[Xen-devel] pre_parse and strcmp

[Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>]

Hey Jan,

I've been digging a bit in the Xen code to figure out how to use the xen.cfg
file as it seemed not to work at all for me.

I finally narrowed it down to the fact that the file, while looking OK:

[root@localhost fedora]# more XEN.CFG 

[global]
default=linux

[linux]
options="console=vga,com1 com1=115200,8n1,pci,0 loglvl=all noreboot 
guest_loglvl=all iommu=verbose,no-intremap,debug"

kernel=vmlinuz-3.17.0-rc7+ root=/dev/mapper/fedora-root console=hvc0

ramdisk=initramfs-3.17.0-rc7+.img

Was typed up by me on the EFI shell instead of written from Linux.

Which means:
[root@localhost fedora]# file *.cfg
grub.cfg: ASCII text
xen.cfg:  Little-endian UTF-16 Unicode text, with CRLF, CR line terminators

Ends up looking at so (this is right before pre_parse, with a function that 
prints
each character and then if it sees an control it prints _):


[[_g_l_o_b_a_l_]_____d_e_f_a_u_l_t_=_l_i_n_u_x_________[_l_i_n_u_x_]_____o_p_t_i_o_n_s_=_"_c_o_n_s_o_l_e_=_v_g_a_,_c_o_m_1_
 _c_o_m_1_=_1_1_5_2_0_0_,_8_n_1_,_p_c_i_,_0_ _l_o_g_l_v_l_=_a_l_l_ 
_n_o_r_e_b_o_o_t_ _g_u_e_s_t___l_o_g_l_v_l_=_a_l_l_ 
_i_o_m_m_u_=_v_e_r_b_o_s_e_,_n_o_-_i_n_t_r_e_m_a_p_,_d_e_b_u_g_"_____k_e_r_n_e_l_=_v_m_l_i_n_u_z_-_3_._1_7_._0_-_r_c_7_+_
 _r_o_o_t_=_/_d_e_v_/_m_a_p_p_e_r_/_f_e_d_o_r_a_-_r_o_o_t_ 
_c_o_n_s_o_l_e_=_h_v_c_0_____r_a_m_d_i_s_k_=_i_n_i_t_r_a_m_f_s_-_3_._1_7_._0_-_r_c_7_+_._i_m_g_____________


Which pre_parse deals with - it replaces all of those pesky control ones to \0.

That means the 'get_value' is asked to find the 'default' in global, and
while it finds '[' it uses 'strncmp' to see if the 'default' is there.
The value that is there is 'd_e_f_a_u_l_t' (_ replaces the \0
character) which of course does not match with 'default'.



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