Add pacman (alpm) parser support (#943)

Co-authored-by: Christopher Phillips <christopher.phillips@anchore.com>

syft/linux/identify_release.go

@@ -111,6 +111,10 @@ func parseOsRelease(contents string) (*Release, error) {
 		IDLike:           idLike,
 		Version:          values["VERSION"],
 		VersionID:        values["VERSION_ID"],
+		VersionCodename:  values["VERSION_CODENAME"],
+		BuildID:          values["BUILD_ID"],
+		ImageID:          values["IMAGE_ID"],
+		ImageVersion:     values["IMAGE_VERSION"],
 		Variant:          values["VARIANT"],
 		VariantID:        values["VARIANT_ID"],
 		HomeURL:          values["HOME_URL"],

syft/linux/identify_release_test.go

@@ -125,6 +125,7 @@ func TestIdentifyRelease(t *testing.T) {
 				ID:               "ubuntu",
 				IDLike:           []string{"debian"},
 				Version:          "20.04 LTS (Focal Fossa)",
+				VersionCodename:  "focal",
 				VersionID:        "20.04",
 				HomeURL:          "https://www.ubuntu.com/",
 				SupportURL:       "https://help.ubuntu.com/",
@@ -217,6 +218,7 @@ func TestIdentifyRelease(t *testing.T) {
 				Name:         "Arch Linux",
 				ID:           "arch",
 				IDLike:       nil,
+				BuildID:      "rolling",
 				HomeURL:      "https://www.archlinux.org/",
 				SupportURL:   "https://bbs.archlinux.org/",
 				BugReportURL: "https://bugs.archlinux.org/",
@@ -349,6 +351,7 @@ func TestParseOsRelease(t *testing.T) {
 				IDLike:           []string{"debian"},
 				Version:          "20.04 LTS (Focal Fossa)",
 				VersionID:        "20.04",
+				VersionCodename:  "focal",
 				HomeURL:          "https://www.ubuntu.com/",
 				SupportURL:       "https://help.ubuntu.com/",
 				BugReportURL:     "https://bugs.launchpad.net/ubuntu/",

syft/linux/release.go

@@ -8,6 +8,10 @@ type Release struct {
 	IDLike           []string `cyclonedx:"idLike"` // list of operating system identifiers in the same syntax as the ID= setting. It should list identifiers of operating systems that are closely related to the local operating system in regards to packaging and programming interfaces.
 	Version          string   // identifies the operating system version, excluding any OS name information, possibly including a release code name, and suitable for presentation to the user.
 	VersionID        string   `cyclonedx:"versionID"` // identifies the operating system version, excluding any OS name information or release code name, and suitable for processing by scripts or usage in generated filenames.
+	VersionCodename  string   `cyclonedx:"versionCodename"`
+	BuildID          string   `cyclonedx:"buildID"` // A string uniquely identifying the system image originally used as the installation base.
+	ImageID          string   `cyclonedx:"imageID"`
+	ImageVersion     string   `cyclonedx:"imageVersion"`
 	Variant          string   `cyclonedx:"variant"`   // identifies a specific variant or edition of the operating system suitable for presentation to the user.
 	VariantID        string   `cyclonedx:"variantID"` // identifies a specific variant or edition of the operating system. This may be interpreted by other packages in order to determine a divergent default configuration.
 	HomeURL          string
@@ -30,6 +34,9 @@ func (r *Release) String() string {
 	if r.Version != "" {
 		return r.ID + " " + r.Version
 	}
+	if r.VersionID != "" {
+		return r.ID + " " + r.VersionID
+	}
 
-	return r.ID + " " + r.VersionID
+	return r.ID + " " + r.BuildID
 }