weenix

1 files changed, 120 insertions, 6 deletions

diff --git a/kernel/api/syscall.c b/kernel/api/syscall.c
index ed771ac..e077631 100644
--- a/kernel/api/syscall.c
+++ b/kernel/api/syscall.c
@@ -69,8 +69,48 @@ void syscall_init(void) { intr_register(INTR_SYSCALL, syscall_handler); }
  */
 static long sys_read(read_args_t *args)
 {
-    NOT_YET_IMPLEMENTED("VM: sys_read");
-    return -1;
+    // NOT_YET_IMPLEMENTED("VM: sys_read");
+
+    // Initialize a read_args_t struct locally in kernel space and copy from userland args.
+    read_args_t kargs;
+    long ret = copy_from_user(&kargs, args, sizeof(kargs));
+    ERROR_OUT_RET(ret);
+
+    // Allocate a temporary buffer (a page-aligned block of n pages that are enough space to store the number of bytes to read)
+    size_t size_in_pages = (kargs.nbytes + PAGE_SIZE - 1) / PAGE_SIZE;
+    void *addr = (void *)page_alloc_n(size_in_pages);
+    if (!addr)
+    {
+        ERROR_OUT_RET(-ENOMEM);
+    }
+
+    // Call do_read() with the buffer and then copy the buffer to the userland args after the system call
+    ret = do_read(kargs.fd, addr, kargs.nbytes);
+    // if ret < 0, free the temporary buffer and return -1
+    if (ret < 0)
+    {
+        page_free_n(addr, size_in_pages);
+        ERROR_OUT_RET(ret);
+    }
+    // if read nothing, free the temporary buffer and return 0
+    if (ret == 0)
+    {
+        page_free_n(addr, size_in_pages);
+        return 0;
+    }
+
+    // copy the buffer to the userland args after the system call
+    ret = copy_to_user(kargs.buf, addr, ret);
+    // if ret < 0, free the temporary buffer and return -1
+    if (ret < 0)
+    {
+        page_free_n(addr, size_in_pages);
+        ERROR_OUT_RET(ret);
+    }
+
+    // Make sure to free the temporary buffer allocated
+    page_free_n(addr, size_in_pages);
+    return ret;
 }
 
 /*
@@ -84,8 +124,42 @@ static long sys_read(read_args_t *args)
  */
 static long sys_write(write_args_t *args)
 {
-    NOT_YET_IMPLEMENTED("VM: sys_write");
-    return -1;
+    // NOT_YET_IMPLEMENTED("VM: sys_write");
+
+    // Initialize a write_args_t struct locally in kernel space and copy from userland args.
+    write_args_t kargs;
+    long ret = copy_from_user(&kargs, args, sizeof(kargs));
+    ERROR_OUT_RET(ret);
+
+    // Allocate a temporary buffer (a page-aligned block of n pages that are enough space to store the number of bytes to write)
+    size_t size_in_pages = (kargs.nbytes + PAGE_SIZE - 1) / PAGE_SIZE;
+    void *addr = (void *)page_alloc_n(size_in_pages);
+    if (!addr)
+    {
+        ERROR_OUT_RET(-ENOMEM);
+    }
+
+    // Copy the buffer from the userland args to the temporary buffer
+    ret = copy_from_user(addr, kargs.buf, kargs.nbytes);
+    // if ret < 0, free the temporary buffer and return -1
+    if (ret < 0)
+    {
+        page_free_n(addr, size_in_pages);
+        ERROR_OUT_RET(ret);
+    }
+
+    // Call do_write() with the buffer and then copy the buffer to the userland args after the system call
+    ret = do_write(kargs.fd, addr, kargs.nbytes);
+    // if ret < 0, free the temporary buffer and return -1
+    if (ret < 0)
+    {
+        page_free_n(addr, size_in_pages);
+        ERROR_OUT_RET(ret);
+    }
+
+    // Make sure to free the temporary buffer allocated
+    page_free_n(addr, size_in_pages);
+    return ret;
 }
 
 /*
@@ -100,8 +174,48 @@ static long sys_write(write_args_t *args)
  */
 static long sys_getdents(getdents_args_t *args)
 {
-    NOT_YET_IMPLEMENTED("VM: sys_getdents");
-    return -1;
+    // NOT_YET_IMPLEMENTED("VM: sys_getdents");
+
+    // Copy the arguments from user memory
+    getdents_args_t kargs;
+    long ret = copy_from_user(&kargs, args, sizeof(kargs));
+    ERROR_OUT_RET(ret);
+
+    // Check that the count field is at least the size of a dirent_t
+    if (kargs.count < sizeof(dirent_t))
+    {
+        ERROR_OUT_RET(-EINVAL);
+    }
+
+    size_t count_read = 0;
+    
+    // iterate over the directory entries
+    while (count_read * sizeof(dirent_t) <= kargs.count)
+    {
+        // read count / sizeof(dirent_t) directory entries into the provided dirp and call do_getdent
+        dirent_t d;
+        ret = do_getdent(kargs.fd, &d);
+        ERROR_OUT_RET(ret); // error check
+
+        // if read nothing, break
+        if (ret == 0)
+        {
+            break;
+        }
+        // if you read a different size than dirent_t, break
+        if (ret != sizeof(dirent_t))
+        {
+            break;
+        }
+
+        // copy the dirent_t to the userland args after the system call
+        ret = copy_to_user(kargs.dirp + count_read, &d, sizeof(dirent_t));
+        ERROR_OUT_RET(ret); // error check
+
+        count_read++;
+    }
+
+    return count_read * sizeof(dirent_t);
 }
 
 #ifdef __MOUNTING__