Correct abspath implementation

realpath doesn't return a path if the file doesn't exist,
but $(abspath) in make does.

Bug: 229132189
Test: ./out/rbcrun ./build/make/tests/run.rbc
Change-Id: Ief7f634024cc52a9e8c5e478666b15512512f0d8

core/product_config.rbc

@@ -400,12 +400,26 @@ def _soong_config_get(g, nsname, var):
     """Gets to the value of the variable in the namespace."""
     return g.get(_soong_config_namespaces_key, {}).get(nsname, {}).get(var, None)
 
-
-def _abspath(path):
+def _abspath(paths):
     """Provided for compatibility, to be removed later."""
-    if type(path) == "list":
-        path = " ".join(path)
-    return rblf_shell("realpath "+path)
+    cwd = rblf_shell('pwd')
+    results = []
+    for path in __words(paths):
+        if path[0] != "/":
+            path = cwd + "/" + path
+
+        resultparts = []
+        for part in path.split('/'):
+            if part == "." or part == "":
+                continue
+            elif part == "..":
+                if resultparts:
+                    resultparts.pop()
+            else:
+                resultparts.append(part)
+        results.append("/" + "/".join(resultparts))
+
+    return " ".join(results)
 
 
 def _addprefix(prefix, string_or_list):

tests/run.rbc

@@ -72,6 +72,14 @@ assert_eq("foo.c no_folder", rblf.notdir("src/foo.c no_folder"))
 assert_eq("", rblf.notdir("/"))
 assert_eq("", rblf.notdir(""))
 
+cwd = rblf_shell('pwd')
+assert_eq(cwd+"/foo/bar", rblf.abspath("foo/bar"))
+assert_eq(cwd+"/bar", rblf.abspath("foo/.././bar"))
+assert_eq(cwd+"/bar", rblf.abspath("foo/..////bar//"))
+assert_eq("/foo/baz", rblf.abspath("/foo/bar/../baz"))
+assert_eq(cwd+"/foo/bar "+cwd+"/foo/baz", rblf.abspath("foo/bar foo/baz"))
+assert_eq("/baz", rblf.abspath("/../../../../../../../../../../../../../../../../baz"))
+
 assert_eq(
     ["build/make/tests/board.rbc", "build/make/tests/board_input_vars.rbc"],
     rblf.expand_wildcard("build/make/tests/board*.rbc")