In both version 0.4 and 0.5-dev everything is as you show
until: pointer_to_array(Ptr{UInt8}(ptr[]), sz[], true)
then
julia> pointer_to_array(Ptr{UInt8}(ptr[]), sz[], true)
140685948747867-element Array{UInt8,1}:
signal (11): Segmentation fault
while loading no file, in expression starting on line 0
alignment at ./show.jl:1104
unknown function (ip: 0x7ff401d4117f)
[inline] at
/home/centos/buildbot/slave/package_tarball64/build/src/julia_internal.h:63
jl_call_method_internal at
/home/centos/buildbot/slave/package_tarball64/build/src/gf.c:1914
...
jl_apply_generic at
/home/centos/buildbot/slave/package_tarball64/build/src/gf.c:1917
run_frontend at ./REPL.jl:860
run_repl at ./REPL.jl:168
unknown function (ip: 0x7ff4023431e3)
[inline] at
/home/centos/buildbot/slave/package_tarball64/build/src/julia_internal.h:63
jl_call_method_internal at
/home/centos/buildbot/slave/package_tarball64/build/src/gf.c:1914
_start at ./client.jl:342
unknown function (ip: 0x7ff6042f0199)
jl_apply_generic at
/home/centos/buildbot/slave/package_tarball64/build/src/gf.c:1917
unknown function (ip: 0x401c64)
unknown function (ip: 0x40181f)
__libc_start_main at /lib/x86_64-linux-gnu/libc.so.6 (unknown line)
unknown function (ip: 0x401865)
/home/jas/Desktop/Juliav05: line 2: 4104 Segmentation fault
/usr/bin/julia
_
(generic Linux version of julia)
On Wednesday, March 9, 2016 at 2:55:31 PM UTC-5, Jeffrey Sarnoff wrote:
>
> Thank you, much appreciated.
>
> On Wednesday, March 9, 2016 at 2:52:01 PM UTC-5, Yichao Yu wrote:
>>
>> On Wed, Mar 9, 2016 at 1:05 PM, Jeffrey Sarnoff
>> <[email protected]> wrote:
>> > I am bound to the api, at least for calling into the application. I
>> don't
>> > know how to do either of the things you recommend. Could you point me
>> to an
>> > example?
>>
>> See below. Note that the `open_memstream` API may not be widely
>> available on non-Linux. (Apparently it's aded to POSIX though...)
>> The reason you have to deal directly with C FILE* is that the C FILE*
>> API is not designed to be extensible (or at least there's no portable
>> API to do so). Therefore, you can't convert a opaque julia IO object
>> to a C FILE* and let C libraries write through it instead...
>>
>> ```
>> julia> p_cstdout = unsafe_load(cglobal(:stdout, Ptr{Void}))
>> Ptr{Void} @0x00007f6dcb81f600
>>
>> julia> ccall(:fwrite, Csize_t, (Cstring, Csize_t, Csize_t, Ptr{Void}),
>> "aaa\n", 4, 1, p_cstdout)
>> aaa
>> 0x0000000000000001
>>
>> julia> ptr = Ref{Ptr{Void}}()
>> Base.RefValue{Ptr{Void}}(Ptr{Void} @0x000000000000000e)
>>
>> julia> sz = Ref{Csize_t}()
>> Base.RefValue{UInt64}(0x00007f6bc942f5f0)
>>
>> julia> strstm = ccall(:open_memstream, Ptr{Void}, (Ptr{Ptr{Void}},
>> Ptr{Csize_t}), ptr, sz)
>> Ptr{Void} @0x0000000002638f70
>>
>> julia> ccall(:fwrite, Csize_t, (Cstring, Csize_t, Csize_t, Ptr{Void}),
>> "aaa\n", 4, 1, strstm)
>> 0x0000000000000001
>>
>> julia> ccall(:fwrite, Csize_t, (Cstring, Csize_t, Csize_t, Ptr{Void}),
>> "aaa\n", 4, 1, strstm)
>> 0x0000000000000001
>>
>> julia> sz[]
>> 0x00007f6bc942f5f0
>>
>> julia> ccall(:fclose, Cint, (Ptr{Void},), strstm)
>> 0
>>
>> julia> sz[]
>> 0x0000000000000008
>>
>> julia> pointer_to_array(Ptr{UInt8}(ptr[]), sz[], true)
>> 8-element Array{UInt8,1}:
>> 0x61
>> 0x61
>> 0x61
>> 0x0a
>> 0x61
>> 0x61
>> 0x61
>> 0x0a
>>
>> julia> ary = ans
>> 8-element Array{UInt8,1}:
>> 0x61
>> 0x61
>> 0x61
>> 0x0a
>> 0x61
>> 0x61
>> 0x61
>> 0x0a
>>
>> julia> bytestring(ary)
>> "aaa\naaa\n"
>> ```
>>
>> >
>> > On Wednesday, March 9, 2016 at 12:58:20 PM UTC-5, Yichao Yu wrote:
>> >>
>> >>
>> >> On Mar 9, 2016 12:38 PM, "Jeffrey Sarnoff" <[email protected]>
>> wrote:
>> >> >
>> >> > I am trying to wrap this so it will (a) print to STDOUT (b) (if
>> >> > possible) print to a string:
>> >> > void arf_fprint(FILE * file, const arf_t x)ΒΆ
>> >> >
>> >> > Prints x as an integer mantissa and exponent to the stream file.
>> >> >
>> >> >
>> >> > arf_t is made with arf(x), that works.
>> >> >
>> >> >
>> >> > this:
>> >> >
>> >> > function arf_fprint(x::arb)
>> >> >
>> >> > a = arf(x); s=STDOUT
>> >> >
>> >> > ccall((:arf_fprint, :libarb), Void, (Ptr{s},
>> >> > Ptr{arf_struct},), &s, &a)
>> >>
>> >> Julia does not use c FILE*, if you are bound to this api, you should
>> >> probably fetch the c stream with cglobal or construct a string stream
>> with
>> >> platform dependent api.
>> >>
>> >> >
>> >> > end
>> >> >
>> >> > does this:
>> >> > ERROR: TypeError: Ptr: in parameter, expected Type{T}, got Base.TTY
>> >> > in arf_fprint at none:3
>> >> >
>>
>
