Various small changes

s3fs/core.py

@@ -463,6 +463,8 @@ def bulk_delete(self, pathlist):
         pathlist : listof strings
             The keys to remove, must all be in the same bucket.
         """
+        if not pathlist:
+            return
         buckets = {split_path(path)[0] for path in pathlist}
         if len(buckets) > 1:
             raise ValueError("Bulk delete files should refer to only one bucket")
@@ -643,8 +645,8 @@ def __init__(self, s3, path, mode='rb', block_size=5 * 2 ** 20):
                 else:
                     try:
                         self.mpu = s3.s3.create_multipart_upload(Bucket=bucket, Key=key)
-                    except (ClientError, ParamValidationError):
-                        raise IOError('Open for write failed', path)
+                    except (ClientError, ParamValidationError) as e:
+                        raise IOError('Open for write failed', path, e)
                     self.loc = self.size
                     out = self.s3.s3.upload_part_copy(Bucket=self.bucket, Key=self.key,
                                 PartNumber=1, UploadId=self.mpu['UploadId'],
@@ -824,8 +826,8 @@ def flush(self, force=False, retries=10):
             try:
                 self.mpu = self.mpu or self.s3.s3.create_multipart_upload(
                                 Bucket=self.bucket, Key=self.key)
-            except (ClientError, ParamValidationError):
-                raise IOError('Initating write failed: %s' % self.path)
+            except (ClientError, ParamValidationError) as e:
+                raise IOError('Initating write failed: %s' % self.path, e)
 
             while True:
                 try:
@@ -842,8 +844,8 @@ def flush(self, force=False, retries=10):
                     else:
                         raise IOError('Write failed after %i retries' % retries,
                                       self)
-                except:
-                    raise IOError('Write failed', self)
+                except Exception as e:
+                    raise IOError('Write failed', self, e)
             self.parts.append({'PartNumber': part, 'ETag': out['ETag']})
             self.buffer = io.BytesIO()
 
@@ -870,8 +872,8 @@ def close(self):
                 try:
                     self.s3.s3.put_object(Bucket=self.bucket, Key=self.key,
                                            Body=self.buffer.read())
-                except (ClientError, ParamValidationError):
-                    raise IOError('Write failed: %s' % self.path)
+                except (ClientError, ParamValidationError) as e:
+                    raise IOError('Write failed: %s' % self.path, e)
             self.s3.invalidate_cache(self.bucket)
         self.closed = True
 

s3fs/mapping.py

@@ -2,7 +2,7 @@
 from collections import MutableMapping
 import os
 
-from .core import S3FileSystem
+from .core import S3FileSystem, split_path
 
 
 class S3Map(MutableMapping):
@@ -30,12 +30,19 @@ class S3Map(MutableMapping):
     b'Hello World'
     """
 
-    def __init__(self, root, s3=None, check=False):
+    def __init__(self, root, s3=None, check=False, create=False):
         self.s3 = s3 or S3FileSystem.current()
         self.root = root
         if check:
             self.s3.touch(root+'/a')
             self.s3.rm(root+'/a')
+        else:
+            bucket = split_path(root)[0]
+            if create:
+                self.s3.mkdir(bucket)
+            elif not self.s3.exists(bucket):
+                raise ValueError("Bucket %s does not exist."
+                        " Create bucket with the ``create=True`` keyword")
 
     def clear(self):
         """Remove all keys below root - empties out mapping

s3fs/tests/test_mapping.py

@@ -91,3 +91,17 @@ def test_bytearray(s3):
     d['x'] = bytearray(b'123')
 
     assert d['x'] == b'123'
+
+
+def test_new_bucket(s3):
+    try:
+        d = S3Map('new-bucket', s3)
+        assert False
+    except ValueError as e:
+        assert 'create=True' in str(e)
+
+    d = S3Map('new-bucket', s3, create=True)
+    assert not d
+
+    d = S3Map('new-bucket/new-directory', s3)
+    assert not d