kernel+libc: Add unlink(), rmdir(), remove()

kernel/CMakeLists.txt

@@ -36,6 +36,7 @@ set(SOURCES
     src/sys/getdents.cpp
     src/sys/stat.cpp
     src/sys/chdir.cpp
+    src/sys/link.cpp
     src/fs/VFS.cpp
     src/fs/tmpfs/FileSystem.cpp
     src/fs/devices/DeviceRegistry.cpp

kernel/src/fs/VFS.h

@@ -43,6 +43,10 @@ namespace VFS
 
         virtual Result<void> add_entry(SharedPtr<Inode> inode, const char* name) = 0;
 
+        virtual Result<void> remove_entry(const char* name) = 0;
+
+        virtual usize entries() const = 0;
+
         // File-specific methods
         virtual Result<usize> read(u8* buf, usize offset, usize length) const = 0;
 
@@ -67,6 +71,9 @@ namespace VFS
             return 0;
         }
 
+        virtual void did_link() = 0;
+        virtual void did_unlink() = 0;
+
         // Metadata changers
         virtual Result<void> chmod(mode_t mode) = 0;
 
@@ -110,6 +117,16 @@ namespace VFS
             return err(ENOTDIR);
         }
 
+        Result<void> remove_entry(const char*) override
+        {
+            return err(ENOTDIR);
+        }
+
+        usize entries() const override
+        {
+            return 0;
+        }
+
         bool blocking() const override
         {
             return false;
@@ -151,6 +168,16 @@ namespace VFS
             return err(ENOTDIR);
         }
 
+        Result<void> remove_entry(const char*) override
+        {
+            return err(ENOTDIR);
+        }
+
+        usize entries() const override
+        {
+            return 0;
+        }
+
         InodeType type() const override
         {
             return InodeType::Device;

kernel/src/fs/tmpfs/FileSystem.cpp

@@ -79,6 +79,22 @@ namespace TmpFS
 
         TRY(m_entries.try_append(move(entry)));
 
+        inode->did_link();
+
+        return {};
+    }
+
+    Result<void> DirInode::remove_entry(const char* name)
+    {
+        SharedPtr<VFS::Inode> inode = TRY(find(name));
+
+        if (inode->type() == VFS::InodeType::Directory && inode->entries() != 2) return err(ENOTEMPTY);
+
+        m_entries.remove_first_matching(
+            [&](const VFS::DirectoryEntry& entry) { return !strcmp(entry.name.chars(), name); });
+
+        inode->did_unlink();
+
         return {};
     }
 

kernel/src/fs/tmpfs/FileSystem.h

@@ -96,6 +96,16 @@ namespace TmpFS
             return {};
         }
 
+        void did_link() override
+        {
+            m_nlinks++;
+        }
+
+        void did_unlink() override
+        {
+            m_nlinks--;
+        }
+
         virtual ~FileInode() = default;
 
       private:
@@ -105,6 +115,7 @@ namespace TmpFS
         mode_t m_mode;
         u32 m_uid { 0 };
         u32 m_gid { 0 };
+        u32 m_nlinks { 0 };
     };
 
     class DeviceInode : public VFS::DeviceInode
@@ -196,6 +207,16 @@ namespace TmpFS
             return {};
         }
 
+        void did_link() override
+        {
+            m_nlinks++;
+        }
+
+        void did_unlink() override
+        {
+            m_nlinks--;
+        }
+
         virtual ~DeviceInode() = default;
 
       private:
@@ -205,6 +226,7 @@ namespace TmpFS
         mode_t m_mode;
         u32 m_uid { 0 };
         u32 m_gid { 0 };
+        u32 m_nlinks { 0 };
     };
 
     class DirInode : public VFS::Inode
@@ -298,6 +320,23 @@ namespace TmpFS
             return VFS::InodeType::Directory;
         }
 
+        void did_link() override
+        {
+        }
+
+        void did_unlink() override
+        {
+            m_self = {};
+            m_entries.clear();
+        }
+
+        usize entries() const override
+        {
+            return m_entries.size();
+        }
+
+        Result<void> remove_entry(const char* name) override;
+
         Result<SharedPtr<VFS::Inode>> create_file(const char* name) override;
         Result<SharedPtr<VFS::Inode>> create_subdirectory(const char* name) override;
 

kernel/src/sys/link.cpp

@@ -0,0 +1,32 @@
+#include "memory/MemoryManager.h"
+#include "sys/Syscall.h"
+#include "thread/Scheduler.h"
+#include <luna/PathParser.h>
+
+Result<u64> sys_unlink(Registers*, SyscallArgs args)
+{
+    auto path = TRY(MemoryManager::strdup_from_user(args[0]));
+    int flags = (int)args[1];
+
+    Thread* current = Scheduler::current();
+
+    PathParser parser = TRY(PathParser::create(path.chars()));
+
+    auto dirname = TRY(parser.dirname());
+    auto basename = TRY(parser.basename());
+
+    if (basename.view() == ".") return err(EINVAL);
+
+    auto inode = TRY(VFS::resolve_path(dirname.chars(), current->auth, current->current_directory));
+    if (!VFS::can_write(inode, current->auth)) return err(EACCES);
+
+    if (flags > 0)
+    {
+        auto child = TRY(inode->find(basename.chars()));
+        if (child->type() != VFS::InodeType::Directory) return err(ENOTDIR);
+    }
+
+    TRY(inode->remove_entry(basename.chars()));
+
+    return 0;
+}

libc/CMakeLists.txt

@@ -53,7 +53,7 @@ add_custom_target(libc
     COMMAND ${CMAKE_AR} -x $<TARGET_FILE:bare_libc>
     COMMAND ${CMAKE_AR} -x $<TARGET_FILE:luna>
     COMMAND ${CMAKE_AR} -rcs ${CMAKE_CURRENT_BINARY_DIR}/libc.a *.o
-    COMMAND rm *.o
+    COMMAND /usr/bin/rm *.o
     WORKING_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR}
     DEPENDS bare_libc luna crt0
 )

libc/include/stdio.h

@@ -128,6 +128,9 @@ extern "C"
     /* Write an error message to standard error. */
     void perror(const char* s);
 
+    /* Remove a file from the filesystem. */
+    int remove(const char* path);
+
 #ifdef __cplusplus
 }
 #endif

libc/include/unistd.h

@@ -103,6 +103,12 @@ extern "C"
     /* Retrieve the current working directory. */
     char* getcwd(char* buf, size_t size);
 
+    /* Remove a name from the filesystem. */
+    int unlink(const char* path);
+
+    /* Remove a directory from the filesystem. */
+    int rmdir(const char* path);
+
 #ifdef __cplusplus
 }
 #endif

libc/src/stdio.cpp

@@ -336,6 +336,12 @@ extern "C"
         if (s && *s) fprintf(stderr, "%s: ", s);
         fprintf(stderr, "%s\n", strerror(err));
     }
+
+    int remove(const char* path)
+    {
+        // On Luna, unlink() allows removal of directories.
+        return unlink(path);
+    }
 }
 
 void debug_log_impl(const char* format, va_list ap)

libc/src/unistd.cpp

@@ -6,6 +6,7 @@
 #include <stdarg.h>
 #include <stdint.h>
 #include <stdlib.h>
+#include <sys/stat.h>
 #include <sys/syscall.h>
 #include <unistd.h>
 
@@ -300,4 +301,16 @@ extern "C"
             return buf;
         }
     }
+
+    int unlink(const char* path)
+    {
+        long rc = syscall(SYS_unlink, path, 0);
+        __errno_return(rc, int);
+    }
+
+    int rmdir(const char* path)
+    {
+        long rc = syscall(SYS_unlink, path, 1);
+        __errno_return(rc, int);
+    }
 }

libluna/include/luna/Syscall.h

@@ -4,7 +4,7 @@
     _e(exit) _e(clock_gettime) _e(mmap) _e(munmap) _e(usleep) _e(open) _e(close) _e(read) _e(getpid) _e(write)         \
         _e(lseek) _e(mkdir) _e(execve) _e(mknod) _e(fork) _e(waitpid) _e(getppid) _e(fcntl) _e(getdents) _e(getuid)    \
             _e(geteuid) _e(getgid) _e(getegid) _e(setuid) _e(setgid) _e(seteuid) _e(setegid) _e(chmod) _e(chown)       \
-                _e(ioctl) _e(stat) _e(fstat) _e(chdir) _e(getcwd)
+                _e(ioctl) _e(stat) _e(fstat) _e(chdir) _e(getcwd) _e(unlink)
 
 enum Syscalls
 {

libluna/include/luna/Vector.h

@@ -111,13 +111,7 @@ template <typename T> class Vector
     {
         if (m_size == 0) return {};
 
-        T item = move(m_data[0]);
-
-        m_size--;
-
-        memmove(m_data, m_data + 1, m_size * sizeof(T));
-
-        return move(item);
+        return remove_at(0);
     }
 
     const T& operator[](usize index) const
@@ -177,8 +171,41 @@ template <typename T> class Vector
         return m_size;
     }
 
+    T remove_at(usize index)
+    {
+        check(index < m_size);
+
+        T item = move(m_data[index]);
+
+        memmove(m_data + index, m_data + (index + 1), (m_size - (index + 1)) * sizeof(T));
+
+        m_size--;
+
+        return move(item);
+    }
+
+    template <typename Callback> Option<T> remove_first_matching(Callback callback)
+    {
+        Option<usize> index = {};
+
+        for (usize i = 0; i < m_size; i++)
+        {
+            if (callback(m_data[i]))
+            {
+                index = i;
+                break;
+            }
+        }
+
+        if (!index.has_value()) return {};
+
+        return remove_at(index.value());
+    }
+
     void clear()
     {
+        for (usize i = 0; i < m_size; i++) { m_data[i].~T(); }
+
         m_size = m_capacity = 0;
         free_impl(m_data);
         m_data = nullptr;