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https://issues.apache.org/jira/browse/ARROW-2118?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16395586#comment-16395586
 ] 

ASF GitHub Bot commented on ARROW-2118:
---------------------------------------

wesm commented on a change in pull request #1735: ARROW-2118: [C++] Fix 
misleading error when memory mapping a zero-length file
URL: https://github.com/apache/arrow/pull/1735#discussion_r173889736
 
 

 ##########
 File path: cpp/src/arrow/io/file.cc
 ##########
 @@ -624,16 +624,22 @@ class MemoryMappedFile::MemoryMap : public MutableBuffer 
{
       is_mutable_ = false;
     }
 
-    void* result = mmap(nullptr, static_cast<size_t>(file_->size()), 
prot_flags, map_mode,
-                        file_->fd(), 0);
-    if (result == MAP_FAILED) {
-      std::stringstream ss;
-      ss << "Memory mapping file failed, errno: " << errno;
-      return Status::IOError(ss.str());
+    size_ = file_->size();
+
+    void* result = nullptr;
+
+    // Memory mapping fails when file size is 0
+    if (size_ > 0) {
+      result =
+          mmap(nullptr, static_cast<size_t>(size_), prot_flags, map_mode, 
file_->fd(), 0);
+      if (result == MAP_FAILED) {
+        std::stringstream ss;
+        ss << "Memory mapping file failed, errno: " << errno;
 
 Review comment:
   OK, this code is unchanged from the original version, but I'll add this

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> [Python] Improve error message when calling parquet.read_table on an empty 
> file
> -------------------------------------------------------------------------------
>
>                 Key: ARROW-2118
>                 URL: https://issues.apache.org/jira/browse/ARROW-2118
>             Project: Apache Arrow
>          Issue Type: Improvement
>          Components: Python
>            Reporter: Wes McKinney
>            Assignee: Wes McKinney
>            Priority: Major
>              Labels: pull-request-available
>             Fix For: 0.9.0
>
>
> Currently it raises an exception about memory mapping failing



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