errno: Include error code names in output

And align the output nicely while we're at it. :^)

1 files changed, 25 insertions, 10 deletions

diff --git a/Userland/Utilities/errno.cpp b/Userland/Utilities/errno.cpp
index ddf19e2db6..dacf548b9d 100644
--- a/Userland/Utilities/errno.cpp
+++ b/Userland/Utilities/errno.cpp
@@ -1,5 +1,6 @@
 /*
  * Copyright (c) 2021, the SerenityOS developers.
+ * Copyright (c) 2023, Sam Atkins <atkinssj@serenityos.org>
  *
  * SPDX-License-Identifier: BSD-2-Clause
  */
@@ -8,6 +9,12 @@
 #include <LibMain/Main.h>
 #include <string.h>
 
+Array<StringView, EMAXERRNO + 1> s_errno_names = {
+#define __ENUMERATE_ERRNO_CODE(c, s) #c##sv,
+    ENUMERATE_ERRNO_CODES(__ENUMERATE_ERRNO_CODE)
+#undef __ENUMERATE_ERRNO_CODE
+};
+
 ErrorOr<int> serenity_main(Main::Arguments arguments)
 {
     bool list = false;
@@ -20,10 +27,18 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
     args_parser.add_option(search, "Search for error descriptions containing keyword", "search", 's');
     args_parser.parse(arguments);
 
+    auto max_name_length = 0;
+    for (int i = 0; i < sys_nerr; i++) {
+        max_name_length = max(max_name_length, s_errno_names[i].length());
+    }
+
+    auto output_errno_description = [max_name_length](int errno_code, auto error_string) {
+        outln("{:{}} {:>2} {}", s_errno_names[errno_code], max_name_length, errno_code, error_string);
+    };
+
     if (list) {
-        for (int i = 0; i < sys_nerr; i++) {
-            outln("{} {}", i, strerror(i));
-        }
+        for (int i = 0; i < sys_nerr; i++)
+            output_errno_description(i, strerror(i));
         return 0;
     }
 
@@ -33,25 +48,25 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
     if (search) {
         for (int i = 0; i < sys_nerr; i++) {
             auto error = DeprecatedString::formatted("{}", strerror(i));
-            if (error.contains(keyword, CaseSensitivity::CaseInsensitive)) {
-                outln("{} {}", i, error);
-            }
+            if (error.contains(keyword, CaseSensitivity::CaseInsensitive))
+                output_errno_description(i, error);
         }
         return 0;
     }
 
-    auto maybe_errno = keyword.to_int();
-    if (!maybe_errno.has_value()) {
+    auto maybe_error_code = keyword.to_int();
+    if (!maybe_error_code.has_value()) {
         warnln("ERROR: Not understood: {}", keyword);
         return 1;
     }
+    auto error_code = maybe_error_code.value();
 
-    auto error = DeprecatedString::formatted("{}", strerror(maybe_errno.value()));
+    auto error = strerror(error_code);
     if (error == "Unknown error"sv) {
         warnln("ERROR: Unknown errno: {}", keyword);
         return 1;
     }
-    outln("{} {}", keyword, error);
+    output_errno_description(error_code, error);
 
     return 0;
 }