kernel+libc+apps: Add a source parameter to the mount() system call

This way, they can't be modified by mmap() or munmap().

CMakeLists.txt

@@ -5,7 +5,7 @@ set(CMAKE_CXX_COMPILER_WORKS 1)
 
 set(CMAKE_CROSSCOMPILING true)
 
-project(Luna LANGUAGES C CXX ASM ASM_NASM VERSION 0.2.0)
+project(Luna LANGUAGES C CXX ASM ASM_NASM VERSION 0.3.0)
 
 set(LUNA_ROOT ${CMAKE_CURRENT_LIST_DIR})
 set(LUNA_BASE ${CMAKE_CURRENT_LIST_DIR}/base)

apps/mkdir.cpp

@@ -20,8 +20,7 @@ begin:
     if (rc.error() == EEXIST) return {};
     if (rc.error() == ENOENT)
     {
-        PathParser parser = TRY(PathParser::create(path.chars()));
+        auto parent = TRY(PathParser::dirname(path));
-        auto parent = TRY(parser.dirname());
 
         TRY(mkdir_recursively(parent.view(), (0777 & ~s_umask) | S_IWUSR | S_IXUSR));
 

kernel/src/arch/x86_64/CPU.cpp

@@ -80,32 +80,14 @@ void decode_page_fault_error_code(u64 code)
 
     decode_page_fault_error_code(regs->error);
 
+    CPU::print_stack_trace_at(regs);
+
     if (!is_in_kernel(regs))
     {
         // FIXME: Kill this process with SIGSEGV once we have signals and all that.
         kerrorln("Current task %zu was terminated because of a page fault", Scheduler::current()->id);
-        if (Scheduler::current()->is_kernel) Scheduler::current()->state = ThreadState::Dying;
+        Scheduler::current()->exit_and_signal_parent(127);
-        else
-        {
-            auto* current = Scheduler::current();
-            auto* parent = current->parent;
-            if (parent && parent->state == ThreadState::Waiting)
-            {
-                auto child = *parent->child_being_waited_for;
-                if (child == -1 || child == (pid_t)current->id)
-                {
-                    parent->child_being_waited_for = (pid_t)current->id;
-                    parent->wake_up();
     }
-            }
-            current->state = ThreadState::Exited;
-        }
-        Scheduler::current()->status = 127;
-        kernel_yield();
-        unreachable();
-    }
-
-    CPU::print_stack_trace_at(regs);
 
     CPU::efficient_halt();
 }
@@ -118,6 +100,13 @@ void decode_page_fault_error_code(u64 code)
 
     CPU::print_stack_trace_at(regs);
 
+    if (!is_in_kernel(regs))
+    {
+        // FIXME: Kill this process with SIGSEGV once we have signals and all that.
+        kerrorln("Current task %zu was terminated because of a general protection fault", Scheduler::current()->id);
+        Scheduler::current()->exit_and_signal_parent(127);
+    }
+
     CPU::efficient_halt();
 }
 
@@ -302,14 +291,14 @@ namespace CPU
         asm volatile("hlt");
     }
 
-    [[noreturn]] void efficient_halt() // Halt the CPU, using the lowest power possible. On x86-64 we do this using the
+    [[noreturn]] void efficient_halt() // Halt the CPU, using the lowest power possible. On x86-64 we do this using
-                                       // "hlt" instruction, which puts the CPU into a low-power idle state until the
+                                       // the "hlt" instruction, which puts the CPU into a low-power idle state
-                                       // next interrupt arrives... and we disable interrupts beforehand.
+                                       // until the next interrupt arrives... and we disable interrupts beforehand.
     {
         asm volatile("cli"); // Disable interrupts
     loop:
-        asm volatile("hlt"); // Let the cpu rest and pause until the next interrupt arrives... which in this case should
+        asm volatile("hlt"); // Let the cpu rest and pause until the next interrupt arrives... which in this case
-                             // be never (unless an NMI arrives) :)
+                             // should be never (unless an NMI arrives) :)
         goto loop;           // Safeguard: if we ever wake up, start our low-power rest again
     }
 

kernel/src/fs/VFS.cpp

@@ -71,14 +71,13 @@ namespace VFS
 
     Result<SharedPtr<Inode>> create_directory(const char* path, Credentials auth, SharedPtr<Inode> working_directory)
     {
-        auto parser = TRY(PathParser::create(path));
+        auto parent_path = TRY(PathParser::dirname(path));
-        auto parent_path = TRY(parser.dirname());
 
         auto parent_inode = TRY(resolve_path(parent_path.chars(), auth, working_directory));
 
         if (!can_write(parent_inode, auth)) return err(EACCES);
 
-        auto child_name = TRY(parser.basename());
+        auto child_name = TRY(PathParser::basename(path));
 
         TRY(validate_filename(child_name.view()));
 
@@ -87,14 +86,13 @@ namespace VFS
 
     Result<SharedPtr<Inode>> create_file(const char* path, Credentials auth, SharedPtr<Inode> working_directory)
     {
-        auto parser = TRY(PathParser::create(path));
+        auto parent_path = TRY(PathParser::dirname(path));
-        auto parent_path = TRY(parser.dirname());
 
         auto parent_inode = TRY(resolve_path(parent_path.chars(), auth, working_directory));
 
         if (!can_write(parent_inode, auth)) return err(EACCES);
 
-        auto child_name = TRY(parser.basename());
+        auto child_name = TRY(PathParser::basename(path));
 
         TRY(validate_filename(child_name.view()));
 
@@ -189,9 +187,8 @@ namespace VFS
 
     Result<void> pivot_root(const char* new_root, const char* put_old, SharedPtr<VFS::Inode> working_directory)
     {
-        auto root_parser = TRY(PathParser::create(new_root));
+        auto new_root_parent = TRY(PathParser::dirname(new_root));
-        auto new_root_parent = TRY(root_parser.dirname());
+        auto new_root_path = TRY(PathParser::basename(new_root));
-        auto new_root_path = TRY(root_parser.basename());
 
         auto new_root_parent_inode = TRY(VFS::resolve_path(new_root_parent.chars(), Credentials {}, working_directory));
         auto new_root_inode = TRY(new_root_parent_inode->find(new_root_path.chars()));
@@ -200,9 +197,8 @@ namespace VFS
         if (!new_root_inode->is_mountpoint()) return err(EINVAL);
         if (new_root_inode->fs() == g_root_inode->fs()) return err(EBUSY);
 
-        auto parser = TRY(PathParser::create(put_old));
+        auto parent_path = TRY(PathParser::dirname(put_old));
-        auto parent_path = TRY(parser.dirname());
+        auto child = TRY(PathParser::basename(put_old));
-        auto child = TRY(parser.basename());
 
         kdbgln("vfs: Pivoting root from / to %s, using %s as new root", put_old, new_root);
 
@@ -228,9 +224,8 @@ namespace VFS
     Result<void> mount(const char* path, SharedPtr<VFS::FileSystem> fs, Credentials auth,
                        SharedPtr<VFS::Inode> working_directory)
     {
-        auto parser = TRY(PathParser::create(path));
+        auto parent_path = TRY(PathParser::dirname(path));
-        auto parent_path = TRY(parser.dirname());
+        auto child = TRY(PathParser::basename(path));
-        auto child = TRY(parser.basename());
 
         kinfoln("vfs: Mounting filesystem on target %s", path);
 
@@ -249,9 +244,8 @@ namespace VFS
 
     Result<void> umount(const char* path, Credentials auth, SharedPtr<VFS::Inode> working_directory)
     {
-        auto parser = TRY(PathParser::create(path));
+        auto parent_path = TRY(PathParser::dirname(path));
-        auto parent_path = TRY(parser.dirname());
+        auto child = TRY(PathParser::basename(path));
-        auto child = TRY(parser.basename());
 
         if (child.view() == "/") return err(EBUSY);
 

kernel/src/memory/UserVM.cpp

@@ -91,7 +91,7 @@ Result<u64> UserVM::alloc_region(usize count, bool persistent)
     return err(ENOMEM);
 }
 
-Result<bool> UserVM::set_region(u64 address, usize count, bool used)
+Result<bool> UserVM::set_region(u64 address, usize count, bool used, bool persistent)
 {
     if (address >= VM_END) return err(EINVAL);
 
@@ -112,6 +112,7 @@ Result<bool> UserVM::set_region(u64 address, usize count, bool used)
         if (region->start >= address && region->end <= end)
         {
             region->used = used;
+            region->persistent = persistent;
             if (region->start == address && region->end == end)
             {
                 try_merge_region_with_neighbors(region);
@@ -125,6 +126,7 @@ Result<bool> UserVM::set_region(u64 address, usize count, bool used)
             auto* middle_region = TRY(split_region(region, address));
             TRY(split_region(middle_region, end));
             middle_region->used = used;
+            middle_region->persistent = persistent;
             return true;
         }
 
@@ -133,6 +135,7 @@ Result<bool> UserVM::set_region(u64 address, usize count, bool used)
             bool finished = region->end == end;
             auto* split = TRY(split_region(region, address));
             split->used = used;
+            split->persistent = persistent;
             try_merge_region_with_neighbors(split);
             if (!finished) continue;
             return true;
@@ -142,6 +145,7 @@ Result<bool> UserVM::set_region(u64 address, usize count, bool used)
         {
             TRY(split_region(region, end));
             region->used = used;
+            region->persistent = persistent;
             try_merge_region_with_neighbors(region);
             return true;
         }

kernel/src/memory/UserVM.h

@@ -21,14 +21,14 @@ class UserVM
 
     Result<u64> alloc_region(usize count, bool persistent = false);
 
-    Result<bool> test_and_alloc_region(u64 address, usize count)
+    Result<bool> test_and_alloc_region(u64 address, usize count, bool persistent = false)
     {
-        return set_region(address, count, true);
+        return set_region(address, count, true, persistent);
     }
 
     Result<bool> free_region(u64 address, usize count)
     {
-        return set_region(address, count, false);
+        return set_region(address, count, false, false);
     }
 
     static Result<OwnedPtr<UserVM>> try_create();
@@ -36,7 +36,7 @@ class UserVM
     Result<OwnedPtr<UserVM>> clone();
 
   private:
-    Result<bool> set_region(u64 address, usize count, bool used);
+    Result<bool> set_region(u64 address, usize count, bool used, bool persistent);
     Result<void> create_default_region();
     Result<void> create_null_region();
     void try_merge_region_with_neighbors(VMRegion* region);

kernel/src/sys/exit.cpp

@@ -7,25 +7,5 @@ Result<u64> sys_exit(Registers*, SyscallArgs args)
 
     Thread* current = Scheduler::current();
 
-    Scheduler::for_each_child(current, [](Thread* child) {
+    current->exit_and_signal_parent(status);
-        child->parent = Scheduler::init_thread();
-        return true;
-    });
-
-    auto* parent = current->parent;
-    if (parent && parent->state == ThreadState::Waiting)
-    {
-        auto child = *parent->child_being_waited_for;
-        if (child == -1 || child == (pid_t)current->id)
-        {
-            parent->child_being_waited_for = (pid_t)current->id;
-            parent->wake_up();
-        }
-    }
-
-    current->status = status;
-    current->state = ThreadState::Exited;
-
-    kernel_yield();
-    unreachable();
 }

kernel/src/sys/link.cpp

@@ -13,10 +13,8 @@ Result<u64> sys_unlinkat(Registers*, SyscallArgs args)
 
     Thread* current = Scheduler::current();
 
-    PathParser parser = TRY(PathParser::create(path.chars()));
+    auto dirname = TRY(PathParser::dirname(path.view()));
-
+    auto basename = TRY(PathParser::basename(path.view()));
-    auto dirname = TRY(parser.dirname());
-    auto basename = TRY(parser.basename());
 
     if (basename.view() == ".") return err(EINVAL);
 
@@ -47,14 +45,13 @@ Result<u64> sys_symlinkat(Registers*, SyscallArgs args)
 
     auto* current = Scheduler::current();
 
-    auto parser = TRY(PathParser::create(linkpath.chars()));
+    auto parent = TRY(PathParser::dirname(linkpath.view()));
-    auto parent = TRY(parser.dirname());
 
     auto parent_inode = TRY(current->resolve_atfile(dirfd, parent, false, true));
 
     if (!VFS::can_write(parent_inode, current->auth)) return err(EACCES);
 
-    auto child_name = TRY(parser.basename());
+    auto child_name = TRY(PathParser::basename(linkpath.view()));
 
     TRY(VFS::validate_filename(child_name.view()));
 
@@ -101,8 +98,7 @@ Result<u64> sys_linkat(Registers*, SyscallArgs args)
 
     auto* current = Scheduler::current();
 
-    auto parser = TRY(PathParser::create(newpath.chars()));
+    auto parent = TRY(PathParser::dirname(newpath.view()));
-    auto parent = TRY(parser.dirname());
 
     // FIXME: Use AT_SYMLINK_FOLLOW.
     auto target = TRY(current->resolve_atfile(olddirfd, oldpath, flags & AT_EMPTY_PATH, false));
@@ -115,7 +111,7 @@ Result<u64> sys_linkat(Registers*, SyscallArgs args)
 
     if (!VFS::can_write(parent_inode, current->auth)) return err(EACCES);
 
-    auto child_name = TRY(parser.basename());
+    auto child_name = TRY(PathParser::basename(newpath.view()));
 
     TRY(VFS::validate_filename(child_name.view()));
 

kernel/src/thread/ELF.cpp

@@ -102,9 +102,8 @@ namespace ELFLoader
                 if (can_write_segment(program_header.p_flags)) flags |= MMU::ReadWrite;
                 if (can_execute_segment(program_header.p_flags)) flags &= ~MMU::NoExecute;
 
-                // FIXME: Set this memory range to persistent so that munmap() cannot remove it.
                 if (!TRY(vm->test_and_alloc_region(
-                        base_vaddr, get_blocks_from_size(program_header.p_memsz + vaddr_diff, ARCH_PAGE_SIZE))))
+                        base_vaddr, get_blocks_from_size(program_header.p_memsz + vaddr_diff, ARCH_PAGE_SIZE), true)))
                     return err(ENOMEM);
 
                 // Allocate physical memory for the segment

kernel/src/thread/Thread.cpp

@@ -1,5 +1,6 @@
 #include "thread/Thread.h"
 #include "memory/MemoryManager.h"
+#include "thread/Scheduler.h"
 #include <bits/atfile.h>
 #include <bits/open-flags.h>
 #include <luna/Alloc.h>
@@ -68,6 +69,33 @@ Result<SharedPtr<VFS::Inode>> Thread::resolve_atfile(int dirfd, const String& pa
     return VFS::resolve_path(path.chars(), this->auth, descriptor->inode, follow_last_symlink);
 }
 
+[[noreturn]] void Thread::exit_and_signal_parent(u8 _status)
+{
+    if (is_kernel) state = ThreadState::Dying;
+    else
+    {
+        Scheduler::for_each_child(this, [](Thread* child) {
+            child->parent = Scheduler::init_thread();
+            return true;
+        });
+
+        if (parent && parent->state == ThreadState::Waiting)
+        {
+            auto child = *parent->child_being_waited_for;
+            if (child == -1 || child == (pid_t)id)
+            {
+                parent->child_being_waited_for = (pid_t)id;
+                parent->wake_up();
+            }
+        }
+
+        state = ThreadState::Exited;
+    }
+    status = _status;
+    kernel_yield();
+    unreachable();
+}
+
 bool FileDescriptor::should_append()
 {
     return flags & O_APPEND;

kernel/src/thread/Thread.h

@@ -99,6 +99,8 @@ struct Thread : public LinkedListNode<Thread>
 
     PageDirectory* directory;
 
+    [[noreturn]] void exit_and_signal_parent(u8 status);
+
     bool is_idle()
     {
         return state == ThreadState::Idle;

kernel/src/thread/ThreadImage.cpp

@@ -1,6 +1,7 @@
 #include "thread/ThreadImage.h"
 #include "memory/MemoryManager.h"
 #include "thread/Thread.h"
+#include <luna/Alignment.h>
 #include <luna/CString.h>
 
 static constexpr usize DEFAULT_USER_STACK_PAGES = 6;
@@ -10,8 +11,7 @@ static Result<void> create_stacks(Stack& user_stack, Stack& kernel_stack, UserVM
 {
     const u64 THREAD_STACK_BASE = 0x10000;
 
-    // FIXME: Set this memory range to persistent so that munmap() cannot remove it.
+    if (!TRY(vm->test_and_alloc_region(THREAD_STACK_BASE, DEFAULT_USER_STACK_PAGES, true))) return err(ENOMEM);
-    if (!TRY(vm->test_and_alloc_region(THREAD_STACK_BASE, DEFAULT_USER_STACK_PAGES))) return err(ENOMEM);
 
     TRY(MemoryManager::alloc_at_zeroed(THREAD_STACK_BASE, DEFAULT_USER_STACK_PAGES,
                                        MMU::ReadWrite | MMU::NoExecute | MMU::User));
@@ -122,7 +122,7 @@ void ThreadImage::apply(Thread* thread)
 
     thread->kernel_stack = m_kernel_stack;
     thread->stack = m_user_stack;
-    thread->set_sp(m_sp);
+    thread->set_sp(align_down<16>(m_sp));
 
     thread->directory = m_directory;
 

libc/CMakeLists.txt

@@ -20,6 +20,7 @@ set(SOURCES
     src/pwd.cpp
     src/grp.cpp
     src/locale.cpp
+    src/scanf.cpp
     src/sys/stat.cpp
     src/sys/mman.cpp
     src/sys/wait.cpp

libc/include/stdio.h

@@ -27,6 +27,9 @@ extern FILE* stderr;
 #define stderr stderr
 
 #define BUFSIZ 1024
+#define FILENAME_MAX                                                                                                   \
+    1024 // As Luna does not impose a limit on this, this is the recommended size for character arrays holding a file
+         // name.
 
 #ifdef __cplusplus
 extern "C"
@@ -41,6 +44,9 @@ extern "C"
     /* Bind a stream to a file descriptor. */
     FILE* fdopen(int fd, const char* mode);
 
+    /* Change the underlying file and mode of a stream. */
+    FILE* freopen(const char* path, const char* mode, FILE* stream);
+
     /* Close a file and frees up its stream. */
     int fclose(FILE* stream);
 
@@ -95,6 +101,9 @@ extern "C"
     /* Read a character from standard input. */
     int getchar(void);
 
+    /* Push a character back to stream so that it can be read again. */
+    int ungetc(int c, FILE* stream);
+
     /* Read a line from stream. */
     char* fgets(char* buf, size_t size, FILE* stream);
 
@@ -122,16 +131,34 @@ extern "C"
     int snprintf(char* buf, size_t max, const char* format, ...);
 
     /* Write formatted output into a buffer. */
-    int vsprintf(char*, const char*, va_list);
+    int vsprintf(char* buf, const char* format, va_list ap);
 
     /* Write up to max bytes of formatted output into a buffer. */
-    int vsnprintf(char*, size_t, const char*, va_list);
+    int vsnprintf(char* buf, size_t max, const char* format, va_list ap);
 
     /* Write formatted output to standard output. */
-    int vprintf(const char*, va_list ap);
+    int vprintf(const char* format, va_list ap);
 
     /* Write formatted output to standard output. */
-    int printf(const char*, ...);
+    int printf(const char* format, ...);
+
+    /* Scan formatted input from a string. */
+    int vsscanf(const char* str, const char* format, va_list ap);
+
+    /* Scan formatted input from a string. */
+    int sscanf(const char* str, const char* format, ...);
+
+    /* Scan formatted input from a file. */
+    int vfscanf(FILE* stream, const char* format, va_list ap);
+
+    /* Scan formatted input from a file. */
+    int fscanf(FILE* stream, const char* format, ...);
+
+    /* Scan formatted input from standard input. */
+    int vscanf(const char* format, va_list ap);
+
+    /* Scan formatted input from standard input. */
+    int scanf(const char* format, ...);
 
     /* Write a string followed by a newline to standard output. */
     int puts(const char* s);

libc/src/scanf.cpp

@@ -0,0 +1,263 @@
+#include <errno.h>
+#include <luna/CType.h>
+#include <luna/NumberParsing.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#define FLAG_DISCARD (1 << 0)
+#define FLAG_ALLOC (1 << 1)
+#define FLAG_WIDTH (1 << 2)
+#define FLAG_LONG (1 << 3)
+#define FLAG_LONG_LONG (1 << 4)
+#define FLAG_SHORT (1 << 5)
+#define FLAG_CHAR (1 << 6)
+
+static int parse_flags(const char** format)
+{
+    int result = 0;
+
+    while (true)
+    {
+        switch (**format)
+        {
+        case '*':
+            result |= FLAG_DISCARD;
+            (*format)++;
+            break;
+        case 'm':
+            result |= FLAG_ALLOC;
+            (*format)++;
+            break;
+        default: return result;
+        }
+    }
+}
+
+static size_t parse_width(const char** format, int& flags)
+{
+    size_t result = 0;
+
+    if (_isdigit(**format))
+    {
+        result = scan_unsigned_integer(format);
+        flags |= FLAG_WIDTH;
+    }
+
+    return result;
+}
+
+static void parse_type(const char** format, int& flags)
+{
+    // FIXME: Support %j (intmax_t/uintmax_t)
+    switch (**format)
+    {
+    case 'h':
+        flags |= FLAG_SHORT;
+        (*format)++;
+        if (**format == 'h')
+        {
+            flags |= FLAG_CHAR;
+            (*format)++;
+        }
+        break;
+    case 'l':
+        flags |= FLAG_LONG;
+        (*format)++;
+        if (**format == 'l')
+        {
+            flags |= FLAG_LONG_LONG;
+            (*format)++;
+        }
+        break;
+    case 't':
+        flags |= (sizeof(ptrdiff_t) == sizeof(long)) ? FLAG_LONG : FLAG_LONG_LONG;
+        (*format)++;
+        break;
+    case 'z':
+        flags |= (sizeof(size_t) == sizeof(long)) ? FLAG_LONG : FLAG_LONG_LONG;
+        (*format)++;
+        break;
+    default: break;
+    }
+}
+
+static void write_parsed_signed_integer(ssize_t value, int flags, va_list ap)
+{
+    if (flags & FLAG_LONG_LONG) *va_arg(ap, signed long long*) = (signed long long)value;
+    else if (flags & FLAG_LONG)
+        *va_arg(ap, signed long*) = (signed long)value;
+    else if (flags & FLAG_SHORT)
+        *va_arg(ap, signed int*) = (signed short)value;
+    else if (flags & FLAG_CHAR)
+        *va_arg(ap, signed int*) = (signed char)value;
+    else
+        *va_arg(ap, signed int*) = (signed int)value;
+}
+
+static void write_parsed_unsigned_integer(size_t value, int flags, va_list ap)
+{
+    if (flags & FLAG_LONG_LONG) *va_arg(ap, unsigned long long*) = (unsigned long long)value;
+    else if (flags & FLAG_LONG)
+        *va_arg(ap, unsigned long*) = (unsigned long)value;
+    else if (flags & FLAG_SHORT)
+        *va_arg(ap, unsigned int*) = (unsigned short)value;
+    else if (flags & FLAG_CHAR)
+        *va_arg(ap, unsigned int*) = (unsigned char)value;
+    else
+        *va_arg(ap, unsigned int*) = (unsigned int)value;
+}
+
+#define WHITESPACE_CHARACTERS " \t\f\r\n\v"
+
+static void skip_whitespace(const char** str)
+{
+    *str += strspn(*str, WHITESPACE_CHARACTERS);
+}
+
+extern "C"
+{
+    int vsscanf(const char* str, const char* format, va_list ap)
+    {
+        int parsed = 0;
+        const char* s = str; // Keep a pointer to the beginning of the string for %n
+
+        if (*str == 0) return EOF;
+
+        while (*format)
+        {
+            if (*format != '%')
+            {
+            normal:
+                if (!_isspace(*format))
+                {
+                    if (*str != *format) return parsed;
+                    str++;
+                    format++;
+                    if (*str == 0) return parsed;
+                    continue;
+                }
+
+                skip_whitespace(&format);
+                skip_whitespace(&str);
+                if (*str == 0) return parsed;
+                continue;
+            }
+            else
+            {
+                format++;
+                if (*format == '%')
+                {
+                    skip_whitespace(&str);
+                    goto normal;
+                }
+
+                int flags = parse_flags(&format);
+                size_t width = parse_width(&format, flags);
+                parse_type(&format, flags);
+                char specifier = *format++;
+                if (!specifier) return parsed;
+
+                switch (specifier)
+                {
+                case 's': {
+                    skip_whitespace(&str);
+                    size_t chars = strcspn(str, WHITESPACE_CHARACTERS);
+                    if (!chars) return parsed;
+                    if ((flags & FLAG_WIDTH) && chars > width) chars = width;
+                    if (!(flags & FLAG_DISCARD))
+                    {
+                        char* ptr;
+                        if (flags & FLAG_ALLOC)
+                        {
+                            ptr = (char*)malloc(chars + 1);
+                            if (!ptr) return parsed;
+                            *va_arg(ap, char**) = ptr;
+                        }
+                        else
+                            ptr = va_arg(ap, char*);
+                        memcpy(ptr, str, chars);
+                        ptr[chars] = 0;
+                    }
+                    str += chars;
+                    parsed++;
+                    break;
+                }
+                case 'c': {
+                    if (strlen(str) < width) return parsed;
+                    if (!(flags & FLAG_WIDTH)) width = 1;
+                    if (!(flags & FLAG_DISCARD))
+                    {
+                        char* ptr;
+                        if (flags & FLAG_ALLOC)
+                        {
+                            ptr = (char*)malloc(width);
+                            if (!ptr) return parsed;
+                            *va_arg(ap, char**) = ptr;
+                        }
+                        else
+                            ptr = va_arg(ap, char*);
+                        memcpy(ptr, str, width);
+                    }
+                    str += width;
+                    parsed++;
+                    break;
+                }
+                case 'd': {
+                    skip_whitespace(&str);
+                    ssize_t value = scan_signed_integer(&str, 10);
+                    if (!(flags & FLAG_DISCARD)) write_parsed_signed_integer(value, flags, ap);
+                    parsed++;
+                    break;
+                }
+                case 'i': {
+                    skip_whitespace(&str);
+                    ssize_t value = scan_signed_integer(&str, 0);
+                    if (!(flags & FLAG_DISCARD)) write_parsed_signed_integer(value, flags, ap);
+                    parsed++;
+                    break;
+                }
+                case 'o': {
+                    skip_whitespace(&str);
+                    size_t value = scan_unsigned_integer(&str, 8);
+                    if (!(flags & FLAG_DISCARD)) write_parsed_unsigned_integer(value, flags, ap);
+                    parsed++;
+                    break;
+                }
+                case 'u': {
+                    skip_whitespace(&str);
+                    size_t value = scan_unsigned_integer(&str, 10);
+                    if (!(flags & FLAG_DISCARD)) write_parsed_unsigned_integer(value, flags, ap);
+                    parsed++;
+                    break;
+                }
+                case 'X':
+                case 'x': {
+                    skip_whitespace(&str);
+                    size_t value = scan_unsigned_integer(&str, 16);
+                    if (!(flags & FLAG_DISCARD)) write_parsed_unsigned_integer(value, flags, ap);
+                    parsed++;
+                    break;
+                }
+                case 'p': {
+                    skip_whitespace(&str);
+                    size_t value = scan_unsigned_integer(&str, 16);
+                    if (!(flags & FLAG_DISCARD)) *va_arg(ap, void**) = (void*)value;
+                    parsed++;
+                    break;
+                }
+                case 'n': {
+                    if (!(flags & FLAG_DISCARD)) *va_arg(ap, int*) = (int)(str - s);
+                    break;
+                }
+                default: {
+                    fprintf(stderr, "vsscanf: unknown conversion specifier: %%%c\n", specifier);
+                    return parsed;
+                }
+                }
+            }
+        }
+
+        return parsed;
+    }
+}

libc/src/stdio.cpp

@@ -11,6 +11,13 @@ FILE* stdin = nullptr;
 FILE* stderr = nullptr;
 FILE* stdout = nullptr;
 
+static const char* read_tmpdir()
+{
+    const char* tmpdir = getenv("TMPDIR");
+    if (!tmpdir) return "/tmp";
+    return tmpdir;
+}
+
 static int fopen_parse_mode(const char* mode)
 {
     int result = 0;
@@ -46,6 +53,12 @@ static int fdopen_check_compatible_mode(int fd, int new_flags)
 
 extern "C"
 {
+    int fflush(FILE*)
+    {
+        // FIXME: Files are not buffered right now.
+        return 0;
+    }
+
     FILE* fopen(const char* path, const char* mode)
     {
         int flags;
@@ -85,6 +98,25 @@ extern "C"
         return f;
     }
 
+    FILE* freopen(const char* path, const char* mode, FILE* stream)
+    {
+        int flags;
+
+        if ((flags = fopen_parse_mode(mode)) < 0) return nullptr;
+
+        close(stream->_fd);
+
+        if (!path) { fail("FIXME: freopen() called with path=nullptr"); }
+
+        int fd = open(path, flags, 0666);
+        if (fd < 0) { return nullptr; }
+
+        stream->_fd = fd;
+        clearerr(stream);
+
+        return stream;
+    }
+
     int fclose(FILE* stream)
     {
         if (close(stream->_fd) < 0) return EOF;
@@ -381,6 +413,54 @@ extern "C"
         return rc;
     }
 
+    int sscanf(const char* str, const char* format, ...)
+    {
+        va_list ap;
+        va_start(ap, format);
+
+        int rc = vsscanf(str, format, ap);
+
+        va_end(ap);
+
+        return rc;
+    }
+
+    int vfscanf(FILE* stream, const char* format, va_list ap)
+    {
+        char buf[BUFSIZ];
+        if (!fgets(buf, sizeof(buf), stream)) return EOF;
+        return vsscanf(buf, format, ap);
+    }
+
+    int fscanf(FILE* stream, const char* format, ...)
+    {
+        va_list ap;
+        va_start(ap, format);
+
+        int rc = vfscanf(stream, format, ap);
+
+        va_end(ap);
+
+        return rc;
+    }
+
+    int vscanf(const char* format, va_list ap)
+    {
+        return vfscanf(stdin, format, ap);
+    }
+
+    int scanf(const char* format, ...)
+    {
+        va_list ap;
+        va_start(ap, format);
+
+        int rc = vfscanf(stdin, format, ap);
+
+        va_end(ap);
+
+        return rc;
+    }
+
     int puts(const char* s)
     {
         if (fputs(s, stdout) < 0) return -1;
@@ -404,12 +484,16 @@ extern "C"
 
     FILE* tmpfile()
     {
-        // FIXME: use /tmp as the directory when the tmpfs is mounted only there.
+        int fd = open(read_tmpdir(), O_RDWR | O_TMPFILE, 0600);
-        int fd = open("/", O_RDWR | O_TMPFILE, 0600);
         if (fd < 0) return nullptr;
 
         FILE* f = fdopen(fd, "w+b");
         if (!f) close(fd);
         return f;
     }
+
+    int ungetc(int, FILE*)
+    {
+        fail("FIXME: ungetc: not implemented");
+    }
 }

libluna/include/luna/NumberParsing.h

@@ -2,10 +2,10 @@
 #include <luna/Types.h>
 
 // Parse an unsigned integer and advance *str to point to the first non-digit character after the number.
-usize scan_unsigned_integer(const char** str);
+usize scan_unsigned_integer(const char** str, int base = 10);
 
 // Parse a signed integer and advance *str to point to the first non-digit character after the number.
-isize scan_signed_integer(const char** str);
+isize scan_signed_integer(const char** str, int base = 10);
 
 // Parse an unsigned integer, similar to strtoull().
 usize parse_unsigned_integer(const char* str, const char** endptr, int base);

libluna/include/luna/PathParser.h

@@ -37,8 +37,8 @@ class PathParser
         return m_already_called_next ? (bool)m_strtok_saved_state : is_not_delim(*m_copy);
     }
 
-    Result<String> basename();
+    static Result<String> basename(StringView path);
-    Result<String> dirname();
+    static Result<String> dirname(StringView path);
 
     Option<const char*> next();
 

libluna/include/luna/Vector.h

@@ -212,7 +212,7 @@ template <typename T> class Vector
     {
         Vector<T> other;
         TRY(other.try_reserve(m_capacity));
-        memcpy(other.m_data, m_data, m_size);
+        memcpy(other.m_data, m_data, m_size * sizeof(T));
         other.m_size = m_size;
         return other;
     }

libluna/src/Format.cpp

@@ -150,7 +150,7 @@ static usize parse_precision(const char** format, flags_t& flags, va_list ap)
     return result;
 }
 
-static void parse_length(const char** format, flags_t& flags)
+static void parse_type(const char** format, flags_t& flags)
 {
     // FIXME: Support %j (intmax_t/uintmax_t)
     switch (**format)
@@ -415,7 +415,7 @@ Result<usize> cstyle_format(const char* format, callback_t callback, void* arg,
         flags_t flags = parse_flags(&format);
         const usize width = parse_width(&format, flags, ap);
         usize precision = parse_precision(&format, flags, ap);
-        parse_length(&format, flags);
+        parse_type(&format, flags);
 
         conv_state vstate = { flags, width, precision };
 
@@ -503,15 +503,18 @@ usize vstring_format(char* buf, usize max, const char* format, va_list ap)
                        [](char c, void* arg) -> Result<void> {
                            StringFormatInfo* info_arg = (StringFormatInfo*)arg;
                            if (!info_arg->remaining) return {};
+                           if (info_arg->buffer)
+                           {
                                *(info_arg->buffer) = c;
                                info_arg->buffer++;
+                           }
                            info_arg->remaining--;
                            return {};
                        },
                        &info, ap)
                        .value();
 
-    *(info.buffer) = 0;
+    if (info.buffer) *(info.buffer) = 0;
 
     return result;
 }

libluna/src/NumberParsing.cpp

@@ -89,12 +89,12 @@ isize parse_signed_integer(const char* str, const char** endptr, int base)
     return negative ? -(isize)rc : (isize)rc;
 }
 
-usize scan_unsigned_integer(const char** str)
+usize scan_unsigned_integer(const char** str, int base)
 {
-    return parse_unsigned_integer(*str, str, 10);
+    return parse_unsigned_integer(*str, str, base);
 }
 
-isize scan_signed_integer(const char** str)
+isize scan_signed_integer(const char** str, int base)
 {
-    return parse_signed_integer(*str, str, 10);
+    return parse_signed_integer(*str, str, base);
 }

libluna/src/PathParser.cpp

@@ -35,9 +35,9 @@ Option<const char*> PathParser::next()
     return result;
 }
 
-Result<String> PathParser::basename()
+Result<String> PathParser::basename(StringView path)
 {
-    char* copy = strdup(m_original);
+    char* copy = strdup(path.chars());
     if (!copy) return err(ENOMEM);
 
     auto guard = make_scope_guard([copy] { free_impl(copy); });
@@ -48,9 +48,9 @@ Result<String> PathParser::basename()
     return String::from_cstring(result);
 }
 
-Result<String> PathParser::dirname()
+Result<String> PathParser::dirname(StringView path)
 {
-    char* copy = strdup(m_original);
+    char* copy = strdup(path.chars());
     if (!copy) return err(ENOMEM);
 
     auto guard = make_scope_guard([copy] { free_impl(copy); });

libluna/src/Stack.cpp

@@ -6,5 +6,5 @@ Stack::Stack(u64 base, usize bytes) : m_base(base), m_bytes(bytes)
 
 u64 Stack::top() const
 {
-    return (m_base + m_bytes) - sizeof(void*);
+    return (m_base + m_bytes) - 16;
 }

libos/src/ArgumentParser.cpp

@@ -118,7 +118,7 @@ namespace os
 
         bool is_still_parsing_flags = true;
 
-        Vector<PositionalArgument> positional_args = TRY(m_positional_args.deep_copy());
+        Vector<PositionalArgument> positional_args = TRY(m_positional_args.shallow_copy());
 
         for (int i = 1; i < argc; i++)
         {

tests/CMakeLists.txt

@@ -19,6 +19,7 @@ luna_test(libluna/TestUtf8.cpp TestUtf8)
 luna_test(libluna/TestFormat.cpp TestFormat)
 luna_test(libluna/TestHashTable.cpp TestHashTable)
 luna_test(libluna/TestCPath.cpp TestCPath)
+luna_test(libc/TestScanf.cpp TestScanf)
 
 luna_app(run-tests.cpp run-tests)
 endif()

tests/libc/TestScanf.cpp

@@ -0,0 +1,91 @@
+#include <stdio.h>
+#include <string.h>
+#include <test.h>
+
+// FIXME: Add more tests.
+
+TestResult test_basic_scanf()
+{
+    char hello[21];
+    char world[21];
+
+    int parsed = sscanf("hello world", "%20s %20s", hello, world);
+    validate(parsed == 2);
+
+    validate(!strcmp(hello, "hello"));
+    validate(!strcmp(world, "world"));
+
+    test_success;
+}
+
+TestResult test_incomplete_scanf()
+{
+    char hello[21];
+    char world[21];
+
+    int parsed = sscanf("hello ", "%20s %20s", hello, world);
+    validate(parsed == 1);
+
+    validate(!strcmp(hello, "hello"));
+
+    test_success;
+}
+
+TestResult test_integer_scanf()
+{
+    int hour;
+    int min;
+
+    int parsed = sscanf("23:59", "%d:%d", &hour, &min);
+    validate(parsed == 2);
+
+    validate(hour == 23);
+    validate(min == 59);
+
+    test_success;
+}
+
+TestResult test_integer_auto_base_scanf()
+{
+    int a;
+    int b;
+    int c;
+
+    int parsed = sscanf("65, \t0x23, 0755", "%i, %i, %i", &a, &b, &c);
+    validate(parsed == 3);
+
+    validate(a == 65);
+    validate(b == 0x23);
+    validate(c == 0755);
+
+    test_success;
+}
+
+TestResult test_scanf_characters_consumed()
+{
+    int hour;
+    int min;
+    int nr_chars;
+
+    int parsed = sscanf("23:59", "%d:%d%n", &hour, &min, &nr_chars);
+    validate(parsed == 2);
+
+    validate(hour == 23);
+    validate(min == 59);
+    validate(nr_chars == 5);
+
+    test_success;
+}
+
+Result<void> test_main()
+{
+    test_prelude;
+
+    run_test(test_basic_scanf);
+    run_test(test_incomplete_scanf);
+    run_test(test_integer_scanf);
+    run_test(test_integer_auto_base_scanf);
+    run_test(test_scanf_characters_consumed);
+
+    return {};
+}