Userland: Add a simple mktemp(1) utility

Userland/Utilities/mktemp.cpp

@@ -0,0 +1,137 @@
+/*
+ * Copyright (c) 2021, Idan Horowitz <idan.horowitz@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/LexicalPath.h>
+#include <LibCore/ArgsParser.h>
+#include <stdio.h>
+#include <string.h>
+#include <sys/stat.h>
+
+constexpr const char* default_template = "tmp.XXXXXXXXXX";
+
+static char* generate_random_filename(const char* pattern)
+{
+    char* new_filename = strdup(pattern);
+    int pattern_length = strlen(pattern);
+
+    static constexpr char random_characters[] = "abcdefghijklmnopqrstuvwxyz0123456789";
+    for (auto i = pattern_length - 1; i >= 0; --i) {
+        if (pattern[i] != 'X')
+            break;
+        new_filename[i] = random_characters[(arc4random() % (sizeof(random_characters) - 1))];
+    }
+
+    return new_filename;
+}
+
+static char* make_temp(const char* pattern, bool directory, bool dry_run)
+{
+    for (int i = 0; i < 100; ++i) {
+        char* path = generate_random_filename(pattern);
+        if (dry_run) {
+            struct stat stat;
+            auto rc = lstat(path, &stat);
+            if (rc < 0 && errno == ENOENT)
+                return path;
+        } else if (directory) {
+            if (!mkdir(path, 0700))
+                return path;
+        } else {
+            auto fd = open(path, O_RDWR | O_CREAT | O_EXCL, S_IRUSR | S_IWUSR);
+            if (fd >= 0) {
+                close(fd);
+                return path;
+            }
+        }
+        free(path);
+    }
+    return nullptr;
+}
+
+int main(int argc, char** argv)
+{
+    if (pledge("stdio rpath wpath cpath", nullptr)) {
+        perror("pledge");
+        return 1;
+    }
+
+    const char* file_template = nullptr;
+    bool create_directory = false;
+    bool dry_run = false;
+    bool quiet = false;
+    const char* target_directory = nullptr;
+
+    Core::ArgsParser args_parser;
+    args_parser.set_general_help("Create a temporary file or directory, safely, and print its name.");
+    args_parser.add_positional_argument(file_template, "The template must contain at least 3 consecutive 'X's", "template", Core::ArgsParser::Required::No);
+    args_parser.add_option(create_directory, "Create a temporary directory instead of a file", "directory", 'd');
+    args_parser.add_option(dry_run, "Do not create anything, just print a unique name", "dry-run", 'u');
+    args_parser.add_option(quiet, "Do not print diagnostics about file/directory creation failure", "quiet", 'q');
+    args_parser.add_option(target_directory, "Create TEMPLATE relative to DIR", "tmpdir", 'p', "DIR");
+    args_parser.parse(argc, argv);
+
+    if (!target_directory) {
+        if (file_template) { // If a custom template is specified we assume the target directory is the current directory
+            target_directory = getcwd(nullptr, 0);
+        } else {
+            LexicalPath template_path(file_template);
+            const char* env_directory = getenv("TMPDIR");
+            target_directory = env_directory && *env_directory ? env_directory : "/tmp";
+        }
+    }
+
+    if (!file_template) {
+        file_template = default_template;
+    }
+
+    if (!String(file_template).find("XXX").has_value()) {
+        if (!quiet)
+            warnln("Too few X's in template {}", file_template);
+        return 1;
+    }
+
+    LexicalPath target_path(String::formatted("{}/{}", target_directory, file_template));
+    if (!target_path.is_valid()) {
+        if (!quiet)
+            warnln("Invalid template path {}", target_path.string().characters());
+        return 1;
+    }
+
+    char* final_path = make_temp(target_path.string().characters(), create_directory, dry_run);
+    if (!final_path) {
+        if (!quiet) {
+            if (create_directory)
+                warnln("Failed to create directory via template {}", target_path.string().characters());
+            else
+                warnln("Failed to create file via template {}", target_path.string().characters());
+        }
+        return 1;
+    }
+
+    outln(final_path);
+    free(final_path);
+    return 0;
+}