From fb30259fd188b039cc88d148f34c683c258ebf9b Mon Sep 17 00:00:00 2001
From: Timothy DeHerrera <tim@nrdxp.dev>
Date: Wed, 11 Jan 2023 13:53:42 -0700
Subject: [PATCH] path-info: implement --filter-substitutable

Fixes #3946

Filters out any paths from the output which are already available in
the configured substituters. Useful in CI environments, to avoid builds
that are already cached.
---
 src/nix/path-info.cc | 35 +++++++++++++++++++++++++++++++++--
 src/nix/path-info.md |  9 +++++++++
 2 files changed, 42 insertions(+), 2 deletions(-)

diff --git a/src/nix/path-info.cc b/src/nix/path-info.cc
index 613c5b1918d..10ceacf12b0 100644
--- a/src/nix/path-info.cc
+++ b/src/nix/path-info.cc
@@ -16,6 +16,7 @@ struct CmdPathInfo : StorePathsCommand, MixJSON
     bool showClosureSize = false;
     bool humanReadable = false;
     bool showSigs = false;
+    bool showSubStatus = false;
 
     CmdPathInfo()
     {
@@ -45,6 +46,14 @@ struct CmdPathInfo : StorePathsCommand, MixJSON
             .description = "Show signatures.",
             .handler = {&showSigs, true},
         });
+
+        addFlag({
+            .longName = "filter-substitutable",
+            .description =
+                "Query path availability in the configured substituters, printing only those that are not available. "
+                "When used with `--json`, a `substitutable` boolean is added to the output.",
+            .handler = {&showSubStatus, true},
+        });
     }
 
     std::string description() override
@@ -86,14 +95,36 @@ struct CmdPathInfo : StorePathsCommand, MixJSON
         for (auto & storePath : storePaths)
             pathLen = std::max(pathLen, store->printStorePath(storePath).size());
 
+        StorePathSet substitutablePaths;
+        if (showSubStatus)
+            substitutablePaths = store->querySubstitutablePaths(StorePathSet(storePaths.begin(), storePaths.end()));
+
         if (json) {
-            std::cout << store->pathInfoToJSON(
+            auto json = store->pathInfoToJSON(
                 // FIXME: preserve order?
                 StorePathSet(storePaths.begin(), storePaths.end()),
-                true, showClosureSize, SRI, AllowInvalid).dump();
+                true, showClosureSize, SRI, AllowInvalid);
+
+            if (showSubStatus) {
+                for (auto & v : json) {
+                    std::string const storePathS = v["path"];
+                    v["substitutable"] = (bool) substitutablePaths.count(store->parseStorePath(storePathS));
+                }
+            }
+            std::cout << json.dump();
         }
 
         else {
+            StorePaths missingPaths;
+
+            if (showSubStatus) {
+                for (auto & path : storePaths) {
+                    if (!substitutablePaths.count(path))
+                      missingPaths.emplace_back(std::move(path));
+                }
+
+                storePaths = missingPaths;
+            }
 
             for (auto & storePath : storePaths) {
                 auto info = store->queryPathInfo(storePath);
diff --git a/src/nix/path-info.md b/src/nix/path-info.md
index b30898ac0f0..e569e0557ed 100644
--- a/src/nix/path-info.md
+++ b/src/nix/path-info.md
@@ -39,6 +39,15 @@ R""(
 
   ```
 
+* Print all dependant paths which do not exist in any configured binary cache:
+
+  ```console
+  # nix path-info -r --filter-substitutable /nix/store/blzxgyvrk32ki6xga10phr4sby2xf25q-geeqie-1.5.1
+  /nix/store/blzxgyvrk32ki6xga10phr4sby2xf25q-geeqie-1.5.1
+  /nix/store/w2vgpk3rdl6smqz7ixxywqapgagsarjf-fbida-2.14
+  ...
+  ```
+
 * Print the 10 most recently added paths (using --json and the jq(1)
   command):