68 lines
1.4 KiB
C++
68 lines
1.4 KiB
C++
#include "config.h"
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#include "immutable.hh"
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#include "util.hh"
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <fcntl.h>
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#if HAVE_LINUX_FS_H
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#include <linux/fs.h>
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#include <sys/ioctl.h>
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#include <errno.h>
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#endif
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namespace nix {
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void changeMutable(const Path & path, bool mut)
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{
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#if defined(FS_IOC_SETFLAGS) && defined(FS_IOC_GETFLAGS) && defined(FS_IMMUTABLE_FL)
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/* Don't even try if we're not root. One day we should support
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the CAP_LINUX_IMMUTABLE capability. */
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if (getuid() != 0) return;
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/* The O_NOFOLLOW is important to prevent us from changing the
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mutable bit on the target of a symlink (which would be a
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security hole). */
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AutoCloseFD fd = open(path.c_str(), O_RDONLY | O_NOFOLLOW);
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if (fd == -1) {
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if (errno == ELOOP) return; // it's a symlink
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throw SysError(format("opening file `%1%'") % path);
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}
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unsigned int flags = 0, old;
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/* Silently ignore errors getting/setting the immutable flag so
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that we work correctly on filesystems that don't support it. */
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if (ioctl(fd, FS_IOC_GETFLAGS, &flags)) return;
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old = flags;
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if (mut) flags &= ~FS_IMMUTABLE_FL;
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else flags |= FS_IMMUTABLE_FL;
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if (old == flags) return;
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if (ioctl(fd, FS_IOC_SETFLAGS, &flags)) return;
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#endif
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}
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void makeImmutable(const Path & path)
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{
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changeMutable(path, false);
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}
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void makeMutable(const Path & path)
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{
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changeMutable(path, true);
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}
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}
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