Add our first utility, getconf(1)

2 files changed, 650 insertions, 0 deletions

diff --git a/getconf/getconf.1 b/getconf/getconf.1
new file mode 100644
index 0000000..35f9c13
--- /dev/null
+++ b/getconf/getconf.1
@@ -0,0 +1,110 @@
+.Dd April 9, 2016
+.Dt GETCONF 1 "Base Commands Manual"
+.Os "Adélie Linux"
+
+.Sh NAME
+.Nm getconf
+.Nd get system configuration values
+
+.Sh SYNOPSIS
+.Nm
+.Op Fl v Ar specification
+.Ar system_var
+
+.Nm
+.Op Fl v Ar specification
+.Ar path_var
+.Ar pathname
+
+.Sh DESCRIPTION
+In the first form, the
+.Nm
+utility prints the value of the system variable specified by
+.Ar system_var
+on the currently running system, under the specification given for the
+.Fl v
+argument if specified.
+
+Valid system variables are one of the following:
+
+.Bl -bullet -offset indent -compact
+.It
+The variable name of a valid parameter to the
+.Xr sysconf 3
+function as specified in
+.St -p1003.1-2008 ,
+excluding braces.  The variables
+.Dq _SC_CLK_TCK ,
+.Dq _SC_GETGR_R_SIZE_MAX ,
+and
+.Dq _SC_GETPW_R_SIZE_MAX
+are not supported.
+.It
+A valid parameter to the
+.Xr confstr 3
+function as specified in
+.St -p1003.1-2008 ,
+excluding the
+.Dq _CS_
+prefix.
+.It
+A constant listed under the
+.Dq Maximum Values
+or
+.Dq Minimum Values
+section of the
+.Aq Pa limits.h
+header as specified in
+.St -p1003.1-2008 ,
+excluding braces.
+.El
+
+In the second form, the
+.Nm
+utility prints the value of the path variable specified by
+.Ar path_var
+for the path specified by
+.Ar pathname
+on the currently running system, under the specification given for the
+.Fl v
+argument if specified.
+
+Valid path variables are those accepted by the
+.Xr fpathconf 3
+function as specified in
+.St -p1003.1-2008 ,
+exluding braces.
+
+.Sh OPTIONS
+.Bl -tag
+.It -v
+Indicates the specification to use.  Currently, this option is unsupported and
+will be ignored.
+.El
+
+.Sh DIAGNOSTICS
+.Ex -std
+
+.Sh SEE ALSO
+
+.Xr confstr 3 ,
+.Xr fpathconf 3 ,
+.Xr sysconf 3 .
+
+.Sh STANDARDS
+The eventual goal for the
+.Nm
+utility is full conformance to
+.St -p1003.1 2013 Edition.
+
+.Sh AUTHORS
+.An A. Wilcox
+.Aq awilfox@adelielinux.org
+
+.Sh BUGS
+The
+.Fl v
+argument is not currently handled correctly.
+.Pp
+.Ar path_var
+variables are not yet supported.
diff --git a/getconf/getconf.c b/getconf/getconf.c
new file mode 100644
index 0000000..0f2b5d0
--- /dev/null
+++ b/getconf/getconf.c
@@ -0,0 +1,540 @@
+/*
+ * getconf - get important system configuration values from the shell.
+ * Copyright (c) 2016 Adélie Linux Team.  All rights reserved.
+ * Licensed under the NCSA open source license.
+ * See LICENSE file included with this source for more information.
+ */
+
+
+#include <errno.h>	/* errno */
+#include <limits.h>	/* limit_vars */
+#include <stdbool.h>	/* bool type and true/false */
+#include <stdio.h>	/* stderr, fprintf */
+#include <stdlib.h>	/* malloc, free */
+#include <string.h>	/* strlen */
+#include <strings.h>	/* strcasecmp */
+#include <unistd.h>	/* sysconf + _SC friends, confstr + _CS friends */
+
+typedef struct variable_mapping
+{
+	const char *variable;
+	const int value;
+} var_map_t;
+
+/* For variables that are valid, but undefined in this implementation */
+#define _UNDEFINED_VARIABLE_ 0x7FEEDFEE
+
+const var_map_t sysconf_vars[] = {
+	/* max */
+	{ "AIO_LISTIO_MAX", _SC_AIO_LISTIO_MAX },
+	{ "AIO_MAX", _SC_AIO_MAX },
+#if defined(_SC_AIO_PRIO_DELTA_MAX)
+	{ "AIO_PRIO_DELTA_MAX", _SC_AIO_PRIO_DELTA_MAX },
+#else /* NetBSD */
+	{ "AIO_PRIO_DELTA_MAX", _UNDEFINED_VARIABLE_ },
+#endif
+	{ "ARG_MAX", _SC_ARG_MAX },
+	{ "ATEXIT_MAX", _SC_ATEXIT_MAX },
+	{ "BC_BASE_MAX", _SC_BC_BASE_MAX },
+	{ "BC_DIM_MAX", _SC_BC_DIM_MAX },
+	{ "BC_SCALE_MAX", _SC_BC_SCALE_MAX },
+	{ "BC_STRING_MAX", _SC_BC_STRING_MAX },
+	{ "CHILD_MAX", _SC_CHILD_MAX },
+	{ "COLL_WEIGHTS_MAX", _SC_COLL_WEIGHTS_MAX },
+#if defined(_SC_DELAYTIMER_MAX)
+	{ "DELAYTIMER_MAX", _SC_DELAYTIMER_MAX },
+#else /* NetBSD */
+	{ "DELAYTIMER_MAX", _UNDEFINED_VARIABLE_ },
+#endif
+	{ "EXPR_NEST_MAX", _SC_EXPR_NEST_MAX },
+	{ "HOST_NAME_MAX", _SC_HOST_NAME_MAX },
+	{ "IOV_MAX", _SC_IOV_MAX },
+	{ "LINE_MAX", _SC_LINE_MAX },
+	{ "LOGIN_NAME_MAX", _SC_LOGIN_NAME_MAX },
+	{ "NGROUPS_MAX", _SC_NGROUPS_MAX },
+	{ "MQ_OPEN_MAX", _SC_MQ_OPEN_MAX },
+	{ "MQ_PRIO_MAX", _SC_MQ_PRIO_MAX },
+	{ "OPEN_MAX", _SC_OPEN_MAX },
+	{ "PAGE_SIZE", _SC_PAGE_SIZE },
+	{ "PAGESIZE", _SC_PAGESIZE },
+	{ "PTHREAD_DESTRUCTOR_ITERATIONS", _SC_THREAD_DESTRUCTOR_ITERATIONS },
+	{ "PTHREAD_KEYS_MAX", _SC_THREAD_KEYS_MAX },
+	{ "PTHREAD_STACK_MIN", _SC_THREAD_STACK_MIN },
+	{ "PTHREAD_THREADS_MAX", _SC_THREAD_THREADS_MAX },
+	{ "RE_DUP_MAX", _SC_RE_DUP_MAX },
+#if defined(_SC_RTSIG_MAX)
+	{ "RTSIG_MAX", _SC_RTSIG_MAX },
+#else /* NetBSD */
+	{ "RTSIG_MAX", _UNDEFINED_VARIABLE_ },
+#endif
+#if defined(_SC_SEM_NSEMS_MAX)
+	{ "SEM_NSEMS_MAX", _SC_SEM_NSEMS_MAX },
+#else /* NetBSD */
+	{ "SEM_NSEMS_MAX", _UNDEFINED_VARIABLE_ },
+#endif
+#if defined(_SC_SEM_VALUE_MAX)
+	{ "SEM_VALUE_MAX", _SC_SEM_VALUE_MAX },
+#else /* NetBSD */
+	{ "SEM_VALUE_MAX", _UNDEFINED_VARIABLE_ },
+#endif
+#if defined(_SC_SIGQUEUE_MAX)
+	{ "SIGQUEUE_MAX", _SC_SIGQUEUE_MAX },
+#else /* NetBSD */
+	{ "SIGQUEUE_MAX", _UNDEFINED_VARIABLE_ },
+#endif
+	{ "STREAM_MAX", _SC_STREAM_MAX },
+	{ "SYMLOOP_MAX", _SC_SYMLOOP_MAX },
+#if defined(_SC_TIMER_MAX)
+	{ "TIMER_MAX", _SC_TIMER_MAX },
+#else /* NetBSD */
+	{ "TIMER_MAX", _UNDEFINED_VARIABLE_ },
+#endif
+	{ "TTY_NAME_MAX", _SC_TTY_NAME_MAX },
+	{ "TZNAME_MAX", _SC_TZNAME_MAX },
+
+	/* POSIX */
+#if defined(_SC_ADVISORY_INFO)
+	{ "_POSIX_ADVISORY_INFO", _SC_ADVISORY_INFO },
+#else /* NetBSD */
+	{ "_POSIX_ADVISORY_INFO", _UNDEFINED_VARIABLE_ },
+#endif
+	{ "_POSIX_BARRIERS", _SC_BARRIERS },
+	{ "_POSIX_ASYNCHRONOUS_IO", _SC_ASYNCHRONOUS_IO },
+	{ "_POSIX_CLOCK_SELECTION", _SC_CLOCK_SELECTION },
+#if defined(_SC_CPUTIME)
+	{ "_POSIX_CPUTIME", _SC_CPUTIME },
+#else /* NetBSD */
+	{ "_POSIX_CPUTIME", _UNDEFINED_VARIABLE_ },
+#endif
+	{ "_POSIX_FSYNC", _SC_FSYNC },
+#if defined(_SC_IPV6)
+	{ "_POSIX_IPV6", _SC_IPV6 },
+#else /* NetBSD */
+	{ "_POSIX_IPV6", _UNDEFINED_VARIABLE_ },
+#endif
+	{ "_POSIX_JOB_CONTROL", _SC_JOB_CONTROL },
+	{ "_POSIX_MAPPED_FILES", _SC_MAPPED_FILES },
+	{ "_POSIX_MEMLOCK", _SC_MEMLOCK },
+	{ "_POSIX_MEMLOCK_RANGE", _SC_MEMLOCK_RANGE },
+	{ "_POSIX_MEMORY_PROTECTION", _SC_MEMORY_PROTECTION },
+	{ "_POSIX_MESSAGE_PASSING", _SC_MESSAGE_PASSING },
+	{ "_POSIX_MONOTONIC_CLOCK", _SC_MONOTONIC_CLOCK },
+#if defined(_SC_PRIORITIZED_IO)
+	{ "_POSIX_PRIORITIZED_IO", _SC_PRIORITIZED_IO },
+#else /* NetBSD */
+	{ "_POSIX_PRIORITIZED_IO", _UNDEFINED_VARIABLE_ },
+#endif
+	{ "_POSIX_PRIORITY_SCHEDULING", _SC_PRIORITY_SCHEDULING },
+#if defined(_SC_RAW_SOCKETS)
+	{ "_POSIX_RAW_SOCKETS", _SC_RAW_SOCKETS },
+#else /* NetBSD */
+	{ "_POSIX_RAW_SOCKETS", _UNDEFINED_VARIABLE_ },
+#endif
+	{ "_POSIX_READER_WRITER_LOCKS", _SC_READER_WRITER_LOCKS },
+#if defined(_SC_REALTIME_SIGNALS)
+	{ "_POSIX_REALTIME_SIGNALS", _SC_REALTIME_SIGNALS },
+#else /* NetBSD */
+	{ "_POSIX_REALTIME_SIGNALS", _UNDEFINED_VARIABLE_ },
+#endif
+	{ "_POSIX_REGEXP", _SC_REGEXP },
+	{ "_POSIX_SAVED_IDS", _SC_SAVED_IDS },
+	{ "_POSIX_SEMAPHORES", _SC_SEMAPHORES },
+#if defined(_SC_SHARED_MEMORY_OBJECTS)
+	{ "_POSIX_SHARED_MEMORY_OBJECTS", _SC_SHARED_MEMORY_OBJECTS },
+#else /* NetBSD */
+	{ "_POSIX_SHARED_MEMORY_OBJECTS", _UNDEFINED_VARIABLE_ },
+#endif
+	{ "_POSIX_SHELL", _SC_SHELL },
+	{ "_POSIX_SPAWN", _SC_SPAWN },
+	{ "_POSIX_SPIN_LOCKS", _SC_SPIN_LOCKS },
+#if defined(_SC_SPORADIC_SERVER)
+	{ "_POSIX_SPORADIC_SERVER", _SC_SPORADIC_SERVER },
+#else /* NetBSD */
+	{ "_POSIX_SPORADIC_SERVER", _UNDEFINED_VARIABLE_ },
+#endif
+#if defined(_SC_SS_REPL_MAX)
+	{ "_POSIX_SS_REPL_MAX", _SC_SS_REPL_MAX },
+#else /* FreeBSD */
+	{ "_POSIX_SS_REPL_MAX", _UNDEFINED_VARIABLE_ },
+#endif
+	{ "_POSIX_SYNCHRONIZED_IO", _SC_SYNCHRONIZED_IO },
+	{ "_POSIX_THREAD_ATTR_STACKADDR", _SC_THREAD_ATTR_STACKADDR },
+	{ "_POSIX_THREAD_ATTR_STACKSIZE", _SC_THREAD_ATTR_STACKSIZE },
+#if defined(_SC_THREAD_CPUTIME)
+	{ "_POSIX_THREAD_CPUTIME", _SC_THREAD_CPUTIME },
+#else /* NetBSD */
+	{ "_POSIX_THREAD_CPUTIME", _UNDEFINED_VARIABLE_ },
+#endif
+	{ "_POSIX_THREAD_PRIO_INHERIT", _SC_THREAD_PRIO_INHERIT },
+	{ "_POSIX_THREAD_PRIO_PROTECT", _SC_THREAD_PRIO_PROTECT },
+	{ "_POSIX_THREAD_PRIO_PROTECT", _UNDEFINED_VARIABLE_ },
+	{ "_POSIX_THREAD_PRIORITY_SCHEDULING", _SC_THREAD_PRIORITY_SCHEDULING },
+	{ "_POSIX_THREAD_PROCESS_SHARED", _SC_THREAD_PROCESS_SHARED },
+#if defined(_SC_THREAD_ROBUST_PRIO_INHERIT)
+	{ "_POSIX_THREAD_ROBUST_PRIO_INHERIT", _SC_THREAD_ROBUST_PRIO_INHERIT },
+#else /* FreeBSD */
+	{ "_POSIX_THREAD_ROBUST_PRIO_INHERIT", _UNDEFINED_VARIABLE_ },
+#endif
+#if defined(_SC_THREAD_ROBUST_PRIO_PROTECT)
+	{ "_POSIX_THREAD_ROBUST_PRIO_PROTECT", _SC_THREAD_ROBUST_PRIO_PROTECT },
+#else /* FreeBSD */
+	{ "_POSIX_THREAD_ROBUST_PRIO_PROTECT", _UNDEFINED_VARIABLE_ },
+#endif
+	{ "_POSIX_THREAD_SAFE_FUNCTIONS", _SC_THREAD_SAFE_FUNCTIONS },
+#if defined(_SC_THREAD_SPORADIC_SERVER)
+	{ "_POSIX_THREAD_SPORADIC_SERVER", _SC_THREAD_SPORADIC_SERVER },
+#else /* NetBSD */
+	{ "_POSIX_THREAD_SPORADIC_SERVER", _UNDEFINED_VARIABLE_ },
+#endif
+	{ "_POSIX_THREADS", _SC_THREADS },
+#if defined(_SC_TIMEOUTS)
+	{ "_POSIX_TIMEOUTS", _SC_TIMEOUTS },
+#else /* NetBSD */
+	{ "_POSIX_TIMEOUTS", _UNDEFINED_VARIABLE_ },
+#endif
+	{ "_POSIX_TIMERS", _SC_TIMERS },
+#if defined(_SC_TRACE)
+	{ "_POSIX_TRACE", _SC_TRACE },
+#else /* NetBSD */
+	{ "_POSIX_TRACE", _UNDEFINED_VARIABLE_ },
+#endif
+#if defined(_SC_TRACE_EVENT_FILTER)
+	{ "_POSIX_TRACE_EVENT_FILTER", _SC_TRACE_EVENT_FILTER },
+#else /* NetBSD */
+	{ "_POSIX_TRACE_EVENT_FILTER", _UNDEFINED_VARIABLE_ },
+#endif
+#if defined(_SC_TRACE_EVENT_NAME_MAX)
+	{ "_POSIX_TRACE_EVENT_NAME_MAX", _SC_TRACE_EVENT_NAME_MAX },
+#else /* FreeBSD */
+	{ "_POSIX_TRACE_EVENT_NAME_MAX", _UNDEFINED_VARIABLE_ },
+#endif
+#if defined(_SC_TRACE_INHERIT)
+	{ "_POSIX_TRACE_INHERIT", _SC_TRACE_INHERIT },
+#else /* NetBSD */
+	{ "_POSIX_TRACE_INHERIT", _UNDEFINED_VARIABLE_ },
+#endif
+#if defined(_SC_TRACE_LOG)
+	{ "_POSIX_TRACE_LOG", _SC_TRACE_LOG },
+#else /* NetBSD */
+	{ "_POSIX_TRACE_LOG", _UNDEFINED_VARIABLE_ },
+#endif
+#if defined(_SC_TRACE_NAME_MAX)
+	{ "_POSIX_TRACE_NAME_MAX", _SC_TRACE_NAME_MAX },
+#else /* FreeBSD */
+	{ "_POSIX_TRACE_NAME_MAX", _UNDEFINED_VARIABLE_ },
+#endif
+#if defined(_SC_TRACE_SYS_MAX)
+	{ "_POSIX_TRACE_SYS_MAX", _SC_TRACE_SYS_MAX },
+#else /* FreeBSD */
+	{ "_POSIX_TRACE_SYS_MAX", _UNDEFINED_VARIABLE_ },
+#endif
+#if defined(_SC_TRACE_USER_EVENT_MAX)
+	{ "_POSIX_TRACE_USER_EVENT_MAX", _SC_TRACE_USER_EVENT_MAX },
+#else /* FreeBSD */
+	{ "_POSIX_TRACE_USER_EVENT_MAX", _UNDEFINED_VARIABLE_ },
+#endif
+#if defined(_SC_TYPED_MEMORY_OBJECTS)
+	{ "_POSIX_TYPED_MEMORY_OBJECTS", _SC_TYPED_MEMORY_OBJECTS },
+#else /* NetBSD */
+	{ "_POSIX_TYPED_MEMORY_OBJECTS", _UNDEFINED_VARIABLE_ },
+#endif
+	{ "_POSIX_VERSION", _SC_VERSION },
+#if defined(_SC_V7_ILP32_OFF32)
+	{ "_POSIX_V7_ILP32_OFF32", _SC_V7_ILP32_OFF32 },
+#else /* FreeBSD */
+	{ "_POSIX_V7_ILP32_OFF32", _UNDEFINED_VARIABLE_ },
+#endif
+#if defined(_SC_V7_ILP32_OFFBIG)
+	{ "_POSIX_V7_ILP32_OFFBIG", _SC_V7_ILP32_OFFBIG },
+#else /* FreeBSD */
+	{ "_POSIX_V7_ILP32_OFFBIG", _UNDEFINED_VARIABLE_ },
+#endif
+#if defined(_SC_V7_LP64_OFF64)
+	{ "_POSIX_V7_LP64_OFF64", _SC_V7_LP64_OFF64 },
+#else /* FreeBSD */
+	{ "_POSIX_V7_LP64_OFF64", _UNDEFINED_VARIABLE_ },
+#endif
+#if defined(_SC_V7_LPBIG_OFFBIG)
+	{ "_POSIX_V7_LPBIG_OFFBIG", _SC_V7_LPBIG_OFFBIG },
+#else /* FreeBSD */
+	{ "_POSIX_V7_LPBIG_OFFBIG", _UNDEFINED_VARIABLE_ },
+#endif
+
+	/* POSIX.2 */
+	{ "_POSIX2_C_BIND", _SC_2_C_BIND },
+	{ "_POSIX2_C_DEV", _SC_2_C_DEV },
+	{ "_POSIX2_CHAR_TERM", _SC_2_CHAR_TERM },
+	{ "_POSIX2_FORT_DEV", _SC_2_FORT_DEV },
+	{ "_POSIX2_FORT_RUN", _SC_2_FORT_RUN },
+	{ "_POSIX2_LOCALEDEF", _SC_2_LOCALEDEF },
+	{ "_POSIX2_PBS", _SC_2_PBS },
+	{ "_POSIX2_PBS_ACCOUNTING", _SC_2_PBS_ACCOUNTING },
+	{ "_POSIX2_PBS_CHECKPOINT", _SC_2_PBS_CHECKPOINT },
+	{ "_POSIX2_PBS_LOCATE", _SC_2_PBS_LOCATE },
+	{ "_POSIX2_PBS_MESSAGE", _SC_2_PBS_MESSAGE },
+	{ "_POSIX2_PBS_TRACK", _SC_2_PBS_TRACK },
+	{ "_POSIX2_SW_DEV", _SC_2_SW_DEV },
+	{ "_POSIX2_UPE", _SC_2_UPE },
+	{ "_POSIX2_VERSION", _SC_2_VERSION },
+
+	/* X/Open */
+#if defined(_SC_XOPEN_CRYPT)
+	{ "_XOPEN_CRYPT", _SC_XOPEN_CRYPT },
+#else /* NetBSD */
+	{ "_XOPEN_CRYPT", _UNDEFINED_VARIABLE_ },
+#endif
+#if defined(_SC_XOPEN_ENH_I18N)
+	{ "_XOPEN_ENH_I18N", _SC_XOPEN_ENH_I18N },
+#else /* NetBSD */
+	{ "_XOPEN_ENH_I18N", _UNDEFINED_VARIABLE_ },
+#endif
+#if defined(_SC_XOPEN_REALTIME)
+	{ "_XOPEN_REALTIME", _SC_XOPEN_REALTIME },
+#else /* NetBSD */
+	{ "_XOPEN_REALTIME", _UNDEFINED_VARIABLE_ },
+#endif
+#if defined(_SC_XOPEN_REALTIME_THREADS)
+	{ "_XOPEN_REALTIME_THREADS", _SC_XOPEN_REALTIME_THREADS },
+#else /* NetBSD */
+	{ "_XOPEN_REALTIME_THREADS", _UNDEFINED_VARIABLE_ },
+#endif
+	{ "_XOPEN_SHM", _SC_XOPEN_SHM },
+#if defined(_SC_XOPEN_STREAMS)
+	{ "_XOPEN_STREAMS", _SC_XOPEN_STREAMS },
+#else /* NetBSD */
+	{ "_XOPEN_STREAMS", _UNDEFINED_VARIABLE_ },
+#endif
+#if defined(_SC_XOPEN_UNIX)
+	{ "_XOPEN_UNIX", _SC_XOPEN_UNIX },
+#else /* NetBSD */
+	{ "_XOPEN_UNIX", _UNDEFINED_VARIABLE_ },
+#endif
+#if defined(_SC_XOPEN_UUCP)
+	{ "_XOPEN_UUCP", _SC_XOPEN_UUCP },
+#else /* glibc */
+	{ "_XOPEN_UUCP", _UNDEFINED_VARIABLE_ },
+#endif
+#if defined(_SC_XOPEN_VERSION)
+	{ "_XOPEN_VERSION", _SC_XOPEN_VERSION }
+#else /* NetBSD */
+	{ "_XOPEN_VERSION", _UNDEFINED_VARIABLE_ }
+#endif
+};
+
+
+const int sysvar_count = sizeof(sysconf_vars) / sizeof(sysconf_vars[0]);
+
+
+const var_map_t confstr_vars[] = {
+	{ "PATH", _CS_PATH },
+#if defined(_CS_V7_ENV)
+	{ "V7_ENV", _CS_V7_ENV }
+#else
+	{ "V7_ENV", _UNDEFINED_VARIABLE_ }
+#endif
+};
+
+
+const int confstr_count = sizeof(confstr_vars) / sizeof(confstr_vars[0]);
+
+
+const var_map_t limit_vars[] = {
+	{ "_POSIX_AIO_LISTIO_MAX", _POSIX_AIO_LISTIO_MAX },
+	{ "_POSIX_AIO_MAX", _POSIX_AIO_MAX },
+	{ "_POSIX_ARG_MAX", _POSIX_ARG_MAX },
+	{ "_POSIX_CHILD_MAX", _POSIX_CHILD_MAX },
+	{ "_POSIX_DELAYTIMER_MAX", _POSIX_DELAYTIMER_MAX },
+	{ "_POSIX_HOST_NAME_MAX", _POSIX_HOST_NAME_MAX },
+	{ "_POSIX_LINK_MAX", _POSIX_LINK_MAX },
+	{ "_POSIX_LOGIN_NAME_MAX", _POSIX_LOGIN_NAME_MAX },
+	{ "_POSIX_MAX_CANON", _POSIX_MAX_CANON },
+	{ "_POSIX_MAX_INPUT", _POSIX_MAX_INPUT },
+	{ "_POSIX_NAME_MAX", _POSIX_NAME_MAX },
+	{ "_POSIX_NGROUPS_MAX", _POSIX_NGROUPS_MAX },
+	{ "_POSIX_OPEN_MAX", _POSIX_OPEN_MAX },
+	{ "_POSIX_PATH_MAX", _POSIX_PATH_MAX },
+	{ "_POSIX_PIPE_BUF", _POSIX_PIPE_BUF },
+	{ "_POSIX_RE_DUP_MAX", _POSIX_RE_DUP_MAX },
+	{ "_POSIX_RTSIG_MAX", _POSIX_RTSIG_MAX },
+	{ "_POSIX_SEM_NSEMS_MAX", _POSIX_SEM_NSEMS_MAX },
+	{ "_POSIX_SEM_VALUE_MAX", _POSIX_SEM_VALUE_MAX },
+	{ "_POSIX_SIGQUEUE_MAX", _POSIX_SIGQUEUE_MAX },
+	{ "_POSIX_SSIZE_MAX", _POSIX_SSIZE_MAX },
+	{ "_POSIX_STREAM_MAX", _POSIX_STREAM_MAX },
+	{ "_POSIX_SYMLINK_MAX", _POSIX_SYMLINK_MAX },
+	{ "_POSIX_SYMLOOP_MAX", _POSIX_SYMLOOP_MAX },
+	{ "_POSIX_THREAD_DESTRUCTOR_ITERATIONS",
+		_POSIX_THREAD_DESTRUCTOR_ITERATIONS },
+	{ "_POSIX_THREAD_KEYS_MAX", _POSIX_THREAD_KEYS_MAX },
+	{ "_POSIX_THREAD_THREADS_MAX", _POSIX_THREAD_THREADS_MAX },
+	{ "_POSIX_TIMER_MAX", _POSIX_TIMER_MAX },
+	{ "_POSIX_TTY_NAME_MAX", _POSIX_TTY_NAME_MAX },
+	{ "_POSIX_TZNAME_MAX", _POSIX_TZNAME_MAX },
+	{ "_POSIX2_BC_BASE_MAX", _POSIX2_BC_BASE_MAX },
+	{ "_POSIX2_BC_DIM_MAX", _POSIX2_BC_DIM_MAX },
+	{ "_POSIX2_BC_SCALE_MAX", _POSIX2_BC_SCALE_MAX },
+	{ "_POSIX2_BC_STRING_MAX", _POSIX2_BC_STRING_MAX },
+	{ "_POSIX2_CHARCLASS_NAME_MAX", _POSIX2_CHARCLASS_NAME_MAX },
+	{ "_POSIX2_COLL_WEIGHTS_MAX", _POSIX2_COLL_WEIGHTS_MAX },
+	{ "_POSIX2_EXPR_NEST_MAX", _POSIX2_EXPR_NEST_MAX },
+	{ "_POSIX2_LINE_MAX", _POSIX2_LINE_MAX },
+	{ "_POSIX2_RE_DUP_MAX", _POSIX2_RE_DUP_MAX }
+};
+
+
+const int limit_count = sizeof(limit_vars) / sizeof(limit_vars[0]);
+
+
+int do_system_var(char *environment, char *system_var)
+{
+	int var;
+
+	if(strlen(environment) != 0)
+	{
+		fprintf(stderr, "Unsupported environment: %s\n", environment);
+		return EINVAL;
+	}
+
+	for(var = 0; var < sysvar_count; var++)
+	{
+		long int val;
+
+		if(strcasecmp(sysconf_vars[var].variable, system_var) != 0)
+			continue;
+
+		if(sysconf_vars[var].value == _UNDEFINED_VARIABLE_)
+		{
+			printf("undefined\n");
+			return 0;
+		}
+
+		errno = 0;
+
+		val = sysconf(sysconf_vars[var].value);
+		if(errno != 0)
+		{
+			/* We know that this is a valid symbol, so don't break
+			 * expectations (see _POSIX_TRACE_LOG in FreeBSD).
+			 * 
+			 * Note that POSIX states explicitly that results are
+			 * already unspecified if the value is dependent on an
+			 * unsupported POSIX option.  It also indicates that
+			 * *all* variables defined for sysconf *must* return
+			 * a result in getconf.  So, I feel this is the
+			 * strictest way to conform.
+			 */
+			printf("undefined\n");
+			return 0;
+		}
+
+		printf("%ld\n", val);
+		return 0;
+	}
+
+	for(var = 0; var < limit_count; var++)
+	{
+		if(strcasecmp(limit_vars[var].variable, system_var) != 0)
+			continue;
+
+		printf("%d\n", limit_vars[var].value);
+		return 0;
+	}
+
+	for(var = 0; var < confstr_count; var++)
+	{
+		size_t str_len;
+		char *str;
+
+		if(strcasecmp(confstr_vars[var].variable, system_var) != 0)
+			continue;
+
+		if(confstr_vars[var].value == _UNDEFINED_VARIABLE_)
+		{
+			printf("undefined\n");
+			return 0;
+		}
+
+		errno = 0;
+
+		str_len = confstr(confstr_vars[var].value, NULL, 0);
+		if(errno != 0 || str_len == 0)
+		{
+			/* We know that this is a valid symbol, so don't break
+			 * expectations (see above comment for sysconf).
+			 */
+			printf("undefined\n");
+			return 0;
+		}
+
+		str = malloc(str_len);
+		confstr(confstr_vars[var].value, str, str_len);
+		printf("%s\n", str);
+		free(str);
+
+		return 0;
+	}
+
+	fprintf(stderr, "%s: not a recognised system variable\n", system_var);
+	return EINVAL;
+}
+
+
+int do_path_var(char *environment, char *path_var, char *pathname)
+{
+	return -1;
+}
+
+
+int main(int argc, char *argv[])
+{
+	/* The envrionment passed by -v, if any.  Ignored for now. */
+	char *environment = NULL;
+	/* An error occurred during argument parsing */
+	bool arg_error = false;
+	/* The current argument being parsed */
+	int arg;
+
+	while((arg = getopt(argc, argv, ":v:")) != -1)
+	{
+		switch(arg)
+		{
+		case 'v':
+			environment = optarg;
+			break;
+		case ':':
+			fprintf(stderr, "required argument to '-%c' missing\n",
+				optopt);
+			arg_error = true;
+			break;
+		case '?':
+		default:
+			fprintf(stderr, "unrecognised option: '-%c'\n", optopt);
+			arg_error = true;
+			break;
+		}
+	}
+
+	switch(argc - optind)
+	{
+	case 1:
+		return do_system_var(environment, argv[optind++]);
+	case 2:
+		return do_path_var(environment, argv[optind], argv[optind+1]);
+	default:
+		/* just show usage. */
+		arg_error = true;
+		break;
+	}
+
+	if(arg_error)
+	{
+		fprintf(stderr, "usage:\n");
+		fprintf(stderr, "getconf [-v specification] system_var\n");
+		fprintf(stderr,
+			"getconf [-v specification] path_var pathname\n");
+		fprintf(stderr, "\n\tRetrieve system configuration value.\n");
+		return EINVAL;
+	}
+
+	return 0;
+}