 | Package package |
 | package | name_main/package:0:0:0:0 | Package package |
 | package | no_py_extension/package:0:0:0:0 | Package package |

python/ql/test/3/library-tests/six/pointsto.expected

@@ -5,5 +5,4 @@
 | six.moves.range | builtin-class range |
 | six.moves.urllib | Package six.moves.urllib |
 | six.moves.urllib.parse | Module six.moves.urllib_parse |
-| six.moves.urllib.parse.urlsplit | Function urlsplit |
 | six.moves.zip | builtin-class zip |

python/ql/test/experimental/library-tests/CallGraph-implicit-init/example.py

@@ -16,7 +16,13 @@
 
 from foo.bar.a import afunc
 from foo_explicit.bar.a import explicit_afunc
+from not_root.baz.foo import foo_func
+from not_root.baz.bar.a import afunc as afunc2
 
 afunc() # $ pt,tt="foo/bar/a.py:afunc"
 
 explicit_afunc() # $ pt,tt="foo_explicit/bar/a.py:explicit_afunc"
+
+foo_func() # $ pt,tt="not_root/baz/foo.py:foo_func"
+
+afunc2() # $ pt,tt="not_root/baz/bar/a.py:afunc"

python/ql/test/experimental/library-tests/CallGraph-implicit-init/foo/bar/a.py

@@ -1,3 +1,6 @@
 def afunc():
-  print("afunc called")
-  return 1
+    print("afunc called")
+    return 1
+
+from foo.foo import foo_func
+foo_func() # $ pt,tt="foo/foo.py:foo_func"

python/ql/test/experimental/library-tests/CallGraph-implicit-init/foo/foo.py

@@ -0,0 +1,2 @@
+def foo_func():
+    print("foo_func called")

python/ql/test/experimental/library-tests/CallGraph-implicit-init/foo_explicit/bar/a.py

@@ -1,3 +1,6 @@
 def explicit_afunc():
-  print("explicit_afunc called")
-  return 1
+    print("explicit_afunc called")
+    return 1
+
+from foo_explicit.foo_explicit import foo_explicit_func
+foo_explicit_func() # $ pt,tt="foo_explicit/foo_explicit.py:foo_explicit_func"