feat(kernel): implemented shared memory resource with a POSIX compatible api

kernel/arch/aarch64/syscall/linux_syscalls.h

@@ -5,15 +5,15 @@
 
 namespace syscall::linux_nr {
 
+constexpr uint64_t FCNTL            = 25;
+constexpr uint64_t IOCTL            = 29;
+constexpr uint64_t UNLINKAT         = 35;
+constexpr uint64_t FTRUNCATE        = 46;
+constexpr uint64_t OPENAT           = 56;
+constexpr uint64_t CLOSE            = 57;
 constexpr uint64_t READ             = 63;
 constexpr uint64_t WRITE            = 64;
-constexpr uint64_t CLOSE            = 57;
-constexpr uint64_t IOCTL            = 29;
 constexpr uint64_t WRITEV           = 66;
-constexpr uint64_t OPENAT           = 56;
-constexpr uint64_t MUNMAP           = 215;
-constexpr uint64_t MMAP             = 222;
-constexpr uint64_t MPROTECT         = 226;
 constexpr uint64_t EXIT             = 93;
 constexpr uint64_t EXIT_GROUP       = 94;
 constexpr uint64_t SET_TID_ADDRESS  = 96;
@@ -23,7 +23,10 @@ constexpr uint64_t BIND             = 200;
 constexpr uint64_t LISTEN           = 201;
 constexpr uint64_t ACCEPT           = 202;
 constexpr uint64_t CONNECT          = 203;
-constexpr uint64_t FCNTL            = 25;
+constexpr uint64_t MUNMAP           = 215;
+constexpr uint64_t MMAP             = 222;
+constexpr uint64_t MPROTECT         = 226;
+constexpr uint64_t MEMFD_CREATE     = 279;
 
 } // namespace syscall::linux_nr
 

kernel/arch/x86_64/syscall/linux_syscalls.h

@@ -9,23 +9,26 @@ constexpr uint64_t READ             = 0;
 constexpr uint64_t WRITE            = 1;
 constexpr uint64_t OPEN             = 2;
 constexpr uint64_t CLOSE            = 3;
-constexpr uint64_t IOCTL            = 16;
-constexpr uint64_t WRITEV           = 20;
 constexpr uint64_t MMAP             = 9;
 constexpr uint64_t MPROTECT         = 10;
 constexpr uint64_t MUNMAP           = 11;
-constexpr uint64_t OPENAT           = 257;
-constexpr uint64_t EXIT             = 60;
-constexpr uint64_t ARCH_PRCTL       = 158;
-constexpr uint64_t SET_TID_ADDRESS  = 218;
-constexpr uint64_t EXIT_GROUP       = 231;
+constexpr uint64_t IOCTL            = 16;
+constexpr uint64_t WRITEV           = 20;
 constexpr uint64_t SOCKET           = 41;
 constexpr uint64_t CONNECT          = 42;
 constexpr uint64_t ACCEPT           = 43;
 constexpr uint64_t BIND             = 49;
 constexpr uint64_t LISTEN           = 50;
 constexpr uint64_t SOCKETPAIR       = 53;
+constexpr uint64_t EXIT             = 60;
 constexpr uint64_t FCNTL            = 72;
+constexpr uint64_t FTRUNCATE        = 77;
+constexpr uint64_t ARCH_PRCTL       = 158;
+constexpr uint64_t SET_TID_ADDRESS  = 218;
+constexpr uint64_t EXIT_GROUP       = 231;
+constexpr uint64_t OPENAT           = 257;
+constexpr uint64_t UNLINKAT         = 263;
+constexpr uint64_t MEMFD_CREATE     = 319;
 
 } // namespace syscall::linux_nr
 

kernel/fs/fs.cpp

@@ -61,6 +61,7 @@ int32_t node::open(file*, uint32_t)                 { return OK; }
 int32_t node::on_close(file*)                       { return OK; }
 int32_t node::readlink(char*, size_t, size_t*)      { return ERR_NOSYS; }
 int32_t node::create_socket(const char*, size_t, void*, node**) { return ERR_NOSYS; }
+int32_t node::truncate(size_t)                      { return ERR_NOSYS; }
 
 int32_t node::getattr(vattr* attr) {
     if (!attr) return ERR_INVAL;

kernel/fs/fstypes.h

@@ -22,6 +22,7 @@ constexpr uint32_t O_RDONLY = 0;
 constexpr uint32_t O_WRONLY = 1;
 constexpr uint32_t O_RDWR   = 2;
 constexpr uint32_t O_CREAT  = 0x40;
+constexpr uint32_t O_EXCL   = 0x80;
 constexpr uint32_t O_TRUNC  = 0x200;
 constexpr uint32_t O_APPEND   = 0x400;
 constexpr uint32_t O_NONBLOCK = 0x800;

kernel/fs/node.h

@@ -47,6 +47,7 @@ class node : public rc::ref_counted<node> {
 
     // --- Metadata ---
     virtual int32_t getattr(vattr* attr);
+    virtual int32_t truncate(size_t size);
 
     // --- Symlink ---
     virtual int32_t readlink(char* buf, size_t size, size_t* out_len);

kernel/fs/ramfs/ramfs.cpp

@@ -481,4 +481,55 @@ int32_t file_node::getattr(fs::vattr* attr) {
     return fs::OK;
 }
 
+int32_t file_node::truncate(size_t size) {
+    size_t max_alignable = ~(pmm::PAGE_SIZE - 1);
+    if (size > max_alignable) {
+        return fs::ERR_INVAL;
+    }
+
+    sync::irq_lock_guard guard(m_lock);
+
+    uint32_t needed = static_cast<uint32_t>(
+        pmm::page_align_up(size) / pmm::PAGE_SIZE);
+
+    if (needed > m_page_count) {
+        int32_t rc = ensure_capacity(needed);
+        if (rc != fs::OK) {
+            return rc;
+        }
+
+        for (uint32_t i = m_page_count; i < needed; i++) {
+            pmm::phys_addr_t phys = pmm::alloc_page();
+            if (phys == 0) {
+                m_size = static_cast<size_t>(i) * pmm::PAGE_SIZE;
+                m_page_count = i;
+                return fs::ERR_NOMEM;
+            }
+            m_pages[i] = static_cast<uint8_t*>(paging::phys_to_virt(phys));
+            string::memset(m_pages[i], 0, pmm::PAGE_SIZE);
+        }
+        m_page_count = needed;
+    } else if (needed < m_page_count) {
+        for (uint32_t i = needed; i < m_page_count; i++) {
+            if (m_pages[i]) {
+                pmm::phys_addr_t phys =
+                    reinterpret_cast<uintptr_t>(m_pages[i]) - g_boot_info.hhdm_offset;
+                pmm::free_page(phys);
+                m_pages[i] = nullptr;
+            }
+        }
+        m_page_count = needed;
+    }
+
+    if (size < m_size && needed > 0) {
+        size_t tail_off = size % pmm::PAGE_SIZE;
+        if (tail_off != 0 && m_pages[needed - 1]) {
+            string::memset(m_pages[needed - 1] + tail_off, 0, pmm::PAGE_SIZE - tail_off);
+        }
+    }
+
+    m_size = size;
+    return fs::OK;
+}
+
 } // namespace ramfs

kernel/fs/ramfs/ramfs.h

@@ -45,6 +45,7 @@ class file_node : public fs::node {
     ssize_t write(fs::file* f, const void* buf, size_t count) override;
     int64_t seek(fs::file* f, int64_t offset, int whence) override;
     int32_t getattr(fs::vattr* attr) override;
+    int32_t truncate(size_t size) override;
 
 private:
     int32_t ensure_capacity(uint32_t needed_pages);