Thanks for the detailed response João! As it turns out, I didn't have any
.dylib files as part of the downloaded code, but I was able to figure out
how to compile the code and I believe I've got the library installed
locally now.
When you reference that most of my Ptr{Uint8} values are really just
looking for string inputs, can I modify the Julia function signature to
take ::ASCIIString instead? Or is this something where I have the leave the
type signatures as they are, but understand what the function is actually
looking for from the documentation?
On Sunday, August 31, 2014 9:19:21 PM UTC-4, João Felipe Santos wrote:
>
> Hello Randy,
>
> the following comes from my experience with ccall and Julia documentation.
> Please anyone correct me if I explained any of the internals wrong!
>
> The API seems to be really simple so pretty much everything can be done
> with standard Julia types. Clang.jl seems to have generated correct code
> for it.
>
> Regarding 2, liboauth.dylib (or .dll, or .so on Linux) has to be loaded
> and passed to ccall. You can load it by hand using dlopen, like this:
>
> liboauth = dlopen("/path/of/liboauth.dylib")
>
> This will raise an error if the path is not valid. If the library is in
> your environment's standard path, you can pass its name to ccall as a
> string instead of creating a pointer with dlopen.
>
> Most of the Ptr{Uint8} you got in the code generated by Clang.jl are
> actually mapping char *, which are C strings (ASCII, not Unicode). For
> example, let's say you wanted to call puts from libc, which is a function
> that gets a string as its argument, prints it to the screen followed by a
> newline, and returns the number of printed characters. You could do it like
> this:
>
> ccall((:puts, "libc"), Cint, (Ptr{Uint8},), "Hello, Randy")
>
> So, you basically can pass your string as the function argument and it
> should work. You don't need to pass a pointer, but it's good to know that
> your Julia ASCIIString was converted to Ptr{Uint8} internally.
>
> With this you should be able to call functions, but you still need to be
> able to recover their output. The second argument to ccall is the C
> function return type, but note that often C functions do not return their
> output in the return type, but in a variable which was passed by reference
> as one of its arguments. I don't know enough of liboauth to know what's the
> case, so you will need to check the documentation. See the sections
> http://docs.julialang.org/en/release-0.3/manual/calling-c-and-fortran-code/#accessing-data-through-a-pointer
>
> and
> http://docs.julialang.org/en/release-0.3/manual/calling-c-and-fortran-code/#passing-pointers-for-modifying-inputs
>
> for more details on that.
>
> --
> João Felipe Santos
>
>
> On Sun, Aug 31, 2014 at 8:17 PM, Randy Zwitch <[email protected]
> <javascript:>> wrote:
>
>> Hi all -
>>
>> I've been trying to learn more about C and how Julia interacts and
>> decided to play around with Clang.jl. I decided I was going to wrap
>> liboauth from here:
>>
>> http://liboauth.sourceforge.net/oauth_8h_source.html
>>
>> I downloaded the C source, which resided in my OSX Downloads directory.
>> Using the following Julia code generated a bunch of output:
>>
>> [1]:
>>
>> using Clang.wrap_c
>>
>> In [2]:
>>
>> context = wrap_c.init(; output_file="liboauth.jl",
>> header_library=x->"liboauth", common_file="liboauth.jl",
>> clang_diagnostics=true)
>>
>> context.options.wrap_structs = true
>>
>> wrap_c.wrap_c_headers(context,
>> ["/Users/randyzwitch/Downloads/liboauth-1.0.3/src/oauth.h"])
>>
>> WARNING: wrap_c_headers: deprecated
>> /Users/randyzwitch/Downloads/liboauth-1.0.3/src/oauth.h:112:46: error:
>> unknown type name 'size_t'
>> /Users/randyzwitch/Downloads/liboauth-1.0.3/src/oauth.h:138:54: error:
>> unknown type name 'size_t'
>> /Users/randyzwitch/Downloads/liboauth-1.0.3/src/oauth.h:138:86: error:
>> unknown type name 'size_t'
>> /Users/randyzwitch/Downloads/liboauth-1.0.3/src/oauth.h:315:67: error:
>> unknown type name 'size_t'
>> /Users/randyzwitch/Downloads/liboauth-1.0.3/src/oauth.h:315:81: error:
>> unknown type name 'size_t'
>> /Users/randyzwitch/Downloads/liboauth-1.0.3/src/oauth.h:320:66: error:
>> unknown type name 'size_t'
>> /Users/randyzwitch/Downloads/liboauth-1.0.3/src/oauth.h:320:80: error:
>> unknown type name 'size_t'
>> /Users/randyzwitch/Downloads/liboauth-1.0.3/src/oauth.h:519:28: error:
>> unknown type name 'size_t'
>> /Users/randyzwitch/Downloads/liboauth-1.0.3/src/oauth.h:532:30: error:
>> unknown type name 'size_t'
>> /Users/randyzwitch/Downloads/liboauth-1.0.3/src/oauth.h:670:61: error:
>> unknown type name 'size_t'
>> /Users/randyzwitch/Downloads/liboauth-1.0.3/src/oauth.h:688:57: error:
>> unknown type name 'size_t'
>> /Users/randyzwitch/Downloads/liboauth-1.0.3/src/oauth.h:715:43: error:
>> unknown type name 'size_t'
>> /Users/randyzwitch/Downloads/liboauth-1.0.3/src/oauth.h:717:70: warning:
>> type specifier missing, defaults to 'int' [-Wimplicit-int]
>> /Users/randyzwitch/Downloads/liboauth-1.0.3/src/oauth.h:717:77: warning:
>> type specifier missing, defaults to 'int' [-Wimplicit-int]
>> /Users/randyzwitch/Downloads/liboauth-1.0.3/src/oauth.h:717:77: error:
>> redefinition of parameter 'size_t'
>> /Users/randyzwitch/Downloads/liboauth-1.0.3/src/oauth.h:717:70: note:
>> previous declaration is here
>> /Users/randyzwitch/Downloads/liboauth-1.0.3/src/oauth.h:741:24: error:
>> unknown type name 'size_t'
>> /Users/randyzwitch/Downloads/liboauth-1.0.3/src/oauth.h:771:43: error:
>> unknown type name 'size_t'
>> /Users/randyzwitch/Downloads/liboauth-1.0.3/src/oauth.h:773:70: warning:
>> type specifier missing, defaults to 'int' [-Wimplicit-int]
>> /Users/randyzwitch/Downloads/liboauth-1.0.3/src/oauth.h:773:77: warning:
>> type specifier missing, defaults to 'int' [-Wimplicit-int]
>> /Users/randyzwitch/Downloads/liboauth-1.0.3/src/oauth.h:773:77: error:
>> redefinition of parameter 'size_t'
>> /Users/randyzwitch/Downloads/liboauth-1.0.3/src/oauth.h:773:70: note:
>> previous declaration is here
>>
>> WRAPPING HEADER: /Users/randyzwitch/Downloads/liboauth-1.0.3/src/oauth.h
>>
>> WARNING: Not wrapping MacroInstantiation OA_GCC_VERSION_AT_LEAST
>> WARNING: Not wrapping MacroInstantiation attribute_deprecated
>> WARNING: Not wrapping MacroInstantiation attribute_deprecated
>> WARNING: Not wrapping MacroInstantiation attribute_deprecated
>> WARNING: Not wrapping MacroInstantiation attribute_deprecated
>> WARNING: Not wrapping MacroInstantiation attribute_deprecated
>> WARNING: Not wrapping MacroInstantiation attribute_deprecated
>> WARNING: Not wrapping MacroInstantiation attribute_deprecated
>> WARNING: Not wrapping MacroInstantiation attribute_deprecated
>> WARNING: Not wrapping MacroInstantiation attribute_deprecated
>> WARNING: Not wrapping MacroInstantiation attribute_deprecated
>> WARNING: Not wrapping MacroInstantiation attribute_deprecated
>> WARNING: Not wrapping MacroInstantiation attribute_deprecated
>> WARNING: Not wrapping MacroInstantiation attribute_deprecated
>>
>> writing liboauth.jl
>>
>> Out[2]:
>>
>> 1-element Array{Any,1}:
>> nothing
>>
>>
>>
>> Output:
>>
>>
>> const LIBOAUTH_VERSION = "1.0.3"
>> const LIBOAUTH_VERSION_MAJOR = 1
>> const LIBOAUTH_VERSION_MINOR = 0
>> const LIBOAUTH_VERSION_MICRO = 3
>> const LIBOAUTH_CUR = 8
>> const LIBOAUTH_REV = 7
>> const LIBOAUTH_AGE = 8
>>
>> # Skipping MacroDefinition: OA_GCC_VERSION_AT_LEAST ( x , y ) ( __GNUC__
>> > x || __GNUC__ == x && __GNUC_MINOR__ >= y )
>> # Skipping MacroDefinition: attribute_deprecated __attribute__ ( (
>> deprecated ) )
>>
>> # begin enum ANONYMOUS_1
>> typealias ANONYMOUS_1 Uint32
>> const OA_HMAC = (uint32)(0)
>> const OA_RSA = (uint32)(1)
>> const OA_PLAINTEXT = (uint32)(2)
>> # end enum ANONYMOUS_1
>>
>> # begin enum OAuthMethod
>> typealias OAuthMethod Uint32
>> const OA_HMAC = (uint32)(0)
>> const OA_RSA = (uint32)(1)
>> const OA_PLAINTEXT = (uint32)(2)
>> # end enum OAuthMethod
>> function oauth_sign_hmac_sha1(m::Ptr{Uint8},k::Ptr{Uint8})
>>
>> ccall((:oauth_sign_hmac_sha1,liboauth),Ptr{Uint8},(Ptr{Uint8},Ptr{Uint8}),m,k)
>> end
>>
>> function
>> oauth_sign_hmac_sha1_raw(m::Ptr{Uint8},ml::Cint,k::Ptr{Uint8},kl::Cint)
>>
>> ccall((:oauth_sign_hmac_sha1_raw,liboauth),Ptr{Uint8},(Ptr{Uint8},Cint,Ptr{Uint8},Cint),m,ml,k,kl)
>> end
>>
>> function oauth_sign_plaintext(m::Ptr{Uint8},k::Ptr{Uint8})
>>
>> ccall((:oauth_sign_plaintext,liboauth),Ptr{Uint8},(Ptr{Uint8},Ptr{Uint8}),m,k)
>> end
>>
>> function oauth_sign_rsa_sha1(m::Ptr{Uint8},k::Ptr{Uint8})
>>
>> ccall((:oauth_sign_rsa_sha1,liboauth),Ptr{Uint8},(Ptr{Uint8},Ptr{Uint8}),m,k)
>> end
>>
>> function oauth_verify_rsa_sha1(m::Ptr{Uint8},c::Ptr{Uint8},s::Ptr{Uint8})
>>
>> ccall((:oauth_verify_rsa_sha1,liboauth),Cint,(Ptr{Uint8},Ptr{Uint8},Ptr{Uint8}),m,c,s)
>> end
>>
>> <snip>
>>
>> My questions are:
>>
>> 1) Did I do this right? I got back a Julia file full of Julia code with
>> ccalls, so it seems like I got back what was expected? There were lots of
>> deprecation warnings in Julia however.
>> 2) How do I actually start using this code for something? Other than
>> unzipping the source code for liboauth, I haven't done anything with the C
>> code other than generating the Julia ccalls. How will this Julia code know
>> how to reference the original source liboauth.h file?
>> 3) The Julia functions are using pointers as input types. Do I literally
>> need to pass a pointer, or can I just provide the data type of the pointer
>> (say, Uint8)?
>>
>> So, am I on the right track? What should I be thinking about if I want to
>> take the next step in actually trying to use these functions?
>>
>
>
