Utilities: Add pathchk

Userland/Libraries/LibC/unistd.cpp

@@ -591,6 +591,8 @@ int mknod(const char* pathname, mode_t mode, dev_t dev)
 long fpathconf([[maybe_unused]] int fd, [[maybe_unused]] int name)
 {
     switch (name) {
+    case _PC_NAME_MAX:
+        return NAME_MAX;
     case _PC_PATH_MAX:
         return PATH_MAX;
     case _PC_VDISABLE:
@@ -603,6 +605,8 @@ long fpathconf([[maybe_unused]] int fd, [[maybe_unused]] int name)
 long pathconf([[maybe_unused]] const char* path, int name)
 {
     switch (name) {
+    case _PC_NAME_MAX:
+        return NAME_MAX;
     case _PC_PATH_MAX:
         return PATH_MAX;
     case _PC_PIPE_BUF:

Userland/Utilities/pathchk.cpp

@@ -0,0 +1,96 @@
+/*
+ * Copyright (c) 2021, the SerenityOS developers.
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <AK/String.h>
+#include <LibCore/ArgsParser.h>
+#include <LibCore/File.h>
+#include <bits/posix1_lim.h>
+#include <unistd.h>
+
+int main(int argc, char** argv)
+{
+    bool fail = false;
+    static bool flag_most_posix = false;
+    static bool flag_portability = false;
+    static bool flag_empty_name_and_leading_dash = false;
+
+    if (pledge("stdio rpath", nullptr) < 0) {
+        perror("pledge");
+        return 1;
+    }
+
+    Vector<const char*> paths;
+
+    Core::ArgsParser args_parser;
+    args_parser.add_option(flag_most_posix, "Check for most POSIX systems", nullptr, 'p');
+    args_parser.add_option(flag_empty_name_and_leading_dash, "Check for empty names and leading dash", nullptr, 'P');
+    args_parser.add_option(flag_portability, "Check portability (equivalent to -p and -P)", "portability", '\0');
+    args_parser.add_positional_argument(paths, "Path to check", "path", Core::ArgsParser::Required::Yes);
+    args_parser.parse(argc, argv);
+
+    if (flag_portability) {
+        flag_most_posix = true;
+        flag_empty_name_and_leading_dash = true;
+    }
+
+    for (auto& path : paths) {
+        auto str_path = String(path);
+        unsigned long path_max = flag_most_posix ? _POSIX_PATH_MAX : pathconf(str_path.characters(), _PC_PATH_MAX);
+        unsigned long name_max = flag_most_posix ? _POSIX_NAME_MAX : pathconf(str_path.characters(), _PC_NAME_MAX);
+
+        if (str_path.length() > path_max) {
+            warnln("{}: limit {} exceeded by length {} of file name '{}'", argv[0], path_max, str_path.length(), str_path);
+            fail = true;
+            continue;
+        }
+
+        if (flag_most_posix) {
+            // POSIX portable file name character set (a-z A-Z 0-9 . _ -)
+            for (long unsigned i = 0; i < str_path.length(); ++i) {
+                auto c = path[i];
+                if (!(c >= 'a' && c <= 'z') && !(c >= 'A' && c <= 'Z') && !(c >= '0' && c <= '9') && c != '/' && c != '.' && c != '-' && c != '_') {
+                    warnln("{}: non-portable character '{}' in file name '{}'", argv[0], path[i], str_path);
+                    fail = true;
+                    continue;
+                }
+            }
+        } else {
+            struct stat st;
+            if (lstat(str_path.characters(), &st) < 0) {
+                if (errno != ENOENT) {
+                    warnln("{}: directory is not searchable '{}'", argv[0], str_path);
+                    fail = true;
+                    continue;
+                }
+            }
+        }
+
+        if (flag_empty_name_and_leading_dash) {
+            if (str_path.is_empty()) {
+                warnln("{}: empty file name", argv[0]);
+                fail = true;
+                continue;
+            }
+        }
+
+        for (auto& component : str_path.split('/')) {
+            if (flag_empty_name_and_leading_dash) {
+                if (component.starts_with('-')) {
+                    warnln("{}: leading '-' in a component of file name '{}'", argv[0], str_path);
+                    fail = true;
+                    break;
+                }
+            }
+            if (component.length() > name_max) {
+                warnln("{}: limit {} exceeded by length {} of file name component '{}'", argv[0], name_max, component.length(), component.characters());
+                fail = true;
+                break;
+            }
+        }
+    }
+
+    return fail;
+}