nix-gh/src/libutil/immutable.hh
Eelco Dolstra bd013b6f98 On Linux, make the Nix store really read-only by using the immutable bit
I was bitten one time too many by Python modifying the Nix store by
creating *.pyc files when run as root.  On Linux, we can prevent this
by setting the immutable bit on files and directories (as in ‘chattr
+i’).  This isn't supported by all filesystems, so it's not an error
if setting the bit fails.  The immutable bit is cleared by the garbage
collector before deleting a path.  The only tricky aspect is in
optimiseStore(), since it's forbidden to create hard links to an
immutable file.  Thus optimiseStore() temporarily clears the immutable
bit before creating the link.
2012-02-15 01:31:56 +01:00

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#ifndef __IMMUTABLE_H
#define __IMMUTABLE_H
#include <types.hh>
namespace nix {
/* Make the given path immutable, i.e., prevent it from being modified
in any way, even by root. This is a no-op on platforms that do not
support this, or if the calling user is not privileged. On Linux,
this is implemented by doing the equivalent of chattr +i path. */
void makeImmutable(const Path & path);
/* Make the given path mutable. */
void makeMutable(const Path & path);
}
#endif /* !__IMMUTABLE_H */