nix hash path, and preperatory refactors

- `nix store add` supports text hashing With functional test ensuring it matches `builtins.toFile`. - Factored-out flags for both commands - Move all common reusable flags to `libcmd` - They are not part of the *definition* of the CLI infra, just a usag of it. - The `libstore` flag couldn't go in `args.hh` in libutil anyways, would be awkward for it to live alone - Shuffle around `Cmd*` hierarchy so flags for deprecated commands don't end up on the new ones
NixOS · Feb 21, 2024 · 2642764 · 2642764
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commit 2642764
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diff --git a/src/libcmd/misc-store-flags.cc b/src/libcmd/misc-store-flags.cc
@@ -0,0 +1,121 @@
+#include "misc-store-flags.hh"
+
+namespace nix::flag
+{
+
+static void hashFormatCompleter(AddCompletions & completions, size_t index, std::string_view prefix)
+{
+    for (auto & format : hashFormats) {
+        if (hasPrefix(format, prefix)) {
+            completions.add(format);
+        }
+    }
+}
+
+Args::Flag hashFormatWithDefault(std::string && longName, HashFormat * hf)
+{
+    assert(*hf == nix::HashFormat::SRI);
+    return Args::Flag {
+            .longName = std::move(longName),
+            .description = "Hash format (`base16`, `nix32`, `base64`, `sri`). Default: `sri`.",
+            .labels = {"hash-format"},
+            .handler = {[hf](std::string s) {
+                *hf = parseHashFormat(s);
+            }},
+            .completer = hashFormatCompleter,
+    };
+}
+
+Args::Flag hashFormatOpt(std::string && longName, std::optional<HashFormat> * ohf)
+{
+    return Args::Flag {
+            .longName = std::move(longName),
+            .description = "Hash format (`base16`, `nix32`, `base64`, `sri`).",
+            .labels = {"hash-format"},
+            .handler = {[ohf](std::string s) {
+                *ohf = std::optional<HashFormat>{parseHashFormat(s)};
+            }},
+            .completer = hashFormatCompleter,
+    };
+}
+
+static void hashAlgoCompleter(AddCompletions & completions, size_t index, std::string_view prefix)
+{
+    for (auto & algo : hashAlgorithms)
+        if (hasPrefix(algo, prefix))
+            completions.add(algo);
+}
+
+Args::Flag hashAlgo(std::string && longName, HashAlgorithm * ha)
+{
+    return Args::Flag {
+            .longName = std::move(longName),
+            .description = "Hash algorithm (`md5`, `sha1`, `sha256`, or `sha512`).",
+            .labels = {"hash-algo"},
+            .handler = {[ha](std::string s) {
+                *ha = parseHashAlgo(s);
+            }},
+            .completer = hashAlgoCompleter,
+    };
+}
+
+Args::Flag hashAlgoOpt(std::string && longName, std::optional<HashAlgorithm> * oha)
+{
+    return Args::Flag {
+            .longName = std::move(longName),
+            .description = "Hash algorithm (`md5`, `sha1`, `sha256`, or `sha512`). Can be omitted for SRI hashes.",
+            .labels = {"hash-algo"},
+            .handler = {[oha](std::string s) {
+                *oha = std::optional<HashAlgorithm>{parseHashAlgo(s)};
+            }},
+            .completer = hashAlgoCompleter,
+    };
+}
+
+Args::Flag fileIngestionMethod(FileIngestionMethod * method)
+{
+    return Args::Flag {
+        .longName  = "mode",
+        // FIXME indentation carefully made for context, this is messed up.
+        .description = R"(
+    How to compute the hash of the input.
+    One of:
+
+    - `nar` (the default): Serialises the input as an archive (following the [_Nix Archive Format_](https://edolstra.github.io/pubs/phd-thesis.pdf#page=101)) and passes that to the hash function.
+
+    - `flat`: Assumes that the input is a single file and directly passes it to the hash function;
+        )",
+        .labels = {"file-ingestion-method"},
+        .handler = {[method](std::string s) {
+            *method = parseFileIngestionMethod(s);
+        }},
+    };
+}
+
+Args::Flag contentAddressMethod(ContentAddressMethod * method)
+{
+    return Args::Flag {
+        .longName  = "mode",
+        // FIXME indentation carefully made for context, this is messed up.
+        .description = R"(
+    How to compute the content-address of the store object.
+    One of:
+
+    - `nar` (the default): Serialises the input as an archive (following the [_Nix Archive Format_](https://edolstra.github.io/pubs/phd-thesis.pdf#page=101)) and passes that to the hash function.
+
+    - `flat`: Assumes that the input is a single file and directly passes it to the hash function;
+
+    - `text`: Like `flat`, but used for
+      [derivations](@docroot@/glossary.md#store-derivation) serialized in store object and 
+      [`builtins.toFile`](@docroot@/language/builtins.html#builtins-toFile).
+      For advanced use-cases only;
+      for regular usage prefer `nar` and `flat.
+        )",
+        .labels = {"content-address-method"},
+        .handler = {[method](std::string s) {
+            *method = ContentAddressMethod::parse(s);
+        }},
+    };
+}
+
+}
diff --git a/src/libcmd/misc-store-flags.hh b/src/libcmd/misc-store-flags.hh
@@ -0,0 +1,21 @@
+#include "args.hh"
+#include "content-address.hh"
+
+namespace nix::flag {
+
+Args::Flag hashAlgo(std::string && longName, HashAlgorithm * ha);
+static inline Args::Flag hashAlgo(HashAlgorithm * ha)
+{
+    return hashAlgo("hash-algo", ha);
+}
+Args::Flag hashAlgoOpt(std::string && longName, std::optional<HashAlgorithm> * oha);
+Args::Flag hashFormatWithDefault(std::string && longName, HashFormat * hf);
+Args::Flag hashFormatOpt(std::string && longName, std::optional<HashFormat> * ohf);
+static inline Args::Flag hashAlgoOpt(std::optional<HashAlgorithm> * oha)
+{
+    return hashAlgoOpt("hash-algo", oha);
+}
+Args::Flag fileIngestionMethod(FileIngestionMethod * method);
+Args::Flag contentAddressMethod(ContentAddressMethod * method);
+
+}
diff --git a/src/libutil/args.cc b/src/libutil/args.cc
@@ -544,73 +544,6 @@ nlohmann::json Args::toJSON()
     return res;
 }
 
-static void hashFormatCompleter(AddCompletions & completions, size_t index, std::string_view prefix)
-{
-    for (auto & format : hashFormats) {
-        if (hasPrefix(format, prefix)) {
-            completions.add(format);
-        }
-    }
-}
-
-Args::Flag Args::Flag::mkHashFormatFlagWithDefault(std::string &&longName, HashFormat * hf) {
-    assert(*hf == nix::HashFormat::SRI);
-    return Flag{
-            .longName = std::move(longName),
-            .description = "Hash format (`base16`, `nix32`, `base64`, `sri`). Default: `sri`.",
-            .labels = {"hash-format"},
-            .handler = {[hf](std::string s) {
-                *hf = parseHashFormat(s);
-            }},
-            .completer = hashFormatCompleter,
-    };
-}
-
-Args::Flag Args::Flag::mkHashFormatOptFlag(std::string && longName, std::optional<HashFormat> * ohf) {
-    return Flag{
-            .longName = std::move(longName),
-            .description = "Hash format (`base16`, `nix32`, `base64`, `sri`).",
-            .labels = {"hash-format"},
-            .handler = {[ohf](std::string s) {
-                *ohf = std::optional<HashFormat>{parseHashFormat(s)};
-            }},
-            .completer = hashFormatCompleter,
-    };
-}
-
-static void hashAlgoCompleter(AddCompletions & completions, size_t index, std::string_view prefix)
-{
-    for (auto & algo : hashAlgorithms)
-        if (hasPrefix(algo, prefix))
-            completions.add(algo);
-}
-
-Args::Flag Args::Flag::mkHashAlgoFlag(std::string && longName, HashAlgorithm * ha)
-{
-    return Flag{
-            .longName = std::move(longName),
-            .description = "Hash algorithm (`md5`, `sha1`, `sha256`, or `sha512`).",
-            .labels = {"hash-algo"},
-            .handler = {[ha](std::string s) {
-                *ha = parseHashAlgo(s);
-            }},
-            .completer = hashAlgoCompleter,
-    };
-}
-
-Args::Flag Args::Flag::mkHashAlgoOptFlag(std::string && longName, std::optional<HashAlgorithm> * oha)
-{
-    return Flag{
-            .longName = std::move(longName),
-            .description = "Hash algorithm (`md5`, `sha1`, `sha256`, or `sha512`). Can be omitted for SRI hashes.",
-            .labels = {"hash-algo"},
-            .handler = {[oha](std::string s) {
-                *oha = std::optional<HashAlgorithm>{parseHashAlgo(s)};
-            }},
-            .completer = hashAlgoCompleter,
-    };
-}
-
 static void _completePath(AddCompletions & completions, std::string_view prefix, bool onlyDirs)
 {
     completions.setType(Completions::Type::Filenames);

diff --git a/src/libutil/args.hh b/src/libutil/args.hh
@@ -155,6 +155,8 @@ protected:
      */
     using CompleterClosure = std::function<CompleterFun>;
 
+public:
+
     /**
      * Description of flags / options
      *
@@ -175,19 +177,10 @@ protected:
         CompleterClosure completer;
 
         std::optional<ExperimentalFeature> experimentalFeature;
-
-        static Flag mkHashAlgoFlag(std::string && longName, HashAlgorithm * ha);
-        static Flag mkHashAlgoFlag(HashAlgorithm * ha) {
-            return mkHashAlgoFlag("hash-algo", ha);
-        }
-        static Flag mkHashAlgoOptFlag(std::string && longName, std::optional<HashAlgorithm> * oha);
-        static Flag mkHashAlgoOptFlag(std::optional<HashAlgorithm> * oha) {
-            return mkHashAlgoOptFlag("hash-algo", oha);
-        }
-        static Flag mkHashFormatFlagWithDefault(std::string && longName, HashFormat * hf);
-        static Flag mkHashFormatOptFlag(std::string && longName, std::optional<HashFormat> * ohf);
     };
 
+protected:
+
     /**
      * Index of all registered "long" flag descriptions (flags like
      * `--long`).
@@ -206,6 +199,8 @@ protected:
      */
     virtual bool processFlag(Strings::iterator & pos, Strings::iterator end);
 
+public:
+
     /**
      * Description of positional arguments
      *
@@ -220,6 +215,8 @@ protected:
         CompleterClosure completer;
     };
 
+protected:
+
     /**
      * Queue of expected positional argument forms.
      *

diff --git a/src/nix/add-to-store.cc b/src/nix/add-to-store.cc
@@ -3,6 +3,7 @@
 #include "store-api.hh"
 #include "archive.hh"
 #include "posix-source-accessor.hh"
+#include "misc-store-flags.hh"
 
 using namespace nix;
 
@@ -26,23 +27,9 @@ struct CmdAddToStore : MixDryRun, StoreCommand
             .handler = {&namePart},
         });
 
-        addFlag({
-            .longName  = "mode",
-            .description = R"(
-    How to compute the hash of the input.
-    One of:
-
-    - `nar` (the default): Serialises the input as an archive (following the [_Nix Archive Format_](https://edolstra.github.io/pubs/phd-thesis.pdf#page=101)) and passes that to the hash function.
-
-    - `flat`: Assumes that the input is a single file and directly passes it to the hash function;
-            )",
-            .labels = {"hash-mode"},
-            .handler = {[this](std::string s) {
-                this->caMethod = parseFileIngestionMethod(s);
-            }},
-        });
+        addFlag(flag::contentAddressMethod(&caMethod));
 
-        addFlag(Flag::mkHashAlgoFlag(&hashAlgo));
+        addFlag(flag::hashAlgo(&hashAlgo));
     }
 
     void run(ref<Store> store) override
@@ -63,7 +50,6 @@ struct CmdAddToStore : MixDryRun, StoreCommand
 
 struct CmdAdd : CmdAddToStore
 {
-
     std::string description() override
     {
         return "Add a file or directory to the Nix store";