1 files changed, 66 insertions, 0 deletions
diff --git a/utils/llvm-build/llvmbuild/configutil.py b/utils/llvm-build/llvmbuild/configutil.py
new file mode 100644
index 0000000..b5582c3
--- /dev/null
+++ b/utils/llvm-build/llvmbuild/configutil.py
@@ -0,0 +1,66 @@
+"""
+Defines utilities useful for performing standard "configuration" style tasks.
+"""
+
+import re
+import os
+
+def configure_file(input_path, output_path, substitutions):
+    """configure_file(input_path, output_path, substitutions) -> bool
+
+    Given an input and output path, "configure" the file at the given input path
+    by replacing variables in the file with those given in the substitutions
+    list. Returns true if the output file was written.
+
+    The substitutions list should be given as a list of tuples (regex string,
+    replacement), where the regex and replacement will be used as in 're.sub' to
+    execute the variable replacement.
+
+    The output path's parent directory need not exist (it will be created).
+
+    If the output path does exist and the configured data is not different than
+    it's current contents, the output file will not be modified. This is
+    designed to limit the impact of configured files on build dependencies.
+    """
+
+    # Read in the input data.
+    f = open(input_path, "rb")
+    try:
+        data = f.read()
+    finally:
+        f.close()
+
+    # Perform the substitutions.
+    for regex_string,replacement in substitutions:
+        regex = re.compile(regex_string)
+        data = regex.sub(replacement, data)
+
+    # Ensure the output parent directory exists.
+    output_parent_path = os.path.dirname(os.path.abspath(output_path))
+    if not os.path.exists(output_parent_path):
+        os.makedirs(output_parent_path)
+
+    # If the output path exists, load it and compare to the configured contents.
+    if os.path.exists(output_path):
+        current_data = None
+        try:
+            f = open(output_path, "rb")
+            try:
+                current_data = f.read()
+            except:
+                current_data = None
+            f.close()
+        except:
+            current_data = None
+
+        if current_data is not None and current_data == data:
+            return False
+
+    # Write the output contents.
+    f = open(output_path, "wb")
+    try:
+        f.write(data)
+    finally:
+        f.close()
+
+    return True