mbox_conf.c

[詳解]

/*++
/* NAME
/*  mbox_conf 3
/* SUMMARY
/*  mailbox lock configuration
/* SYNOPSIS
/*  #include <mbox_conf.h>
/*
/*  int mbox_lock_mask(string)
/*  const char *string;
/*
/*  ARGV    *mbox_lock_names()
/* DESCRIPTION
/*  The functions in this module translate between external
/*  mailbox locking method names and internal representations.
/*
/*  mbox_lock_mask() translates a string with locking method names
/*  into a bit mask. Names are separated by comma or whitespace.
/*  The following gives the method names and corresponding bit
/*  mask value:
/* .IP "flock (MBOX_FLOCK_LOCK)"
/*  Use flock() style lock after opening the file. This is the mailbox
/*  locking method traditionally used on BSD-ish systems (including
/*  Ultrix and SunOS). It is not suitable for remote file systems.
/* .IP "fcntl (MBOX_FCNTL_LOCK)"
/*  Use fcntl() style lock after opening the file. This is the mailbox
/*  locking method on System-V-ish systems (Solaris, AIX, IRIX, HP-UX).
/*  This method is supposed to work for remote systems, but often
/*  has problems.
/* .IP "dotlock (MBOX_DOT_LOCK)"
/*  Create a lock file with the name \fIfilename\fB.lock\fR. This
/*  method pre-dates kernel locks. This works with remote file systems,
/*  modulo cache coherency problems.
/* .PP
/*  mbox_lock_names() returns an array with the names of available
/*  mailbox locking methods. The result should be given to argv_free().
/* DIAGNOSTICS
/*  Fatal errors: undefined locking method name.
/* LICENSE
/* .ad
/* .fi
/*  The Secure Mailer license must be distributed with this software.
/* AUTHOR(S)
/*  Wietse Venema
/*  IBM T.J. Watson Research
/*  P.O. Box 704
/*  Yorktown Heights, NY 10598, USA
/*--*/

/* System library. */

#include <sys_defs.h>

/* Utility library. */

#include <name_mask.h>
#include <argv.h>

/* Global library. */

#include <mail_params.h>
#include <mbox_conf.h>

 /*
  * The table with available mailbox locking methods. Some systems have
  * flock() locks; all POSIX-compatible systems have fcntl() locks. Even
  * though some systems do not use dotlock files by default (4.4BSD), such
  * locks can be necessary when accessing mailbox files over NFS.
  */
static const NAME_MASK mbox_mask[] = {
#ifdef HAS_FLOCK_LOCK
    "flock", MBOX_FLOCK_LOCK,
#endif
#ifdef HAS_FCNTL_LOCK
    "fcntl", MBOX_FCNTL_LOCK,
#endif
    "dotlock", MBOX_DOT_LOCK,
    0,
};

/* mbox_lock_mask - translate mailbox lock names to bit mask */

int     mbox_lock_mask(const char *string)
{
    return (name_mask(VAR_MAILBOX_LOCK, mbox_mask, string));
}

/* mbox_lock_names - return available mailbox lock method names */

ARGV   *mbox_lock_names(void)
{
    const NAME_MASK *np;
    ARGV   *argv;

    argv = argv_alloc(2);
    for (np = mbox_mask; np->name != 0; np++)
    argv_add(argv, np->name, ARGV_END);
    argv_terminate(argv);
    return (argv);
}