+/**
+ * Write all data to a file descriptor.
+ *
+ * \param fd The file descriptor.
+ * \param buf The buffer to be sent.
+ * \param len The length of \a buf.
+ *
+ * This is like \ref write_nonblock() but returns \p -E_SHORT_WRITE if not
+ * all data could be written.
+ *
+ * \return Number of bytes written on success, negative error code else.
+ */
+int write_all(int fd, const char *buf, size_t len)
+{
+ int ret = write_nonblock(fd, buf, len);
+
+ if (ret < 0)
+ return ret;
+ if (ret != len)
+ return -E_SHORT_WRITE;
+ return ret;
+}
+
+/**
+ * Write a buffer given by a format string.
+ *
+ * \param fd The file descriptor.
+ * \param fmt A format string.
+ *
+ * \return The return value of the underlying call to \ref write_all().
+ */
+__printf_2_3 int write_va_buffer(int fd, const char *fmt, ...)
+{
+ char *msg;
+ int ret;
+
+ PARA_VSPRINTF(fmt, msg);
+ ret = write_buffer(fd, msg);
+ free(msg);
+ return ret;
+}
+