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Fix seeking on binary input ports with putback buffers.

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Fixes <http://bugs.gnu.org/20302>.
Reported by David Kastrup <dak@gnu.org>.

* libguile/r6rs-ports.c (bip_end_input): New static function.
  (initialize_bytevector_input_ports): Register it.
  (bip_seek): Rewrite to handle putback buffers, based on st_seek from
  strports.c.
This commit is contained in:
Mark H Weaver 2015-09-06 07:35:58 -04:00
parent e1788828df
commit 448eb30e3d
1 changed files with 55 additions and 30 deletions
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71
libguile/r6rs-ports.c
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@ -125,45 +125,69 @@ bip_fill_input (SCM port)
return result;
}
static void
bip_end_input (SCM port, int offset)
{
scm_t_port *c_port = SCM_PTAB_ENTRY (port);
if (c_port->read_pos - c_port->read_buf < offset)
scm_misc_error ("bip_end_input", "negative position", SCM_EOL);
c_port->read_pos -= offset;
}
static scm_t_off
bip_seek (SCM port, scm_t_off offset, int whence)
#define FUNC_NAME "bip_seek"
{
scm_t_off c_result = 0;
scm_t_port *c_port = SCM_PTAB_ENTRY (port);
scm_t_off target;
if (offset == 0 && whence == SEEK_CUR)
/* special case to avoid disturbing the putback buffer. */
{
if (c_port->read_buf == c_port->putback_buf)
target = c_port->saved_read_pos - c_port->saved_read_buf
- (c_port->read_end - c_port->read_pos);
else
target = c_port->read_pos - c_port->read_buf;
}
else
{
scm_t_off base = 0;
/* If the putback buffer is currently active, this will dump its
contents, switch back to the main read buffer, and move
read_pos backwards as needed to account for the bytes that were
put back. */
if (c_port->read_buf == c_port->putback_buf)
scm_end_input (port);
switch (whence)
{
case SEEK_CUR:
offset += c_port->read_pos - c_port->read_buf;
/* Fall through. */
case SEEK_SET:
if (c_port->read_buf + offset <= c_port->read_end)
{
c_port->read_pos = c_port->read_buf + offset;
c_result = offset;
}
else
scm_out_of_range (FUNC_NAME, scm_from_int (offset));
base = c_port->read_pos - c_port->read_buf;
break;
case SEEK_END:
if (c_port->read_end - offset >= c_port->read_buf)
{
c_port->read_pos = c_port->read_end - offset;
c_result = c_port->read_pos - c_port->read_buf;
}
else
scm_out_of_range (FUNC_NAME, scm_from_int (offset));
base = c_port->read_end - c_port->read_buf;
break;
case SEEK_SET:
base = 0;
break;
default:
scm_wrong_type_arg_msg (FUNC_NAME, 0, port,
"invalid `seek' parameter");
"invalid `whence' argument");
}
return c_result;
if (offset > SCM_T_OFF_MAX - base) /* Overflow check */
scm_out_of_range (FUNC_NAME, scm_from_int (offset));
target = base + offset;
if (target < 0 || target > c_port->read_end - c_port->read_buf)
scm_out_of_range (FUNC_NAME, scm_from_int (offset));
c_port->read_pos = c_port->read_buf + target;
}
return target;
}
#undef FUNC_NAME
@ -176,6 +200,7 @@ initialize_bytevector_input_ports (void)
scm_make_port_type ("r6rs-bytevector-input-port", bip_fill_input,
NULL);
scm_set_port_end_input (bytevector_input_port_type, bip_end_input);
scm_set_port_seek (bytevector_input_port_type, bip_seek);
}