Comment 2 for bug 271020

Using an extremely long -cmd leads to stack protector being tripped. The ExecString and TempName should probably be dynamically allocated based on the strlen of the command.

---

*** stack smashing detected ***: jhead terminated
======= Backtrace: =========
/lib/tls/i686/cmov/libc.so.6(__fortify_fail+0x48)[0xb7ee5138]
/lib/tls/i686/cmov/libc.so.6(__fortify_fail+0x0)[0xb7ee50f0]
jhead[0x804944a]
[0x20202020]
======= Memory map: ========
08048000-08056000 r-xp 00000000 fe:00 33760719 /usr/bin/jhead
08056000-08057000 rw-p 0000e000 fe:00 33760719 /usr/bin/jhead
08057000-08079000 rw-p 08057000 00:00 0 [heap]
b7df7000-b7df8000 rw-p b7df7000 00:00 0
b7df8000-b7f41000 r-xp 00000000 fe:00 51342253 /lib/tls/i686/cmov/libc-2.7.so
b7f41000-b7f42000 r--p 00149000 fe:00 51342253 /lib/tls/i686/cmov/libc-2.7.so
b7f42000-b7f44000 rw-p 0014a000 fe:00 51342253 /lib/tls/i686/cmov/libc-2.7.so
b7f44000-b7f47000 rw-p b7f44000 00:00 0
b7f47000-b7f6a000 r-xp 00000000 fe:00 51342261 /lib/tls/i686/cmov/libm-2.7.so
b7f6a000-b7f6c000 rw-p 00023000 fe:00 51342261 /lib/tls/i686/cmov/libm-2.7.so
b7f87000-b7f91000 r-xp 00000000 fe:00 125830164 /lib/libgcc_s.so.1
b7f91000-b7f92000 rw-p 0000a000 fe:00 125830164 /lib/libgcc_s.so.1
b7f92000-b7f95000 rw-p b7f92000 00:00 0
b7f95000-b7f96000 r-xp b7f95000 00:00 0 [vdso]
b7f96000-b7fb0000 r-xp 00000000 fe:00 125830168 /lib/ld-2.7.so
b7fb0000-b7fb2000 rw-p 00019000 fe:00 125830168 /lib/ld-2.7.so
bfa5d000-bfa72000 rw-p bffeb000 00:00 0 [stack]