Import "getconf" as a UNIX utility

src/getconf.c

@@ -0,0 +1,209 @@
+/* $Id$ */
+/* Copyright (c) 2020 Pierre Pronchery <khorben@defora.org> */
+/* This file is part of DeforaOS Unix utils */
+/* This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, version 3 of the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>. */
+
+
+
+#include <limits.h>
+#include <unistd.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+#include <errno.h>
+
+/* constants */
+#ifndef PROGNAME
+# define PROGNAME	"getconf"
+#endif
+
+
+/* getconf */
+/* private */
+/* types */
+typedef struct _getconf_catalog
+{
+	int name;
+	char const * string;
+} getconf_catalog;
+
+
+/* constants */
+static const getconf_catalog _getconf_catalog_confstr[] =
+{
+#ifdef _CS_PATH
+	{ _CS_PATH,	"_CS_PATH"	},
+#endif
+};
+
+static const getconf_catalog _getconf_catalog_limits[] =
+{
+#ifdef NGROUPS_MAX
+	{ NGROUPS_MAX,	"NGROUPS_MAX"	},
+#endif
+};
+
+static const getconf_catalog _getconf_catalog_pathconf[] =
+{
+#ifdef _PC_FILESIZEBITS
+	{ _PC_FILESIZEBITS,	"FILESIZEBITS"	},
+#endif
+#ifdef _PC_LINK_MAX
+	{ _PC_LINK_MAX,		"LINK_MAX"	},
+#endif
+#ifdef _PC_MAX_CANON
+	{ _PC_MAX_CANON,	"MAX_CANON"	},
+#endif
+#ifdef _PC_MAX_INPUT
+	{ _PC_MAX_INPUT,	"MAX_INPUT"	},
+#endif
+#ifdef _PC_NAME_MAX
+	{ _PC_NAME_MAX,		"NAME_MAX"	},
+#endif
+#ifdef _PC_PATH_MAX
+	{ _PC_PATH_MAX,		"PATH_MAX"	},
+#endif
+#ifdef _PC_PIPE_BUF
+	{ _PC_PIPE_BUF,		"PIPE_BUF"	},
+#endif
+};
+
+
+/* prototypes */
+static int _getconf(char const * specification, char const * var,
+		char const * path);
+static int _getconf_error(char const * message, int ret);
+static int _usage(void);
+
+
+/* functions */
+/* getconf */
+static int _getconf_confstr(char const * var);
+static int _getconf_limits(char const * var);
+static int _getconf_pathconf(char const * var, char const * path);
+
+static int _getconf(char const * specification, char const * var,
+		char const * path)
+{
+	if(path != NULL)
+		return _getconf_pathconf(var, path);
+	if(strncmp(var, "_SC_", 4) == 0)
+		return _getconf_confstr(var);
+	return _getconf_limits(var);
+}
+
+static int _getconf_confstr(char const * var)
+{
+	size_t i;
+	size_t cnt = sizeof(_getconf_catalog_confstr)
+		/ sizeof(*_getconf_catalog_confstr);
+	char * buf;
+
+	for(i = 0; i < cnt; i++)
+		if(strcmp(_getconf_catalog_confstr[i].string, var) == 0)
+			break;
+	if(i == cnt)
+		return _getconf_error(var, -ENOENT);
+	/* obtain the required size */
+	if((cnt = confstr(_getconf_catalog_confstr[i].name, NULL, 0)) == 0)
+		return _getconf_error(var, 2);
+	if((buf = malloc(cnt)) == NULL)
+		return _getconf_error(var, 2);
+	if((cnt = confstr(_getconf_catalog_confstr[i].name, buf, cnt)) == 0)
+	{
+		free(buf);
+		return _getconf_error(var, 2);
+	}
+	printf("%s\n", buf);
+	free(buf);
+	return 0;
+}
+
+static int _getconf_limits(char const * var)
+{
+	size_t i;
+	size_t cnt = sizeof(_getconf_catalog_limits)
+		/ sizeof(*_getconf_catalog_limits);
+
+	for(i = 0; i < cnt; i++)
+		if(strcmp(_getconf_catalog_limits[i].string, var) == 0)
+			break;
+	if(i == cnt)
+		return _getconf_error(var, -ENOENT);
+	printf("%d\n", _getconf_catalog_limits[i].name);
+	return 0;
+}
+
+static int _getconf_pathconf(char const * var, char const * path)
+{
+	size_t i;
+	size_t cnt = sizeof(_getconf_catalog_pathconf)
+		/ sizeof(*_getconf_catalog_pathconf);
+	long value;
+
+	for(i = 0; i < cnt; i++)
+		if(strcmp(_getconf_catalog_pathconf[i].string, var) == 0)
+			break;
+	if(i == cnt)
+		return _getconf_error(var, -ENOENT);
+	if((value = pathconf(path, _getconf_catalog_pathconf[i].name)) < 0)
+		return _getconf_error(var, 2);
+	printf("%ld\n", value);
+	return 0;
+}
+
+
+/* error */
+static int _getconf_error(char const * message, int ret)
+{
+	fputs(PROGNAME ": ", stderr);
+	if(ret < 0)
+	{
+		fprintf(stderr, "%s%s%s\n", (message != NULL) ? message : "",
+				(message != NULL) ? ": " : "", strerror(-ret));
+		return -ret;
+	}
+	perror(message);
+	return ret;
+}
+
+
+/* usage */
+static int _usage(void)
+{
+	fputs("Usage: " PROGNAME " [-v specification] system_var\n"
+"       " PROGNAME " [-v specification] path_var pathname\n", stderr);
+	return 1;
+}
+
+
+/* main */
+int main(int argc, char * argv[])
+{
+	int o;
+	char const * specification = NULL;
+
+	while((o = getopt(argc, argv, "v:")) != -1)
+		switch(o)
+		{
+			case 'v':
+				specification = optarg;
+				break;
+			default:
+				return _usage();
+		}
+	if(optind + 1 != argc && optind + 2 != argc)
+		return _usage();
+	return (_getconf(specification, argv[optind], argv[optind + 1]) == 0)
+		? 0 : 2;
+}

src/project.conf

@@ -1,4 +1,4 @@
-targets=basename,cat,chgrp,chmod,chown,cksum,cmp,cp,date,df,dirname,du,echo,false,file,find,grep,head,id,kill,link,ln,locale,logname,ls,mkdir,mkfifo,more,mv,nice,pr,printf,ps,pwd,renice,rm,rmdir,sleep,strings,tail,test,time,touch,true,tty,uname,uniq,unlink,wc,who
+targets=basename,cat,chgrp,chmod,chown,cksum,cmp,cp,date,df,dirname,du,echo,false,file,find,getconf,grep,head,id,kill,link,ln,locale,logname,ls,mkdir,mkfifo,more,mv,nice,pr,printf,ps,pwd,renice,rm,rmdir,sleep,strings,tail,test,time,touch,true,tty,uname,uniq,unlink,wc,who
 cflags=-W -Wall -g -O2 -fPIE -D_FORTIFY_SOURCE=2 -fstack-protector
 ldflags=-pie -Wl,-z,relro -Wl,-z,now
 dist=Makefile,common.c
@@ -87,6 +87,11 @@ type=binary
 sources=find.c
 install=$(BINDIR)
 
+[getconf]
+type=binary
+sources=getconf.c
+install=$(BINDIR)
+
 [grep]
 type=binary
 sources=grep.c