hi,
the parameter validation for the optional "start" and "end" arguments to
"recvfrom!" are off by one if "end" is passed. From libguile/socket.c
(master commit 64c89458e6):
...
if (SCM_UNBNDP (end))
cend = SCM_BYTEVECTOR_LENGTH (buf);
else
{
cend = scm_to_size_t (end);
if (SCM_UNLIKELY (cend >= SCM_BYTEVECTOR_LENGTH (buf)
|| cend < offset))
scm_out_of_range (FUNC_NAME, end);
}
...
"end" is the optional end argument, "offset" is 0 or "start" if start
was given. The check must be:
cend > SCM_BYTEVECTOR_LENGTH (buf) || cend <= offset
to allow filling the last byte in the buffer and verify that start is
not equal to end. A workaround to skip the validation is to not pass
end. But i think a better way would be to always validate start (and
end), if one (or both) of them are passed. A potentional fix is
attached.
If you need any additional information, please let me know.
Thank you for your great work!
- d4ryus
diff --git a/libguile/socket.c b/libguile/socket.c
index 64354f1f1..d6e676744 100644
--- a/libguile/socket.c
+++ b/libguile/socket.c
@@ -1480,21 +1480,24 @@ SCM_DEFINE (scm_recvfrom, "recvfrom!", 2, 3, 0,
SCM_VALIDATE_BYTEVECTOR (1, buf);
- if (SCM_UNBNDP (start))
- offset = 0;
- else
- offset = scm_to_size_t (start);
-
if (SCM_UNBNDP (end))
cend = SCM_BYTEVECTOR_LENGTH (buf);
else
{
cend = scm_to_size_t (end);
- if (SCM_UNLIKELY (cend >= SCM_BYTEVECTOR_LENGTH (buf)
- || cend < offset))
+ if (SCM_UNLIKELY (cend > SCM_BYTEVECTOR_LENGTH (buf)))
scm_out_of_range (FUNC_NAME, end);
}
+ if (SCM_UNBNDP (start))
+ offset = 0;
+ else
+ {
+ offset = scm_to_size_t (start);
+ if (SCM_UNLIKELY (cend <= offset))
+ scm_out_of_range (FUNC_NAME, start);
+ }
+
SCM_SYSCALL (rv = recvfrom (fd,
SCM_BYTEVECTOR_CONTENTS (buf) + offset,
cend - offset, flg,
