Add ln(1).

utils/.gitignore

@@ -26,3 +26,4 @@ type
 mkdir
 rmdir
 which
+ln

utils/Makefile

@@ -42,6 +42,7 @@ type \
 mkdir \
 rmdir \
 which \
+ln \
 
 INSTALLBINARIES:=$(addprefix $(DESTDIR)$(BINDIR)/,$(BINARIES))
 

utils/ln.cpp

@@ -0,0 +1,132 @@
+/*******************************************************************************
+
+    Copyright(C) Jonas 'Sortie' Termansen 2013.
+
+    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, either version 3 of the License, or (at your option)
+    any later version.
+
+    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/>.
+
+    ln.cpp
+    Create a hard or symbolic link.
+
+*******************************************************************************/
+
+#include <errno.h>
+#include <error.h>
+#include <fcntl.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+#if !defined(VERSIONSTR)
+#define VERSIONSTR "unknown version"
+#endif
+
+void Usage(FILE* fp, const char* argv0)
+{
+	fprintf(fp, "Usage: %s [OPTION]... TARGET LINK_NAME\n", argv0);
+	fprintf(fp, "Create a hard or symbolic link.\n");
+}
+
+void Help(FILE* fp, const char* argv0)
+{
+	Usage(fp, argv0);
+}
+
+void Version(FILE* fp, const char* argv0)
+{
+	fprintf(fp, "%s (Sortix) %s\n", argv0, VERSIONSTR);
+	fprintf(fp, "License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>.\n");
+	fprintf(fp, "This is free software: you are free to change and redistribute it.\n");
+	fprintf(fp, "There is NO WARRANTY, to the extent permitted by law.\n");
+}
+
+int main(int argc, char* argv[])
+{
+	const char* argv0 = argv[0];
+	bool force = false;
+	bool symbolic = false;
+	bool verbose = false;
+	for ( int i = 1; i < argc; i++ )
+	{
+		const char* arg = argv[i];
+		if ( arg[0] != '-' )
+			continue;
+		argv[i] = NULL;
+		if ( !strcmp(arg, "--") )
+			break;
+		if ( arg[1] != '-' )
+			for ( size_t i = 1; arg[i]; i++ )
+				switch ( arg[i] )
+				{
+				case 'f': force = true; break;
+				case 's': symbolic = true; break;
+				case 'v': verbose = true; break;
+				default:
+					fprintf(stderr, "%s: unknown option -- '%c'\n", argv0, arg[i]);
+					Usage(stderr, argv0);
+					exit(1);
+				}
+		else if ( !strcmp(arg, "--force") )
+			force = true;
+		else if ( !strcmp(arg, "--symbolic") )
+			symbolic = true;
+		else if ( !strcmp(arg, "--verbose") )
+			verbose = true;
+		else if ( !strcmp(arg, "--help") ) { Help(stdout, argv0); exit(0); }
+		else if ( !strcmp(arg, "--usage") ) { Usage(stdout, argv0); exit(0); }
+		else if ( !strcmp(arg, "--version") ) { Version(stdout, argv0); exit(0); }
+		else
+		{
+			fprintf(stderr, "%s: unknown option: %s\n", argv0, arg);
+			Usage(stderr, argv0);
+			exit(1);
+		}
+	}
+
+	for ( int i = 0; i < argc; i++ )
+		while ( i < argc && !argv[i] )
+		{
+			for ( int n = i; n < argc; n++ )
+				argv[n] = argv[n+1];
+			argc--;
+		}
+
+	if ( argc != 3 )
+	{
+		const char* what = argc < 3 ? "missing" : "extra";
+		fprintf(stderr, "%s: %s operand\n", argv0, what);
+		Usage(stderr, argv0);
+		exit(1);
+	}
+
+	const char* oldname = argv[1];
+	const char* newname = argv[2];
+
+	if ( force )
+		unlink(newname);
+
+	if ( symbolic )
+		fprintf(stderr, "%s: symbolic links are not supported, creating hard "
+		                "link instead\n", argv0);
+
+	int ret = link(oldname, newname);
+	if ( ret == 0  )
+	{
+		if ( verbose )
+			printf("`%s' => `%s'\n", newname, oldname);
+	}
+	else
+		error(0, errno, "`%s' => `%s'", newname, oldname);
+	return ret ? 1 : 0;
+}