support GBK codepage

[zhanleewo]

The code page CP936 or MS936 has another alias name GBK.

[joachimmetz]

@zhanleewo thanks for the changes

However there appears some debate if GBK is the same as CP936
https://en.wikipedia.org/wiki/GBK_(character_encoding)

I'll have a more detailed look. In which context do you want to translate "gbk" to "cp936"?

[codecov]

Codecov Report

Merging #5 into master will decrease coverage by 0.77%.
The diff coverage is 0%.

@@            Coverage Diff             @@
##           master       #5      +/-   ##
==========================================
- Coverage   96.56%   95.79%   -0.78%     
==========================================
  Files           3        3              
  Lines         495      499       +4     
==========================================
  Hits          478      478              
- Misses         17       21       +4

Impacted Files	Coverage Δ
libclocale/libclocale_codepage.c	98.91% <0%> (-1.09%)	⬇️

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[zhanleewo]

yes.
In China. I use vmware creating a vm, and I use your libvmdk to parse the vmdk file i created. there is a failure show that the encoding is GBK.

So I think the libclocal should support this code page.

[joachimmetz]

Maybe in that case putting this check in libvmdk might be safer, seeing the different interpretations of gbk. Also see: libyal/libvmdk#10

Do you know which tool created the VMDK?

[zhanleewo]

vmware workstation for windows. chinese edition.

[zhanleewo]

U did may great things. if u need any adtional information to address this issue.I can do my best to help u fixed this issue.

[joachimmetz]

assuming gbk equals cp936 for vmware workstation for windows, chinese edition

Pending changes for libvmdk

diff --git a/libvmdk/libvmdk_descriptor_file.c b/libvmdk/libvmdk_descriptor_file.c
index 8a27e7b..d18cab5 100644
--- a/libvmdk/libvmdk_descriptor_file.c
+++ b/libvmdk/libvmdk_descriptor_file.c
@@ -966,12 +966,19 @@ int libvmdk_descriptor_file_read_header(
                                         value );
                                }
 #endif
-                               if( ( value_length == 5 )
-                                && ( value[ 0 ] == 'U' )
-                                && ( value[ 1 ] == 'T' )
-                                && ( value[ 2 ] == 'F' )
-                                && ( value[ 3 ] == '-' )
-                                && ( value[ 4 ] == '8' ) )
+                               if( ( value_length == 3 )
+                                && ( value[ 0 ] == 'G' )
+                                && ( value[ 1 ] == 'B' )
+                                && ( value[ 2 ] == 'K' ) )
+                               {
+                                       descriptor_file->encoding = LIBUNA_CODEPAGE_WINDOWS_936;
+                               }
+                               else if( ( value_length == 5 )
+                                     && ( value[ 0 ] == 'U' )
+                                     && ( value[ 1 ] == 'T' )
+                                     && ( value[ 2 ] == 'F' )
+                                     && ( value[ 3 ] == '-' )
+                                     && ( value[ 4 ] == '8' ) )
                                {
                                        descriptor_file->encoding = 0;

if u need any adtional information to address this issue.I can do my best to help u fixed this issue.

Ideally I would like to know what gbk actually refers to for VMDK, but cp936 seems to be relatively safe for now. To get full closer on this I'd first need to know which character values help distinguish between different variants of GBK.

[joachimmetz]

Changes for libvmdk libyal/libvmdk@a3f6142

[zhanleewo]

Thank you.

[joachimmetz]

@zhanleewo thanks, based on that link, one thing that could be useful is to create a VMDK with an "euro sign" that can be shared. That should give more resolution on which encoding is actually used.

[joachimmetz]

I'll close this issue in favor of libyal/libvmdk#10

[zhanleewo]

https://en.m.wikipedia.org/wiki/Code_page_936_(Microsoft_Windows)

I think this is helpful. the difference between GBK and cp639 is listed.

[joachimmetz]

thx