Userland/uniq: Add uniq utility

Add an implementation for uniq. While it will be nice in the future to
make more hardened versions of sort and uniq in the future, this
implementation of uniq is compatible with the current version of sort
and its buffer sizes.

This version supports optional input and output files along with stdin
and stdout.

1 files changed, 100 insertions, 0 deletions

diff --git a/Userland/uniq.cpp b/Userland/uniq.cpp
new file mode 100644
index 0000000000..0034c1cb62
--- /dev/null
+++ b/Userland/uniq.cpp
@@ -0,0 +1,100 @@
+/*
+ * Copyright (c) 2020, Matthew L. Curry <matthew.curry@gmail.com>
+ * 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/RefPtr.h>
+#include <LibCore/ArgsParser.h>
+#include <errno.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+struct linebuf {
+    char* buf = NULL;
+    size_t len = 0;
+};
+
+static FILE* get_stream(const char* filepath, const char* perms)
+{
+    FILE* ret;
+
+    if (filepath == nullptr) {
+        if (perms[0] == 'r')
+            return stdin;
+        return stdout;
+    }
+
+    ret = fopen(filepath, perms);
+    if (ret == nullptr) {
+        perror("fopen");
+        exit(1);
+    }
+
+    return ret;
+}
+
+int main(int argc, char** argv)
+{
+    if (pledge("stdio rpath wpath cpath", nullptr) > 0) {
+        perror("pledge");
+        return 1;
+    }
+
+    const char* inpath = nullptr;
+    const char* outpath = nullptr;
+    Core::ArgsParser args_parser;
+    args_parser.add_positional_argument(inpath, "Input file", "input", Core::ArgsParser::Required::No);
+    args_parser.add_positional_argument(outpath, "Output file", "output", Core::ArgsParser::Required::No);
+    args_parser.parse(argc, argv);
+
+    FILE* infile = get_stream(inpath, "r");
+    FILE* outfile = get_stream(outpath, "w");
+
+    struct linebuf buffers[2];
+    struct linebuf* previous = &(buffers[0]);
+    struct linebuf* current = &(buffers[1]);
+    bool first_run = true;
+    for (;;) {
+        errno = 0;
+        ssize_t rc = getline(&(current->buf), &(current->len), infile);
+        if (rc < 0 && errno != 0) {
+            perror("getline");
+            exit(1);
+        }
+        if (rc < 0)
+            break;
+        if (!first_run && strcmp(current->buf, previous->buf) == 0)
+            continue;
+
+        fputs(current->buf, outfile);
+        AK::swap(current, previous);
+        first_run = false;
+    }
+
+    fclose(infile);
+    fclose(outfile);
+
+    return 0;
+}