If we filled the script->child buffer before the child had a chance to read any
input, we'd sleep forever in write_all(pty->master), and the child would sleep
forever in write(1<pty->slave>)
By putting the master PTY in non-blocking mode, we can poll(pty->master,
POLLOUT) and keep supplying more data as the child reads from the buffer
Fixes Debian bug #1003095
Signed-off-by: Karel Zak <kzak@redhat.com>
Kernel 5.15 returns empty content for topology/thread_siblings on
aarch64 platform, which in conjunction of uninitialized `buf` memory
buffer results in the garbage:
(gdb) p buf
$14 = " @\377\367\177\000\000\000\275\000\347j\032\236"
This garbage is then being later consumed by underlying helper functions
like for example cpumask_parse() and this leads to the following crash
later:
in __libc_free (p=0x7ff7f67c00) at src/malloc/mallocng/free.c:105
in free (p=<optimized out>) at src/malloc/free.c:5
in add_cpuset_to_array (setsize=<optimized out>, set=<optimized out>, items=<optimized out>, ary=<optimized out>) at ../sys-utils/lscpu-topology.c:29
in cputype_read_topology (cxt=cxt@entry=0x7ff7fffe70, ct=0x4298a0) at ../sys-utils/lscpu-topology.c:153
in lscpu_read_topology (cxt=cxt@entry=0x7ff7fffe70) at ../sys-utils/lscpu-topology.c:629
in main (argc=1, argv=0x7ffffffdb8) at ../sys-utils/lscpu.c:1341
It looks like the problem is that current logic expects fgets() to set
errno on failure, but fgets() is not documented to do so and and neither
glibc nor musl set errno. So if errno was set to 0 before fgets() call,
the failure from fgets() is ignored and then invalid buffer is being
parsed.
Fixes: #1810
Suggested-by: Thomas Weißschuh <thomas@t-8ch.de>
Signed-off-by: Petr Štetiar <ynezz@true.cz>
Karel Zak