getrlimit(2)							   System Calls 						      getrlimit(2)

NAME

       getrlimit, setrlimit - control maximum system resource consumption

SYNOPSIS

       #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 a variety of system resources by a process and each process it creates may be obtained with the getrlimit()
       and set with setrlimit() functions.

       Each call to either getrlimit() or setrlimit() identifies a specific resource to be operated upon as well as a resource limit.  A  resource
       limit  is  a  pair  of  values:	one specifying the current (soft) limit, the other a maximum (hard) limit. Soft limits may be changed by a
       process to any value that is less than or equal to the hard limit. A process may (irreversibly) lower its hard limit to any value  that	is
       greater than or equal to the soft limit. Only a process with {PRIV_SYS_RESOURCE} asserted in the effective set can raise a hard limit. Both
       hard and soft limits can be changed in a single call to setrlimit() subject to the constraints described above. Limits may have	an  "infi-
       nite" value of RLIM_INFINITY. The rlp argument is a pointer to struct rlimit that includes the following members:

	 rlim_t    rlim_cur;	 /* current (soft) limit */
	 rlim_t    rlim_max;	 /* hard limit */

       The type rlim_t is an arithmetic data type to which objects of type int, size_t, and  off_t can be cast without loss of information.

       The possible resources, their descriptions, and the actions taken when the current limit is exceeded are summarized as follows:

       RLIMIT_CORE	The  maximum  size  of a core file in bytes that may be created by a process. A limit of  0 will prevent the creation of a
			core file. The writing of a core file will terminate at this size.

       RLIMIT_CPU	The maximum amount of CPU time in seconds used by a process. This is a soft limit only.  The SIGXCPU signal is sent to the
			process. If the process is holding or ignoring SIGXCPU, the behavior is scheduling class defined.

       RLIMIT_DATA	The maximum size of a process's heap in bytes.	The brk(2) function will fail with  errno set to  ENOMEM.

       RLIMIT_FSIZE	The  maximum  size of a file in bytes that may be created by a process. A limit of  0 will prevent the creation of a file.
			The SIGXFSZ signal is sent to the process. If the process is holding or ignoring  SIGXFSZ, continued attempts to  increase
			the size of a file beyond the limit will fail with  errno set to  EFBIG.

       RLIMIT_NOFILE	One more than the maximum value that the system may assign to a newly created descriptor. This limit constrains the number
			of file descriptors that a process may create.

       RLIMIT_STACK	The maximum size of a process's stack in bytes. The system will not automatically grow the stack beyond this limit.

			Within a process, setrlimit() will increase the limit on the size of your stack, but will not move current memory segments
			to  allow  for	that growth. To guarantee that the process stack can grow to the limit, the limit must be altered prior to
			the execution of the process in which the new stack size is to be used.

			Within a multithreaded process, setrlimit() has no impact on the stack size limit for the calling thread  if  the  calling
			thread	is not the main thread. A call to setrlimit() for RLIMIT_STACK impacts only the main thread's stack, and should be
			made only from the main thread, if at all.

			The SIGSEGV signal is sent to the process. If the process is holding or ignoring  SIGSEGV, or is catching  SIGSEGV and has
			not  made arrangements to use an alternate stack (see sigaltstack(2)), the disposition of  SIGSEGV will be set to  SIG_DFL
			before it is sent.

       RLIMIT_VMEM	The maximum size of a process's mapped address space in bytes.	If this limit is exceeded, the brk(2) and   mmap(2)  func-
			tions  will  fail  with  errno set to  ENOMEM. In addition, the automatic stack growth will fail with the effects outlined
			above.

       RLIMIT_AS	This is the maximum size of a process's total available memory, in bytes.  If this limit is  exceeded,	the  brk(2),  mal-
			loc(3C),  mmap(2)  and	sbrk(2) functions will fail with errno set to ENOMEM. In addition, the automatic stack growth will
			fail with the effects outlined above.

       Because limit information is stored in the per-process information, the shell builtin ulimit command must directly execute this system call
       if it is to affect all future processes created by the shell.

       The value of the current limit of the following resources affect these implementation defined parameters:

		  Limit 	     Implementation Defined Constant
       RLIMIT_FSIZE		     FCHR_MAX
       RLIMIT_NOFILE		     OPEN_MAX

       When using the getrlimit() function, if a resource limit can be represented correctly in an object of type  rlim_t, then its representation
       is returned; otherwise, if the value of the resource limit is equal to that of the corresponding saved hard limit, the  value  returned	is
       RLIM_SAVED_MAX; otherwise the value returned is RLIM_SAVED_CUR.

       When  using  the  setrlimit()  function,  if  the  requested new limit is RLIM_INFINITY, the new limit will be "no limit"; otherwise if the
       requested new limit is RLIM_SAVED_MAX, the new limit will be the corresponding saved hard limit; otherwise, if the requested new  limit	is
       RLIM_SAVED_CUR,	the  new  limit will be the corresponding saved soft limit; otherwise, the new limit will be the requested value. In addi-
       tion, if the corresponding saved limit can be represented correctly in an object of type  rlim_t, then it will be overwritten with the  new
       limit.

       The result of setting a limit to RLIM_SAVED_MAX or RLIM_SAVED_CUR is unspecified unless a previous call to  getrlimit() returned that value
       as the soft or hard limit for the corresponding resource limit.

       A limit whose value is greater than RLIM_INFINITY is permitted.

       The exec family of functions also cause resource limits to be saved.  See exec(2).

RETURN VALUES

       Upon successful completion, getrlimit() and setrlimit() return 0. Otherwise, these functions return -1 and set errno to indicate the error.

ERRORS

       The getrlimit() and setrlimit() functions will fail if:

       EFAULT	 The rlp argument points to an illegal address.

       EINVAL	 An invalid resource was specified; or in a setrlimit() call, the new rlim_cur exceeds the new rlim_max.

       EPERM	 The limit specified to setrlimit() would have raised the maximum limit value and  {PRIV_SYS_RESOURCE}	is  not  asserted  in  the
		 effective set of the current process.

       The setrlimit() function may fail if:

       EINVAL	 The limit specified cannot be lowered because current usage is already higher than the limit.

USAGE

       The getrlimit() and setrlimit() functions have transitional interfaces for 64-bit file offsets.	See lf64(5).

       The rlimit functionality is now provided by the more general resource control facility described on the setrctl(2) manual page. The actions
       associated with the resource limits described above are true at system boot, but an administrator can modify  the  local  configuration	to
       modify  signal  delivery  or  type.  Application authors that utilize rlimits for the purposes of resource awareness should investigate the
       resource controls facility.

ATTRIBUTES

       See attributes(5) for descriptions of the following attributes:

       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE	     |	    ATTRIBUTE VALUE	   |
       +-----------------------------+-----------------------------+
       |Interface Stability	     |Standard			   |
       +-----------------------------+-----------------------------+

SEE ALSO

       rctladm(1M), brk(2), exec(2), fork(2), open(2), setrctl(2), sigaltstack(2),  ulimit(2),	getdtablesize(3C),  malloc(3C),  signal(3C),  sig-
       nal.h(3HEAD), sysconf(3C), attributes(5), lf64(5), privileges(5), resource_controls(5), standards(5)

SunOS 5.11							    21 Aug 2006 						      getrlimit(2)