[bug#52828] [PATCH v2] swh: Do not rely on $PATH for tar and gzip.

[Timothy Sample]

Hi Ludovic,

Ludovic Courtès <ludo@gnu.org> writes:

> What about uses of guix-daemon on other distros?  Perhaps we assume tar
> and gzip are already on PATH?

That’s my guess.  And if those other weird distros don’t have ‘tar’ and
‘gzip’ in “/usr/bin”, I’m sure they’re plenty accustomed to liberally
patching their packages.  ;)

> I’d feel more comfortable with a solution at the package level.  In the
> ‘guix’ package, or perhaps in a Makefile.am, we could hard-code absolute
> file names of tar and gzip in (guix scripts perform-download) and set
> PATH from there.  We’d need to do the same in (guix self) though.
>
> Alternatively, we could change (guix swh) to use Guile-Zlib and the tar
> implementation of Gash-Utils or that of Disarchive.
>
> WDYT?

I’ve attached a new patch that mixes those two suggestions but gets the
first one a little wrong.  It uses the absolute path for ‘tar’, but uses
Guile-zlib for decompression.

I honestly don’t have a strong opinion about when and where to set
‘$PATH’ vs. using a configured, absolute path.  My original patch
assumed that it’s the user’s job to make sure that ‘tar’ and ‘gzip’ are
available to Guix at runtime.  This patch assumes that that linkage
happens at configure time.  The main benefit I could see to setting
‘$PATH’ in ‘(guix scripts perform-download)’ is that we could add our
‘tar’ and ‘gzip’ as a suffix.  This makes it work while allowing users
to choose whatever ‘tar’ and ‘gzip’ they prefer.  The downside is that
whenever we use ‘(guix swh)’ have to remember to make sure that ‘tar’
and ‘gzip’ are available.

Basically, I can to change this to do the setup in ‘perform-download’,
but I really want to understand why.

Thanks!

>From 010666376890b6adf6c14253b1e2651b5c2861e8 Mon Sep 17 00:00:00 2001
From: Timothy Sample <samplet@ngyro.com>
Date: Fri, 14 Jan 2022 18:03:10 -0500
Subject: [PATCH v2] swh: Do not rely on $PATH for tar and gzip.

Fixes <https://bugs.gnu.org/52828>.

* configure.ac: Find the path of the tar utility.
* guix/config.scm.in (%tar): New variable.
* guix/self.scm (specification->package): Add "tar".
(make-config.scm): Add a 'tar' keyword parameter and use it to set
the '%tar' variable.
(compiled-guix): Add a 'tar' keyword parameter, and pass it to
'make-config.scm'; add 'guile-zlib' as an extension for "guix-core".
* guix/swh.scm (swh-download-archive): Use Guile-zlib to decompress
"flat" archives, and use an absolute path when invoking 'tar'.
---
 configure.ac       |  4 ++++
 guix/config.scm.in |  7 ++++++-
 guix/self.scm      | 18 ++++++++++++++----
 guix/swh.scm       | 13 ++++++++-----
 4 files changed, 32 insertions(+), 10 deletions(-)

diff --git a/configure.ac b/configure.ac
index 341cff8fbd..78f599b2f4 100644
--- a/configure.ac
+++ b/configure.ac
@@ -198,6 +198,10 @@ AC_SUBST([GZIP])
 AC_SUBST([BZIP2])
 AC_SUBST([XZ])
 
+dnl The '(guix swh)' module uses 'tar'.
+AC_PATH_PROG([TAR], [tar])
+AC_SUBST([TAR])
+
 LIBGCRYPT_LIBDIR="no"
 LIBGCRYPT_PREFIX="no"
 
diff --git a/guix/config.scm.in b/guix/config.scm.in
index d582d91d74..7b400a9ff8 100644
--- a/guix/config.scm.in
+++ b/guix/config.scm.in
@@ -37,7 +37,9 @@ (define-module (guix config)
             %system
             %gzip
             %bzip2
-            %xz))
+            %xz
+
+            %tar))
 
 ;;; Commentary:
 ;;;
@@ -118,4 +120,7 @@ (define %bzip2
 (define %xz
   "@XZ@")
 
+(define %tar
+  "@TAR@")
+
 ;;; config.scm ends here
diff --git a/guix/self.scm b/guix/self.scm
index 943bb0b498..3944f1a98d 100644
--- a/guix/self.scm
+++ b/guix/self.scm
@@ -1,6 +1,7 @@
 ;;; GNU Guix --- Functional package management for GNU
 ;;; Copyright © 2017, 2018, 2019, 2020, 2021 Ludovic Courtès <ludo@gnu.org>
 ;;; Copyright © 2020 Martin Becze <mjbecze@riseup.net>
+;;; Copyright © 2022 Timothy Sample <samplet@ngyro.com>
 ;;;
 ;;; This file is part of GNU Guix.
 ;;;
@@ -68,6 +69,7 @@ (define specification->package
       ("gzip"       (ref '(gnu packages compression) 'gzip))
       ("bzip2"      (ref '(gnu packages compression) 'bzip2))
       ("xz"         (ref '(gnu packages compression) 'xz))
+      ("tar"        (ref '(gnu packages base) 'tar))
       ("po4a"       (ref '(gnu packages gettext) 'po4a))
       ("gettext"       (ref '(gnu packages gettext) 'gettext-minimal))
       ("gcc-toolchain" (ref '(gnu packages commencement) 'gcc-toolchain))
@@ -749,6 +751,7 @@ (define* (compiled-guix source #:key
                         (gzip (specification->package "gzip"))
                         (bzip2 (specification->package "bzip2"))
                         (xz (specification->package "xz"))
+                        (tar (specification->package "tar"))
                         (guix (specification->package "guix")))
   "Return a file-like object that contains a compiled Guix."
   (define guile-avahi
@@ -832,7 +835,9 @@ (define* (compiled-guix source #:key
                     ,(local-file "../guix/store/schema.sql")))
 
                  #:extensions (list guile-gcrypt
-                                    guile-json)   ;for (guix swh)
+                                    ;; The following are for (guix swh)
+                                    guile-json
+                                    guile-zlib)
                  #:guile-for-build guile-for-build))
 
   (define *extra-modules*
@@ -964,6 +969,7 @@ (define* (compiled-guix source #:key
                     => ,(make-config.scm #:gzip gzip
                                          #:bzip2 bzip2
                                          #:xz xz
+                                         #:tar tar
                                          #:package-name
                                          %guix-package-name
                                          #:package-version
@@ -1071,7 +1077,7 @@ (define %default-config-variables
     (%storedir . "/gnu/store")
     (%sysconfdir . "/etc")))
 
-(define* (make-config.scm #:key gzip xz bzip2
+(define* (make-config.scm #:key gzip xz bzip2 tar
                           (package-name "GNU Guix")
                           (package-version "0")
                           (channel-metadata #f)
@@ -1097,7 +1103,8 @@ (define* (make-config.scm #:key gzip xz bzip2
                                %config-directory
                                %gzip
                                %bzip2
-                               %xz))
+                               %xz
+                               %tar))
 
                    (define %system
                      #$(%current-system))
@@ -1142,7 +1149,10 @@ (define* (make-config.scm #:key gzip xz bzip2
                    (define %bzip2
                      #+(and bzip2 (file-append bzip2 "/bin/bzip2")))
                    (define %xz
-                     #+(and xz (file-append xz "/bin/xz"))))
+                     #+(and xz (file-append xz "/bin/xz")))
+
+                   (define %tar
+                     #+(and tar (file-append tar "/bin/tar"))))
 
                ;; Guile 2.0 *requires* the 'define-module' to be at the
                ;; top-level or the 'toplevel-ref' in the resulting .go file are
diff --git a/guix/swh.scm b/guix/swh.scm
index c7c1c873a2..93bb023192 100644
--- a/guix/swh.scm
+++ b/guix/swh.scm
@@ -3,6 +3,7 @@
 ;;; Copyright © 2020 Jakub Kądziołka <kuba@kadziolka.net>
 ;;; Copyright © 2021 Xinglu Chen <public@yoctocell.xyz>
 ;;; Copyright © 2021 Simon Tournier <zimon.toutoune@gmail.com>
+;;; Copyright © 2022 Timothy Sample <samplet@ngyro.com>
 ;;;
 ;;; This file is part of GNU Guix.
 ;;;
@@ -23,6 +24,7 @@ (define-module (guix swh)
   #:use-module (guix base16)
   #:use-module (guix build utils)
   #:use-module ((guix build syscalls) #:select (mkdtemp!))
+  #:use-module (guix config)
   #:use-module (web uri)
   #:use-module (web client)
   #:use-module (web response)
@@ -35,6 +37,7 @@ (define-module (guix swh)
   #:use-module (ice-9 regex)
   #:use-module (ice-9 popen)
   #:use-module ((ice-9 ftw) #:select (scandir))
+  #:use-module (zlib)
   #:export (%swh-base-url
             %verify-swh-certificate?
             %allow-request?
@@ -674,11 +677,11 @@ (define* (swh-download-archive swhid output
                 swhid)
         #f)
        ((? port? input)
-        (let ((tar (open-pipe* OPEN_WRITE "tar" "-C" directory
-                               (match archive-type
-                                 ('flat "-xzvf")     ;gzipped
-                                 ('git-bare "-xvf")) ;uncompressed
-                               "-")))
+        (let ((input (match archive-type
+                       ;; "flat" archives are compressed.
+                       ('flat (make-zlib-input-port input #:format 'gzip))
+                       ('git-bare input)))
+              (tar (open-pipe* OPEN_WRITE %tar "-C" directory "-xvf" "-")))
           (dump-port input tar)
           (close-port input)
           (let ((status (close-pipe tar)))
-- 
2.34.0