From f441d633b266a4416dfb1dae24fca4576be073b4 Mon Sep 17 00:00:00 2001
From: Max Wash <mbswash@gmail.com>
Date: Sun, 15 Mar 2026 09:41:25 +0000
Subject: [PATCH] lib: c: implement mmap()

---
 lib/libc/io/unistd/mmap.c | 142 +++++++++++++++++++++++++++++++++++++-
 1 file changed, 141 insertions(+), 1 deletion(-)

diff --git a/lib/libc/io/unistd/mmap.c b/lib/libc/io/unistd/mmap.c
index e75fb6b..03e4d67 100644
--- a/lib/libc/io/unistd/mmap.c
+++ b/lib/libc/io/unistd/mmap.c
@@ -1,6 +1,146 @@
+#include <errno.h>
+#include <mango/handle.h>
+#include <mango/task.h>
+#include <mango/vm.h>
+#include <rosetta/fs.h>
+#include <stdbool.h>
 #include <sys/mman.h>
 
+static vm_prot_t vm_prot_from_mmap_prot(int prot)
+{
+	vm_prot_t vm_prot = VM_PROT_USER;
+
+	if (prot & PROT_READ) {
+		vm_prot |= VM_PROT_READ;
+	}
+
+	if (prot & PROT_WRITE) {
+		vm_prot |= VM_PROT_WRITE;
+	}
+
+	if (prot & PROT_EXEC) {
+		vm_prot |= VM_PROT_EXEC;
+	}
+
+	return vm_prot;
+}
+
+static int get_vmo_anon(
+	int fd,
+	int prot,
+	int flags,
+	size_t length,
+	kern_handle_t *out)
+{
+	vm_prot_t vm_prot = vm_prot_from_mmap_prot(prot);
+	kern_status_t status = vm_object_create(NULL, 0, length, vm_prot, out);
+	return __errno_from_kern_status(status);
+}
+
+static int get_vmo(
+	int fd,
+	int prot,
+	int flags,
+	size_t length,
+	kern_handle_t *out)
+{
+	if (fd == -1) {
+		return get_vmo_anon(fd, prot, flags, length, out);
+	}
+
+	int err = 0;
+	kern_status_t status = fs_map(fd, prot, flags, &err, out);
+	if (status != KERN_OK) {
+		return __errno_from_kern_status(status);
+	}
+
+	return err;
+}
+
 void *mmap(void *addr, size_t length, int prot, int flags, int fd, off_t offset)
 {
-	return NULL;
+	int tmp = 0;
+
+	if (flags & MAP_SHARED) {
+		tmp++;
+	}
+
+	if (flags & MAP_SHARED_VALIDATE) {
+		tmp++;
+	}
+
+	if (flags & MAP_PRIVATE) {
+		tmp++;
+	}
+
+	if (tmp != 1) {
+		__set_errno(EINVAL);
+		return MAP_FAILED;
+	}
+
+	if ((flags & MAP_ANONYMOUS) && fd != -1) {
+		__set_errno(EINVAL);
+		return MAP_FAILED;
+	}
+
+	if (!(flags & MAP_ANONYMOUS) && fd == -1) {
+		__set_errno(EINVAL);
+		return MAP_FAILED;
+	}
+
+	kern_status_t status = KERN_OK;
+	kern_handle_t self = KERN_HANDLE_INVALID,
+		      address_space = KERN_HANDLE_INVALID;
+
+	status = task_self(&self);
+	if (status != KERN_OK) {
+		__set_errno(__errno_from_kern_status(status));
+		return MAP_FAILED;
+	}
+
+	status = task_get_address_space(self, &address_space);
+	kern_handle_close(self);
+	if (status != KERN_OK) {
+		__set_errno(__errno_from_kern_status(status));
+		return MAP_FAILED;
+	}
+
+	kern_handle_t vmo = KERN_HANDLE_INVALID;
+	int err = get_vmo(fd, prot, flags, length, &vmo);
+	if (err != SUCCESS) {
+		kern_handle_close(address_space);
+		__set_errno(err);
+		return MAP_FAILED;
+	}
+
+	virt_addr_t map_address = 0;
+	vm_prot_t vm_prot = vm_prot_from_mmap_prot(prot);
+	if (addr && (flags & MAP_FIXED)) {
+		status = address_space_map(
+			address_space,
+			(virt_addr_t)addr,
+			vmo,
+			offset,
+			length,
+			vm_prot,
+			&map_address);
+	} else {
+		status = address_space_map(
+			address_space,
+			MAP_ADDRESS_ANY,
+			vmo,
+			offset,
+			length,
+			vm_prot,
+			&map_address);
+	}
+
+	kern_handle_close(vmo);
+	kern_handle_close(address_space);
+	if (status != KERN_OK) {
+		__set_errno(__errno_from_kern_status(status));
+		return MAP_FAILED;
+	}
+
+	return (void *)map_address;
 }