convert : ability to lazy-load safetensors remotely without downloading to disk

convert_hf_to_gguf.py

@@ -5470,6 +5470,10 @@ def parse_args() -> argparse.Namespace:
         "--print-supported-models", action="store_true",
         help="Print the supported models"
     )
+    parser.add_argument(
+        "--remote", action="store_true",
+        help="(Experimental) Read safetensors file remotely without downloading to disk. Config and tokenizer files will still be downloaded. To use this feature, you need to specify Hugging Face model repo name instead of a local directory. For example: 'HuggingFaceTB/SmolLM2-1.7B'",
+    )
 
     args = parser.parse_args()
     if not args.print_supported_models and args.model is None:
@@ -5510,6 +5514,14 @@ def main() -> None:
 
     dir_model = args.model
 
+    if args.remote:
+        from huggingface_hub import snapshot_download
+        local_dir = snapshot_download(
+            repo_id=str(dir_model),
+            allow_patterns=["LICENSE", "*.json", "*.md", "*.txt", "tokenizer.model"])
+        dir_model = Path(local_dir)
+        logger.info(f"Downloaded config and tokenizer to {local_dir}")
+
     if not dir_model.is_dir():
         logger.error(f'Error: {args.model} is not a directory')
         sys.exit(1)
@@ -5531,6 +5543,9 @@ def main() -> None:
 
     if args.outfile is not None:
         fname_out = args.outfile
+    elif args.remote:
+        # if remote, use the model ID as the output file name
+        fname_out = Path("./" + str(args.model).replace("/", "-") + "-{ftype}.gguf")
     else:
         fname_out = dir_model
 

gguf-py/gguf/utility.py

@@ -2,6 +2,8 @@
 
 from typing import Literal
 
+import json
+
 
 def fill_templated_filename(filename: str, output_type: str | None) -> str:
     # Given a file name fill in any type templates e.g. 'some-model-name.{ftype}.gguf'
@@ -67,3 +69,173 @@ def naming_convention(model_name: str | None, base_name: str | None, finetune_st
     kind = f"-{model_type.strip().replace(' ', '-')}" if model_type is not None else ""
 
     return f"{name}{parameters}{finetune}{version}{encoding}{kind}"
+
+
+class SafetensorRemote:
+    """
+    Uility class to handle remote safetensor files.
+    This class is designed to work with Hugging Face model repositories.
+
+    Example (one model has single safetensor file, the other has multiple):
+        for model_id in ["ngxson/TEST-Tiny-Llama4", "Qwen/Qwen2.5-7B-Instruct"]:
+            tensors = SafetensorRemote.get_list_tensors_hf_model(model_id)
+            print(json.dumps(tensors, indent=2))
+
+    Example reading tensor data:
+        tensors = SafetensorRemote.get_list_tensors_hf_model(model_id)
+        for name, meta in tensors.items():
+            dtype, shape, offset_start, size, remote_safetensor_url = meta
+            # read the tensor data
+            data = SafetensorRemote.get_data_by_range(remote_safetensor_url, offset_start, size)
+            print(data)
+    """
+
+    BASE_DOMAIN = "https://huggingface.co"
+    ALIGNMENT = 8 # bytes
+
+    @classmethod
+    def get_list_tensors_hf_model(cls, model_id: str) -> dict[str, tuple[str, list[int], int, int, str]]:
+        """
+        Get list of tensors from a Hugging Face model repository.
+
+        Returns a dictionary of tensor names and their metadata.
+        Each tensor is represented as a tuple of (dtype, shape, offset_start, size, remote_safetensor_url)
+        """
+        # case 1: model has only one single model.safetensor file
+        is_single_file = cls.check_file_exist(f"{cls.BASE_DOMAIN}/{model_id}/resolve/main/model.safetensors")
+        if is_single_file:
+            url = f"{cls.BASE_DOMAIN}/{model_id}/resolve/main/model.safetensors"
+            tensors: dict[str, tuple[str, list[int], int, int, str]] = {}
+            for key, val in cls.get_list_tensors(url).items():
+                tensors[key] = (*val, url) # populate the url
+            return tensors
+
+        # case 2: model has multiple files
+        index_url = f"{cls.BASE_DOMAIN}/{model_id}/resolve/main/model.safetensors.index.json"
+        is_multiple_files = cls.check_file_exist(index_url)
+        if is_multiple_files:
+            # read the index file
+            index_data = cls.get_data_by_range(index_url, 0)
+            index_str = index_data.decode('utf-8')
+            index_json = json.loads(index_str)
+            assert index_json.get("weight_map") is not None, "weight_map not found in index file"
+            weight_map = index_json["weight_map"]
+            # get the list of files
+            all_files = list(set(weight_map.values()))
+            all_files.sort() # make sure we load shard files in order
+            # get the list of tensors
+            tensors = {}
+            for file in all_files:
+                url = f"{cls.BASE_DOMAIN}/{model_id}/resolve/main/{file}"
+                for key, val in cls.get_list_tensors(url).items():
+                    tensors[key] = (*val, url) # populate the url
+            return tensors
+
+        raise ValueError(f"Model {model_id} does not have any safetensor files")
+
+    @classmethod
+    def get_list_tensors(cls, url: str) -> dict[str, tuple[str, list[int], int, int]]:
+        """
+        Get list of tensors from a remote safetensor file.
+
+        Returns a dictionary of tensor names and their metadata.
+        Each tensor is represented as a tuple of (dtype, shape, offset_start, size)
+        """
+        metadata, data_start_offset = cls.get_metadata(url)
+        res: dict[str, tuple[str, list[int], int, int]] = {}
+
+        for name, meta in metadata.items():
+            if name == "__metadata__":
+                continue
+            if not isinstance(meta, dict):
+                raise ValueError(f"Invalid metadata for tensor '{name}': {meta}")
+            try:
+                dtype = meta["dtype"]
+                shape = meta["shape"]
+                offset_start_relative, offset_end_relative = meta["data_offsets"]
+                size = offset_end_relative - offset_start_relative
+                offset_start = data_start_offset + offset_start_relative
+                res[name] = (dtype, shape, offset_start, size)
+            except KeyError as e:
+                raise ValueError(f"Missing key in metadata for tensor '{name}': {e}, meta = {meta}")
+
+        return res
+
+    @classmethod
+    def get_metadata(cls, url: str) -> tuple[dict, int]:
+        """
+        Get JSON metadata from a remote safetensor file.
+
+        Returns tuple of (metadata, data_start_offset)
+        """
+        # Request first 5MB of the file (hopefully enough for metadata)
+        read_size = 5 * 1024 * 1024
+        raw_data = cls.get_data_by_range(url, 0, read_size)
+
+        # Parse header
+        # First 8 bytes contain the metadata length as u64 little-endian
+        if len(raw_data) < 8:
+            raise ValueError("Not enough data to read metadata size")
+        metadata_length = int.from_bytes(raw_data[:8], byteorder='little')
+
+        # Calculate the data start offset
+        data_start_offset = 8 + metadata_length
+        alignment = SafetensorRemote.ALIGNMENT
+        if data_start_offset % alignment != 0:
+            data_start_offset += alignment - (data_start_offset % alignment)
+
+        # Check if we have enough data to read the metadata
+        if len(raw_data) < 8 + metadata_length:
+            raise ValueError(f"Could not read complete metadata. Need {8 + metadata_length} bytes, got {len(raw_data)}")
+
+        # Extract metadata bytes and parse as JSON
+        metadata_bytes = raw_data[8:8 + metadata_length]
+        metadata_str = metadata_bytes.decode('utf-8')
+        try:
+            metadata = json.loads(metadata_str)
+            return metadata, data_start_offset
+        except json.JSONDecodeError as e:
+            raise ValueError(f"Failed to parse safetensor metadata as JSON: {e}")
+
+    @classmethod
+    def get_data_by_range(cls, url: str, start: int, size: int = -1) -> bytes:
+        """
+        Get raw byte data from a remote file by range.
+        If size is not specified, it will read the entire file.
+        """
+        import requests
+        from urllib.parse import urlparse
+
+        parsed_url = urlparse(url)
+        if not parsed_url.scheme or not parsed_url.netloc:
+            raise ValueError(f"Invalid URL: {url}")
+
+        headers = {}
+        if size > -1:
+            headers = {"Range": f"bytes={start}-{start + size}"}
+        response = requests.get(url, allow_redirects=True, headers=headers)
+        response.raise_for_status()
+
+        # Get raw byte data
+        return response.content[:size]
+
+    @classmethod
+    def check_file_exist(cls, url: str) -> bool:
+        """
+        Check if a file exists at the given URL.
+        Returns True if the file exists, False otherwise.
+        """
+        import requests
+        from urllib.parse import urlparse
+
+        parsed_url = urlparse(url)
+        if not parsed_url.scheme or not parsed_url.netloc:
+            raise ValueError(f"Invalid URL: {url}")
+
+        try:
+            headers = {"Range": "bytes=0-0"}
+            response = requests.head(url, allow_redirects=True, headers=headers)
+            # Success (2xx) or redirect (3xx)
+            return 200 <= response.status_code < 400
+        except requests.RequestException:
+            return False