Userland: Implement shuf for basic shuffling

Author: https://github.com/BenWiederhake
Commit: https://github.com/SerenityOS/serenity/commit/de98f69bfed
Pull-request: https://github.com/SerenityOS/serenity/pull/5010

Userland/Utilities/shuf.cpp

@@ -0,0 +1,76 @@
+/*
+ * Copyright (c) 2021, Ben Wiederhake <BenWiederhake.GitHub@gmx.de>
+ * 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.
+ *
+ * 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.
+ */
+
+#include <AK/String.h>
+#include <AK/Vector.h>
+#include <errno.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+int main([[maybe_unused]] int argc, [[maybe_unused]] char** argv)
+{
+    if (pledge("stdio", nullptr) > 0) {
+        perror("pledge");
+        return 1;
+    }
+
+    Vector<String> lines;
+
+    for (;;) {
+        char* buffer = nullptr;
+        ssize_t buflen = 0;
+        size_t n;
+        errno = 0;
+        buflen = getline(&buffer, &n, stdin);
+        if (buflen == -1 && errno != 0) {
+            perror("getline");
+            exit(1);
+        }
+        if (buflen == -1)
+            break;
+        lines.append({ buffer, AK::ShouldChomp::Chomp });
+    }
+
+    // Fisher-Yates shuffle
+    String tmp;
+    for (size_t i = lines.size() - 1; i >= 1; --i) {
+        size_t j = arc4random_uniform(i + 1);
+        // Swap i and j
+        if (i == j)
+            continue;
+        tmp = move(lines[j]);
+        lines[j] = move(lines[i]);
+        lines[i] = move(tmp);
+    }
+
+    for (auto& line : lines) {
+        fputs(line.characters(), stdout);
+        fputc('\n', stdout);
+    }
+
+    return 0;
+}