server/internal: copy bmizerany/ollama-go to internal package (#9294)

This commit copies (without history) the bmizerany/ollama-go repository
with the intention of integrating it into the ollama as a replacement
for the pushing, and pulling of models, and management of the cache they
are pushed and pulled from.

New homes for these packages will be determined as they are integrated
and we have a better understanding of proper package boundaries.

server/internal/cache/blob/digest_test.go

@@ -0,0 +1,63 @@
+package blob
+
+import (
+	"encoding/json"
+	"testing"
+)
+
+func TestParseDigest(t *testing.T) {
+	cases := []struct {
+		in    string
+		valid bool
+	}{
+		{"sha256-0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef", true},
+		{"sha256:0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef", true},
+
+		// too short
+		{"sha256-0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcde", false},
+		{"sha256:0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcde", false},
+
+		// too long
+		{"sha256-0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef0", false},
+		{"sha256:0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef0", false},
+
+		// invalid prefix
+		{"sha255-0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef", false},
+		{"sha255:0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef", false},
+		{"sha256!0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef", false},
+
+		// invalid hex
+		{"sha256-XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX", false},
+		{"sha256:XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX", false},
+	}
+
+	for _, tt := range cases {
+		got, err := ParseDigest(tt.in)
+		if tt.valid && err != nil {
+			t.Errorf("ParseDigest(%q) = %v, %v; want valid", tt.in, got, err)
+		}
+		want := "sha256:" + tt.in[7:]
+		if tt.valid && got.String() != want {
+			t.Errorf("ParseDigest(%q).String() = %q, want %q", tt.in, got.String(), want)
+		}
+	}
+}
+
+func TestDigestMarshalText(t *testing.T) {
+	const s = `"sha256-0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef"`
+	var d Digest
+	if err := json.Unmarshal([]byte(s), &d); err != nil {
+		t.Errorf("json.Unmarshal: %v", err)
+	}
+	out, err := json.Marshal(d)
+	if err != nil {
+		t.Errorf("json.Marshal: %v", err)
+	}
+	want := `"sha256:0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef"`
+	if string(out) != want {
+		t.Errorf("json.Marshal: got %s, want %s", out, want)
+	}
+	if err := json.Unmarshal([]byte(`"invalid"`), &Digest{}); err == nil {
+		t.Errorf("json.Unmarshal: expected error")
+	}
+}