spec: get_file: don't pollute with files and fds (fsspec#1191)

* spec: get_file: don't pollute with files and fds

Currently if anything happens in fs.open we will leave an empty file in user's
workspace and also won't close the file descriptor. Both things are pretty bad.

* http: _get_file: don't leak file descriptor

fsspec/implementations/http.py

@@ -246,13 +246,20 @@ async def _get_file(
 
             callback.set_size(size)
             self._raise_not_found_for_status(r, rpath)
-            if not isfilelike(lpath):
-                lpath = open(lpath, "wb")
-            chunk = True
-            while chunk:
-                chunk = await r.content.read(chunk_size)
-                lpath.write(chunk)
-                callback.relative_update(len(chunk))
+            if isfilelike(lpath):
+                outfile = lpath
+            else:
+                outfile = open(lpath, "wb")
+
+            try:
+                chunk = True
+                while chunk:
+                    chunk = await r.content.read(chunk_size)
+                    outfile.write(chunk)
+                    callback.relative_update(len(chunk))
+            finally:
+                if not isfilelike(lpath):
+                    outfile.close()
 
     async def _put_file(
         self,

fsspec/spec.py

@@ -848,25 +848,26 @@ def get_file(
         """Copy single remote file to local"""
         if isfilelike(lpath):
             outfile = lpath
-        else:
-            if self.isdir(rpath):
-                os.makedirs(lpath, exist_ok=True)
-                return None
+        elif self.isdir(rpath):
+            os.makedirs(lpath, exist_ok=True)
+            return None
 
+        with self.open(rpath, "rb", **kwargs) as f1:
             if outfile is None:
                 outfile = open(lpath, "wb")
 
-        with self.open(rpath, "rb", **kwargs) as f1:
-            callback.set_size(getattr(f1, "size", None))
-            data = True
-            while data:
-                data = f1.read(self.blocksize)
-                segment_len = outfile.write(data)
-                if segment_len is None:
-                    segment_len = len(data)
-                callback.relative_update(segment_len)
-        if not isfilelike(lpath):
-            outfile.close()
+            try:
+                callback.set_size(getattr(f1, "size", None))
+                data = True
+                while data:
+                    data = f1.read(self.blocksize)
+                    segment_len = outfile.write(data)
+                    if segment_len is None:
+                        segment_len = len(data)
+                    callback.relative_update(segment_len)
+            finally:
+                if not isfilelike(lpath):
+                    outfile.close()
 
     def get(self, rpath, lpath, recursive=False, callback=_DEFAULT_CALLBACK, **kwargs):
         """Copy file(s) to local.