r0 = openat(0xffffffffffffff9c, &(0x7f0000000100)='./file1\x00', 0x42, 0x0)
pwrite64(r0, &(0x7f0000000140)=' ', 0x1, 0x0)
r1 = openat$tcp_mem(0xffffffffffffff9c, &(0x7f00000000c0)='/proc/sys/net/ipv4/tcp_rmem\x00', 0x1, 0x0)
sendfile(r1, r0, 0x0, 0x3ff)