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Index > Windows > Call func from DLL written at Golang.

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greendruid



Joined: 15 Jan 2021
Posts: 3
greendruid
Hello!
I faced with the trouble to passing parameters to the function, called from DLL written at Golang. I try send 'string' ('db'), but the 'function-receiver' show a unclear junk. I think, that is data's type problem. In the similar code at 'c' has been used the next construction:
Code:
GoString tstr = lpFunc("test");
char* cTstr = malloc(tstr.n + 1);
if (!cTstr) 
    memcpy(cTstr, tstr.p, tstr.n);
cTstr[tstr.n] = '\0';
printf("Message from DLL: %s\n", tStr);
    

Also 'GoString' has been defined in 'h' file:
Code:
#ifndef GO_CGO_GOSTRING_TYPEDEF
typedef struct { const char *p; ptrdiff_t n; } _GoString_;
#endif
    

Should I focused at Golang's feature for find a solution? Or I could to prepare a data special in fasm before sending to the function? In the future I'll need to pass 'byte array' to another function.

FASM source:
Code:
format PE64 console
entry start
include 'c:\fasm\include\win64a.inc'
section '.text' code readable executable
start:
        sub     rsp,8
        invoke  PrintHello,[message]
        invoke  ExitProcess,0
section '.data' data readable
  message db "test data",0
section '.idata' import data readable writeable
  library kernel32,'KERNEL32.DLL',\
          writemsg,'goDLL.dll'
  include 'c:/fasm/include/api/kernel32.inc'
  import writemsg,\
         PrintHello,'PrintHello'
    


Part src at Golang:
Code:
//export PrintHello
func PrintHello(s *C.char)(r string){
        t := C.GoString((*C.char)(unsafe.Pointer(s)))
        //fmt.Printf("Test message %v\n", len(t))
        //fmt.Println("Test message %v", t)
        return "test from dll";
}
    


Thank you!
Post 15 Jan 2021, 14:45
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ProMiNick



Joined: 24 Mar 2012
Posts: 672
Location: Russian Federation, Sochi
ProMiNick
greendruid wrote:
Code:
        invoke  PrintHello,[message]    
my eyes crying, why not this:
Code:
        invoke  PrintHello,message    

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Post 15 Jan 2021, 15:37
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greendruid



Joined: 15 Jan 2021
Posts: 3
greendruid
ProMiNick wrote:
greendruid wrote:
Code:
        invoke  PrintHello,[message]    
my eyes crying, why not this:
Code:
        invoke  PrintHello,message    


Hi, thanks for you attention! My mistake (copy the one of draft). But no success if I changing to a correct version (without square brackets).
Post 15 Jan 2021, 16:24
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ProMiNick



Joined: 24 Mar 2012
Posts: 672
Location: Russian Federation, Sochi
ProMiNick
Code:
section '.data' data readable
  dd -1
  message db "test data",0    

maybe string format:
Code:
length dword ; struct negate offset
string char[] ; struct zero offset ; zero terminated    
Post 16 Jan 2021, 04:10
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greendruid



Joined: 15 Jan 2021
Posts: 3
greendruid
ProMiNick wrote:

Code:
length dword ; struct negate offset
string char[] ; struct zero offset ; zero terminated    

No success. Output in terminal looks like:
Code:
�☼H�� �
    

I can to fix something in the DLL. Maybe I should change a data type to '[]byte' (byte array) in Golang library and pass a data as bytes (fix in fasm src)?
Post 17 Jan 2021, 10:08
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Ali.Z



Joined: 08 Jan 2018
Posts: 526
Ali.Z
i would say you better double check the reference manual for that specific function, see what arguments it takes and what calling conventions it use.

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Post 17 Jan 2021, 23:13
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