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Make the hashes mirrors used by builtins.fetchurl configurable

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In particular, this allows it to be disabled in our tests.
This commit is contained in:
Eelco Dolstra 2017-07-17 13:07:08 +02:00
parent 4ec6eb1fdf
commit 49304bae81
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GPG key ID: 8170B4726D7198DE
4 changed files with 42 additions and 8 deletions
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28
doc/manual/command-ref/conf-file.xml
View file

@ -660,6 +660,34 @@ password <replaceable>my-password</replaceable>
</varlistentry>
<varlistentry xml:id="conf-hashed-mirrors"><term><literal>hashed-mirrors</literal></term>
<listitem><para>A list of web servers used by
<function>builtins.fetchurl</function> to obtain files by
hash. The default is
<literal>http://tarballs.nixos.org/</literal>. Given a hash type
<replaceable>ht</replaceable> and a base-16 hash
<replaceable>h</replaceable>, Nix will try to download the file
from
<literal>hashed-mirror/<replaceable>ht</replaceable>/<replaceable>h</replaceable></literal>.
This allows files to be downloaded even if they have disappeared
from their original URI. For example, given the default mirror
<literal>http://tarballs.nixos.org/</literal>, when building the derivation
<programlisting>
builtins.fetchurl {
url = https://example.org/foo-1.2.3.tar.xz;
sha256 = "2c26b46b68ffc68ff99b453c1d30413413422d706483bfa0f98a5e886266e7ae";
}
</programlisting>
Nix will attempt to download this file from
<literal>http://tarballs.nixos.org/sha256/2c26b46b68ffc68ff99b453c1d30413413422d706483bfa0f98a5e886266e7ae</literal>
first. If it is not available there, if will try the original URI.</para></listitem>
</varlistentry>
</variablelist>
</para>

15
src/libstore/builtins.cc
View file

@ -38,12 +38,15 @@ void builtinFetchurl(const BasicDerivation & drv, const std::string & netrcData)
std::shared_ptr<std::string> data;
try {
if (getAttr("outputHashMode") == "flat")
data = fetch("http://tarballs.nixos.org/" + getAttr("outputHashAlgo") + "/" + getAttr("outputHash"));
} catch (Error & e) {
debug(e.what());
}
if (getAttr("outputHashMode") == "flat")
for (auto hashedMirror : settings.hashedMirrors.get())
try {
if (!hasSuffix(hashedMirror, "/")) hashedMirror += '/';
data = fetch(hashedMirror + getAttr("outputHashAlgo") + "/" + getAttr("outputHash"));
break;
} catch (Error & e) {
debug(e.what());
}
if (!data) data = fetch(getAttr("url"));

3
src/libstore/globals.hh
View file

@ -327,6 +327,9 @@ public:
"Whether builders can acquire new privileges by calling programs with "
"setuid/setgid bits or with file capabilities."};
#endif
Setting<Strings> hashedMirrors{this, {"http://tarballs.nixos.org/"}, "hashed-mirrors",
"A list of servers used by builtins.fetchurl to fetch files by hash."};
};

4
tests/fetchurl.sh
View file

@ -5,7 +5,7 @@ clearStore
# Test fetching a flat file.
hash=$(nix-hash --flat --type sha256 ./fetchurl.sh)
outPath=$(nix-build '<nix/fetchurl.nix>' --argstr url file://$(pwd)/fetchurl.sh --argstr sha256 $hash --no-out-link)
outPath=$(nix-build '<nix/fetchurl.nix>' --argstr url file://$(pwd)/fetchurl.sh --argstr sha256 $hash --no-out-link --option hashed-mirrors '')
cmp $outPath fetchurl.sh
@ -14,7 +14,7 @@ clearStore
hash=$(nix hash-file --type sha512 --base64 ./fetchurl.sh)
outPath=$(nix-build '<nix/fetchurl.nix>' --argstr url file://$(pwd)/fetchurl.sh --argstr sha512 $hash --no-out-link)
outPath=$(nix-build '<nix/fetchurl.nix>' --argstr url file://$(pwd)/fetchurl.sh --argstr sha512 $hash --no-out-link --option hashed-mirrors '')
cmp $outPath fetchurl.sh