bpo-37064: Add -k and -a options to pathfix.py tool (GH-16387)

* bpo-37064: Add option -k to Tools/scripts/pathfix.py (GH-15548)

Add flag -k to pathscript.py script: preserve shebang flags.

(cherry picked from commit 50254ac4c179cb412e90682098c97db786143929)

* bpo-37064: Add option -a to pathfix.py tool (GH-15717)

Add option -a to Tools/Scripts/pathfix.py script: add flags.

(cherry picked from commit 1dc1acbd73f05f14c974b7ce1041787d7abef31e)

1 files changed, 59 insertions, 5 deletions

diff --git a/Tools/scripts/pathfix.py b/Tools/scripts/pathfix.py
index 1a0cf1c..237a3d9 100755
--- a/Tools/scripts/pathfix.py
+++ b/Tools/scripts/pathfix.py
@@ -1,6 +1,6 @@
 #!/usr/bin/env python3
 
-# Change the #! line occurring in Python scripts.  The new interpreter
+# Change the #! line (shebang) occurring in Python scripts.  The new interpreter
 # pathname must be given with a -i option.
 #
 # Command line arguments are files or directories to be processed.
@@ -10,7 +10,13 @@
 # arguments).
 # The original file is kept as a back-up (with a "~" attached to its name),
 # -n flag can be used to disable this.
-#
+
+# Sometimes you may find shebangs with flags such as `#! /usr/bin/env python -si`.
+# Normally, pathfix overwrites the entire line, including the flags.
+# To change interpreter and keep flags from the original shebang line, use -k.
+# If you want to keep flags and add to them one single literal flag, use option -a.
+
+
 # Undoubtedly you can do this using find and sed or perl, but this is
 # a nice example of Python code that recurses down a directory tree
 # and uses regular expressions.  Also note several subtleties like
@@ -33,16 +39,21 @@ rep = sys.stdout.write
 new_interpreter = None
 preserve_timestamps = False
 create_backup = True
+keep_flags = False
+add_flags = b''
 
 
 def main():
     global new_interpreter
     global preserve_timestamps
     global create_backup
-    usage = ('usage: %s -i /interpreter -p -n file-or-directory ...\n' %
+    global keep_flags
+    global add_flags
+
+    usage = ('usage: %s -i /interpreter -p -n -k -a file-or-directory ...\n' %
              sys.argv[0])
     try:
-        opts, args = getopt.getopt(sys.argv[1:], 'i:pn')
+        opts, args = getopt.getopt(sys.argv[1:], 'i:a:kpn')
     except getopt.error as msg:
         err(str(msg) + '\n')
         err(usage)
@@ -54,6 +65,13 @@ def main():
             preserve_timestamps = True
         if o == '-n':
             create_backup = False
+        if o == '-k':
+            keep_flags = True
+        if o == '-a':
+            add_flags = a.encode()
+            if b' ' in add_flags:
+                err("-a option doesn't support whitespaces")
+                sys.exit(2)
     if not new_interpreter or not new_interpreter.startswith(b'/') or \
            not args:
         err('-i option or file-or-directory missing\n')
@@ -70,10 +88,14 @@ def main():
             if fix(arg): bad = 1
     sys.exit(bad)
 
+
 ispythonprog = re.compile(r'^[a-zA-Z0-9_]+\.py$')
+
+
 def ispython(name):
     return bool(ispythonprog.match(name))
 
+
 def recursedown(dirname):
     dbg('recursedown(%r)\n' % (dirname,))
     bad = 0
@@ -96,6 +118,7 @@ def recursedown(dirname):
         if recursedown(fullname): bad = 1
     return bad
 
+
 def fix(filename):
 ##  dbg('fix(%r)\n' % (filename,))
     try:
@@ -164,12 +187,43 @@ def fix(filename):
     # Return success
     return 0
 
+
+def parse_shebang(shebangline):
+    shebangline = shebangline.rstrip(b'\n')
+    start = shebangline.find(b' -')
+    if start == -1:
+        return b''
+    return shebangline[start:]
+
+
+def populate_flags(shebangline):
+    old_flags = b''
+    if keep_flags:
+        old_flags = parse_shebang(shebangline)
+        if old_flags:
+            old_flags = old_flags[2:]
+    if not (old_flags or add_flags):
+        return b''
+    # On Linux, the entire string following the interpreter name
+    # is passed as a single argument to the interpreter.
+    # e.g. "#! /usr/bin/python3 -W Error -s" runs "/usr/bin/python3 "-W Error -s"
+    # so shebang should have single '-' where flags are given and
+    # flag might need argument for that reasons adding new flags is
+    # between '-' and original flags
+    # e.g. #! /usr/bin/python3 -sW Error
+    return b' -' + add_flags + old_flags
+
+
 def fixline(line):
     if not line.startswith(b'#!'):
         return line
+
     if b"python" not in line:
         return line
-    return b'#! ' + new_interpreter + b'\n'
+
+    flags = populate_flags(line)
+    return b'#! ' + new_interpreter + flags + b'\n'
+
 
 if __name__ == '__main__':
     main()