apps: Add mktemp

apps/CMakeLists.txt

@@ -29,3 +29,4 @@ luna_app(umount.cpp umount)
 luna_app(ps.cpp ps)
 luna_app(time.cpp time)
 luna_app(ln.cpp ln)
+luna_app(mktemp.cpp mktemp)

apps/mktemp.cpp

@@ -0,0 +1,40 @@
+#include <errno.h>
+#include <luna/String.h>
+#include <os/ArgumentParser.h>
+#include <os/File.h>
+#include <stdlib.h>
+#include <time.h>
+#include <unistd.h>
+
+Result<int> luna_main(int argc, char** argv)
+{
+    srand((unsigned)time(NULL));
+
+    bool make_directory { false };
+    StringView template_sv;
+
+    os::ArgumentParser parser;
+    parser.add_description("Create a temporary file or directory safely and print its name.");
+    parser.add_system_program_info("mktemp"_sv);
+    parser.add_switch_argument(make_directory, 'd', "directory"_sv, "make a directory instead of a file"_sv);
+    parser.add_positional_argument(template_sv, "template"_sv, "/tmp/tmp.XXXXXX"_sv);
+    parser.parse(argc, argv);
+
+    String str = TRY(String::from_string_view(template_sv));
+
+    if (make_directory)
+    {
+        if (mkdtemp(str.mutable_data()) == nullptr) return err(errno);
+    }
+    else
+    {
+        int fd = -1;
+        fd = mkstemp(str.mutable_data());
+        if (fd < 0) return err(errno);
+        close(fd);
+    }
+
+    os::println("%s"_sv, str.chars());
+
+    return 0;
+}

libc/src/stdlib.cpp

@@ -228,7 +228,7 @@ extern "C"
     static void generate_random_character(char* ptr)
     {
         constexpr const char chars[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789_";
-        *ptr = chars[rand() % sizeof(chars)];
+        *ptr = chars[rand() % (sizeof(chars) - 1)];
     }
 
     static int check_template(char* _template, size_t* len)

libluna/include/luna/String.h

@@ -75,6 +75,11 @@ class String
         return m_inline ? m_inline_storage : m_string;
     }
 
+    char* mutable_data()
+    {
+        return m_inline ? m_inline_storage : m_string;
+    }
+
     usize length() const
     {
         return m_length;