Use and respect the passfile connection parameter (#1129)

* Use and respect the passfile connection parameter

The postgres documentation[1] regarding the password file, states
that:

password file to use can be specified using the connection parameter
passfile or the environment variable PGPASSFILE.

The current implementation of lib/pq only respects the environment
variable PGPASSFILE. This is not correct, but also limiting, as
the PGPASSFILE is global and we might want to use different files
for different clients in the same program.

Fixing that is easy, by just checking the parameter passfile first,
and if not, pull the value from PGPASSFILE.

This also moves the parsing of PGPASSFILE to `parseEnviron`.
Now the connection only checks the parameter passfile, that
is populated by `parseEnviron`.

[1] https://www.postgresql.org/docs/current/libpq-pgpass.html

conn.go

@@ -233,7 +233,8 @@ func (cn *conn) handlePgpass(o values) {
 	if _, ok := o["password"]; ok {
 		return
 	}
-	filename := os.Getenv("PGPASSFILE")
+	// Get passfile from the options
+	filename := o["passfile"]
 	if filename == "" {
 		// XXX this code doesn't work on Windows where the default filename is
 		// XXX %APPDATA%\postgresql\pgpass.conf
@@ -2038,6 +2039,8 @@ func parseEnviron(env []string) (out map[string]string) {
 			accrue("user")
 		case "PGPASSWORD":
 			accrue("password")
+		case "PGPASSFILE":
+			accrue("passfile")
 		case "PGSERVICE", "PGSERVICEFILE", "PGREALM":
 			unsupported()
 		case "PGOPTIONS":

conn_test.go

@@ -174,7 +174,10 @@ func TestPgpass(t *testing.T) {
 	}
 	testAssert("", "ok", "missing .pgpass, unexpected error %#v")
 	os.Setenv("PGPASSFILE", pgpassFile)
+	defer os.Unsetenv("PGPASSFILE")
 	testAssert("host=/tmp", "fail", ", unexpected error %#v")
+	os.Unsetenv("PGPASSFILE")
+
 	os.Remove(pgpassFile)
 	pgpass, err := os.OpenFile(pgpassFile, os.O_RDWR|os.O_CREATE, 0644)
 	if err != nil {
@@ -189,6 +192,7 @@ localhost:*:*:*:pass_C
 	if err != nil {
 		t.Fatalf("Unexpected error writing pgpass file %#v", err)
 	}
+	defer os.Remove(pgpassFile)
 	pgpass.Close()
 
 	assertPassword := func(extra values, expected string) {
@@ -211,19 +215,22 @@ localhost:*:*:*:pass_C
 			t.Fatalf("For %v expected %s got %s", extra, expected, pw)
 		}
 	}
+	// missing passfile means empty psasword
+	assertPassword(values{"host": "server", "dbname": "some_db", "user": "some_user"}, "")
 	// wrong permissions for the pgpass file means it should be ignored
-	assertPassword(values{"host": "example.com", "user": "foo"}, "")
+	assertPassword(values{"host": "example.com", "passfile": pgpassFile, "user": "foo"}, "")
 	// fix the permissions and check if it has taken effect
 	os.Chmod(pgpassFile, 0600)
-	assertPassword(values{"host": "server", "dbname": "some_db", "user": "some_user"}, "pass_A")
-	assertPassword(values{"host": "example.com", "user": "foo"}, "pass_fallback")
-	assertPassword(values{"host": "example.com", "dbname": "some_db", "user": "some_user"}, "pass_B")
+
+	assertPassword(values{"host": "server", "passfile": pgpassFile, "dbname": "some_db", "user": "some_user"}, "pass_A")
+	assertPassword(values{"host": "example.com", "passfile": pgpassFile, "user": "foo"}, "pass_fallback")
+	assertPassword(values{"host": "example.com", "passfile": pgpassFile, "dbname": "some_db", "user": "some_user"}, "pass_B")
 	// localhost also matches the default "" and UNIX sockets
-	assertPassword(values{"host": "", "user": "some_user"}, "pass_C")
-	assertPassword(values{"host": "/tmp", "user": "some_user"}, "pass_C")
-	// cleanup
-	os.Remove(pgpassFile)
-	os.Setenv("PGPASSFILE", "")
+	assertPassword(values{"host": "", "passfile": pgpassFile, "user": "some_user"}, "pass_C")
+	assertPassword(values{"host": "/tmp", "passfile": pgpassFile, "user": "some_user"}, "pass_C")
+	// passfile connection parameter takes precedence
+	os.Setenv("PGPASSFILE", "/tmp")
+	assertPassword(values{"host": "server", "passfile": pgpassFile, "dbname": "some_db", "user": "some_user"}, "pass_A")
 }
 
 func TestExec(t *testing.T) {

connector_test.go

@@ -7,6 +7,7 @@ import (
 	"context"
 	"database/sql"
 	"database/sql/driver"
+	"os"
 	"testing"
 )
 
@@ -66,3 +67,21 @@ func TestNewConnector_Driver(t *testing.T) {
 	}
 	txn.Rollback()
 }
+
+func TestNewConnector_Environ(t *testing.T) {
+	name := ""
+	os.Setenv("PGPASSFILE", "/tmp/.pgpass")
+	defer os.Unsetenv("PGPASSFILE")
+	c, err := NewConnector(name)
+	if err != nil {
+		t.Fatal(err)
+	}
+	for key, expected := range map[string]string{
+		"passfile": "/tmp/.pgpass",
+	} {
+		if got := c.opts[key]; got != expected {
+			t.Fatalf("Getting values from environment variables, for %v expected %s got %s", key, expected, got)
+		}
+	}
+
+}