Reopen a file descriptor with another access?

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http://stackoverflow.com – Assume the OS is linux. Suppose I opened a file for write and get a file descriptor fdw. Is it possible to get another file descriptor fdr, with read-only access to the file without calling open again? The reason I don't want to call open is the underlying file may have been moved or even unlinked in the file system by other processes, so re-use the same file name is not reliable against such actions. So my question is: is there anyway to open a file descriptor with different access right if given only a file descriptor? dup or dup2 doesn't change the access right, I think. (HowTos)