file_limit.c

[詳解]

/*++
/* NAME
/*  file_limit 3
/* SUMMARY
/*  limit the file size
/* SYNOPSIS
/*  #include <iostuff.h>
/*
/*  off_t   get_file_limit()
/*
/*  void    set_file_limit(limit)
/*  off_t   limit;
/* DESCRIPTION
/*  This module manipulates the process-wide file size limit.
/*  The limit is specified in bytes.
/*
/*  get_file_limit() looks up the process-wide file size limit.
/*
/*  set_file_limit() sets the process-wide file size limit to
/*  \fIlimit\fR.
/* DIAGNOSTICS
/*  All errors are fatal.
/* SEE ALSO
/*  setrlimit(2)
/*  ulimit(2)
/* 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>
#ifdef USE_ULIMIT
#include <ulimit.h>
#else
#include <sys/time.h>
#include <sys/resource.h>
#include <signal.h>
#endif
#include <limits.h>

/* Utility library. */

#include <msg.h>
#include <iostuff.h>

#define ULIMIT_BLOCK_SIZE   512

/* get_file_limit - get process-wide file size limit */

off_t   get_file_limit(void)
{
    off_t   limit;

#ifdef USE_ULIMIT
    if ((limit = ulimit(UL_GETFSIZE, 0)) < 0)
    msg_fatal("ulimit: %m");
    if (limit > OFF_T_MAX / ULIMIT_BLOCK_SIZE)
    limit = OFF_T_MAX / ULIMIT_BLOCK_SIZE;
    return (limit * ULIMIT_BLOCK_SIZE);
#else
    struct rlimit rlim;

    if (getrlimit(RLIMIT_FSIZE, &rlim) < 0)
    msg_fatal("getrlimit: %m");
    limit = rlim.rlim_cur;
    return (limit < 0 ? OFF_T_MAX : rlim.rlim_cur);
#endif                      /* USE_ULIMIT */
}

/* set_file_limit - process-wide file size limit */

void    set_file_limit(off_t limit)
{
#ifdef USE_ULIMIT
    if (ulimit(UL_SETFSIZE, limit / ULIMIT_BLOCK_SIZE) < 0)
    msg_fatal("ulimit: %m");
#else
    struct rlimit rlim;

    rlim.rlim_cur = rlim.rlim_max = limit;
    if (setrlimit(RLIMIT_FSIZE, &rlim) < 0)
    msg_fatal("setrlimit: %m");
#ifdef SIGXFSZ
    if (signal(SIGXFSZ, SIG_IGN) == SIG_ERR)
    msg_fatal("signal(SIGXFSZ,SIG_IGN): %m");
#endif
#endif                      /* USE_ULIMIT */
}