recv: Don't segfault on invalid chunk values.

If recv->open() fails, para_recv segfaults after

	==10129== Conditional jump or move depends on uninitialised value(s)
	==10129==    at 0x41BA18A: vfprintf (vfprintf.c:1634)
	==10129==    by 0x41BE3D8: buffered_vfprintf (vfprintf.c:2311)
	==10129==    by 0x41B975C: vfprintf (vfprintf.c:1289)
	==10129==    by 0x804C6AF: stderr_log (in /home/maan/scm/paraslash/para_recv)
	==10129==    by 0x804A193: main (recv.c:114)

This happens for example with the afh_receiver if the given start
chunk is bigger than the end chunk, e.g. when para_recv is executed as

	./para_recv -r 'afh -b -80 -e -89 -f foo.opus'

The reason for the bug is we zero-out the stdout structure too late.
Fix this by initializing the stdout task structure upfront rather
than using memset().

This bug was introduced a year ago in commit b01605d7 (Avoid unwanted
log messages during startup) which moved down the call to memset().

diff --git a/recv.c b/recv.c
index 7a5549aaa27fe49f267d5cdcf122e8b244649f34..f28809da6c2b8c5b03f975e940cbe61cbdd4b27c 100644 (file)
--- a/recv.c
+++ b/recv.c
@@ -63,7 +63,7 @@ int main(int argc, char *argv[])
        int ret, r_opened = 0, receiver_num;
        struct receiver *r = NULL;
        struct receiver_node rn;
-       struct stdout_task sot;
+       struct stdout_task sot = {.btrn = NULL};
        static struct sched s;
 
        recv_cmdline_parser(argc, argv, &conf);
@@ -89,7 +89,6 @@ int main(int argc, char *argv[])
                goto out;
        r_opened = 1;
 
-       memset(&sot, 0, sizeof(struct stdout_task));
        sot.btrn = btr_new_node(&(struct btr_node_description)
                EMBRACE(.parent = rn.btrn, .name = "stdout"));
        stdout_set_defaults(&sot);