Make default hash lib configurable without code changes via CLI argument

comfy/cli_args.py

@@ -109,6 +109,8 @@ class LatentPreviewMethod(enum.Enum):
 vram_group.add_argument("--novram", action="store_true", help="When lowvram isn't enough.")
 vram_group.add_argument("--cpu", action="store_true", help="To use the CPU for everything (slow).")
 
+parser.add_argument("--duplicate-check-hash-function", type=str, choices=['md5', 'sha1', 'sha256', 'sha512'], default='sha256', help="Allows you to choose the hash function to use for duplicate filename / contents comparison. Default is sha256.")
+
 
 parser.add_argument("--disable-smart-memory", action="store_true", help="Force ComfyUI to agressively offload to regular ram instead of keeping models in vram when it can.")
 parser.add_argument("--deterministic", action="store_true", help="Make pytorch use slower deterministic algorithms when it can. Note that this might not make images deterministic in all cases.")

server.py

@@ -156,10 +156,16 @@ def get_dir_by_type(dir_type):
             return type_dir, dir_type
 
         def compare_image_hash(filepath, image):
+            # This eval operation is *safe* because we can only accept certain strings passed in via args.
+            # Because that can only be one of 'md5', 'sha1', 'sha256', or 'sha512' which we already define
+            # in comfy.cli_args as an argument passable to the args and only from a set of options, we can
+            # safely use an eval here, as the eval data is "safe" already.
+            hasher = eval(f"hashlib.{args.duplicate_check_hash_function}")
+
             # function to compare hashes of two images to see if it already exists, fix to #3465
             if os.path.exists(filepath):
-                a = hashlib.sha256()
-                b = hashlib.sha256()
+                a = hasher()
+                b = hasher()
                 with open(filepath, "rb") as f:
                     a.update(f.read())
                     b.update(image.file.read())