+ {
+ scm_remember_upto_here_1 (str);
+ return SCM_BOOL_F;
+ }
+ }
+
+ scm_remember_upto_here_1 (str);
+ return scm_from_long (chars_read);
+}
+#undef FUNC_NAME
+
+SCM_DEFINE (scm_write_string_partial, "write-string/partial", 1, 3, 0,
+ (SCM str, SCM port_or_fdes, SCM start, SCM end),
+ "Write characters from a string @var{str} to a port or file\n"
+ "descriptor. A port must have an underlying file descriptor\n"
+ "--- a so-called fport. This procedure is\n"
+ "scsh-compatible and can efficiently write large strings.\n"
+ "It will:\n\n"
+ "@itemize\n"
+ "@item\n"
+ "attempt to write the entire string, unless the @var{start}\n"
+ "and/or @var{end} arguments are supplied. i.e., @var{start}\n"
+ "defaults to 0 and @var{end} defaults to\n"
+ "@code{(string-length str)}\n"
+ "@item\n"
+ "use the current output port if @var{port_of_fdes} is not\n"
+ "supplied.\n"
+ "@item\n"
+ "in the case of a buffered port, store the characters in the\n"
+ "port's output buffer, if all will fit. If they will not fit\n"
+ "then any existing buffered characters will be flushed\n"
+ "before attempting\n"
+ "to write the new characters directly to the underlying file\n"
+ "descriptor. If the port is in non-blocking mode and\n"
+ "buffered characters can not be flushed immediately, then an\n"
+ "@code{EAGAIN} system-error exception will be raised (Note:\n"
+ "scsh does not support the use of non-blocking buffered ports.)\n"
+ "@item\n"
+ "write fewer than the requested number of\n"
+ "characters in some cases, e.g., if interrupted by a signal or\n"
+ "if not all of the output can be accepted immediately.\n"
+ "@item\n"
+ "wait indefinitely for at least one character\n"
+ "from @var{str} to be accepted by the port, unless the port is\n"
+ "in non-blocking mode.\n"
+ "@item\n"
+ "return the number of characters accepted by the port.\n"
+ "@item\n"
+ "return 0 if the port is in non-blocking mode and can not accept\n"
+ "at least one character from @var{str} immediately\n"
+ "@item\n"
+ "return 0 immediately if the request size is 0 bytes.\n"
+ "@end itemize")
+#define FUNC_NAME s_scm_write_string_partial
+{
+ const char *src;
+ long write_len;
+ int fdes;
+
+ {
+ size_t offset;
+ size_t last;
+
+ SCM_VALIDATE_STRING (1, str);
+ src = scm_i_string_chars (str);
+ scm_i_get_substring_spec (scm_i_string_length (str),
+ start, &offset, end, &last);
+ src += offset;
+ write_len = last - offset;
+ }
+
+ if (write_len == 0)
+ return SCM_INUM0;
+
+ if (scm_is_integer (port_or_fdes))
+ fdes = scm_to_int (port_or_fdes);
+ else
+ {
+ SCM port = SCM_UNBNDP (port_or_fdes) ? scm_cur_outp : port_or_fdes;
+ scm_t_port *pt;
+ off_t space;
+
+ SCM_VALIDATE_OPFPORT (2, port);
+ SCM_VALIDATE_OUTPUT_PORT (2, port);
+ pt = SCM_PTAB_ENTRY (port);
+ /* filling the last character in the buffer would require a flush. */
+ space = pt->write_end - pt->write_pos - 1;
+ if (space >= write_len)
+ {
+ memcpy (pt->write_pos, src, write_len);
+ pt->write_pos += write_len;
+ return scm_from_long (write_len);
+ }
+ if (pt->write_pos > pt->write_buf)
+ scm_flush (port);
+ fdes = SCM_FPORT_FDES (port);