Add path primop.

builtins.path allows specifying the name of a path (which makes paths
with store-illegal names now addable), allows adding paths with flat
instead of recursive hashes, allows specifying a filter (so is a
generalization of filterSource), and allows specifying an expected
hash (enabling safe path adding in pure mode).
This commit is contained in:
Shea Levy 2018-01-25 07:05:57 -08:00
parent 98f3c75a0e
commit 69d82e5c58
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GPG key ID: 5C0BD6957D86FE27
8 changed files with 162 additions and 27 deletions

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@ -308,8 +308,9 @@ stdenv.mkDerivation { … }
</varlistentry>
<varlistentry><term><function>builtins.filterSource</function>
<replaceable>e1</replaceable> <replaceable>e2</replaceable></term>
<varlistentry xml:id='builtin-filterSource'>
<term><function>builtins.filterSource</function>
<replaceable>e1</replaceable> <replaceable>e2</replaceable></term>
<listitem>
@ -768,6 +769,75 @@ Evaluates to <literal>[ "foo" ]</literal>.
</varlistentry>
<varlistentry>
<term>
<function>builtins.path</function>
<replaceable>args</replaceable>
</term>
<listitem>
<para>
An enrichment of the built-in path type, based on the attributes
present in <replaceable>args</replaceable>. All are optional
except <varname>path</varname>:
</para>
<variablelist>
<varlistentry>
<term>path</term>
<listitem>
<para>The underlying path.</para>
</listitem>
</varlistentry>
<varlistentry>
<term>name</term>
<listitem>
<para>
The name of the path when added to the store. This can
used to reference paths that have nix-illegal characters
in their names, like <literal>@</literal>.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>filter</term>
<listitem>
<para>
A function of the type expected by
<link linkend="builtin-filterSource">builtins.filterSource</link>,
with the same semantics.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>recursive</term>
<listitem>
<para>
When <literal>false</literal>, when
<varname>path</varname> is added to the store it is with a
flat hash, rather than a hash of the NAR serialization of
the file. Thus, <varname>path</varname> must refer to a
regular file, not a directory. This allows similar
behavior to <literal>fetchurl</literal>. Defaults to
<literal>true</literal>.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>sha256</term>
<listitem>
<para>
When provided, this is the expected hash of the file at
the path. Evaluation will fail if the hash is incorrect,
and providing a hash allows
<literal>builtins.path</literal> to be used even when the
<literal>pure-eval</literal> nix config option is on.
</para>
</listitem>
</varlistentry>
</variablelist>
</listitem>
</varlistentry>
<varlistentry><term><function>builtins.pathExists</function>
<replaceable>path</replaceable></term>