usr/bin/link: POSIX link implementation

1 files changed, 57 insertions, 0 deletions

diff --git a/usr.bin/link/link.c b/usr.bin/link/link.c
new file mode 100644
index 0000000..ed48857
--- /dev/null
+++ b/usr.bin/link/link.c
@@ -0,0 +1,57 @@
+/*
+ * link.c -- Create a link between two paths, per link(1p).
+ *
+ * Copyright (c) 2019 Kiyoshi Aman, all rights reserved.
+ *
+ * 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.
+ *
+ * 3. Neither the name of the copyright holder nor the names of its
+ *    contributors may be used to endorse or promote products derived
+ *    from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS 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
+ * COPYRIGHT HOLDER 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.
+ */
+
+#define _POSIX_C_SOURCE 200112L
+
+#include <unistd.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <errno.h>
+
+int main(int argc, char **argv) {
+    int error = 0;
+    if ((argc < 3) || (argc > 3)) {
+        fprintf(stderr, "Usage: %s file1 file2\n\nCreates a hard link for file1 which points to file2.\n", argv[0]);
+        exit(EXIT_FAILURE);
+    }
+    if ((error = link(argv[1], argv[2])) != 0) {
+        char msg[128];
+        strerror_r(errno, msg, 128);
+        fprintf(stderr, "Could not create link: %s\n", msg);
+    } else {
+        return EXIT_SUCCESS;
+    }
+}