1 files changed, 150 insertions, 0 deletions
diff --git a/ln.c b/ln.c
new file mode 100644
index 0000000..468e4da
--- /dev/null
+++ b/ln.c
@@ -0,0 +1,150 @@
+/*
+ * UNG's Not GNU
+ *
+ * Copyright (c) 2011-2019, Jakob Kaivo <jkk@ung.org>
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+#define _POSIX_C_SOURCE 200809L
+#include <errno.h>
+#include <fcntl.h>
+#include <locale.h>
+#include <stdio.h>
+#include <string.h>
+#include <sys/stat.h>
+#include <unistd.h>
+
+#ifndef O_SEARCH
+#define O_SEARCH 0
+#endif
+
+static int ln(const char *path, int dirfd, int sym, int force, int flag)
+{
+	struct stat st;
+	if (fstatat(dirfd, path, &st, 0) == 0) {
+		if (!force) {
+			fprintf(stderr, "ln: %s: %s\n", strerror(EEXIST));
+			return 1;
+		}
+		
+		if (unlinkat(dirfd, path, 0) != 0) {
+			fprintf(stderr, "ln: %s: %s\n", strerror(errno));
+			return 1;
+		}
+	}
+
+	if (sym) {
+		if (symlinkat(path, dirfd, path) != 0) {
+			fprintf(stderr, "ln: %s: %s\n", strerror(errno));
+			return 1;
+		}
+	} else {
+		if (linkat(AT_FDCWD, path, dirfd, path, flag) != 0) {
+			fprintf(stderr, "ln: %s: %s\n", strerror(errno));
+			return 1;
+		}
+	}
+	
+	return 0;
+}
+
+int main(int argc, char *argv[])
+{
+	setlocale(LC_ALL, "");
+
+	int flag = 0;
+	int symbolic = 0;
+	int force = 0;
+
+	int c;
+	while ((c = getopt(argc, argv, "fsLP")) != -1) {
+		switch (c) {
+		case 'L':
+			flag = AT_SYMLINK_FOLLOW;
+			break;
+
+		case 'P':
+			flag = 0;
+			break;
+
+		case 's':
+			symbolic = 1;
+			break;
+
+		case 'f':
+			force = 1;
+			break;
+
+		default:
+			return 1;
+		}
+	}
+
+	if (argc - optind < 2) {
+		fprintf(stderr, "ln: missing operands\n");
+		return 1;
+	}
+
+	char *target = argv[argc - 1];
+
+	int dirfd = open(target, O_SEARCH | O_DIRECTORY);
+	if (dirfd == -1) {
+		if (errno == ENOTDIR) {
+			/* not a directory */
+		} else if (errno == ENOENT) {
+			/* doesn't exist */
+		} else {
+			return 1;
+		}
+	}
+
+	if (argc - optind == 2) {
+		struct stat st;
+		if (stat(target, &st) == 0) {
+			if (S_ISDIR(st.st_mode)) {
+				return ln(argv[optind], dirfd, symbolic, force, flag);
+			}
+
+			if (!force) {
+				fprintf(stderr, "ln: %s: %s\n", target, strerror(EEXIST));
+				return 1;
+			}
+
+			if (unlink(target) != 0) {
+				fprintf(stderr, "ln: %s: %s\n", target, strerror(errno));
+				return 1;
+			}
+		}
+
+		int r = symbolic ? symlink(argv[optind], target) :
+				link(argv[optind], target);
+		if (r != 0) {
+			fprintf(stderr, "ln: %s -> %s: %s\n", argv[optind], target, strerror(errno));
+		}
+
+		return r;
+	}
+
+	int r = 0;
+	do {
+		r |= ln(argv[optind++], dirfd, symbolic, force, flag);
+	} while (optind < argc - 1);
+	return r;
+}