Python: Model functions that will raise

on non-existing files.

Author: yoff

python/ql/lib/semmle/python/frameworks/Stdlib.qll

@@ -196,23 +196,36 @@ private module StdlibPrivate {
   }
 
   /**
-   * A call to `os.path.exists` or `os.path.lexists` will check if a file exists on the file system.
-   * The `os.path` module offers e number of methods for checking if a file exists and/or has certain
+   * The `os.path` module offers a number of methods for checking if a file exists and/or has certain
    * properties, leading to a file system access.
+   * A call to `os.path.exists` or `os.path.lexists` will check if a file exists on the file system.
    * (Although, on some platforms, the check may return `false` due to missing permissions.)
+   * A call to `os.path.getatime` will raise `OSError` if the file does not exist or is inaccessible.
    * See:
-   *  - https://docs.python.org/3/library/os.path.html#os.path.exists
-   *  - https://docs.python.org/3/library/os.path.html#os.path.lexists
-   *  - https://docs.python.org/3/library/os.path.html#os.path.isfile
-   *  - https://docs.python.org/3/library/os.path.html#os.path.isdir
-   *  - https://docs.python.org/3/library/os.path.html#os.path.islink
-   *  - https://docs.python.org/3/library/os.path.html#os.path.ismount
+   * - https://docs.python.org/3/library/os.path.html#os.path.exists
+   * - https://docs.python.org/3/library/os.path.html#os.path.lexists
+   * - https://docs.python.org/3/library/os.path.html#os.path.isfile
+   * - https://docs.python.org/3/library/os.path.html#os.path.isdir
+   * - https://docs.python.org/3/library/os.path.html#os.path.islink
+   * - https://docs.python.org/3/library/os.path.html#os.path.ismount
+   * - https://docs.python.org/3/library/os.path.html#os.path.getatime
+   * - https://docs.python.org/3/library/os.path.html#os.path.getmtime
+   * - https://docs.python.org/3/library/os.path.html#os.path.getctime
+   * - https://docs.python.org/3/library/os.path.html#os.path.getsize
+   * - https://docs.python.org/3/library/os.path.html#os.path.realpath
    */
   private class OsPathProbingCall extends FileSystemAccess::Range, DataFlow::CallCfgNode {
     OsPathProbingCall() {
       this =
         os::path()
-            .getMember(["exists", "lexists", "isfile", "isdir", "islink", "ismount"])
+            .getMember([
+                // these check if the file exists
+                "exists", "lexists", "isfile", "isdir", "islink", "ismount",
+                // these raise errors if the file does not exist
+                "getatime", "getmtime", "getctime", "getsize",
+                // this will resolve symlinks
+                "realpath"
+              ])
             .getACall()
     }
 
@@ -221,6 +234,17 @@ private module StdlibPrivate {
     }
   }
 
+  /** A call to `os.path.samefile` will raise an exception if an `os.stat()` call on either pathname fails. */
+  private class OsPathSamefileCall extends FileSystemAccess::Range, DataFlow::CallCfgNode {
+    OsPathSamefileCall() { this = os::path().getMember("samefile").getACall() }
+
+    override DataFlow::Node getAPathArgument() {
+      result in [
+          this.getArg(0), this.getArgByName("path1"), this.getArg(1), this.getArgByName("path2")
+        ]
+    }
+  }
+
   /**
    * A call to `os.path.normpath`.
    * See https://docs.python.org/3/library/os.path.html#os.path.normpath