Fix panic in apkdb parsing on empty "provides" values (anchore#1494)

* Add failing test for strip version specifiers panic

Signed-off-by: Dan Luhring <dluhring@chainguard.dev>

* Fix test

Signed-off-by: Dan Luhring <dluhring@chainguard.dev>

* Prevent panic scenario in helper func

Signed-off-by: Dan Luhring <dluhring@chainguard.dev>

* Fix lint issue

Signed-off-by: Dan Luhring <dluhring@chainguard.dev>

* add tests for apk stripVersionSpecifier() and remove caller empty value check

Signed-off-by: Alex Goodman <alex.goodman@anchore.com>

Signed-off-by: Dan Luhring <dluhring@chainguard.dev>
Signed-off-by: Alex Goodman <alex.goodman@anchore.com>
Co-authored-by: Alex Goodman <alex.goodman@anchore.com>

syft/pkg/cataloger/apkdb/parse_apk_db.go

@@ -361,5 +361,11 @@ func stripVersionSpecifier(s string) string {
 	// examples:
 	// musl>=1                 --> musl
 	// cmd:scanelf=1.3.4-r0    --> cmd:scanelf
-	return splitAny(s, "<>=")[0]
+
+	items := splitAny(s, "<>=")
+	if len(items) == 0 {
+		return s
+	}
+
+	return items[0]
 }

syft/pkg/cataloger/apkdb/parse_apk_db_test.go

@@ -911,6 +911,27 @@ func Test_discoverPackageDependencies(t *testing.T) {
 				}
 			},
 		},
+		{
+			name: "strip version specifiers with empty provides value",
+			genFn: func() ([]pkg.Package, []artifact.Relationship) {
+				a := pkg.Package{
+					Name: "package-a",
+					Metadata: pkg.ApkMetadata{
+						Dependencies: []string{"so:libc.musl-x86_64.so.1"},
+					},
+				}
+				a.SetID()
+				b := pkg.Package{
+					Name: "package-b",
+					Metadata: pkg.ApkMetadata{
+						Provides: []string{""},
+					},
+				}
+				b.SetID()
+
+				return []pkg.Package{a, b}, nil
+			},
+		},
 		{
 			name: "depends on package name",
 			genFn: func() ([]pkg.Package, []artifact.Relationship) {
@@ -1126,3 +1147,42 @@ func newLocationReadCloser(t *testing.T, path string) source.LocationReadCloser
 
 	return source.NewLocationReadCloser(source.NewLocation(path), f)
 }
+
+func Test_stripVersionSpecifier(t *testing.T) {
+	tests := []struct {
+		name    string
+		version string
+		want    string
+	}{
+		{
+			name:    "empty expression",
+			version: "",
+			want:    "",
+		},
+		{
+			name:    "no expression",
+			version: "cmd:foo",
+			want:    "cmd:foo",
+		},
+		{
+			name:    "=",
+			version: "cmd:scanelf=1.3.4-r0",
+			want:    "cmd:scanelf",
+		},
+		{
+			name:    ">=",
+			version: "cmd:scanelf>=1.3.4-r0",
+			want:    "cmd:scanelf",
+		},
+		{
+			name:    "<",
+			version: "cmd:scanelf<1.3.4-r0",
+			want:    "cmd:scanelf",
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			assert.Equal(t, tt.want, stripVersionSpecifier(tt.version))
+		})
+	}
+}