Function sys_write

components/lwp/lwp_syscall.c:494–533

* @brief Writes data from a buffer to a file descriptor. * * This system call writes up to `nbyte` bytes of data from the buffer pointed * to by `buf` to the file descriptor specified by `fd`. * * @param fd The file descriptor to write to. This should be a valid file * descriptor obtained through system calls like `open()` or `socket()`. * @param buf A pointer to the buffer contai

 * @see sys_read(), write()
 */
ssize_t sys_write(int fd, const void *buf, size_t nbyte)
{
#ifdef ARCH_MM_MMU
    void *kmem = RT_NULL;
    ssize_t ret = -1;

    if (nbyte)
    {
        if (!lwp_user_accessable((void *)buf, nbyte))
        {
            return -EFAULT;
        }

        kmem = kmem_get(nbyte);
        if (!kmem)
        {
            return -ENOMEM;
        }

        lwp_get_from_user(kmem, (void *)buf, nbyte);
    }

    ret = write(fd, kmem, nbyte);
    if (ret < 0)
    {
        ret = GET_ERRNO();
    }

    kmem_put(kmem);

    return ret;
#else
    if (!lwp_user_accessable((void *)buf, nbyte))
    {
        return -EFAULT;
    }
    ssize_t ret = write(fd, buf, nbyte);
    return (ret < 0 ? GET_ERRNO() : ret);
#endif
}

/**
 * @brief Repositions the file offset of the open file descriptor.