The return value of strrchr in disk_query_information is not properly tested causing segfaults like these:
GNU gdb 6.8
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(gdb) run -u quux -p z0ran -g 1024x768 -x m -z -a 8 -T GUIS -r disk:floppy=. 10.4.10.20
Starting program: /usr/bin/rdesktop -u quux -p z0ran -g 1024x768 -x m -z -a 8 -T GUIS -r disk:floppy=. 10.4.10.20
Autoselected keyboard map pl
Program received signal SIGSEGV, Segmentation fault.
0x0000000000425673 in disk_query_information (handle=<value optimized out>, info_class=4, out=0x7fff2c7fd2d0) at disk.c:643
643 disk.c: No such file or directory.
#0 0x0000000000425673 in disk_query_information (handle=<value optimized out>, info_class=4, out=0x7fff2c7fd2d0) at disk.c:643
#1 0x0000000000423052 in rdpdr_process_irp (s=0x6b2fc0) at rdpdr.c:570
#2 0x000000000042361f in rdpdr_process (s=0x7d3ef0) at rdpdr.c:799
#3 0x00000000004174ed in sec_recv (rdpver=0x7fff2c7fd41f "\003\030�\177,�\177") at secure.c:828
#4 0x0000000000418bb0 in rdp_recv (type=0x7fff2c7fd47f "") at rdp.c:89
#5 0x0000000000419a35 in rdp_loop (deactivated=0x7fff2c7fd81c, ext_disc_reason=0x7fff2c7fd818) at rdp.c:1411
#6 0x000000000041a4f4 in rdp_main_loop (deactivated=0x7fff2c7fd81c, ext_disc_reason=0x7fff2c7fd818) at rdp.c:1396
#7 0x0000000000407463 in main (argc=<value optimized out>, argv=<value optimized out>) at rdesktop.c:954