feat: add metadata resolve in module

packer/README.md

@@ -1,45 +1,55 @@
 # sarasacw-omrf-packer
 
+## Metadata
+
 All packer used properties are stored in target Rust manifest file as metadata style.
 There is an example about how to define them in `Cargo.toml`.
 
 ```toml
 [package.metadata.omrf]
-# Configures the minimum required sarasacw-omrf-packer version. 
-# Trying to run with an older version causes an error.
-# This property is optional. If there is no specification, no version constraint is applied.
+# Minimum required version of sarasacw-omrf-packer.
+# Running with an older version fails with an error.
+# This property is optional; when omitted, no version constraint is enforced.
 min_version = "1.0.0"
 
-[package.metadata.omrf.headers]
-assets = [
-    # `from` is the relative path to directory where this Cargo.toml is.
-    # `to` is the relative path to `include` directory which is the subdirectory of installation directory.
-    # Blank `to` means that put it directly in `include` directory.
+# Header files to distribute. Each entry installs one file (or, with glob
+# expansion, a set of files) into the `include` directory of the installation.
+# Each entry carries a `from` source path and a `to` destination path.
+# This property is required. If you really want to distribute nothing header files,
+# leave empty list here.
+headers = [
+    # `from` is a path relative to the directory that contains this `Cargo.toml`.
+    # `to` is a path relative to the `include` directory (a subdirectory of the install directory).
+    # An empty `to` places the file directly under the `include` directory.
     { from = "cbindgen/my_crate.h", to = "" },
     { from = "cbindgen/our_crate.h", to = "SomePrefix" },
-    # `from` support UNIX style pathname pattern expansion.
-    # It will find the toppest immutable component of given pattern.
-    # In this exmaple, this toppest immutable component is `pattern/with`.
-    # And use that as the root directory and put found files to `to` directory 
-    # with preserving directory hierarchy.
-    { from = "pattern/with/**/*", to = "" }
-    { from = "pattern/with/**/*", to = "AllInOne" }
+    # `from` also supports UNIX-style glob (pathname) expansion.
+    # The matcher uses the leading literal portion of the pattern (`pattern/with`
+    # here) as the root directory and copies every matched file into the `to`
+    # directory, preserving the directory hierarchy beneath that root.
+    { from = "pattern/with/**/*", to = "" },
+    # The same pattern, but nested under an `AllInOne` prefix.
+    { from = "pattern/with/**/*", to = "AllInOne" },
 ]
 
 [package.metadata.omrf.cmake]
-# Configures the namespace part of CMake target.
-# This property is optional. The default value is extracted from the name of target Rust project.
+# Namespace part of the generated CMake target.
+# This property is optional; it defaults to the name of the target Rust project.
 namespace_name = "foobar"
-# Configures the target part of CMake target.
-# This property is optional. The default value is extracted from the name of target Rust project.
+# Target-name part of the generated CMake target.
+# This property is optional; it defaults to the name of the target Rust project.
 target_name = "foobar"
 
 [package.metadata.omrf.pkgconfig]
-# Configures the human-readable name of this package.
-# This property is optional. The default value is extracted from the name of target Rust project.
+# Human-readable name of the package.
+# This property is optional; it defaults to the name of the target Rust project.
 name = "Foo Bar"
-# Configures the brief description of this package.
-# This property is optional. The default value is extracted from the description of target Rust project.
-name = "a brown fox jumps over a lazy dog."
+# Brief description of the package.
+# This property is optional; it defaults to the description of the target Rust project.
+description = "a brown fox jumps over a lazy dog."
 
 ```
+
+## Environment Variables
+
+- `OMRF_PACKER_CARGO`: Path to the `cargo` executable used to collect project metadata. When unset, the packer invokes `cargo` as resolved from `PATH`.