toys/posix/ulimit.c

/* ulimit.c - Modify resource limits
 *
 * Copyright 2015 Rob Landley <rob@landley.net>
 *
 * See http://pubs.opengroup.org/onlinepubs/9699919799/utilities/ulimit.html
 * And man prlimit(2).
 *
 * Deviations from posix: The units on -f are supposed to be 512 byte
 * "blocks" (no other options are specified, and even hard drives don't
 * do that anymore). Bash uses 1024 byte blocks, so they don't care either.
 * We consistently use bytes everywhere we can.
 *
 * Deviations from bash: Sizes are in bytes (instead of -p 512 and -f 1024).
 * Bash's -p value has been wrong since 2010 (git 35f3d14dbbc5).
 * The kernel implementation of RLIMIT_LOCKS (-x) was removed from Linux in
 * 2003. Bash never implemented -b (it's in the help but unrecognized at
 * runtime). We support -P to affect processes other than us.

USE_ULIMIT(NEWTOY(ulimit, ">1P#<1SHavutsrRqpnmlifedc[-SH][!apvutsrRqnmlifedc]", TOYFLAG_USR|TOYFLAG_BIN))

config ULIMIT
  bool "ulimit"
  default y
  depends on TOYBOX_PRLIMIT
  help
    usage: ulimit [-P PID] [-SHRacdefilmnpqrstuv] [LIMIT]

    Print or set resource limits for process number PID. If no LIMIT specified
    (or read-only -ap selected) display current value (sizes in bytes).
    Default is ulimit -P $PPID -Sf" (show soft filesize of your shell).
    
    -S  Set/show soft limit          -H  Set/show hard (maximum) limit
    -a  Show all limits              -c  Core file size
    -d  Process data segment         -e  Max scheduling priority
    -f  Output file size             -i  Pending signal count
    -l  Locked memory                -m  Resident Set Size
    -n  Number of open files         -p  Pipe buffer
    -q  Posix message queue          -r  Max Real-time priority
    -R  Realtime latency (usec)      -s  Stack size
    -t  Total CPU time (in seconds)  -u  Maximum processes (under this UID)
    -v  Virtual memory size          -P  PID to affect (default $PPID)
*/

#define FOR_ulimit
#include "toys.h"

GLOBALS(
  long pid;
)

// This is a linux kernel syscall added in 2.6.36 (git c022a0acad53) which
// glibc only exports a wrapper prototype for if you #define _FSF_HURD_RULZE.
int prlimit(pid_t pid, int resource, const struct rlimit *new_limit,
  struct rlimit *old_limit);

// I'd like to sort the RLIMIT values 0-15, but mips, alpha and sparc
// override the asm-generic values for 5-9. Also, the kernel implementation
// of RLIMIT_LOCKS (-x) was removed from Linux in 2003.
void ulimit_main(void)
{
  struct rlimit rr;
  int i;
  // Order is cdefilmnqRrstuv
  char map[] = {RLIMIT_CORE, RLIMIT_DATA, RLIMIT_NICE, RLIMIT_FSIZE,
                RLIMIT_SIGPENDING, RLIMIT_MEMLOCK, RLIMIT_RSS, RLIMIT_NOFILE, 0,
                RLIMIT_MSGQUEUE, RLIMIT_RTTIME, RLIMIT_RTPRIO, RLIMIT_STACK,
                RLIMIT_CPU, RLIMIT_NPROC, RLIMIT_AS};

  if (!(toys.optflags&(FLAG_H-1))) toys.optflags |= FLAG_f;
  if ((toys.optflags&(FLAG_a|FLAG_p)) && toys.optc) error_exit("can't set -ap");

  // Fetch data
  if (!(toys.optflags&FLAG_P)) TT.pid = getppid();

  for (i=0; i<sizeof(map); i++) {
    char *flags="cdefilmnpqRrstuv";

    int get = toys.optflags&(FLAG_a|(1<<i));

    if (get && prlimit(TT.pid, map[i], 0, &rr)) perror_exit("-%c", flags[i]);
    if (!toys.optc) {
      if (toys.optflags&FLAG_a) printf("-%c: ", flags[i]);
      if (get) {
        if ((1<<i)&FLAG_p) {
          if (toys.optflags&FLAG_H)
            xreadfile("/proc/sys/fs/pipe-max-size", toybuf, sizeof(toybuf));
          else {
            int pp[2];

            xpipe(pp);
            sprintf(toybuf, "%d\n", fcntl(*pp, F_GETPIPE_SZ));
          }
          printf("%s", toybuf);
        } else {
          rlim_t rl = (toys.optflags&FLAG_H) ? rr.rlim_max : rr.rlim_cur;

          if (rl == RLIM_INFINITY) printf("unlimited\n");
          else printf("%ld\n", (long)rl);
        }
      }
    }
    if (toys.optflags&(1<<i)) break;
  }

  if (toys.optflags&(FLAG_a|FLAG_p)) return;

  if (toys.optc) {
    rlim_t val;

    if (tolower(**toys.optargs) == 'u') val = RLIM_INFINITY;
    else val = atolx_range(*toys.optargs, 0, LONG_MAX);

    if (toys.optflags&FLAG_H) rr.rlim_max = val;
    else rr.rlim_cur = val;
    if (prlimit(TT.pid, map[i], &rr, 0)) perror_exit(0);
  }
}