Utilities: Add an implementation of 'comm'

Add an implementation of 'comm' -- compare files line by line

Base/usr/share/man/man1/comm.md

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+## Name
+
+comm - compare two sorted files line by line
+
+## Synopsis
+
+```**sh
+$ comm [options...] <file1> <file2>
+```
+
+## Description
+
+`comm` compares two **sorted** files specified by `file1` and `file2` line by line alphabetically. One of file1 and file2, but not both, can be `-`, in which case `comm` will read from the standard input for that file.
+
+With no options, `comm` produces a three column output, indented by tabs, of lines unique to `file1`, lines unique to `file2`, and lines common to both files. `comm` provides options to suppress the output of a specific column, use case insensitive comparison or print a summary.
+
+## Options
+
+* `-1`: Suppress the output of column 1 (lines unique to `file1`)
+* `-2`: Suppress the output of column 2 (lines unique to `file2`)
+* `-3`: Suppress the output of column 3 (lines common to `file1` and `file2`)
+* `-i`: Use case insensitive comparison of lines
+* `-c`, `--color`: Always print colored output even if the standard output is not a tty
+* `--no-color`: Do not print colored output
+* `-t`, `--total`: Print a summary
+
+## Arguments
+
+* `file1`: First file to compare. (`-` for the standard input)
+* `file2`: Second file to compare. (`-` for the standard input)
+
+## Examples
+
+```sh
+# Files should be sorted first
+$ sort < file1 > file1_sorted
+$ sort < file2 > file2_sorted
+
+# Display the default three-column output
+$ comm file1_sorted file2_sorted
+
+# Read one sorted file from the standard input
+# and only display column 3
+$ sort < file1 | comm -12c - file2_sorted | less
+
+# Use case insensitive comparison,
+# suppress output of all columns
+# and print a summary
+$ comm -123it file1_sorted file2_sorted
+```

Userland/Utilities/CMakeLists.txt

@@ -1,7 +1,7 @@
 file(GLOB CMD_SOURCES  CONFIGURE_DEPENDS "*.cpp")
 list(APPEND SPECIAL_TARGETS test install)
 list(APPEND REQUIRED_TARGETS
-    arp base64 basename cat chmod chown chroot clear cp cut date dd df dirname dmesg du echo env expr false fgrep
+    arp base64 basename cat chmod chown chroot clear comm cp cut date dd df dirname dmesg du echo env expr false fgrep
     file find grep groups head host hostname id ifconfig kill killall ln ls mkdir mount mv nproc
     pgrep pidof ping pmap ps readlink realpath reboot rm rmdir seq shutdown sleep sort stat stty su tail test
     touch tr true umount uname uniq uptime w wc which whoami xargs yes less

Userland/Utilities/comm.cpp

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+/*
+ * Copyright (c) 2021, the SerenityOS developers.
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <LibCore/ArgsParser.h>
+#include <LibCore/File.h>
+#include <string.h>
+#include <strings.h>
+#include <unistd.h>
+
+#define COL1_COLOR "\x1B[32m{}\x1B[0m"
+#define COL2_COLOR "\x1B[34m{}\x1B[0m"
+#define COL3_COLOR "\x1B[31m{}\x1B[0m"
+
+int main(int argc, char** argv)
+{
+    if (pledge("stdio rpath", nullptr) < 0) {
+        perror("pledge");
+        return 1;
+    }
+
+    String file1_path, file2_path;
+    bool suppress_col1 { false };
+    bool suppress_col2 { false };
+    bool suppress_col3 { false };
+    bool case_insensitive { false };
+    bool color { false };
+    bool no_color { false };
+    bool print_total { false };
+
+    Core::ArgsParser args_parser;
+    args_parser.set_general_help("Compare two sorted files line by line");
+    args_parser.add_option(suppress_col1, "Suppress column 1 (lines unique to file1)", nullptr, '1');
+    args_parser.add_option(suppress_col2, "Suppress column 2 (lines unique to file2)", nullptr, '2');
+    args_parser.add_option(suppress_col3, "Suppress column 3 (lines common to both files)", nullptr, '3');
+    args_parser.add_option(case_insensitive, "Use case-insensitive comparison of lines", nullptr, 'i');
+    args_parser.add_option(color, "Always print colored output", "color", 'c');
+    args_parser.add_option(no_color, "Do not print colored output", "no-color", 0);
+    args_parser.add_option(print_total, "Print a summary", "total", 't');
+    args_parser.add_positional_argument(file1_path, "First file to compare", "file1");
+    args_parser.add_positional_argument(file2_path, "Second file to compare", "file2");
+    args_parser.parse(argc, argv);
+
+    if (color && no_color) {
+        warnln("Cannot specify 'color' and 'no-color' together");
+        return 1;
+    }
+
+    bool print_color = isatty(STDOUT_FILENO);
+    if (color)
+        print_color = true;
+    else if (no_color)
+        print_color = false;
+
+    if (file1_path == "-" && file2_path == "-") {
+        warnln("File1 and file2 cannot both be the standard input");
+        return 1;
+    }
+
+    auto process_file = [](const String& path, auto& file, int file_number) {
+        if (path == "-") {
+            file = Core::File::standard_input();
+        } else {
+            auto file_or_error = Core::File::open(path, Core::OpenMode::ReadOnly);
+            if (file_or_error.is_error()) {
+                warnln("Failed to open file{} '{}': {}", file_number, path, file_or_error.error());
+                return false;
+            }
+            if (Core::File::is_directory(path)) {
+                warnln("Failed to open file{} '{}': is a directory", file_number, path);
+                return false;
+            }
+            file = file_or_error.value();
+        }
+        return true;
+    };
+
+    RefPtr<Core::File> file1, file2;
+    if (!(process_file(file1_path, file1, 1) && process_file(file2_path, file2, 2)))
+        return 1;
+
+    char tab { '\t' };
+    size_t tab_count { 0 };
+    String col1_fmt, col2_fmt, col3_fmt;
+    if (!suppress_col1)
+        col1_fmt = String::formatted("{}{}", String::repeated(tab, tab_count++), print_color ? COL1_COLOR : "{}");
+    if (!suppress_col2)
+        col2_fmt = String::formatted("{}{}", String::repeated(tab, tab_count++), print_color ? COL2_COLOR : "{}");
+    if (!suppress_col3)
+        col3_fmt = String::formatted("{}{}", String::repeated(tab, tab_count++), print_color ? COL3_COLOR : "{}");
+
+    auto cmp = [&](const String& str1, const String& str2) {
+        if (case_insensitive)
+            return strcasecmp(str1.characters(), str2.characters());
+        else
+            return strcmp(str1.characters(), str2.characters());
+    };
+
+    auto process_remaining = [](const String& fmt, auto& file, int& count, bool print) {
+        while (file->can_read_line()) {
+            ++count;
+            auto line = file->read_line();
+            if (print)
+                outln(fmt, line);
+        }
+    };
+
+    bool read_file1 { true };
+    bool read_file2 { true };
+    int col1_count { 0 };
+    int col2_count { 0 };
+    int col3_count { 0 };
+    String file1_line, file2_line;
+
+    while (file1->can_read_line() && file2->can_read_line()) {
+        if (read_file1)
+            file1_line = file1->read_line();
+        if (read_file2)
+            file2_line = file2->read_line();
+
+        int cmp_result = cmp(file1_line, file2_line);
+
+        if (!cmp_result) {
+            ++col3_count;
+            read_file1 = read_file2 = true;
+            if (!suppress_col3)
+                outln(col3_fmt, file1_line);
+        } else if (cmp_result < 0) {
+            ++col1_count;
+            read_file1 = true;
+            read_file2 = false;
+            if (!suppress_col1)
+                outln(col1_fmt, file1_line);
+        } else {
+            ++col2_count;
+            read_file1 = false;
+            read_file2 = true;
+            if (!suppress_col2)
+                outln(col2_fmt, file2_line);
+        }
+    }
+
+    process_remaining(col1_fmt, file1, col1_count, !suppress_col1);
+    process_remaining(col2_fmt, file2, col2_count, !suppress_col2);
+
+    if (print_total)
+        outln(print_color ? COL1_COLOR "\t" COL2_COLOR "\t" COL3_COLOR "\ttotal" : "{}\t{}\t{}\ttotal", col1_count, col2_count, col3_count);
+
+    return 0;
+}