Difference between revisions of "Web/Literature/Static linking"
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(Added basic example, will add more regarding this) |
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| − | [[Category:Web|*]] |
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| − | {{Web infobox}} |
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| − | {{Template:Stub}} |
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| − | '''This article is out of date, it refers to GHC 6.8 and Database.SQLite. Please someone update it with a more recent example, if necessary.''' |
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| − | == Deploying statically linked applications == |
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| − | Linking your applications statically by giving the flags <tt>-static |
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| − | -optl-static</tt> to GHC will avoid problems with missing libraries on |
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| − | the web server. |
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| − | For example, this simple program, |
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| − | <haskell> |
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| − | import Database.SQLite |
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| − | main = print "hey, test this" |
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| − | </haskell> |
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| − | when compiled as $ ghc A.hs --make is dynamically linked against: |
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| − | <haskell> |
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| − | $ ldd A |
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| − | A: |
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| − | Start End Type Open Ref GrpRef Name |
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| − | 0000000000000000 0000000000000000 exe 1 0 0 A |
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| − | 0000000041a85000 0000000041ee5000 rlib 0 1 0 /usr/local/lib/libsqlite3.so.9.0 |
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| − | 0000000049b04000 0000000049f1d000 rlib 0 1 0 /usr/lib/libm.so.2.3 |
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| − | 0000000042213000 000000004264f000 rlib 0 1 0 /usr/local/lib/libgmp.so.7.0 |
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| − | 0000000047d0e000 00000000481e0000 rlib 0 1 0 /usr/lib/libc.so.42.0 |
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| − | 0000000047900000 0000000047900000 rtld 0 1 0 /usr/libexec/ld.so |
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| − | </haskell> |
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| − | Now, we can just pass some linker flags through to statically link this lot, |
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| − | <haskell> |
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| − | $ ghc A.hs --make -optl-static -no-recomp |
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| − | $ ldd A |
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| − | ldd: A: not a dynamic executable |
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| − | $ file A |
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| − | A: ELF 64-bit LSB executable, AMD64, version 1, for OpenBSD, statically linked, not stripped |
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| − | </haskell> |
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| − | You could also use the [[Haskell Web Server]]. |
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| − | '''Caveats:''' |
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| − | * The <tt>-static</tt> flag in GHC 6.8.2 does not link the libraries in the correct order, resulting in a link failure (which you can hack around if you have to by shuffling <tt>-lpthread</tt> after <tt>-lrt</tt> in the gargantuan linker invocation). This problem should disappear with GHC 6.8.3. |
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| − | * Sometimes you will need to add <tt>extra-libraries</tt> fields to various libraries' <tt>.cabal</tt> files. This manifests as missing symbols. Note that many linkers are sensitive to the order of the <tt>-l</tt> arguments, so the order of libraries in this field matters. |
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