azcopy cp fails if the destination path is at the root of the file system (i.e. /)

[matthiasplappert]

Which version of the AzCopy was used?

10.16.2 and 10.17.0

Which platform are you using? (ex: Windows, Mac, Linux)

Linux

What command did you run?

cd /
azcopy cp <remote-path>/archive.zip archive.zip

What problem was encountered?

azcopy crashes with the following error:

INFO: Scanning...
INFO: Any empty folders will not be processed, because source and/or destination doesn't have full folder support

Job f16add00-4c91-6540-75ba-a088289c557f has started
Log file is located at: /tmp//f16add00-4c91-6540-75ba-a088289c557f.log

panic: runtime error: slice bounds out of range [:-1]

goroutine 109 [running]:
github.com/Azure/azure-storage-azcopy/v10/common.CreateParentDirectoryIfNotExist({0xc000590800, 0x0}, {0x403886fdf8, 0x17258d8})
	/home/vsts/work/1/s/common/writeThoughFile.go:46 +0x6e
github.com/Azure/azure-storage-azcopy/v10/common.CreateDirectoryIfNotExist({0xc000590800, 0x0}, {0x403886fdf8, 0x17258d8})
	/home/vsts/work/1/s/common/writeThoughFile.go:62 +0x16b
github.com/Azure/azure-storage-azcopy/v10/common.CreateParentDirectoryIfNotExist({0xc000590800, 0x3a}, {0x403886fdf8, 0x17258d8})
	/home/vsts/work/1/s/common/writeThoughFile.go:47 +0x5c
github.com/Azure/azure-storage-azcopy/v10/common.CreateFileOfSizeWithWriteThroughOption({0xc000590800, 0x3a}, 0x3767442, 0x0, {0x403886fdf8, 0x17258d8}, 0xe0)
	/home/vsts/work/1/s/common/writeThoughFile_linux.go:31 +0x45
github.com/Azure/azure-storage-azcopy/v10/ste.createDestinationFile({0x10379b8, 0xc000528070}, {0xc000590800, 0x3a}, 0x3767442, 0xcf)
	/home/vsts/work/1/s/ste/xfer-remoteToLocal-file.go:287 +0xf7
github.com/Azure/azure-storage-azcopy/v10/ste.remoteToLocal_file({0x10379b8, 0xc000528070}, {0xffe7e0, 0xc0005a00c0}, {0x406bac9c90, 0xc0005a0000}, 0xef6740)
	/home/vsts/work/1/s/ste/xfer-remoteToLocal-file.go:175 +0x74b
github.com/Azure/azure-storage-azcopy/v10/ste.remoteToLocal({0x10379b8, 0xc000528070}, {0xffe7e0, 0xc0005a00c0}, {0x406bac9c90, 0xc0005a0000}, 0x2c)
	/home/vsts/work/1/s/ste/xfer-remoteToLocal-file.go:44 +0x13f
github.com/Azure/azure-storage-azcopy/v10/ste.computeJobXfer.func4({0x10379b8, 0xc000528070}, {0xffe7e0, 0xc0005a00c0}, {0x406bac9c90, 0xc0005a0000})
	/home/vsts/work/1/s/ste/xfer.go:70 +0x43
github.com/Azure/azure-storage-azcopy/v10/ste.(*jobPartMgr).StartJobXfer(0x1684020, {0x10379b8, 0xc000528070})
	/home/vsts/work/1/s/ste/mgr-JobPartMgr.go:715 +0x50
github.com/Azure/azure-storage-azcopy/v10/ste.(*jobPartTransferMgr).StartJobXfer(0xc000528070)
	/home/vsts/work/1/s/ste/mgr-JobPartTransferMgr.go:237 +0x32
github.com/Azure/azure-storage-azcopy/v10/ste.(*jobMgr).transferProcessor.func1({0x10379b8, 0xc000528070})
	/home/vsts/work/1/s/ste/mgr-JobMgr.go:1015 +0x1b9
github.com/Azure/azure-storage-azcopy/v10/ste.(*jobMgr).transferProcessor(0xc000447880, 0xc0003609c0)
	/home/vsts/work/1/s/ste/mgr-JobMgr.go:1027 +0xc2
created by github.com/Azure/azure-storage-azcopy/v10/ste.NewJobMgr
	/home/vsts/work/1/s/ste/mgr-JobMgr.go:200 +0xbf4

How can we reproduce the problem in the simplest way?

See above. Importantly this only happens if you copy to /, either by cd / or by specifying an absolute path like /archive.zip

Have you found a mitigation/solution?

A workaround is to always copy to /tmp/archive.zip instead and then move out the file via mv /tmp/archive.zip /archive.zip. But I would expect this to work. The error is also extremely cryptic and I spent a lot of time trying to understand why this happens

[siminsavani-msft]

Hi @matthiasplappert , thank you for bringing this up! AzCopy does not work well with root files such as '/' because of the current design. I do agree that the error message could be better and will discuss with the team to see what we can do here.