libos+apps: Add some missing functionality to File and eliminate any trace of C from cat and edit

apps/cat.cpp

@@ -1,34 +1,27 @@
+#include <luna/String.h>
 #include <os/ArgumentParser.h>
+#include <os/File.h>
 
-#include <stdio.h>
-#include <stdlib.h>
-#include <string.h>
+using os::File;
 
-static void do_cat(StringView path)
+static Result<void> do_cat(StringView path)
 {
-    FILE* f;
+    SharedPtr<File> f;
 
-    if (path == "-") f = stdin;
+    auto out = File::standard_output();
+
+    if (path == "-") f = File::standard_input();
     else
-    {
-        f = fopen(path.chars(), "r");
-        if (!f)
-        {
-            perror(path.chars());
-            exit(1);
-        }
-    }
-
-    char buffer[4096];
+        f = TRY(File::open(path, File::ReadOnly));
 
     while (1)
     {
-        size_t nread = fread(buffer, 1, sizeof(buffer), f);
-        if (nread == 0) return;
-        fwrite(buffer, 1, nread, stdout);
+        String line = TRY(f->read_line());
+        if (line.is_empty()) break;
+        out->write(line.view());
     }
 
-    if (f != stdin) fclose(f);
+    return {};
 }
 
 Result<int> luna_main(int argc, char** argv)
@@ -37,11 +30,11 @@ Result<int> luna_main(int argc, char** argv)
 
     os::ArgumentParser parser;
     parser.add_positional_argument(filename, "file"_sv, "-"_sv);
-    Vector<StringView> extra_files = parser.parse(argc, argv).value();
+    Vector<StringView> extra_files = TRY(parser.parse(argc, argv));
 
-    do_cat(filename);
+    TRY(do_cat(filename));
 
-    for (auto file : extra_files) { do_cat(file); }
+    for (auto file : extra_files) TRY(do_cat(file));
 
     return 0;
 }

apps/edit.cpp

@@ -1,9 +1,8 @@
+#include <luna/String.h>
 #include <os/ArgumentParser.h>
 #include <os/File.h>
 
-#include <stdio.h>
-#include <stdlib.h>
-#include <string.h>
+using os::File;
 
 Result<int> luna_main(int argc, char** argv)
 {
@@ -13,15 +12,15 @@ Result<int> luna_main(int argc, char** argv)
     parser.add_positional_argument(pathname, "path"_sv, true);
     parser.parse(argc, argv);
 
-    auto file = TRY(os::File::open_or_create(pathname, os::File::WriteOnly));
+    auto file = TRY(File::open_or_create(pathname, File::WriteOnly));
 
-    char buffer[4096];
+    auto input = File::standard_input();
 
     while (1)
     {
-        char* rc = fgets(buffer, sizeof(buffer), stdin);
-        if (rc == 0) break;
-        TRY(file->write(StringView { buffer }));
+        String line = TRY(input->read_line());
+        if (line.is_empty()) break;
+        TRY(file->write(line.view()));
     }
 
     return 0;

libluna/src/CppABI.cpp

@@ -1,6 +1,54 @@
+typedef void* (*cxa_atexit_func_t)(void*);
+
+struct cxa_atexit_entry
+{
+    cxa_atexit_func_t function;
+    void* argument;
+    void* dso_handle;
+};
+
+#define CXA_ATEXIT_MAX 64
+
+int cxa_atexit_entry_count = 0;
+
+cxa_atexit_entry cxa_atexit_entries[CXA_ATEXIT_MAX];
+
 extern "C"
 {
     void __gxx_personality_v0()
     {
     }
+
+    int __cxa_atexit(cxa_atexit_func_t func, void* arg, void* dso)
+    {
+        if (cxa_atexit_entry_count >= CXA_ATEXIT_MAX) return -1;
+        cxa_atexit_entries[cxa_atexit_entry_count].function = func;
+        cxa_atexit_entries[cxa_atexit_entry_count].argument = arg;
+        cxa_atexit_entries[cxa_atexit_entry_count].dso_handle = dso;
+        cxa_atexit_entry_count++;
+        return 0;
+    }
+
+    void __cxa_finalize(void* f)
+    {
+        int i = cxa_atexit_entry_count;
+        if (!f)
+        {
+            while (i--)
+            {
+                if (cxa_atexit_entries[i].function) { cxa_atexit_entries[i].function(cxa_atexit_entries[i].argument); }
+            }
+        }
+        else
+        {
+            while (i--)
+            {
+                if (cxa_atexit_entries[i].function == (cxa_atexit_func_t)f)
+                {
+                    cxa_atexit_entries[i].function(cxa_atexit_entries[i].argument);
+                    cxa_atexit_entries[i].function = 0;
+                }
+            }
+        }
+    }
 }

libluna/src/StringBuilder.cpp

@@ -29,7 +29,7 @@ Result<void> StringBuilder::add(unsigned long value)
 
 Result<void> StringBuilder::add(char value)
 {
-    return format("%c"_sv, value);
+    return m_data.append_data((const u8*)&value, 1);
 }
 
 Result<void> StringBuilder::format(StringView fmt, ...)

libos/include/os/File.h

@@ -24,15 +24,24 @@ namespace os
         static Result<SharedPtr<File>> open_or_create(StringView path, OpenMode flags, mode_t mode = 0644);
         static Result<SharedPtr<File>> create(StringView path, OpenMode flags, mode_t mode = 0644);
 
+        static SharedPtr<File> standard_input();
+        static SharedPtr<File> standard_output();
+        static SharedPtr<File> standard_error();
+
         void set_close_on_exec();
 
         Result<void> write(StringView str);
 
+        Result<String> read_line();
+
+        Result<int> getchar();
+
         File(Badge<File>);
         ~File();
 
       private:
         static Result<SharedPtr<File>> construct(StringView path, int flags, mode_t mode);
+        static void initialize_standard_streams();
 
         Result<usize> raw_read(u8* buf, usize length);
         Result<usize> raw_write(const u8* buf, usize length);

libos/src/File.cpp

@@ -1,8 +1,13 @@
 #include <fcntl.h>
+#include <luna/StringBuilder.h>
 #include <os/File.h>
 #include <sys/syscall.h>
 #include <unistd.h>
 
+static SharedPtr<os::File> g_stdin = {};
+static SharedPtr<os::File> g_stdout = {};
+static SharedPtr<os::File> g_stderr = {};
+
 namespace os
 {
     File::File(Badge<File>)
@@ -14,9 +19,45 @@ namespace os
         if (m_fd >= 0) close(m_fd);
     }
 
+    void File::initialize_standard_streams()
+    {
+        g_stdin = adopt_shared_if_nonnull(new (std::nothrow) File({}))
+                      .expect_release_value("Cannot open standard input stream");
+        g_stdin->m_fd = STDIN_FILENO;
+
+        g_stdout = adopt_shared_if_nonnull(new (std::nothrow) File({}))
+                       .expect_release_value("Cannot open standard output stream");
+        g_stdout->m_fd = STDOUT_FILENO;
+
+        g_stderr = adopt_shared_if_nonnull(new (std::nothrow) File({}))
+                       .expect_release_value("Cannot open standard error stream");
+        g_stderr->m_fd = STDERR_FILENO;
+    }
+
+    SharedPtr<File> File::standard_input()
+    {
+        if (!g_stdin) initialize_standard_streams();
+
+        return g_stdin;
+    }
+
+    SharedPtr<File> File::standard_output()
+    {
+        if (!g_stdout) initialize_standard_streams();
+
+        return g_stdout;
+    }
+
+    SharedPtr<File> File::standard_error()
+    {
+        if (!g_stderr) initialize_standard_streams();
+
+        return g_stderr;
+    }
+
     Result<SharedPtr<File>> File::construct(StringView path, int flags, mode_t mode)
     {
-        auto file = TRY(adopt_shared(new (std::nothrow) File({})));
+        auto file = TRY(adopt_shared_if_nonnull(new (std::nothrow) File({})));
 
         long rc = syscall(SYS_open, path.chars(), flags, mode);
         int fd = TRY(Result<int>::from_syscall(rc));
@@ -60,6 +101,39 @@ namespace os
         return {};
     }
 
+    Result<String> File::read_line()
+    {
+        Vector<char> data;
+
+        int current;
+        while (true)
+        {
+            current = TRY(getchar());
+
+            if (current == -1) break;
+
+            TRY(data.try_append((char)current));
+
+            if (current == '\n') break;
+        }
+
+        if (!data.size()) return String {};
+
+        TRY(data.try_append('\0'));
+
+        return String::from_cstring(data.data());
+    }
+
+    Result<int> File::getchar()
+    {
+        char value;
+
+        usize nread = TRY(raw_read((u8*)&value, 1));
+        if (!nread) return -1;
+
+        return value;
+    }
+
     void File::set_close_on_exec()
     {
         fcntl(m_fd, F_SETFD, FD_CLOEXEC);