protect#

Change the read/write/execute protection of a mapped region.

Σύνοψη#

protect $map, '<';              # read-only
protect $map, '+<';             # read/write
protect $map, PROT_READ;        # constants also work

Ορίσματα#

  • $lvalue - a currently mapped scalar.

  • $mode - either a string in the same format as open ('<', '+<', '>', '+>'), or a bitmask built from the PROT_* constants.

If the new protection includes write permission the scalar becomes writable; otherwise it is marked read-only and direct assignment raises an exception.

Παραδείγματα#

Load a file read/write, patch it, then lock it down:

map_file my $map, 'data.bin', '+<';
substr $map, 0, 4, "HEAD";
sync $map;
protect $map, '<';             # prevent further writes

Οριακές περιπτώσεις#

  • Protecting an unmapped scalar raises an exception.

  • Protecting an empty mapping updates the scalar’s read-only flag but performs no kernel call.

Διαφορές από το upstream#

Fully compatible with upstream File::Map 0.71.

Δείτε επίσης#

  • sys_map - set protection when creating the mapping.

  • advise - hint access patterns rather than enforce permissions.