Hello! Try following code:
https://gist.github.com/indutny/bc2b05d3f75f6dd81e77 I may be missing some nuances regarding FFI signature, but the main thing is that you are overwriting local variable in a C function, not writing a value to the pointer which it contains. Changing it to `char**` and doing `*out = header` should make it work. Cheers, Fedor. On Tue, Mar 18, 2014 at 11:21 AM, <gilles.gerlin...@gmail.com> wrote: > Hi, > > I have been using node ffi for various libraries but today I am facing an > unexpected difficulty. Here is a simple C function that takes as parameter a > pointer and allocates memory for that pointer. > > int write_headers(char *header) > { > header = calloc(1024, 1); > header[0] = 0x66; > header[1] = 0x4C; > header[2] = 0x61; > header[3] = 0x43; > > return 4; > } > > > In node, I am using the following coffeescript code to call the > write_headers function: > > ref = require 'ref' > ffi = require 'ffi' > > API = { > 'write_headers': ['int', ['pointer']] > } > test = ffi.Library './libtest.so', API > > header = ref.NULL_POINTER > > res = test.write_headers header.ref() > > > I tried various options but never succeeded to get the correct value of > header after the call of the write_headers function in order to get the 4 > values of the header. > > I would appreciate any help on this. > > Thank you,GIlles > > -- > -- > Job Board: http://jobs.nodejs.org/ > Posting guidelines: > https://github.com/joyent/node/wiki/Mailing-List-Posting-Guidelines > You received this message because you are subscribed to the Google > Groups "nodejs" group. > To post to this group, send email to nodejs@googlegroups.com > To unsubscribe from this group, send email to > nodejs+unsubscr...@googlegroups.com > For more options, visit this group at > http://groups.google.com/group/nodejs?hl=en?hl=en > > --- > You received this message because you are subscribed to the Google Groups > "nodejs" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to nodejs+unsubscr...@googlegroups.com. > For more options, visit https://groups.google.com/d/optout. -- -- Job Board: http://jobs.nodejs.org/ Posting guidelines: https://github.com/joyent/node/wiki/Mailing-List-Posting-Guidelines You received this message because you are subscribed to the Google Groups "nodejs" group. To post to this group, send email to nodejs@googlegroups.com To unsubscribe from this group, send email to nodejs+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/nodejs?hl=en?hl=en --- You received this message because you are subscribed to the Google Groups "nodejs" group. To unsubscribe from this group and stop receiving emails from it, send an email to nodejs+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
