wut/libraries/wutdevoptab/devoptab_fs_write.c

#include "devoptab_fs.h"

ssize_t
__wut_fs_write(struct _reent *r,
               void *fd,
               const char *ptr,
               size_t len)
{
   FSStatus status = 0;
   FSCmdBlock cmd;
   uint8_t *alignedWriteBuffer;
   uint32_t bytes, bytesWritten;
   __wut_fs_file_t *file;

   if (!fd || !ptr) {
      r->_errno = EINVAL;
      return -1;
   }

   FSInitCmdBlock(&cmd);
   file = (__wut_fs_file_t *)fd;
   bytesWritten = 0;

   // Check that the file was opened with write access
   if ((file->flags & O_ACCMODE) == O_RDONLY) {
      r->_errno = EBADF;
      return -1;
   }

   // Copy to internal buffer due to alignment requirement and write in chunks.
   alignedWriteBuffer = memalign(0x40, 8192);
   while (len > 0) {
      size_t toWrite = len > 8192 ? 8192 : len;

      // Copy to internal buffer
      memcpy(alignedWriteBuffer, ptr, toWrite);

      // Write the data
      status = FSWriteFile(__wut_devoptab_fs_client, &cmd, alignedWriteBuffer,
                           1, toWrite, file->fd, 0, -1);
      if (status <= 0) {
         break;
      }

      bytes = (uint32_t)status;
      file->offset += bytes;
      bytesWritten += bytes;
      ptr          += bytes;
      len          -= bytes;

      if (bytes < toWrite) {
         break;
      }
   }
   free(alignedWriteBuffer);

   // Return partial write
   if (bytesWritten > 0) {
      return bytesWritten;
   }

   if (status < 0) {
      r->_errno = __wut_fs_translate_error(status);
      return -1;
   }

   return 0;
}