S3 driver creates temporary files in current directory

[0x0badc0de]

As a result if a process is executed on an environment where whole FS is read-only except /tmp directory - uploading to S3 fails with Could not append to the internal temporary file.

That's not the case with GCS which tries to find tmp dir:

io/tensorflow_io_gcs_filesystem/core/gcs_helper.cc

Line 46 in 6110049

char* raw_temp_file_name = TF_GetTempFileName(extension.c_str());

=>
https://github.com/tensorflow/tensorflow/blob/17774a11b576186e439174298af82b096dcd5582/tensorflow/core/platform/path.cc#L329

Compare with S3 which just passes null prefix downstream:

io/tensorflow_io/core/filesystems/s3/s3_filesystem.cc

Line 358 in 6110049

kS3FileSystemAllocationTag, nullptr, "_s3_filesystem_XXXXXX",

TF S3 implementation just uses /tmp:
https://github.com/tensorflow/tensorflow/blob/17774a11b576186e439174298af82b096dcd5582/tensorflow/core/platform/s3/s3_file_system.cc#L57

Quick workaround can be to os.chdir("/tmp") if acceptable.

[yongtang]

Added a PR #1526 for the fix.