[Ur] OpenSSL and C FFI

[Adam Chlipala]

On 10/20/2012 08:54 AM, David Snider wrote:
> |I'm trying to make a C FFI that returns the SHA256 of a string and this is what I get when I try to compile with my library added:
>
> david at ubuntu:~/Projects/UrShop$ urweb urshop
> /usr/bin/ld: /usr/local/lib/liburweb.so: undefined reference to symbol 'SHA256_Init@@OPENSSL_1.0.0'
> /usr/bin/ld: note: 'SHA256_Init@@OPENSSL_1.0.0' is defined in DSO /usr/lib/gcc/x86_64-linux-gnu/4.6/../../../x86_64-linux-gnu/libcrypto.so so try adding it to the linker command line
> /usr/lib/gcc/x86_64-linux-gnu/4.6/../../../x86_64-linux-gnu/libcrypto.so: could not read symbols: Invalid operation
> collect2: ld returned 1 exit status
>
> What step am I missing?|
>    

Run 'urweb' with the '-debug' option and then tweak the gcc command 
lines it uses until they work.  Once you figure out what was wrong, I 
can comment on the right way to get 'urweb' itself to use different 
command lines.
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