CODEWITHSUNDEEP
winapiconcurrency
rienafairefr
rienafairefr

Reputation: 393

Concurrent File read write

I'm on a Win7 platform, I have a third party software that opens and writes to a given file. I would like to intercept the data going into that file and view it, before the process finishes. While the file is being filled, it is visibly getting bigger in explorer, so the data is being written IMO. Of course, any attempt (using any high- or low-level api I know of, writing in Python if it makes any difference) results in an" access is denied" error 5 or "The process cannot access the file because it is being used by another process." error 32.

What am I missing?

Upvotes: 0

Views: 91

Answers (1)

Remy Lebeau
Remy Lebeau

Reputation: 598309

You cannot access the file unless the other app allows it. When it opens/creates the file, it specifies sharing rights for the file. If you try to open the file while it is already open, using flags that are not compatible with the sharing rights, your open will fail. If you want to open the file for read-only access, the other app must open/create the file with read sharing enabled. You can use a tool like SysInternals Process Monitor to see what sharing rights the other app is actually using.

Upvotes: 1

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