Merge pull request #14704 from NixOS/version-output

Introduce `--json-format` for `nix path-info`

doc/manual/rl-next/json-format-changes.md

@@ -6,13 +6,29 @@ issues: []
 
 JSON formats for store path info and derivations have been updated with new versions and structured fields.
 
-## Store Path Info JSON (Version 2)
+## Store Path Info JSON
 
-The store path info JSON format has been updated from version 1 to version 2:
+`nix path-info --json` now requires a `--json-format` flag to specify the output format version.
+Using `--json` without `--json-format` is deprecated and will become an error in a future release.
+For now, it defaults to version 1 with a warning, for a smoother migration.
 
-- **Added `version` field**:
+### Version 1 (`--json-format 1`)
 
-  All store path info JSON now includes `"version": 2`.
+This is the legacy format, preserved for backwards compatibility:
+
+- String-based hash values (e.g., `"narHash": "sha256:FePFYIlM..."`)
+- String-based content addresses (e.g., `"ca": "fixed:r:sha256:1abc..."`)
+- Full store paths in references (e.g., `"/nix/store/abc...-foo"`)
+- Now includes `"storeDir"` field at the top level
+
+### Version 2 (`--json-format 2`)
+
+The new structured format with the following changes:
+
+- **Store path base names in references**:
+
+  References use store path base names (e.g., `"abc...-foo"`) instead of full paths.
+  Combined with `storeDir`, the full path can be reconstructed.
 
 - **Structured `ca` field**:
 
@@ -33,7 +49,16 @@ The store path info JSON format has been updated from version 1 to version 2:
 
 Nix currently only produces, and doesn't consume this format.
 
-**Affected command**: `nix path-info --json`
+Additionally the following field is added to both formats.
+(The `version` tracks breaking changes, and adding fields to outputted JSON is not a breaking change.)
+
+- **`version` field**:
+
+  All store path info JSON now includes `"version": <1|2>`.
+
+- **`storeDir` field**:
+
+  Top-level `"storeDir"` field contains the store directory path (e.g., `"/nix/store"`).
 
 ## Derivation JSON (Version 4)
 

doc/manual/source/protocols/json/schema/nar-info-v1

@@ -1 +0,0 @@
-../../../../../../src/libstore-tests/data/nar-info

doc/manual/source/protocols/json/schema/nar-info-v2

@@ -0,0 +1 @@
+../../../../../../src/libstore-tests/data/nar-info/json-2

doc/manual/source/protocols/json/schema/store-object-info-v2

@@ -1 +1 @@
-../../../../../../src/libstore-tests/data/path-info
+../../../../../../src/libstore-tests/data/path-info/json-2

doc/manual/source/protocols/json/schema/store-object-info-v2.yaml

@@ -63,7 +63,7 @@ $defs:
           - Version 2: Use structured JSON type for `ca`
 
       path:
-        type: string
+        "$ref": "./store-path-v1.yaml"
         title: Store Path
         description: |
           [Store path](@docroot@/store/store-path.md) to the given store object.
@@ -89,7 +89,7 @@ $defs:
         description: |
           An array of [store paths](@docroot@/store/store-path.md), possibly including this one.
         items:
-          type: string
+          "$ref": "./store-path-v1.yaml"
 
       ca:
         oneOf:
@@ -128,7 +128,9 @@ $defs:
       references: { $ref: "#/$defs/base/properties/references" }
       ca: { $ref: "#/$defs/base/properties/ca" }
       deriver:
-        type: ["string", "null"]
+        oneOf:
+          - "$ref": "./store-path-v1.yaml"
+          - type: "null"
         title: Deriver
         description: |
           If known, the path to the [store derivation](@docroot@/glossary.md#gloss-store-derivation) from which this store object was produced.

doc/manual/source/protocols/json/store-object-info.md

@@ -29,13 +29,13 @@
 ### NAR info (minimal)
 
 ```json
-{{#include schema/nar-info-v1/pure.json}}
+{{#include schema/nar-info-v2/pure.json}}
 ```
 
 ### NAR info (with binary cache fields)
 
 ```json
-{{#include schema/nar-info-v1/impure.json}}
+{{#include schema/nar-info-v2/impure.json}}
 ```
 
 <!-- need to convert YAML to JSON first

src/json-schema-checks/meson.build

@@ -154,18 +154,18 @@ schemas += [
     'stem' : 'store-object-info',
     'schema' : schema_dir / 'store-object-info-v2.yaml',
     'files' : [
-      'pure.json',
+      'json-2' / 'pure.json',
-      'impure.json',
+      'json-2' / 'impure.json',
-      'empty_pure.json',
+      'json-2' / 'empty_pure.json',
-      'empty_impure.json',
+      'json-2' / 'empty_impure.json',
     ],
   },
   {
     'stem' : 'nar-info',
     'schema' : schema_dir / 'store-object-info-v2.yaml',
     'files' : [
-      'pure.json',
+      'json-2' / 'pure.json',
-      'impure.json',
+      'json-2' / 'impure.json',
     ],
   },
   {
@@ -182,30 +182,30 @@ schemas += [
     'stem' : 'store-object-info',
     'schema' : schema_dir / 'store-object-info-v2.yaml#/$defs/base',
     'files' : [
-      'pure.json',
+      'json-2' / 'pure.json',
-      'empty_pure.json',
+      'json-2' / 'empty_pure.json',
     ],
   },
   {
     'stem' : 'store-object-info',
     'schema' : schema_dir / 'store-object-info-v2.yaml#/$defs/impure',
     'files' : [
-      'impure.json',
+      'json-2' / 'impure.json',
-      'empty_impure.json',
+      'json-2' / 'empty_impure.json',
     ],
   },
   {
     'stem' : 'nar-info',
     'schema' : schema_dir / 'store-object-info-v2.yaml#/$defs/base',
     'files' : [
-      'pure.json',
+      'json-2' / 'pure.json',
     ],
   },
   {
     'stem' : 'nar-info',
     'schema' : schema_dir / 'store-object-info-v2.yaml#/$defs/narInfo',
     'files' : [
-      'impure.json',
+      'json-2' / 'impure.json',
     ],
   },
 ]

src/libstore-tests/data/nar-info/json-1/impure.json

@@ -0,0 +1,21 @@
+{
+  "ca": "fixed:r:sha256:1lr187v6dck1rjh2j6svpikcfz53wyl3qrlcbb405zlh13x0khhh",
+  "compression": "xz",
+  "deriver": "/nix/store/g1w7hy3qg1w7hy3qg1w7hy3qg1w7hy3q-bar.drv",
+  "downloadHash": "sha256-FePFYIlMuycIXPZbWi7LGEiMmZSX9FMbaQenWBzm1Sc=",
+  "downloadSize": 4029176,
+  "narHash": "sha256-FePFYIlMuycIXPZbWi7LGEiMmZSX9FMbaQenWBzm1Sc=",
+  "narSize": 34878,
+  "references": [
+    "/nix/store/g1w7hy3qg1w7hy3qg1w7hy3qg1w7hy3q-bar",
+    "/nix/store/n5wkd9frr45pa74if5gpz9j7mifg27fh-foo"
+  ],
+  "registrationTime": 23423,
+  "signatures": [
+    "asdf",
+    "qwer"
+  ],
+  "ultimate": true,
+  "url": "nar/1w1fff338fvdw53sqgamddn1b2xgds473pv6y13gizdbqjv4i5p3.nar.xz",
+  "version": 1
+}

src/libstore-tests/data/nar-info/json-1/pure.json

@@ -0,0 +1,10 @@
+{
+  "ca": "fixed:r:sha256:1lr187v6dck1rjh2j6svpikcfz53wyl3qrlcbb405zlh13x0khhh",
+  "narHash": "sha256-FePFYIlMuycIXPZbWi7LGEiMmZSX9FMbaQenWBzm1Sc=",
+  "narSize": 34878,
+  "references": [
+    "/nix/store/g1w7hy3qg1w7hy3qg1w7hy3qg1w7hy3q-bar",
+    "/nix/store/n5wkd9frr45pa74if5gpz9j7mifg27fh-foo"
+  ],
+  "version": 1
+}

src/libstore-tests/data/nar-info/json-1/pure_noversion.json

@@ -0,0 +1,9 @@
+{
+  "ca": "fixed:r:sha256:1lr187v6dck1rjh2j6svpikcfz53wyl3qrlcbb405zlh13x0khhh",
+  "narHash": "sha256-FePFYIlMuycIXPZbWi7LGEiMmZSX9FMbaQenWBzm1Sc=",
+  "narSize": 34878,
+  "references": [
+    "/nix/store/g1w7hy3qg1w7hy3qg1w7hy3qg1w7hy3q-bar",
+    "/nix/store/n5wkd9frr45pa74if5gpz9j7mifg27fh-foo"
+  ]
+}

src/libstore-tests/data/nar-info/json-2/impure.json

@@ -8,7 +8,7 @@
     "method": "nar"
   },
   "compression": "xz",
-  "deriver": "/nix/store/g1w7hy3qg1w7hy3qg1w7hy3qg1w7hy3q-bar.drv",
+  "deriver": "g1w7hy3qg1w7hy3qg1w7hy3qg1w7hy3q-bar.drv",
   "downloadHash": {
     "algorithm": "sha256",
     "format": "base16",
@@ -22,8 +22,8 @@
   },
   "narSize": 34878,
   "references": [
-    "/nix/store/g1w7hy3qg1w7hy3qg1w7hy3qg1w7hy3q-bar",
+    "g1w7hy3qg1w7hy3qg1w7hy3qg1w7hy3q-bar",
-    "/nix/store/n5wkd9frr45pa74if5gpz9j7mifg27fh-foo"
+    "n5wkd9frr45pa74if5gpz9j7mifg27fh-foo"
   ],
   "registrationTime": 23423,
   "signatures": [

src/libstore-tests/data/nar-info/json-2/pure.json

@@ -14,8 +14,8 @@
   },
   "narSize": 34878,
   "references": [
-    "/nix/store/g1w7hy3qg1w7hy3qg1w7hy3qg1w7hy3q-bar",
+    "g1w7hy3qg1w7hy3qg1w7hy3qg1w7hy3q-bar",
-    "/nix/store/n5wkd9frr45pa74if5gpz9j7mifg27fh-foo"
+    "n5wkd9frr45pa74if5gpz9j7mifg27fh-foo"
   ],
   "version": 2
 }

src/libstore-tests/data/path-info/json-1/empty_impure.json

@@ -0,0 +1,11 @@
+{
+  "ca": null,
+  "deriver": null,
+  "narHash": "sha256-FePFYIlMuycIXPZbWi7LGEiMmZSX9FMbaQenWBzm1Sc=",
+  "narSize": 0,
+  "references": [],
+  "registrationTime": null,
+  "signatures": [],
+  "ultimate": false,
+  "version": 1
+}

src/libstore-tests/data/path-info/json-1/empty_pure.json

@@ -0,0 +1,7 @@
+{
+  "ca": null,
+  "narHash": "sha256-FePFYIlMuycIXPZbWi7LGEiMmZSX9FMbaQenWBzm1Sc=",
+  "narSize": 0,
+  "references": [],
+  "version": 1
+}

src/libstore-tests/data/path-info/json-1/impure.json

@@ -0,0 +1,17 @@
+{
+  "ca": "fixed:r:sha256:1lr187v6dck1rjh2j6svpikcfz53wyl3qrlcbb405zlh13x0khhh",
+  "deriver": "/nix/store/g1w7hy3qg1w7hy3qg1w7hy3qg1w7hy3q-bar.drv",
+  "narHash": "sha256-FePFYIlMuycIXPZbWi7LGEiMmZSX9FMbaQenWBzm1Sc=",
+  "narSize": 34878,
+  "references": [
+    "/nix/store/g1w7hy3qg1w7hy3qg1w7hy3qg1w7hy3q-bar",
+    "/nix/store/n5wkd9frr45pa74if5gpz9j7mifg27fh-foo"
+  ],
+  "registrationTime": 23423,
+  "signatures": [
+    "asdf",
+    "qwer"
+  ],
+  "ultimate": true,
+  "version": 1
+}

src/libstore-tests/data/path-info/json-1/pure.json

@@ -0,0 +1,10 @@
+{
+  "ca": "fixed:r:sha256:1lr187v6dck1rjh2j6svpikcfz53wyl3qrlcbb405zlh13x0khhh",
+  "narHash": "sha256-FePFYIlMuycIXPZbWi7LGEiMmZSX9FMbaQenWBzm1Sc=",
+  "narSize": 34878,
+  "references": [
+    "/nix/store/g1w7hy3qg1w7hy3qg1w7hy3qg1w7hy3q-bar",
+    "/nix/store/n5wkd9frr45pa74if5gpz9j7mifg27fh-foo"
+  ],
+  "version": 1
+}

src/libstore-tests/data/path-info/json-1/pure_noversion.json

@@ -0,0 +1,9 @@
+{
+  "ca": "fixed:r:sha256:1lr187v6dck1rjh2j6svpikcfz53wyl3qrlcbb405zlh13x0khhh",
+  "narHash": "sha256-FePFYIlMuycIXPZbWi7LGEiMmZSX9FMbaQenWBzm1Sc=",
+  "narSize": 34878,
+  "references": [
+    "/nix/store/g1w7hy3qg1w7hy3qg1w7hy3qg1w7hy3q-bar",
+    "/nix/store/n5wkd9frr45pa74if5gpz9j7mifg27fh-foo"
+  ]
+}

src/libstore-tests/data/path-info/json-2/impure.json

@@ -7,7 +7,7 @@
     },
     "method": "nar"
   },
-  "deriver": "/nix/store/g1w7hy3qg1w7hy3qg1w7hy3qg1w7hy3q-bar.drv",
+  "deriver": "g1w7hy3qg1w7hy3qg1w7hy3qg1w7hy3q-bar.drv",
   "narHash": {
     "algorithm": "sha256",
     "format": "base16",
@@ -15,8 +15,8 @@
   },
   "narSize": 34878,
   "references": [
-    "/nix/store/g1w7hy3qg1w7hy3qg1w7hy3qg1w7hy3q-bar",
+    "g1w7hy3qg1w7hy3qg1w7hy3qg1w7hy3q-bar",
-    "/nix/store/n5wkd9frr45pa74if5gpz9j7mifg27fh-foo"
+    "n5wkd9frr45pa74if5gpz9j7mifg27fh-foo"
   ],
   "registrationTime": 23423,
   "signatures": [

src/libstore-tests/data/path-info/json-2/pure.json

@@ -14,8 +14,8 @@
   },
   "narSize": 34878,
   "references": [
-    "/nix/store/g1w7hy3qg1w7hy3qg1w7hy3qg1w7hy3q-bar",
+    "g1w7hy3qg1w7hy3qg1w7hy3qg1w7hy3q-bar",
-    "/nix/store/n5wkd9frr45pa74if5gpz9j7mifg27fh-foo"
+    "n5wkd9frr45pa74if5gpz9j7mifg27fh-foo"
   ],
   "version": 2
 }

src/libstore-tests/nar-info.cc

@@ -11,9 +11,19 @@ namespace nix {
 
 using nlohmann::json;
 
-class NarInfoTest : public CharacterizationTest, public LibStoreTest
+class NarInfoTestV1 : public CharacterizationTest, public LibStoreTest
 {
-    std::filesystem::path unitTestData = getUnitTestData() / "nar-info";
+    std::filesystem::path unitTestData = getUnitTestData() / "nar-info" / "json-1";
+
+    std::filesystem::path goldenMaster(PathView testStem) const override
+    {
+        return unitTestData / (testStem + ".json");
+    }
+};
+
+class NarInfoTestV2 : public CharacterizationTest, public LibStoreTest
+{
+    std::filesystem::path unitTestData = getUnitTestData() / "nar-info" / "json-2";
 
     std::filesystem::path goldenMaster(PathView testStem) const override
     {
@@ -59,8 +69,8 @@ static NarInfo makeNarInfo(const Store & store, bool includeImpureInfo)
     return info;
 }
 
-#define JSON_TEST(STEM, PURE)                                                                         \
+#define JSON_READ_TEST_V1(STEM, PURE)                              \
-    TEST_F(NarInfoTest, NarInfo_##STEM##_from_json)                                                   \
+    TEST_F(NarInfoTestV1, NarInfo_##STEM##_from_json)              \
     {                                                              \
         readTest(#STEM, [&](const auto & encoded_) {               \
             auto encoded = json::parse(encoded_);                  \
@@ -68,18 +78,54 @@ static NarInfo makeNarInfo(const Store & store, bool includeImpureInfo)
             auto got = UnkeyedNarInfo::fromJSON(&*store, encoded); \
             ASSERT_EQ(got, expected);                              \
         });                                                        \
-    }                                                                                                 \
+    }
-                                                                                                      \
+
-    TEST_F(NarInfoTest, NarInfo_##STEM##_to_json)                                                     \
+#define JSON_WRITE_TEST_V1(STEM, PURE)                                                                         \
+    TEST_F(NarInfoTestV1, NarInfo_##STEM##_to_json)                                                            \
     {                                                                                                          \
         writeTest(                                                                                             \
             #STEM,                                                                                             \
-            [&]() -> json { return makeNarInfo(*store, PURE).toJSON(&*store, PURE); },                \
+            [&]() -> json { return makeNarInfo(*store, PURE).toJSON(&*store, PURE, PathInfoJsonFormat::V1); }, \
             [](const auto & file) { return json::parse(readFile(file)); },                                     \
             [](const auto & file, const auto & got) { return writeFile(file, got.dump(2) + "\n"); });          \
     }
 
-JSON_TEST(pure, false)
+#define JSON_TEST_V1(STEM, PURE)  \
-JSON_TEST(impure, true)
+    JSON_READ_TEST_V1(STEM, PURE) \
+    JSON_WRITE_TEST_V1(STEM, PURE)
+
+#define JSON_READ_TEST_V2(STEM, PURE)                              \
+    TEST_F(NarInfoTestV2, NarInfo_##STEM##_from_json)              \
+    {                                                              \
+        readTest(#STEM, [&](const auto & encoded_) {               \
+            auto encoded = json::parse(encoded_);                  \
+            auto expected = makeNarInfo(*store, PURE);             \
+            auto got = UnkeyedNarInfo::fromJSON(nullptr, encoded); \
+            ASSERT_EQ(got, expected);                              \
+        });                                                        \
+    }
+
+#define JSON_WRITE_TEST_V2(STEM, PURE)                                                                         \
+    TEST_F(NarInfoTestV2, NarInfo_##STEM##_to_json)                                                            \
+    {                                                                                                          \
+        writeTest(                                                                                             \
+            #STEM,                                                                                             \
+            [&]() -> json { return makeNarInfo(*store, PURE).toJSON(nullptr, PURE, PathInfoJsonFormat::V2); }, \
+            [](const auto & file) { return json::parse(readFile(file)); },                                     \
+            [](const auto & file, const auto & got) { return writeFile(file, got.dump(2) + "\n"); });          \
+    }
+
+#define JSON_TEST_V2(STEM, PURE)  \
+    JSON_READ_TEST_V2(STEM, PURE) \
+    JSON_WRITE_TEST_V2(STEM, PURE)
+
+JSON_TEST_V1(pure, false)
+JSON_TEST_V1(impure, true)
+
+// Test that JSON without explicit version field parses as V1
+JSON_READ_TEST_V1(pure_noversion, false)
+
+JSON_TEST_V2(pure, false)
+JSON_TEST_V2(impure, true)
 
 } // namespace nix

src/libstore-tests/path-info.cc

@@ -10,9 +10,19 @@ namespace nix {
 
 using nlohmann::json;
 
-class PathInfoTest : public CharacterizationTest, public LibStoreTest
+class PathInfoTestV1 : public CharacterizationTest, public LibStoreTest
 {
-    std::filesystem::path unitTestData = getUnitTestData() / "path-info";
+    std::filesystem::path unitTestData = getUnitTestData() / "path-info" / "json-1";
+
+    std::filesystem::path goldenMaster(PathView testStem) const override
+    {
+        return unitTestData / (testStem + ".json");
+    }
+};
+
+class PathInfoTestV2 : public CharacterizationTest, public LibStoreTest
+{
+    std::filesystem::path unitTestData = getUnitTestData() / "path-info" / "json-2";
 
     std::filesystem::path goldenMaster(PathView testStem) const override
     {
@@ -65,8 +75,8 @@ static UnkeyedValidPathInfo makeFull(const Store & store, bool includeImpureInfo
     return makeFullKeyed(store, includeImpureInfo);
 }
 
-#define JSON_TEST(STEM, OBJ, PURE)                                                                    \
+#define JSON_READ_TEST_V1(STEM, OBJ)                                                     \
-    TEST_F(PathInfoTest, PathInfo_##STEM##_from_json)                                                 \
+    TEST_F(PathInfoTestV1, PathInfo_##STEM##_from_json)                                  \
     {                                                                                    \
         readTest(#STEM, [&](const auto & encoded_) {                                     \
             auto encoded = json::parse(encoded_);                                        \
@@ -74,24 +84,61 @@ static UnkeyedValidPathInfo makeFull(const Store & store, bool includeImpureInfo
             auto expected = OBJ;                                                         \
             ASSERT_EQ(got, expected);                                                    \
         });                                                                              \
-    }                                                                                                 \
+    }
-                                                                                                      \
+
-    TEST_F(PathInfoTest, PathInfo_##STEM##_to_json)                                                   \
+#define JSON_WRITE_TEST_V1(STEM, OBJ, PURE)                                                           \
+    TEST_F(PathInfoTestV1, PathInfo_##STEM##_to_json)                                                 \
     {                                                                                                 \
         writeTest(                                                                                    \
             #STEM,                                                                                    \
-            [&]() -> json { return OBJ.toJSON(&*store, PURE); },                                      \
+            [&]() -> json { return OBJ.toJSON(&*store, PURE, PathInfoJsonFormat::V1); },              \
             [](const auto & file) { return json::parse(readFile(file)); },                            \
             [](const auto & file, const auto & got) { return writeFile(file, got.dump(2) + "\n"); }); \
     }
 
-JSON_TEST(empty_pure, makeEmpty(), false)
+#define JSON_TEST_V1(STEM, OBJ, PURE) \
-JSON_TEST(empty_impure, makeEmpty(), true)
+    JSON_READ_TEST_V1(STEM, OBJ)      \
+    JSON_WRITE_TEST_V1(STEM, OBJ, PURE)
 
-JSON_TEST(pure, makeFull(*store, false), false)
+#define JSON_READ_TEST_V2(STEM, OBJ)                                                     \
-JSON_TEST(impure, makeFull(*store, true), true)
+    TEST_F(PathInfoTestV2, PathInfo_##STEM##_from_json)                                  \
+    {                                                                                    \
+        readTest(#STEM, [&](const auto & encoded_) {                                     \
+            auto encoded = json::parse(encoded_);                                        \
+            UnkeyedValidPathInfo got = UnkeyedValidPathInfo::fromJSON(nullptr, encoded); \
+            auto expected = OBJ;                                                         \
+            ASSERT_EQ(got, expected);                                                    \
+        });                                                                              \
+    }
 
-TEST_F(PathInfoTest, PathInfo_full_shortRefs)
+#define JSON_WRITE_TEST_V2(STEM, OBJ, PURE)                                                           \
+    TEST_F(PathInfoTestV2, PathInfo_##STEM##_to_json)                                                 \
+    {                                                                                                 \
+        writeTest(                                                                                    \
+            #STEM,                                                                                    \
+            [&]() -> json { return OBJ.toJSON(nullptr, PURE, PathInfoJsonFormat::V2); },              \
+            [](const auto & file) { return json::parse(readFile(file)); },                            \
+            [](const auto & file, const auto & got) { return writeFile(file, got.dump(2) + "\n"); }); \
+    }
+
+#define JSON_TEST_V2(STEM, OBJ, PURE) \
+    JSON_READ_TEST_V2(STEM, OBJ)      \
+    JSON_WRITE_TEST_V2(STEM, OBJ, PURE)
+
+JSON_TEST_V1(empty_pure, makeEmpty(), false)
+JSON_TEST_V1(empty_impure, makeEmpty(), true)
+JSON_TEST_V1(pure, makeFull(*store, false), false)
+JSON_TEST_V1(impure, makeFull(*store, true), true)
+
+// Test that JSON without explicit version field parses as V1
+JSON_READ_TEST_V1(pure_noversion, makeFull(*store, false))
+
+JSON_TEST_V2(empty_pure, makeEmpty(), false)
+JSON_TEST_V2(empty_impure, makeEmpty(), true)
+JSON_TEST_V2(pure, makeFull(*store, false), false)
+JSON_TEST_V2(impure, makeFull(*store, true), true)
+
+TEST_F(PathInfoTestV2, PathInfo_full_shortRefs)
 {
     ValidPathInfo it = makeFullKeyed(*store, true);
     // it.references = unkeyed.references;

src/libstore/include/nix/store/nar-info.hh

@@ -25,7 +25,8 @@ struct UnkeyedNarInfo : virtual UnkeyedValidPathInfo
     // TODO libc++ 16 (used by darwin) missing `std::optional::operator <=>`, can't do yet
     // auto operator <=>(const NarInfo &) const = default;
 
-    nlohmann::json toJSON(const StoreDirConfig * store, bool includeImpureInfo) const override;
+    nlohmann::json
+    toJSON(const StoreDirConfig * store, bool includeImpureInfo, PathInfoJsonFormat format) const override;
     static UnkeyedNarInfo fromJSON(const StoreDirConfig * store, const nlohmann::json & json);
 };
 

src/libstore/include/nix/store/path-info.hh

@@ -14,6 +14,22 @@ namespace nix {
 class Store;
 struct StoreDirConfig;
 
+/**
+ * JSON format version for path info output.
+ */
+enum class PathInfoJsonFormat {
+    /// Legacy format with string hashes and full store paths
+    V1 = 1,
+    /// New format with structured hashes and store path base names
+    V2 = 2,
+};
+
+/**
+ * Convert an integer version number to PathInfoJsonFormat.
+ * Throws Error if the version is not supported.
+ */
+PathInfoJsonFormat parsePathInfoJsonFormat(uint64_t version);
+
 struct SubstitutablePathInfo
 {
     std::optional<StorePath> deriver;
@@ -114,10 +130,16 @@ struct UnkeyedValidPathInfo
     virtual ~UnkeyedValidPathInfo() {}
 
     /**
+     * @param store If non-null, store paths are rendered as full paths.
+     *              If null, store paths are rendered as base names.
      * @param includeImpureInfo If true, variable elements such as the
      *                          registration time are included.
+     * @param format JSON format version. Version 1 uses string hashes and
+     *               string content addresses. Version 2 uses structured
+     *               hashes and structured content addresses.
      */
-    virtual nlohmann::json toJSON(const StoreDirConfig * store, bool includeImpureInfo) const;
+    virtual nlohmann::json
+    toJSON(const StoreDirConfig * store, bool includeImpureInfo, PathInfoJsonFormat format) const;
     static UnkeyedValidPathInfo fromJSON(const StoreDirConfig * store, const nlohmann::json & json);
 };
 
@@ -196,5 +218,6 @@ using ValidPathInfos = std::map<StorePath, ValidPathInfo>;
 
 } // namespace nix
 
+JSON_IMPL(nix::PathInfoJsonFormat)
 JSON_IMPL(nix::UnkeyedValidPathInfo)
 JSON_IMPL(nix::ValidPathInfo)

src/libstore/nar-info.cc

@@ -132,19 +132,24 @@ std::string NarInfo::to_string(const StoreDirConfig & store) const
     return res;
 }
 
-nlohmann::json UnkeyedNarInfo::toJSON(const StoreDirConfig * store, bool includeImpureInfo) const
+nlohmann::json
+UnkeyedNarInfo::toJSON(const StoreDirConfig * store, bool includeImpureInfo, PathInfoJsonFormat format) const
 {
     using nlohmann::json;
 
-    auto jsonObject = UnkeyedValidPathInfo::toJSON(store, includeImpureInfo);
+    auto jsonObject = UnkeyedValidPathInfo::toJSON(store, includeImpureInfo, format);
 
     if (includeImpureInfo) {
         if (!url.empty())
             jsonObject["url"] = url;
         if (!compression.empty())
             jsonObject["compression"] = compression;
-        if (fileHash)
+        if (fileHash) {
+            if (format == PathInfoJsonFormat::V1)
+                jsonObject["downloadHash"] = fileHash->to_string(HashFormat::SRI, true);
+            else
                 jsonObject["downloadHash"] = *fileHash;
+        }
         if (fileSize)
             jsonObject["downloadSize"] = fileSize;
     }
@@ -154,20 +159,26 @@ nlohmann::json UnkeyedNarInfo::toJSON(const StoreDirConfig * store, bool include
 
 UnkeyedNarInfo UnkeyedNarInfo::fromJSON(const StoreDirConfig * store, const nlohmann::json & json)
 {
-    using nlohmann::detail::value_t;
-
     UnkeyedNarInfo res{UnkeyedValidPathInfo::fromJSON(store, json)};
 
     auto & obj = getObject(json);
 
+    PathInfoJsonFormat format = PathInfoJsonFormat::V1;
+    if (auto * version = optionalValueAt(obj, "version"))
+        format = *version;
+
     if (auto * url = get(obj, "url"))
         res.url = getString(*url);
 
     if (auto * compression = get(obj, "compression"))
         res.compression = getString(*compression);
 
-    if (auto * downloadHash = get(obj, "downloadHash"))
+    if (auto * downloadHash = get(obj, "downloadHash")) {
+        if (format == PathInfoJsonFormat::V1)
+            res.fileHash = Hash::parseSRI(getString(*downloadHash));
+        else
             res.fileHash = *downloadHash;
+    }
 
     if (auto * downloadSize = get(obj, "downloadSize"))
         res.fileSize = getUnsigned(*downloadSize);
@@ -188,7 +199,7 @@ UnkeyedNarInfo adl_serializer<UnkeyedNarInfo>::from_json(const json & json)
 
 void adl_serializer<UnkeyedNarInfo>::to_json(json & json, const UnkeyedNarInfo & c)
 {
-    json = c.toJSON(nullptr, true);
+    json = c.toJSON(nullptr, true, PathInfoJsonFormat::V2);
 }
 
 } // namespace nlohmann

src/libstore/path-info.cc

@@ -8,6 +8,18 @@
 
 namespace nix {
 
+PathInfoJsonFormat parsePathInfoJsonFormat(uint64_t version)
+{
+    switch (version) {
+    case 1:
+        return PathInfoJsonFormat::V1;
+    case 2:
+        return PathInfoJsonFormat::V2;
+    default:
+        throw Error("unsupported path info JSON format version %d; supported versions are 1 and 2", version);
+    }
+}
+
 GENERATE_CMP_EXT(
     ,
     std::weak_ordering,
@@ -149,31 +161,45 @@ ValidPathInfo ValidPathInfo::makeFromCA(
     return res;
 }
 
-nlohmann::json UnkeyedValidPathInfo::toJSON(const StoreDirConfig * store, bool includeImpureInfo) const
+nlohmann::json
+UnkeyedValidPathInfo::toJSON(const StoreDirConfig * store, bool includeImpureInfo, PathInfoJsonFormat format) const
 {
     using nlohmann::json;
 
+    if (format == PathInfoJsonFormat::V1)
+        assert(store);
+
     auto jsonObject = json::object();
 
-    jsonObject["version"] = 2;
+    jsonObject["version"] = format;
+
+    jsonObject["narHash"] = format == PathInfoJsonFormat::V1
+                                ? static_cast<json>(narHash.to_string(HashFormat::SRI, true))
+                                : static_cast<json>(narHash);
 
-    jsonObject["narHash"] = narHash;
     jsonObject["narSize"] = narSize;
 
     {
         auto & jsonRefs = jsonObject["references"] = json::array();
         for (auto & ref : references)
-            jsonRefs.emplace_back(store ? static_cast<json>(store->printStorePath(ref)) : static_cast<json>(ref));
+            jsonRefs.emplace_back(
+                format == PathInfoJsonFormat::V1 ? static_cast<json>(store->printStorePath(ref))
+                                                 : static_cast<json>(ref));
     }
 
+    if (format == PathInfoJsonFormat::V1)
+        jsonObject["ca"] = ca ? static_cast<json>(renderContentAddress(*ca)) : static_cast<json>(nullptr);
+    else
         jsonObject["ca"] = ca;
 
     if (includeImpureInfo) {
-        jsonObject["deriver"] = deriver ? (store ? static_cast<json>(std::optional{store->printStorePath(*deriver)})
+        if (format == PathInfoJsonFormat::V1) {
-                                                 : static_cast<json>(std::optional{*deriver}))
+            jsonObject["deriver"] =
-                                        : static_cast<json>(std::optional<StorePath>{});
+                deriver ? static_cast<json>(store->printStorePath(*deriver)) : static_cast<json>(nullptr);
-
+        } else {
-        jsonObject["registrationTime"] = registrationTime ? (std::optional{registrationTime}) : std::nullopt;
+            jsonObject["deriver"] = deriver;
+        }
+        jsonObject["registrationTime"] = registrationTime ? std::optional{registrationTime} : std::nullopt;
 
         jsonObject["ultimate"] = ultimate;
 
@@ -193,34 +219,51 @@ UnkeyedValidPathInfo UnkeyedValidPathInfo::fromJSON(const StoreDirConfig * store
 
     auto & json = getObject(_json);
 
-    {
+    PathInfoJsonFormat format = PathInfoJsonFormat::V1;
-        auto version = getUnsigned(valueAt(json, "version"));
+    if (auto * version = optionalValueAt(json, "version"))
-        if (version != 2)
+        format = *version;
-            throw Error("Unsupported path info JSON format version %d, only version 2 is currently supported", version);
-    }
 
+    if (format == PathInfoJsonFormat::V1)
+        assert(store);
+
+    if (format == PathInfoJsonFormat::V1)
+        res.narHash = Hash::parseSRI(getString(valueAt(json, "narHash")));
+    else
         res.narHash = valueAt(json, "narHash");
+
     res.narSize = getUnsigned(valueAt(json, "narSize"));
 
     try {
-        auto references = getStringList(valueAt(json, "references"));
+        auto & references = getArray(valueAt(json, "references"));
         for (auto & input : references)
-            res.references.insert(store ? store->parseStorePath(getString(input)) : static_cast<StorePath>(input));
+            res.references.insert(
+                format == PathInfoJsonFormat::V1 ? store->parseStorePath(getString(input))
+                                                 : static_cast<StorePath>(input));
     } catch (Error & e) {
         e.addTrace({}, "while reading key 'references'");
         throw;
     }
 
     try {
+        if (format == PathInfoJsonFormat::V1) {
+            if (auto * rawCa = getNullable(valueAt(json, "ca")))
+                res.ca = ContentAddress::parse(getString(*rawCa));
+        } else {
             res.ca = ptrToOwned<ContentAddress>(getNullable(valueAt(json, "ca")));
+        }
     } catch (Error & e) {
         e.addTrace({}, "while reading key 'ca'");
         throw;
     }
 
-    if (auto * rawDeriver0 = optionalValueAt(json, "deriver"))
+    if (auto * rawDeriver0 = optionalValueAt(json, "deriver")) {
+        if (format == PathInfoJsonFormat::V1) {
             if (auto * rawDeriver = getNullable(*rawDeriver0))
-            res.deriver = store ? store->parseStorePath(getString(*rawDeriver)) : static_cast<StorePath>(*rawDeriver);
+                res.deriver = store->parseStorePath(getString(*rawDeriver));
+        } else {
+            res.deriver = ptrToOwned<StorePath>(getNullable(*rawDeriver0));
+        }
+    }
 
     if (auto * rawRegistrationTime0 = optionalValueAt(json, "registrationTime"))
         if (auto * rawRegistrationTime = getNullable(*rawRegistrationTime0))
@@ -241,6 +284,16 @@ namespace nlohmann {
 
 using namespace nix;
 
+PathInfoJsonFormat adl_serializer<PathInfoJsonFormat>::from_json(const json & json)
+{
+    return parsePathInfoJsonFormat(getUnsigned(json));
+}
+
+void adl_serializer<PathInfoJsonFormat>::to_json(json & json, const PathInfoJsonFormat & format)
+{
+    json = static_cast<int>(format);
+}
+
 UnkeyedValidPathInfo adl_serializer<UnkeyedValidPathInfo>::from_json(const json & json)
 {
     return UnkeyedValidPathInfo::fromJSON(nullptr, json);
@@ -248,7 +301,7 @@ UnkeyedValidPathInfo adl_serializer<UnkeyedValidPathInfo>::from_json(const json
 
 void adl_serializer<UnkeyedValidPathInfo>::to_json(json & json, const UnkeyedValidPathInfo & c)
 {
-    json = c.toJSON(nullptr, true);
+    json = c.toJSON(nullptr, true, PathInfoJsonFormat::V2);
 }
 
 ValidPathInfo adl_serializer<ValidPathInfo>::from_json(const json & json0)

src/nix/path-info.cc

@@ -34,14 +34,17 @@ static uint64_t getStoreObjectsTotalSize(Store & store, const StorePathSet & clo
  *
  * @param showClosureSize If true, the closure size of each path is
  * included.
+ * @param format The JSON format version to use.
  */
-static json pathInfoToJSON(Store & store, const StorePathSet & storePaths, bool showClosureSize)
+static json
+pathInfoToJSON(Store & store, const StorePathSet & storePaths, bool showClosureSize, PathInfoJsonFormat format)
 {
     json::object_t jsonAllObjects = json::object();
 
     for (auto & storePath : storePaths) {
         json jsonObject;
-        auto printedStorePath = store.printStorePath(storePath);
+
+        std::string key = store.printStorePath(storePath);
 
         try {
             auto info = store.queryPathInfo(storePath);
@@ -49,9 +52,13 @@ static json pathInfoToJSON(Store & store, const StorePathSet & storePaths, bool
             // `storePath` has the representation `<hash>-x` rather than
             // `<hash>-<name>` in case of binary-cache stores & `--all` because we don't
             // know the name yet until we've read the NAR info.
-            printedStorePath = store.printStorePath(info->path);
+            key = store.printStorePath(info->path);
 
-            jsonObject = info->toJSON(&store, true);
+            jsonObject = info->toJSON(format == PathInfoJsonFormat::V1 ? &store : nullptr, true, format);
+
+            /* Hack in the store dir for now. TODO update the data type
+               instead. */
+            jsonObject["storeDir"] = store.storeDir;
 
             if (showClosureSize) {
                 StorePathSet closure;
@@ -74,12 +81,11 @@ static json pathInfoToJSON(Store & store, const StorePathSet & storePaths, bool
                     jsonObject["closureDownloadSize"] = totalDownloadSize;
                 }
             }
-
         } catch (InvalidPath &) {
             jsonObject = nullptr;
         }
 
-        jsonAllObjects[printedStorePath] = std::move(jsonObject);
+        jsonAllObjects[key] = std::move(jsonObject);
     }
     return jsonAllObjects;
 }
@@ -90,6 +96,7 @@ struct CmdPathInfo : StorePathsCommand, MixJSON
     bool showClosureSize = false;
     bool humanReadable = false;
     bool showSigs = false;
+    std::optional<PathInfoJsonFormat> jsonFormat;
 
     CmdPathInfo()
     {
@@ -119,6 +126,16 @@ struct CmdPathInfo : StorePathsCommand, MixJSON
             .description = "Show signatures.",
             .handler = {&showSigs, true},
         });
+
+        addFlag({
+            .longName = "json-format",
+            .description =
+                "JSON format version to use (1 or 2). Version 1 uses string hashes and full store paths. Version 2 uses structured hashes and store path base names. This flag will be required in a future release.",
+            .labels = {"version"},
+            .handler = {[this](std::string s) {
+                jsonFormat = parsePathInfoJsonFormat(string2IntWithUnitPrefix<uint64_t>(s));
+            }},
+        });
     }
 
     std::string description() override
@@ -157,7 +174,14 @@ struct CmdPathInfo : StorePathsCommand, MixJSON
                 *store,
                 // FIXME: preserve order?
                 StorePathSet(storePaths.begin(), storePaths.end()),
-                showClosureSize));
+                showClosureSize,
+                jsonFormat
+                    .or_else([&]() {
+                        warn(
+                            "'--json' without '--json-format' is deprecated; please specify '--json-format 1' or '--json-format 2'. This will become an error in a future release.");
+                        return std::optional{PathInfoJsonFormat::V1};
+                    })
+                    .value()));
         }
 
         else {

tests/functional/binary-cache.sh

@@ -18,7 +18,7 @@ outPath=$(nix-build dependencies.nix --no-out-link)
 
 nix copy --to "file://$cacheDir" "$outPath"
 
-readarray -t paths < <(nix path-info --all --json --store "file://$cacheDir" | jq 'keys|sort|.[]' -r)
+readarray -t paths < <(nix path-info --all --json --json-format 2 --store "file://$cacheDir" | jq 'keys|sort|.[]' -r)
 [[ "${#paths[@]}" -eq 3 ]]
 for path in "${paths[@]}"; do
     [[ "$path" =~ -dependencies-input-0$ ]] \

tests/functional/fixed.sh

@@ -14,7 +14,7 @@ nix-build fixed.nix -A bad --no-out-link && fail "should fail"
 # Building with the bad hash should produce the "good" output path as
 # a side-effect.
 [[ -e $path ]]
-nix path-info --json "$path" | jq -e \
+nix path-info --json --json-format 2 "$path" | jq -e \
     '.[].ca == {
         method: "flat",
         hash: {

tests/functional/git-hashing/simple-common.sh

@@ -47,7 +47,7 @@ try2 () {
     hashFromGit=$(git -C "$repo" rev-parse "HEAD:$hashPath")
     [[ "$hashFromGit" == "$expected" ]]
 
-    nix path-info --json "$path" | jq -e \
+    nix path-info --json --json-format 2 "$path" | jq -e \
         --arg algo "$hashAlgo" \
         --arg hash "$hashFromGit" \
         '.[].ca == {

tests/functional/impure-derivations.sh

@@ -30,7 +30,7 @@ path1_stuff=$(echo "$json" | jq -r .[].outputs.stuff)
 [[ $(< "$path1"/n) = 0 ]]
 [[ $(< "$path1_stuff"/bla) = 0 ]]
 
-nix path-info --json "$path1" | jq -e '.[].ca | .method == "nar" and .hash.algorithm == "sha256"'
+nix path-info --json --json-format 2 "$path1" | jq -e '.[].ca | .method == "nar" and .hash.algorithm == "sha256"'
 
 path2=$(nix build -L --no-link --json --file ./impure-derivations.nix impure | jq -r .[].outputs.out)
 [[ $(< "$path2"/n) = 1 ]]

tests/functional/nix-profile.sh

@@ -166,7 +166,7 @@ printf 4.0 > "$flake1Dir"/version
 printf Utrecht > "$flake1Dir"/who
 nix profile add "$flake1Dir"
 [[ $("$TEST_HOME"/.nix-profile/bin/hello) = "Hello Utrecht" ]]
-nix path-info --json "$(realpath "$TEST_HOME"/.nix-profile/bin/hello)" | jq -e '.[].ca | .method == "nar" and .hash.algorithm == "sha256"'
+nix path-info --json --json-format 2 "$(realpath "$TEST_HOME"/.nix-profile/bin/hello)" | jq -e '.[].ca | .method == "nar" and .hash.algorithm == "sha256"'
 
 # Override the outputs.
 nix profile remove simple flake1

tests/functional/path-info.sh

@@ -13,7 +13,7 @@ baz=$(nix store add-file "$TEST_ROOT"/baz)
 nix-store --delete "$baz"
 
 diff --unified --color=always \
-    <(nix path-info --json "$foo" "$bar" "$baz" |
+    <(nix path-info --json --json-format 2 "$foo" "$bar" "$baz" |
         jq --sort-keys 'map_values(.narHash)') \
     <(jq --sort-keys <<-EOF
         {
@@ -31,3 +31,9 @@ diff --unified --color=always \
         }
 EOF
     )
+
+# Test that storeDir is returned in the JSON output
+nix path-info --json --json-format 2 "$foo" | jq -e \
+    --arg foo "$foo" \
+    --arg storeDir "${NIX_STORE_DIR:-/nix/store}" \
+    '.[$foo].storeDir == $storeDir'

tests/functional/signing.sh

@@ -14,7 +14,7 @@ pk2=$(cat "$TEST_ROOT"/pk2)
 outPath=$(nix-build dependencies.nix --no-out-link --secret-key-files "$TEST_ROOT/sk1 $TEST_ROOT/sk2")
 
 # Verify that the path got signed.
-info=$(nix path-info --json "$outPath")
+info=$(nix path-info --json --json-format 2 "$outPath")
 echo "$info" | jq -e '.[] | .ultimate == true'
 TODO_NixOS # looks like an actual bug? Following line fails on NixOS:
 echo "$info" | jq -e '.[] | .signatures.[] | select(startswith("cache1.example.org"))'
@@ -39,7 +39,7 @@ outPath2=$(nix-build simple.nix --no-out-link)
 nix store verify -r "$outPath"
 
 # Verify that the path did not get signed but does have the ultimate bit.
-info=$(nix path-info --json "$outPath2")
+info=$(nix path-info --json --json-format 2 "$outPath2")
 echo "$info" | jq -e '.[] | .ultimate == true'
 echo "$info" | jq -e '.[] | .signatures == []'
 
@@ -58,7 +58,7 @@ nix store verify -r "$outPath2" --sigs-needed 1 --trusted-public-keys "$pk1"
 # Build something content-addressed.
 outPathCA=$(IMPURE_VAR1=foo IMPURE_VAR2=bar nix-build ./fixed.nix -A good.0 --no-out-link)
 
-nix path-info --json "$outPathCA" | jq -e '.[].ca | .method == "flat" and .hash.algorithm == "md5"'
+nix path-info --json --json-format 2 "$outPathCA" | jq -e '.[].ca | .method == "flat" and .hash.algorithm == "md5"'
 
 # Content-addressed paths don't need signatures, so they verify
 # regardless of --sigs-needed.
@@ -73,14 +73,14 @@ nix store verify -r "$outPathCA" --sigs-needed 1000 --trusted-public-keys "$pk1"
 nix copy --to file://"$cacheDir" "$outPath2"
 
 # Verify that signatures got copied.
-info=$(nix path-info --store file://"$cacheDir" --json "$outPath2")
+info=$(nix path-info --store file://"$cacheDir" --json --json-format 2 "$outPath2")
 echo "$info" | jq -e '.[] | .ultimate == false'
 echo "$info" | jq -e '.[] | .signatures.[] | select(startswith("cache1.example.org"))'
 echo "$info" | expect 4 jq -e '.[] | .signatures.[] | select(startswith("cache2.example.org"))'
 
 # Verify that adding a signature to a path in a binary cache works.
 nix store sign --store file://"$cacheDir" --key-file "$TEST_ROOT"/sk2 "$outPath2"
-info=$(nix path-info --store file://"$cacheDir" --json "$outPath2")
+info=$(nix path-info --store file://"$cacheDir" --json --json-format 2 "$outPath2")
 echo "$info" | jq -e '.[] | .signatures.[] | select(startswith("cache1.example.org"))'
 echo "$info" | jq -e '.[] | .signatures.[] | select(startswith("cache2.example.org"))'
 

tests/nixos/fetchers-substitute.nix

@@ -117,12 +117,12 @@
       tarball_store_path = json.loads(tarball_store_path_json)
 
       # Get the NAR hash of the unpacked tarball in SRI format
-      path_info_json = substituter.succeed(f"nix path-info --json {tarball_store_path}").strip()
+      path_info_json = substituter.succeed(f"nix path-info --json-format 2 --json {tarball_store_path}").strip()
       path_info_dict = json.loads(path_info_json)
       # nix path-info returns a dict with store paths as keys
       narHash_obj = path_info_dict[tarball_store_path]["narHash"]
-      # Convert from structured format {"algorithm": "sha256", "format": "base64", "hash": "..."} to SRI string
+      # Convert from structured format {"algorithm": "sha256", "format": "base16", "hash": "..."} to SRI string
-      tarball_hash_sri = f"{narHash_obj['algorithm']}-{narHash_obj['hash']}"
+      tarball_hash_sri = substituter.succeed(f"nix hash convert --to sri {narHash_obj['algorithm']}:{narHash_obj['hash']}").strip()
       print(f"Tarball NAR hash (SRI): {tarball_hash_sri}")
 
       # Also get the old format hash for fetchTarball (which uses sha256 parameter)