Catastrophic Backtracking while using Binds #411

Trying to use Binds in createOptions (binding Windows directory to Linux container) seems to raise catastrophic backtracking. The pattern responsible is MOUNT_WIN_REGEX

The following is the result of applying MOUNT_WIN_REGEX on different binds:

C:/:/app/ took 0.009343099998659454
C:/Folder1/:/app/ took 0.00018330000239075162
C:/Folder1/Folder2/:/app/ took 0.003711700002895668
C:/Folder1/Folder2/Folder3/:/app/ took 0.28317089999836753
C:/Folder1/Folder2/Folder3/Folder4/:/app/ took 18.772531900001923

as you can see, runtime grows exponentially. The fifth depth didn't return any result even after 5 minutes. This is the code I ran:

bind = "C:/"
counter = 1

def match(bind):

    return regex.match(MOUNT_WIN_REGEX, bind)

while counter < 10:
    
    result = timeit.timeit(lambda: match(f"{bind}:/app/"), number=1)
    print(f"{bind}:/app/ took {result}")
    bind += f"Folder{counter}/"
    counter += 1

The reason seems to be the inline modifier (?i) in MOUNT_MODE_REGEX:

The modifier somehow is propagated to the whole pattern. Removing the modifier will solve the catastrophic backtracking, but the pattern won't match paths with capital letters. By including the range A-Z in the pattern, the issue of backtracking resurfaces.

Suggestions:

• split the bind string by :, and apply smaller patterns on split strings instead of applying the huge regex patterns on the whole string
• instead of applying two huge regex patterns, break them up and use if-elif for pattern matching