DragonFly On-Line Manual Pages

GETRLIMIT(2)             DragonFly System Calls Manual            GETRLIMIT(2)

NAME
     getrlimit, setrlimit -- control maximum system resource consumption

LIBRARY
     Standard C Library (libc, -lc)

SYNOPSIS
     #include <sys/types.h>
     #include <sys/time.h>
     #include <sys/resource.h>

     int
     getrlimit(int resource, struct rlimit *rlp);

     int
     setrlimit(int resource, const struct rlimit *rlp);

DESCRIPTION
     Limits on the consumption of system resources by the current process and
     each process it creates may be obtained with the getrlimit() call, and
     set with the setrlimit() call.

     The resource parameter is one of the following:

     RLIMIT_AS          The maximum size (in bytes) of a process' total
                        available memory.  If this limit is exceeded, the
                        malloc(3) and mmap(2) functions will fail and errno
                        set to ENOMEM.  Moreover, the automatic stack growth
                        will fail as well.

     RLIMIT_CORE        The largest size (in bytes) core(5) file that may be
                        created.

     RLIMIT_CPU         The maximum amount of cpu time (in seconds) to be used
                        by each process.

     RLIMIT_DATA        The maximum size (in bytes) of the data segment for a
                        process; this defines how far a program may extend its
                        break with the sbrk(2) system call.

     RLIMIT_FSIZE       The largest size (in bytes) file that may be created.

     RLIMIT_MEMLOCK     The maximum size (in bytes) which a process may lock
                        into memory using the mlock(2) function.

     RLIMIT_NOFILE      The maximum number of open files for this process.

     RLIMIT_NPROC       The maximum number of simultaneous processes for this
                        user id.

     RLIMIT_RSS         The maximum size (in bytes) to which a process's
                        resident set size may grow.  This imposes a limit on
                        the amount of physical memory to be given to a
                        process; if memory is tight, the system will prefer to
                        take memory from processes that are exceeding their
                        declared resident set size.

     RLIMIT_STACK       The maximum size (in bytes) of the stack segment for a
                        process; this defines how far a program's stack
                        segment may be extended.  Stack extension is performed
                        automatically by the system.

     RLIMIT_SBSIZE      The maximum size (in bytes) of socket buffer usage for
                        this user.  This limits the amount of network memory,
                        and hence the amount of mbufs, that this user may hold
                        at any time.

     RLIMIT_POSIXLOCKS  The maximum number of POSIX-type advisory-mode locks
                        available to this user.

     A resource limit is specified as a soft limit and a hard limit.  When a
     soft limit is exceeded a process may receive a signal (for example, if
     the cpu time or file size is exceeded), but it will be allowed to
     continue execution until it reaches the hard limit (or modifies its
     resource limit).  The rlimit structure is used to specify the hard and
     soft limits on a resource,

           struct rlimit {
                   rlim_t  rlim_cur;       /* current (soft) limit */
                   rlim_t  rlim_max;       /* maximum value for rlim_cur */
           };

     Only the super-user may raise the maximum limits.  Other users may only
     alter rlim_cur within the range from 0 to rlim_max or (irreversibly)
     lower rlim_max.

     An ``infinite'' value for a limit is defined as RLIM_INFINITY.

     Because this information is stored in the per-process information, this
     system call must be executed directly by the shell if it is to affect all
     future processes created by the shell; limit is thus a built-in command
     to csh(1).

     The system refuses to extend the data or stack space when the limits
     would be exceeded in the normal way: an sbrk(2) call fails if the data
     space limit is reached.  When the stack limit is reached, the process
     receives a segmentation fault (SIGSEGV); if this signal is not caught by
     a handler using the signal stack, this signal will kill the process.

     A file I/O operation that would create a file larger than the process'
     soft limit will cause the write to fail and a signal SIGXFSZ to be
     generated; this normally terminates the process, but may be caught.  When
     the soft cpu time limit is exceeded, a signal SIGXCPU is sent to the
     offending process.

RETURN VALUES
     Upon successful completion, the value 0 is returned; otherwise the
     value -1 is returned and the global variable errno is set to indicate the
     error.

ERRORS
     Getrlimit() and setrlimit() will fail if:

     [EFAULT]           The address specified for rlp is invalid.

     [EPERM]            The limit specified to setrlimit() would have raised
                        the maximum limit value, and the caller is not the
                        super-user.

SEE ALSO
     csh(1), quota(1), quotactl(2), sigaction(2), sigaltstack(2), sysctl(3),
     ulimit(3)

HISTORY
     The getrlimit() function call appeared in 4.2BSD.

DragonFly 5.5                    March 1, 2019                   DragonFly 5.5