/*      $NetBSD: getconf.c,v 1.38 2024/07/22 21:03:17 rillig Exp $      */

/*-
 * Copyright (c) 1996, 1998 The NetBSD Foundation, Inc.
 * All rights reserved.
 *
 * This code is derived from software contributed to The NetBSD Foundation
 * by J.T. Conklin.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 
 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

#include <sys/cdefs.h>
__RCSID("$NetBSD: getconf.c,v 1.38 2024/07/22 21:03:17 rillig Exp $");

#include <err.h>
#include <errno.h>
#include <limits.h>
#include <locale.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>

struct conf_variable
{
  const char *name;
  enum { SYSCONF, CONFSTR, PATHCONF, CONSTANT } type;
  long value;
};

static void print_longvar(const char *, long);
static void print_strvar(const char *, const char *);
static void printvar(const struct conf_variable *, const char *);
static void usage(void) __dead;

static const struct conf_variable conf_table[] =
{
  { "PATH",                     CONFSTR,        _CS_PATH                },

  /* Utility Limit Minimum Values */
  { "POSIX2_BC_BASE_MAX",       CONSTANT,       _POSIX2_BC_BASE_MAX     },
  { "POSIX2_BC_DIM_MAX",        CONSTANT,       _POSIX2_BC_DIM_MAX      },
  { "POSIX2_BC_SCALE_MAX",      CONSTANT,       _POSIX2_BC_SCALE_MAX    },
  { "POSIX2_BC_STRING_MAX",     CONSTANT,       _POSIX2_BC_STRING_MAX   },
  { "POSIX2_COLL_WEIGHTS_MAX",  CONSTANT,       _POSIX2_COLL_WEIGHTS_MAX },
  { "POSIX2_EXPR_NEST_MAX",     CONSTANT,       _POSIX2_EXPR_NEST_MAX   },
  { "POSIX2_LINE_MAX",          CONSTANT,       _POSIX2_LINE_MAX        },
  { "POSIX2_RE_DUP_MAX",        CONSTANT,       _POSIX2_RE_DUP_MAX      },
  { "POSIX2_VERSION",           CONSTANT,       _POSIX2_VERSION         },

  /* POSIX.1 Minimum Values */
  { "_POSIX_AIO_LISTIO_MAX",    CONSTANT,       _POSIX_AIO_LISTIO_MAX   },  
  { "_POSIX_AIO_MAX",           CONSTANT,       _POSIX_AIO_MAX          },
  { "_POSIX_ARG_MAX",           CONSTANT,       _POSIX_ARG_MAX          },
  { "_POSIX_CHILD_MAX",         CONSTANT,       _POSIX_CHILD_MAX        },
  { "_POSIX_LINK_MAX",          CONSTANT,       _POSIX_LINK_MAX         },
  { "_POSIX_MAX_CANON",         CONSTANT,       _POSIX_MAX_CANON        },
  { "_POSIX_MAX_INPUT",         CONSTANT,       _POSIX_MAX_INPUT        },
  { "_POSIX_MQ_OPEN_MAX",       CONSTANT,       _POSIX_MQ_OPEN_MAX      },
  { "_POSIX_MQ_PRIO_MAX",       CONSTANT,       _POSIX_MQ_PRIO_MAX      },
  { "_POSIX_NAME_MAX",          CONSTANT,       _POSIX_NAME_MAX         },
  { "_POSIX_NGROUPS_MAX",       CONSTANT,       _POSIX_NGROUPS_MAX      },
  { "_POSIX_OPEN_MAX",          CONSTANT,       _POSIX_OPEN_MAX         },
  { "_POSIX_PATH_MAX",          CONSTANT,       _POSIX_PATH_MAX         },
  { "_POSIX_PIPE_BUF",          CONSTANT,       _POSIX_PIPE_BUF         },
  { "_POSIX_SSIZE_MAX",         CONSTANT,       _POSIX_SSIZE_MAX        },
  { "_POSIX_STREAM_MAX",        CONSTANT,       _POSIX_STREAM_MAX       },
  { "_POSIX_TZNAME_MAX",        CONSTANT,       _POSIX_TZNAME_MAX       },

  /* Symbolic Utility Limits */
  { "BC_BASE_MAX",              SYSCONF,        _SC_BC_BASE_MAX         },
  { "BC_DIM_MAX",               SYSCONF,        _SC_BC_DIM_MAX          },
  { "BC_SCALE_MAX",             SYSCONF,        _SC_BC_SCALE_MAX        },
  { "BC_STRING_MAX",            SYSCONF,        _SC_BC_STRING_MAX       },
  { "COLL_WEIGHTS_MAX",         SYSCONF,        _SC_COLL_WEIGHTS_MAX    },
  { "EXPR_NEST_MAX",            SYSCONF,        _SC_EXPR_NEST_MAX       },
  { "LINE_MAX",                 SYSCONF,        _SC_LINE_MAX            },
  { "RE_DUP_MAX",               SYSCONF,        _SC_RE_DUP_MAX          },

  /* Optional Facility Configuration Values */
  { "_POSIX2_C_BIND",           SYSCONF,        _SC_2_C_BIND            },
  { "POSIX2_C_DEV",             SYSCONF,        _SC_2_C_DEV             },
  { "POSIX2_CHAR_TERM",         SYSCONF,        _SC_2_CHAR_TERM         },
  { "POSIX2_FORT_DEV",          SYSCONF,        _SC_2_FORT_DEV          },
  { "POSIX2_FORT_RUN",          SYSCONF,        _SC_2_FORT_RUN          },
  { "POSIX2_LOCALEDEF",         SYSCONF,        _SC_2_LOCALEDEF         },
  { "POSIX2_SW_DEV",            SYSCONF,        _SC_2_SW_DEV            },
  { "POSIX2_UPE",               SYSCONF,        _SC_2_UPE               },

  /* POSIX.1 Configurable System Variables */
  { "AIO_LISTIO_MAX",           SYSCONF,        _SC_AIO_LISTIO_MAX      },
  { "AIO_MAX",                  SYSCONF,        _SC_AIO_MAX             },
  { "ARG_MAX",                  SYSCONF,        _SC_ARG_MAX             },
  { "CHILD_MAX",                SYSCONF,        _SC_CHILD_MAX           },
  { "CLK_TCK",                  SYSCONF,        _SC_CLK_TCK             },
  { "MQ_OPEN_MAX",              SYSCONF,        _SC_MQ_OPEN_MAX         },
  { "MQ_PRIO_MAX",              SYSCONF,        _SC_MQ_PRIO_MAX         },
  { "NGROUPS_MAX",              SYSCONF,        _SC_NGROUPS_MAX         },
  { "OPEN_MAX",                 SYSCONF,        _SC_OPEN_MAX            },
  { "STREAM_MAX",               SYSCONF,        _SC_STREAM_MAX          },
  { "TZNAME_MAX",               SYSCONF,        _SC_TZNAME_MAX          },
  { "_POSIX_JOB_CONTROL",       SYSCONF,        _SC_JOB_CONTROL         },
  { "_POSIX_SAVED_IDS",         SYSCONF,        _SC_SAVED_IDS           },
  { "_POSIX_VERSION",           SYSCONF,        _SC_VERSION             },

  { "LINK_MAX",                 PATHCONF,       _PC_LINK_MAX            },
  { "MAX_CANON",                PATHCONF,       _PC_MAX_CANON           },
  { "MAX_INPUT",                PATHCONF,       _PC_MAX_INPUT           },
  { "NAME_MAX",                 PATHCONF,       _PC_NAME_MAX            },
  { "PATH_MAX",                 PATHCONF,       _PC_PATH_MAX            },
  { "PIPE_BUF",                 PATHCONF,       _PC_PIPE_BUF            },
  { "_POSIX_CHOWN_RESTRICTED",  PATHCONF,       _PC_CHOWN_RESTRICTED    },
  { "_POSIX_NO_TRUNC",          PATHCONF,       _PC_NO_TRUNC            },
  { "_POSIX_VDISABLE",          PATHCONF,       _PC_VDISABLE            },

  /* POSIX.1b Configurable System Variables */
  { "PAGESIZE",                 SYSCONF,        _SC_PAGESIZE            },
  { "_POSIX_ASYNCHRONOUS_IO",   SYSCONF,        _SC_ASYNCHRONOUS_IO     },
  { "_POSIX_FSYNC",             SYSCONF,        _SC_FSYNC               },
  { "_POSIX_MAPPED_FILES",      SYSCONF,        _SC_MAPPED_FILES        },
  { "_POSIX_MEMLOCK",           SYSCONF,        _SC_MEMLOCK             },
  { "_POSIX_MEMLOCK_RANGE",     SYSCONF,        _SC_MEMLOCK_RANGE       },
  { "_POSIX_MEMORY_PROTECTION", SYSCONF,        _SC_MEMORY_PROTECTION   },
  { "_POSIX_MESSAGE_PASSING",   SYSCONF,        _SC_MESSAGE_PASSING     },
  { "_POSIX_MONOTONIC_CLOCK",   SYSCONF,        _SC_MONOTONIC_CLOCK     },
  { "_POSIX_PRIORITY_SCHEDULING", SYSCONF,      _SC_PRIORITY_SCHEDULING },
  { "_POSIX_SEMAPHORES",        SYSCONF,        _SC_SEMAPHORES          },
  { "_POSIX_SHARED_MEMORY_OBJECTS", SYSCONF,    _SC_SHARED_MEMORY_OBJECTS },
  { "_POSIX_SYNCHRONIZED_IO",   SYSCONF,        _SC_SYNCHRONIZED_IO     },
  { "_POSIX_TIMERS",            SYSCONF,        _SC_TIMERS              },

  { "_POSIX_SYNC_IO",           PATHCONF,       _PC_SYNC_IO             },

  /* POSIX.1c Configurable System Variables */
  { "LOGIN_NAME_MAX",           SYSCONF,        _SC_LOGIN_NAME_MAX      },
  { "_POSIX_THREADS",           SYSCONF,        _SC_THREADS             },

  /* POSIX.1j Configurable System Variables */
  { "_POSIX_BARRIERS",          SYSCONF,        _SC_BARRIERS            },
  { "_POSIX_READER_WRITER_LOCKS", SYSCONF,      _SC_READER_WRITER_LOCKS },
  { "_POSIX_SPIN_LOCKS",        SYSCONF,        _SC_SPIN_LOCKS          },

  /* XPG4.2 Configurable System Variables */
  { "IOV_MAX",                  SYSCONF,        _SC_IOV_MAX             },
  { "PAGE_SIZE",                SYSCONF,        _SC_PAGE_SIZE           },
  { "_XOPEN_SHM",               SYSCONF,        _SC_XOPEN_SHM           },

  /* X/Open CAE Spec. Issue 5 Version 2 Configurable System Variables */
  { "FILESIZEBITS",             PATHCONF,       _PC_FILESIZEBITS        },

  /* POSIX.1-2001 XSI Option Group Configurable System Variables */
  { "ATEXIT_MAX",               SYSCONF,        _SC_ATEXIT_MAX          },

  /* POSIX.1-2001 TSF Configurable System Variables */
  { "GETGR_R_SIZE_MAX",         SYSCONF,        _SC_GETGR_R_SIZE_MAX    },
  { "GETPW_R_SIZE_MAX",         SYSCONF,        _SC_GETPW_R_SIZE_MAX    },

  /* Extensions found in Solaris and Linux. */
  { "SC_PHYS_PAGES",            SYSCONF,        _SC_PHYS_PAGES          },
  { "SC_AVPHYS_PAGES",          SYSCONF,        _SC_AVPHYS_PAGES        },

#ifdef _NETBSD_SOURCE
  /* Commonly provided extensions */
  { "NPROCESSORS_CONF",         SYSCONF,        _SC_NPROCESSORS_CONF    },
  { "NPROCESSORS_ONLN",         SYSCONF,        _SC_NPROCESSORS_ONLN    },
#endif  /* _NETBSD_SOURCE */

  { NULL, CONSTANT, 0L }
};

static int a_flag = 0;          /* list all variables */

int
main(int argc, char **argv)
{
        int ch;
        const struct conf_variable *cp;
        const char *varname, *pathname, *vn;
        int found;

        setprogname(argv[0]);
        (void)setlocale(LC_ALL, "");

        while ((ch = getopt(argc, argv, "a")) != -1) {
                switch (ch) {
                case 'a':
                        a_flag = 1;
                        break;
                case '?':
                default:
                        usage();
                }
        }
        argc -= optind;
        argv += optind;

        if (!a_flag) {
                if (argc == 0)
                        usage();
                varname = argv[0];
                argc--;
                argv++;
        } else
                varname = NULL;

        if (argc > 1)
                usage();
        pathname = argv[0];     /* may be NULL */

        found = 0;
        vn = varname;
again:
        for (cp = conf_table; cp->name != NULL; cp++) {
                if (a_flag || strcmp(vn, cp->name) == 0) {
                        if ((cp->type == PATHCONF) == (pathname != NULL)) {
                                printvar(cp, pathname);
                                found = 1;
                        } else if (!a_flag)
                                errx(EXIT_FAILURE,
                                    "%s: invalid variable type", cp->name);
                }
        }

        if (!a_flag && !found) {
                if (*vn++ == '_')
                        goto again;
                errx(EXIT_FAILURE, "%s: unknown variable", varname);
        }

        (void)fflush(stdout);
        return ferror(stdout) ? EXIT_FAILURE : EXIT_SUCCESS;
}

static void
print_longvar(const char *name, long value)
{
        if (a_flag)
                (void)printf("%s = %ld\n", name, value);
        else
                (void)printf("%ld\n", value);
}

static void
print_strvar(const char *name, const char *sval)
{
        if (a_flag)
                (void)printf("%s = %s\n", name, sval);
        else
                (void)printf("%s\n", sval);
}

static void
printvar(const struct conf_variable *cp, const char *pathname)
{
        size_t slen;
        char *sval;
        long val;

        switch (cp->type) {
        case CONSTANT:
                print_longvar(cp->name, cp->value);
                break;

        case CONFSTR:
                errno = 0;
                slen = confstr((int)cp->value, NULL, 0);
                if (slen == 0) {
                        if (errno != 0)

out:                            err(EXIT_FAILURE, "confstr(%ld)", cp->value);
                        else
                                print_strvar(cp->name, "undefined");
                }

                if ((sval = malloc(slen)) == NULL)
                        err(EXIT_FAILURE, "Can't allocate %zu bytes", slen);

                errno = 0;
                if (confstr((int)cp->value, sval, slen) == 0) {
                        if (errno != 0)
                                goto out;
                        else
                                print_strvar(cp->name, "undefined");
                } else
                        print_strvar(cp->name, sval);

                free(sval);
                break;

        case SYSCONF:
                errno = 0;
                if ((val = sysconf((int)cp->value)) == -1) {
                        if (errno != 0)
                                err(EXIT_FAILURE, "sysconf(%ld)", cp->value);
                        print_strvar(cp->name, "undefined");
                } else
                        print_longvar(cp->name, val);
                break;

        case PATHCONF:
                errno = 0;
                if ((val = pathconf(pathname, (int)cp->value)) == -1) {
                        if (errno != 0) {
                                if (a_flag && errno == EINVAL) {
                                        /* Just skip invalid variables */
                                        return;
                                }
                                err(EXIT_FAILURE, "pathconf(%s, %ld)",
                                    pathname, cp->value);
                                /* NOTREACHED */
                        }

                        print_strvar(cp->name, "undefined");
                } else
                        print_longvar(cp->name, val);
                break;
        }
}


static void
usage(void)
{
        const char *p = getprogname();
        (void)fprintf(stderr, "Usage: %s system_var\n\t%s -a\n"
            "\t%s path_var pathname\n\t%s -a pathname\n", p, p, p, p);
        exit(EXIT_FAILURE);
}