Finally hook up the mkdir code to a syscall.

Added a /bin/mkdir that makes directories. How very neat :^)
There are various limitations because of missing functionality.

Kernel/IDEDiskDevice.cpp

@@ -18,6 +18,7 @@
 enum IDECommand : byte {
     IDENTIFY_DRIVE = 0xEC,
     READ_SECTORS = 0x21,
+    WRITE_SECTORS = 0x30,
 };
 
 enum IDEStatus : byte {
@@ -64,11 +65,8 @@ bool IDEDiskDevice::readBlock(unsigned index, byte* out) const
 
 bool IDEDiskDevice::writeBlock(unsigned index, const byte* data)
 {
-    (void) index;
-    (void) data;
-    kprintf("IDEDiskDevice: writeBlock not implemented()\n");
-    notImplemented();
-    return false;
+    write_sectors(index, 1, data);
+    return true;
 }
 
 #ifdef DISK_DEBUG
@@ -221,3 +219,48 @@ bool IDEDiskDevice::read_sectors(dword start_sector, word count, byte* outbuf)
 
     return true;
 }
+
+bool IDEDiskDevice::write_sectors(dword start_sector, word count, const byte* data)
+{
+    LOCKER(m_lock);
+    dbgprintf("%s(%u): IDEDiskDevice::write_sectors request (%u sector(s) @ %u)\n",
+            current->name().characters(),
+            current->pid(),
+            count,
+            start_sector);
+    disableIRQ();
+
+    auto chs = lba_to_chs(start_sector);
+
+    while (IO::in8(IDE0_STATUS) & BUSY);
+
+    //dbgprintf("IDEDiskDevice: Writing %u sector(s) @ LBA %u (%u/%u/%u)\n", count, start_sector, chs.cylinder, chs.head, chs.sector);
+
+    IO::out8(0x1F2, count == 256 ? 0 : LSB(count));
+    IO::out8(0x1F3, chs.sector);
+    IO::out8(0x1F4, LSB(chs.cylinder));
+    IO::out8(0x1F5, MSB(chs.cylinder));
+
+    IO::out8(0x1F6, 0xA0 | chs.head); /* 0xB0 for 2nd device */
+
+    IO::out8(0x3F6, 0x08);
+
+    IO::out8(IDE0_COMMAND, WRITE_SECTORS);
+
+    while (!(IO::in8(IDE0_STATUS) & DRQ));
+
+    byte status = IO::in8(0x1f7);
+    if (status & DRQ) {
+        //dbgprintf("Sending %u bytes (status=%b), data=%p...\n", count * 512, status, data);
+        auto* data_as_words = (const word*)data;
+        for (dword i = 0; i < (count * 512) / 2; ++i) {
+            IO::out16(IDE0_DATA, data_as_words[i]);
+        }
+    }
+
+    m_interrupted = false;
+    enableIRQ();
+    wait_for_irq();
+
+    return true;
+}

Kernel/IDEDiskDevice.h

@@ -34,7 +34,8 @@ private:
 
     void initialize();
     bool wait_for_irq();
-    bool read_sectors(dword start_sector, word count, byte* outbuf);
+    bool read_sectors(dword start_sector, word count, byte* buffer);
+    bool write_sectors(dword start_sector, word count, const byte* data);
 
     SpinLock m_lock;
     word m_cylinders { 0 };

Kernel/Makefile

@@ -44,7 +44,8 @@ ELFLOADER_OBJS = \
 AK_OBJS = \
     ../AK/String.o \
     ../AK/StringImpl.o \
-    ../AK/StringBuilder.o
+    ../AK/StringBuilder.o \
+    ../AK/FileSystemPath.o
 
 OBJS = $(KERNEL_OBJS) $(VFS_OBJS) $(AK_OBJS) $(ELFLOADER_OBJS)
 

Kernel/Process.cpp

@@ -1751,3 +1751,15 @@ int Process::sys$setgroups(size_t count, const gid_t* gids)
         m_gids.set(gids[i]);
     return 0;
 }
+
+int Process::sys$mkdir(const char* pathname, mode_t mode)
+{
+    if (!validate_read_str(pathname))
+        return -EFAULT;
+    if (strlen(pathname) >= 255)
+        return -ENAMETOOLONG;
+    int error;
+    if (!VFS::the().mkdir(pathname, mode, cwd_inode()->identifier(), error))
+        return error;
+    return 0;
+}

Kernel/Process.h

@@ -172,6 +172,7 @@ public:
     int sys$access(const char* pathname, int mode);
     int sys$fcntl(int fd, int cmd, dword extra_arg);
     int sys$ioctl(int fd, unsigned request, unsigned arg);
+    int sys$mkdir(const char* pathname, mode_t mode);
 
     static void initialize();
 

Kernel/Syscall.cpp

@@ -175,6 +175,8 @@ static dword handle(RegisterDump& regs, dword function, dword arg1, dword arg2,
         return current->sys$ioctl((int)arg1, (unsigned)arg2, (unsigned)arg3);
     case Syscall::SC_fstat:
         return current->sys$fstat((int)arg1, (Unix::stat*)arg2);
+    case Syscall::SC_mkdir:
+        return current->sys$mkdir((const char*)arg1, (mode_t)arg2);
     default:
         kprintf("<%u> int0x80: Unknown function %u requested {%x, %x, %x}\n", current->pid(), function, arg1, arg2, arg3);
         break;

Kernel/Syscall.h

@@ -63,6 +63,7 @@
     __ENUMERATE_SYSCALL(access) \
     __ENUMERATE_SYSCALL(fcntl) \
     __ENUMERATE_SYSCALL(ioctl) \
+    __ENUMERATE_SYSCALL(mkdir) \
 
 
 #define DO_SYSCALL_A0(function) Syscall::invoke((dword)(function))

Kernel/sync.sh

@@ -29,6 +29,7 @@ cp -v ../Userland/mm mnt/bin/mm
 cp -v ../Userland/kill mnt/bin/kill
 cp -v ../Userland/tty mnt/bin/tty
 cp -v ../Userland/strsignal mnt/bin/strsignal
+cp -v ../Userland/mkdir mnt/bin/mkdir
 sh sync-local.sh
 cp -v kernel.map mnt/
 umount mnt