Add (guix snix) and the `guix-import' command.

* guix/snix.scm, tests/snix.scm, guix-import.in: New files.
* configure.ac: Output `guix-import' and make it executable.
* Makefile.am (bin_SCRIPTS): Add `guix-import'.
  (MODULES): Add `guix/snix.scm'.
  (TESTS): Add `tests/snix.scm'.

1 files changed, 439 insertions, 0 deletions

diff --git a/guix/snix.scm b/guix/snix.scm
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+;;; Guix --- Nix package management from Guile.         -*- coding: utf-8 -*-
+;;; Copyright (C) 2010, 2011, 2012 Ludovic Courtès <ludo@gnu.org>
+;;;
+;;; This file is part of Guix.
+;;;
+;;; Guix is free software; you can redistribute it and/or modify it
+;;; under the terms of the GNU General Public License as published by
+;;; the Free Software Foundation; either version 3 of the License, or (at
+;;; your option) any later version.
+;;;
+;;; Guix is distributed in the hope that it will be useful, but
+;;; WITHOUT ANY WARRANTY; without even the implied warranty of
+;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+;;; GNU General Public License for more details.
+;;;
+;;; You should have received a copy of the GNU General Public License
+;;; along with Guix.  If not, see <http://www.gnu.org/licenses/>.
+
+(define-module (guix snix)
+  #:use-module (sxml ssax)
+  #:use-module (ice-9 popen)
+  #:use-module (ice-9 match)
+  #:use-module (ice-9 rdelim)
+  #:use-module (ice-9 format)
+  #:use-module (ice-9 regex)
+  #:use-module (ice-9 vlist)
+  #:use-module (srfi srfi-1)
+  #:use-module (srfi srfi-9)
+  #:use-module (srfi srfi-11)
+  #:use-module (srfi srfi-26)
+  #:use-module (srfi srfi-37)
+  #:use-module (system foreign)
+  #:use-module (rnrs bytevectors)
+  #:use-module (guix utils)
+  #:use-module (guix config)
+  #:export (open-nixpkgs
+            xml->snix
+            nixpkgs->guix-package))
+
+;;; Commentary:
+;;;
+;;; Converting Nix code to s-expressions, and then to Guix `package'
+;;; declarations, using the XML output of `nix-instantiate'.
+;;;
+;;; Code:
+
+
+;;;
+;;; SNix.
+;;;
+
+;; Nix object types visible in the XML output of `nix-instantiate' and
+;; mapping to S-expressions (we map to sexps, not records, so that we
+;; can do pattern matching):
+;;
+;;   at               (at varpat attrspat)
+;;   attr             (attribute loc name value)
+;;   attrs            (attribute-set attributes)
+;;   attrspat         (attribute-set-pattern patterns)
+;;   bool             #f|#t
+;;   derivation       (derivation drv-path out-path attributes)
+;;   ellipsis         '...
+;;   expr             (snix loc body ...)
+;;   function         (function loc at|attrspat|varpat)
+;;   int              int
+;;   list             list
+;;   null             'null
+;;   path             string
+;;   string           string
+;;   unevaluated      'unevaluated
+;;   varpat           (varpat name)
+;;
+;; Initially ATTRIBUTES in `derivation' and `attribute-set' was a promise;
+;; however, handling `repeated' nodes makes it impossible to do anything
+;; lazily because the whole SXML tree has to be traversed to maintain the
+;; list of known derivations.
+
+(define (xml-element->snix elem attributes body derivations)
+  "Return an SNix element corresponding to XML element ELEM."
+
+  (define (loc)
+    (location (assq-ref attributes 'path)
+              (assq-ref attributes 'line)
+              (assq-ref attributes 'column)))
+
+  (case elem
+    ((at)
+     (values `(at ,(car body) ,(cadr body)) derivations))
+    ((attr)
+     (let ((name (assq-ref attributes 'name)))
+       (cond ((null? body)
+              (values `(attribute-pattern ,name) derivations))
+             ((and (pair? body) (null? (cdr body)))
+              (values `(attribute ,(loc) ,name ,(car body))
+                      derivations))
+             (else
+              (error "invalid attribute body" name (loc) body)))))
+    ((attrs)
+     (values `(attribute-set ,(reverse body)) derivations))
+    ((attrspat)
+     (values `(attribute-set-pattern ,body) derivations))
+    ((bool)
+     (values (string-ci=? "true" (assq-ref attributes 'value))
+             derivations))
+    ((derivation)
+     (let ((drv-path (assq-ref attributes 'drvPath))
+           (out-path (assq-ref attributes 'outPath)))
+       (if (equal? body '(repeated))
+           (let ((body (vhash-assoc drv-path derivations)))
+             (if (pair? body)
+                 (values `(derivation ,drv-path ,out-path ,(cdr body))
+                         derivations)
+
+                 ;; DRV-PATH hasn't been encountered yet but may be later
+                 ;; (see <http://article.gmane.org/gmane.linux.distributions.nixos/5946>.)
+                 ;; Return an `unresolved' node.
+                 (values `(unresolved
+                           ,(lambda (derivations)
+                              (let ((body (vhash-assoc drv-path derivations)))
+                                (if (pair? body)
+                                    `(derivation ,drv-path ,out-path
+                                                 ,(cdr body))
+                                    (error "no previous occurrence of derivation"
+                                           drv-path)))))
+                         derivations)))
+           (values `(derivation ,drv-path ,out-path ,body)
+                   (vhash-cons drv-path body derivations)))))
+    ((ellipsis)
+     (values '... derivations))
+    ((expr)
+     (values `(snix ,(loc) ,@body) derivations))
+    ((function)
+     (values `(function ,(loc) ,body) derivations))
+    ((int)
+     (values (string->number (assq-ref attributes 'value))
+             derivations))
+    ((list)
+     (values body derivations))
+    ((null)
+     (values 'null derivations))
+    ((path)
+     (values (assq-ref attributes 'value) derivations))
+    ((repeated)
+     (values 'repeated derivations))
+    ((string)
+     (values (assq-ref attributes 'value) derivations))
+    ((unevaluated)
+     (values 'unevaluated derivations))
+    ((varpat)
+     (values `(varpat ,(assq-ref attributes 'name)) derivations))
+    (else (error "unhandled Nix XML element" elem))))
+
+(define (resolve snix derivations)
+  "Return a new SNix tree where `unresolved' nodes from SNIX have been
+replaced by the result of their application to DERIVATIONS, a vhash."
+  (let loop ((node snix)
+             (seen vlist-null))
+    (if (vhash-assq node seen)
+        (values node seen)
+        (match node
+          (('unresolved proc)
+           (let ((n (proc derivations)))
+             (values n seen)))
+          ((tag body ...)
+           (let ((body+seen (fold (lambda (n body+seen)
+                                    (call-with-values
+                                        (lambda ()
+                                          (loop n (cdr body+seen)))
+                                      (lambda (n* seen)
+                                        (cons (cons n* (car body+seen))
+                                              (vhash-consq n #t seen)))))
+                                  (cons '() (vhash-consq node #t seen))
+                                  body)))
+             (values (cons tag (reverse (car body+seen)))
+                     (vhash-consq node #t (cdr body+seen)))))
+          (anything
+           (values anything seen))))))
+
+(define xml->snix
+  (let ((parse
+         (ssax:make-parser NEW-LEVEL-SEED
+                           (lambda (elem-gi attributes namespaces expected-content
+                                    seed)
+                             (cons '() (cdr seed)))
+
+                           FINISH-ELEMENT
+                           (lambda (elem-gi attributes namespaces parent-seed
+                                            seed)
+                             (let ((snix        (car seed))
+                                   (derivations (cdr seed)))
+                               (let-values (((snix derivations)
+                                             (xml-element->snix elem-gi
+                                                                attributes
+                                                                snix
+                                                                derivations)))
+                                 (cons (cons snix (car parent-seed))
+                                       derivations))))
+
+                           CHAR-DATA-HANDLER
+                           (lambda (string1 string2 seed)
+                             ;; Discard inter-node strings, which are blanks.
+                             seed))))
+    (lambda (port)
+      "Return the SNix represention of TREE, an SXML tree as returned by
+parsing the XML output of `nix-instantiate' on Nixpkgs."
+      (match (parse port (cons '() vlist-null))
+        (((snix) . derivations)
+         (resolve snix derivations))))))
+
+(define (attribute-value attribute)
+  "Return the value of ATTRIBUTE."
+  (match attribute
+    (('attribute _ _ value) value)))
+
+(define (derivation-source derivation)
+  "Return the \"src\" attribute of DERIVATION or #f if not found."
+  (match derivation
+    (('derivation _ _ (attributes ...))
+     (find-attribute-by-name "src" attributes))))
+
+(define (derivation-output-path derivation)
+  "Return the output path of DERIVATION."
+  (match derivation
+    (('derivation _ out-path _)
+     out-path)
+    (_ #f)))
+
+(define (source-output-path src)
+  "Return the output path of SRC, the \"src\" attribute of a derivation."
+  (derivation-output-path (attribute-value src)))
+
+(define (source-urls src)
+  "Return the URLs of SRC, the \"src\" attribute of a derivation."
+  (match src
+    (('attribute _ _ ('derivation _ _ (attributes ...)))
+     (match (find-attribute-by-name "urls" attributes)
+       (('attribute _ _ value)
+        value)))
+    (_ #f)))
+
+(define (source-sha256 src)
+  "Return the sha256 of SRC, the \"src\" attribute of a derivation, as a
+bytevector."
+  (match src
+    (('attribute _ _ ('derivation _ _ (attributes ...)))
+     (match (find-attribute-by-name "outputHash" attributes)
+       (('attribute _ _ value)
+        (match value
+          ((= string-length 52)
+           (nix-base32-string->bytevector value))
+          ((= string-length 64)
+           (base16-string->bytevector value))
+          (_
+           (error "unsupported hash format" value))))))
+    (_ #f)))
+
+(define (derivation-source-output-path derivation)
+  "Return the output path of the \"src\" attribute of DERIVATION or #f
+if DERIVATION lacks an \"src\" attribute."
+  (and=> (derivation-source derivation) source-output-path))
+
+(define* (open-nixpkgs nixpkgs #:optional attribute)
+  "Return an input pipe to the XML representation of Nixpkgs.  When
+ATTRIBUTE is true, only that attribute is considered."
+  (with-fluids ((%default-port-encoding "UTF-8"))
+    (let ((cross-system (format #f "{
+  config = \"i686-guix-linux-gnu\";
+  libc = \"glibc\";
+  arch = \"guix\";
+  withTLS = true;
+  float = \"hard\";
+  openssl.system = \"linux-generic32\";
+  platform = (import ~a/pkgs/top-level/platforms.nix).sheevaplug;
+}" nixpkgs)))
+      (apply open-pipe* OPEN_READ
+             %nix-instantiate "--strict" "--eval-only" "--xml"
+
+             ;; Pass a dummy `crossSystem' argument so that `buildInputs' and
+             ;; `buildNativeInputs' are not coalesced.
+             ;; XXX: This is hacky and has other problems.
+             ;"--arg" "crossSystem" cross-system
+
+             `(,@(if attribute
+                     `("-A" ,attribute)
+                     '())
+               ,nixpkgs)))))
+
+(define (pipe-failed? pipe)
+  "Close pipe and return its status if it failed."
+  (let ((status (close-pipe pipe)))
+    (if (or (status:term-sig status)
+            (not (= (status:exit-val status) 0)))
+        status
+        #f)))
+
+(define (find-attribute-by-name name attributes)
+  "Return attribute NAME in ATTRIBUTES, an attribute set or list of SNix
+attributes, or #f if NAME cannot be found."
+  (find (lambda (a)
+          (match a
+            (('attribute _ (? (cut string=? <> name)) _)
+             a)
+            (_ #f)))
+        (match attributes
+          (('attribute-set (attributes ...))
+           attributes)
+          (_
+           attributes))))
+
+(define (package-source-output-path package)
+  "Return the output path of the \"src\" derivation of PACKAGE."
+  (derivation-source-output-path (attribute-value package)))
+
+
+;;;
+;;; Conversion of "Nix expressions" to "Guix expressions".
+;;;
+
+(define (factorize-uri uri version)
+  "Factorize URI, a package tarball URI as a string, such that any occurrences
+of the string VERSION is replaced by the symbol 'version."
+  (let ((version-rx (make-regexp (regexp-quote version))))
+    (match (regexp-exec version-rx uri)
+      (#f
+       uri)
+      (_
+       (let ((indices (fold-matches version-rx uri
+                                    '((0))
+                                    (lambda (m result)
+                                      (match result
+                                        (((start) rest ...)
+                                         `((,(match:end m))
+                                           (,start . ,(match:start m))
+                                           ,@rest)))))))
+         (fold (lambda (index result)
+                 (match index
+                   ((start)
+                    (cons (substring uri start)
+                          result))
+                   ((start . end)
+                    (cons* (substring uri start end)
+                           'version
+                           result))))
+               '()
+               indices))))))
+
+(define (snix-derivation->guix-package derivation)
+  "Return the `package' s-expression corresponding to SNix DERIVATION, a
+Nixpkgs `stdenv.mkDerivation'-style derivation, and the original source
+location of DERIVATION."
+  (match derivation
+    (('derivation _ _ (attributes ...))
+     (let*-values (((full-name loc)
+                    (match (find-attribute-by-name "name" attributes)
+                      (('attribute loc _ value)
+                       (values value loc))
+                      (_
+                       (values #f #f))))
+                   ((name version)
+                    (package-name->name+version full-name)))
+       (define (convert-inputs type)
+         ;; Convert the derivation's input from a list of SNix derivations to
+         ;; a list of name/variable pairs.
+         (match (and=> (find-attribute-by-name type attributes)
+                       attribute-value)
+           (#f
+            '())
+           ((('derivation _ _ (attributes ...)) ...)
+            (map (lambda (attrs)
+                   (let* ((full-name (attribute-value
+                                      (find-attribute-by-name "name" attrs)))
+                          (name      (package-name->name+version full-name)))
+                     (list name
+                           (list 'unquote
+                                 (string->symbol name)))))
+                 attributes))))
+
+       (define (maybe-inputs guix-name inputs)
+         (match inputs
+           (()
+            '())
+           ((inputs ...)
+            (list (list guix-name
+                        (list 'quasiquote inputs))))))
+
+       (define (pretty-uri uri version)
+         (match (factorize-uri uri version)
+           ((items ...)
+            `(string-append ,@items))
+           (x x)))
+
+       (let* ((source  (find-attribute-by-name "src" attributes))
+              (urls    (source-urls source))
+              (sha256  (source-sha256 source))
+              (meta    (and=> (find-attribute-by-name "meta" attributes)
+                              attribute-value)))
+         (values
+          `(package
+             (name ,name)
+             (version ,version)
+             (source (origin
+                      (method http-fetch)
+                      (uri ,(pretty-uri (car urls) version))
+                      (sha256
+                       (base32
+                        ,(bytevector->nix-base32-string sha256)))))
+             (build-system gnu-build-system)
+
+             ;; When doing a native Nixpkgs build, `buildInputs' is empty and
+             ;; everything is in `buildNativeInputs'.  So we can't distinguish
+             ;; between both, here.
+             ,@(maybe-inputs 'inputs
+                             (convert-inputs "buildNativeInputs"))
+             ,@(maybe-inputs 'propagated-inputs
+                             (convert-inputs "propagatedBuildNativeInputs"))
+
+             (home-page ,(and=> (find-attribute-by-name "homepage" meta)
+                                attribute-value))
+             (synopsis ,(and=> (find-attribute-by-name "description" meta)
+                               attribute-value))
+             (description
+              ,(and=> (find-attribute-by-name "longDescription" meta)
+                      attribute-value))
+             (license ,(and=> (find-attribute-by-name "license" meta)
+                              attribute-value)))
+          loc))))))
+
+(define (nixpkgs->guix-package nixpkgs attribute)
+  "Evaluate ATTRIBUTE in NIXPKGS, the file name of a Nixpkgs checkout,
+and return the `package' s-expression corresponding to that package."
+  (let ((port (open-nixpkgs nixpkgs attribute)))
+    (match (xml->snix port)
+      (('snix loc (and drv ('derivation _ ...)))
+       (and (not (pipe-failed? port))
+            (snix-derivation->guix-package drv)))
+      (_
+       (not (pipe-failed? port))))))
+
+;;; snix.scm ends here