nix dump-path: Add

This is primarily useful for extracting NARs from other stores (like
binary caches), which "nix-store --dump" cannot do.
This commit is contained in:
Eelco Dolstra 2017-05-04 14:16:26 +02:00
parent 44309c5067
commit 2da6a42448
No known key found for this signature in database
GPG key ID: 8170B4726D7198DE
3 changed files with 55 additions and 0 deletions

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@ -129,4 +129,14 @@ void StorePathsCommand::run(ref<Store> store)
run(store, storePaths); run(store, storePaths);
} }
void StorePathCommand::run(ref<Store> store)
{
auto storePaths = buildInstallables(store, false);
if (storePaths.size() != 1)
throw UsageError("this command requires exactly one store path");
run(store, *storePaths.begin());
}
} }

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@ -118,6 +118,16 @@ public:
bool useDefaultInstallables() override { return !all; } bool useDefaultInstallables() override { return !all; }
}; };
/* A command that operates on exactly one store path. */
struct StorePathCommand : public InstallablesCommand
{
using StoreCommand::run;
virtual void run(ref<Store> store, const Path & storePath) = 0;
void run(ref<Store> store) override;
};
typedef std::map<std::string, ref<Command>> Commands; typedef std::map<std::string, ref<Command>> Commands;
/* An argument parser that supports multiple subcommands, /* An argument parser that supports multiple subcommands,

35
src/nix/dump-path.cc Normal file
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@ -0,0 +1,35 @@
#include "command.hh"
#include "store-api.hh"
using namespace nix;
struct CmdDumpPath : StorePathCommand
{
std::string name() override
{
return "dump-path";
}
std::string description() override
{
return "dump a store path to stdout (in NAR format)";
}
Examples examples() override
{
return {
Example{
"To get a NAR from the binary cache https://cache.nixos.org/:",
"nix dump-path --store https://cache.nixos.org/ /nix/store/7crrmih8c52r8fbnqb933dxrsp44md93-glibc-2.25"
},
};
}
void run(ref<Store> store, const Path & storePath) override
{
FdSink sink(STDOUT_FILENO);
store->narFromPath(storePath, sink);
}
};
static RegisterCommand r1(make_ref<CmdDumpPath>());