Kernel: Make mkdir() accessible to userspace

kernel/include/errno.h

@@ -6,7 +6,11 @@
 #define EBADF 9
 #define ENOMEM 12
 #define EFAULT 14
+#define EEXIST 17
+#define ENOTDIR 20
 #define EISDIR 21
 #define EINVAL 22
 #define EMFILE 24
+#define ENOSPC 28
 #define ENOSYS 38
+#define ENOTSUP 95

kernel/include/sys/Syscall.h

@@ -18,6 +18,7 @@
 #define SYS_fcntl 13
 #define SYS_mprotect 14
 #define SYS_clock 15
+#define SYS_mkdir 17 // 16 is reserved for fork(), which is WIP in a pull request
 
 namespace Syscall
 {
@@ -42,3 +43,4 @@ void sys_exec(Context* context, const char* pathname);
 void sys_fcntl(Context* context, int fd, int command, uintptr_t arg);
 void sys_mprotect(Context* context, void* address, size_t size, int prot);
 void sys_clock(Context* context);
+void sys_mkdir(Context* context, const char* filename);

kernel/src/fs/VFS.cpp

@@ -132,12 +132,27 @@ int VFS::mkdir(const char* path, const char* name)
     if (!node)
     {
         kwarnln("Attempting to mkdir in %s, which does not exist", path);
-        return -1;
+        return -ENOENT;
+    }
+    if (node->type != VFS_DIRECTORY)
+    {
+        kwarnln("Attempting to mkdir in %s, which is not a directory!!", path);
+        return -ENOTDIR;
     }
     if (!node->mkdir_func)
     {
         kwarnln("Chosen node does not support mkdir()");
-        return -1;
+        return -ENOTSUP;
+    }
+    if (!node->find_func)
+    {
+        kwarnln("Chosen node does not support finddir()");
+        return -ENOTSUP;
+    }
+    if (node->find_func(node, name) != nullptr)
+    {
+        kwarnln("Already exists");
+        return -EEXIST;
     }
     return node->mkdir_func(node, name);
 }

kernel/src/init/InitRD.cpp

@@ -2,6 +2,7 @@
 
 #include "init/InitRD.h"
 #include "bootboot.h"
+#include "errno.h"
 #include "fs/VFS.h"
 #include "io/Serial.h"
 #include "log/Log.h"
@@ -190,23 +191,23 @@ int initrd_mkdir(VFS::Node* node, const char* name) // FIXME: Return proper erro
     if (total_dirs >= 32)
     {
         kwarnln("mkdir() failed: too many directories");
-        return -1;
+        return -ENOSPC;
     }
     if (node->inode > total_dirs)
     {
         kwarnln("mkdir() failed: invalid node");
-        return -1;
+        return -EINVAL;
     }
     if (!(node->type & VFS_DIRECTORY))
     {
         kwarnln("mkdir() failed: not a directory");
-        return -1;
+        return -ENOTDIR;
     }
     InitRD::Directory& parent = dirs[node->inode];
     if (parent.entries == INITRD_MAX_FILES_IN_DIR)
     {
-        kwarnln("mkdir() failed: parent is null");
-        return -1;
+        kwarnln("mkdir() failed: parent is full");
+        return -ENOSPC;
     }
     uint64_t inode = total_dirs;
     VFS::Node& new_node = nodes[total_nodes++];

kernel/src/sys/Syscall.cpp

@@ -27,6 +27,7 @@ void Syscall::entry(Context* context)
     case SYS_fcntl: sys_fcntl(context, (int)context->rdi, (int)context->rsi, context->rdx); break;
     case SYS_mprotect: sys_mprotect(context, (void*)context->rdi, context->rsi, (int)context->rdx); break;
     case SYS_clock: sys_clock(context); break;
+    case SYS_mkdir: sys_mkdir(context, (const char*)context->rdi); break;
     default: context->rax = -ENOSYS; break;
     }
     VMM::exit_syscall_context();

kernel/src/sys/stdio.cpp

@@ -218,3 +218,19 @@ void sys_close(Context* context, int fd)
     context->rax = 0;
     return;
 }
+
+void sys_mkdir(Context* context, const char* filename)
+{
+    char* kfilename = Syscall::strdup_from_user(filename);
+    if (!kfilename)
+    {
+        context->rax = -EFAULT;
+        return;
+    }
+
+    int rc = VFS::mkdir(kfilename);
+
+    kfree(kfilename);
+
+    context->rax = rc;
+}

libs/libc/include/errno.h

@@ -10,10 +10,14 @@ extern int errno;
 #define EBADF 9    // Bad file descriptor
 #define ENOMEM 12  // Cannot allocate memory
 #define EFAULT 14  // Bad address
+#define EEXIST 17  // File exists
+#define ENOTDIR 10 // Not a directory
 #define EISDIR 21  // Is a directory
 #define EINVAL 22  // Invalid argument
 #define EMFILE 24  // Too many open files
+#define ENOSPC 28  // No space left on device
 #define EPIPE 32   // Broken pipe. Not implemented.
 #define ENOSYS 38  // Function not implemented
+#define ENOTSUP 95 // Operation not supported.
 
 #endif