diplodocus.org Git - nmh/blob - sbr/lock_file.h

   1 /* lock_file.h -- lock and unlock files.
   2  *
   3  * This code is Copyright (c) 2017, by the authors of nmh.  See the
   4  * COPYRIGHT file in the root directory of the nmh distribution for
   5  * complete copyright information.
   6  */
   7
   8 /*
   9  * Lock open/close routines.
  10  *
  11  * The lk[f]opendata() functions are designed to open "data" files (anything
  12  * not a mail spool file) using the locking mechanism configured for data
  13  * files.  The lk[f]openspool() functions are for opening the mail spool
  14  * file, which will use the locking algorithm configured for the mail
  15  * spool.
  16  *
  17  * Files opened for reading are locked with a read lock (if possible by
  18  * the underlying lock mechanism), files opened for writing are locked
  19  * using an exclusive lock.  The int * argument is used to indicate failure
  20  * to acquire a lock.
  21  */
  22 int lkopendata(const char *file, int access, mode_t mode, int *failed_to_lock);
  23 int lkopenspool(const char *file, int access, mode_t mode, int *failed_to_lock);
  24 FILE *lkfopendata(const char *file, const char *mode, int *failed_to_lock);
  25 FILE *lkfopenspool(const char *file, const char *mode);
  26 int lkclosedata(int fd, const char *name);
  27 int lkfclosedata(FILE *f, const char *name);
  28 int lkclosespool(int fd, const char *name);
  29 int lkfclosespool(FILE *f, const char *name);