fbadc2b608
It turns out it is also useful to be able to perform other operations on a file created while running as a different uid (eg, write things to that file), and possibly to do this to a file that already exists. This patch adds an optional hook function to the renamed (for more accuracy of purpose) virFileOperation; the hook will be called after the file has been opened (possibly created) and gid/mode checked/set, before closing it. As with the other operations on the file, if the VIR_FILE_OP_AS_UID flag is set, this hook function will be called in the context of a child process forked from the process that called virFileOperation. The implication here is that, while all data in memory is available to this hook function, any modification to that data will not be seen by the caller - the only indication in memory of what happened in the hook will be the return value (which the hook should set to 0 on success, or one of the standard errno values on failure). Another piece of making the function more flexible was to add an "openflags" argument. This arg should contain exactly the flags to be passed to open(2), eg O_RDWR | O_EXCL, etc. In the process of adding the hook to virFileOperation, I also realized that the bits to fix up file owner/group/mode settings after creation were being done in the parent process, which could fail, so I moved them to the child process where they should be. * src/util/util.[ch]: rename and rework virFileCreate-->virFileOperation, and redo flags in virDirCreate * storage/storage_backend.c, storage/storage_backend_fs.c: update the calls to virFileOperation/virDirCreate to reflect changes in the API, but don't yet take advantage of the hook.
LibVirt : simple API for virtualization
Libvirt is a C toolkit to interact with the virtualization capabilities
of recent versions of Linux (and other OSes). It is free software
available under the GNU Lesser General Public License. Virtualization of
the Linux Operating System means the ability to run multiple instances of
Operating Systems concurrently on a single hardware system where the basic
resources are driven by a Linux instance. The library aim at providing
long term stable C API initially for the Xen paravirtualization but
should be able to integrate other virtualization mechanisms if needed.
Daniel Veillard <veillard@redhat.com>