feat(errorsx): cover more syscall errors and add tests (#430)

* feat(errorsx): cover more syscall errors and add tests

Part of https://github.com/ooni/probe/issues/1505

* fix tests

internal/errorsx/generator/main.go

@@ -6,6 +6,7 @@ import (
 	"os"
 	"time"
 
+	"github.com/iancoleman/strcase"
 	"golang.org/x/sys/execabs"
 )
 
@@ -18,13 +19,10 @@ type ErrorSpec struct {
 	Failure string
 }
 
-// TODO(kelmenhorst): find out if we need more system errors here. Currently
-// the code does not generate any mapping if Failure is empty.
-
 // Specs contains all the error specs.
 var Specs = []ErrorSpec{{
 	Errno:   "ECANCELED",
-	Failure: "Interrupted",
+	Failure: "OperationCanceled",
 }, {
 	Errno:   "ECONNREFUSED",
 	Failure: "ConnectionRefused",
@@ -36,53 +34,76 @@ var Specs = []ErrorSpec{{
 	Failure: "HostUnreachable",
 }, {
 	Errno:   "ETIMEDOUT",
-	Failure: "GenericTimeoutError",
+	Failure: "TimedOut",
 }, {
-	Errno: "EAFNOSUPPORT",
+	Errno:   "EAFNOSUPPORT",
+	Failure: "AddressFamilyNotSupported",
 }, {
-	Errno: "EADDRINUSE",
+	Errno:   "EADDRINUSE",
+	Failure: "AddressInUse",
 }, {
-	Errno: "EADDRNOTAVAIL",
+	Errno:   "EADDRNOTAVAIL",
+	Failure: "AddressNotAvailable",
 }, {
-	Errno: "EISCONN",
+	Errno:   "EISCONN",
+	Failure: "AlreadyConnected",
 }, {
-	Errno: "EFAULT",
+	Errno:   "EFAULT",
+	Failure: "BadAddress",
 }, {
-	Errno: "EBADF",
+	Errno:   "EBADF",
+	Failure: "BadFileDescriptor",
 }, {
-	Errno: "ECONNABORTED",
+	Errno:   "ECONNABORTED",
+	Failure: "ConnectionAborted",
 }, {
-	Errno: "EALREADY",
+	Errno:   "EALREADY",
+	Failure: "ConnectionAlreadyInProgress",
 }, {
-	Errno: "EDESTADDRREQ",
+	Errno:   "EDESTADDRREQ",
+	Failure: "DestinationAddressRequired",
 }, {
-	Errno: "EINTR",
+	Errno:   "EINTR",
+	Failure: "Interrupted",
 }, {
-	Errno: "EINVAL",
+	Errno:   "EINVAL",
+	Failure: "InvalidArgument",
 }, {
-	Errno: "EMSGSIZE",
+	Errno:   "EMSGSIZE",
+	Failure: "MessageSize",
 }, {
-	Errno: "ENETDOWN",
+	Errno:   "ENETDOWN",
+	Failure: "NetworkDown",
 }, {
-	Errno: "ENETRESET",
+	Errno:   "ENETRESET",
+	Failure: "NetworkReset",
 }, {
-	Errno: "ENETUNREACH",
+	Errno:   "ENETUNREACH",
+	Failure: "NetworkUnreachable",
 }, {
-	Errno: "ENOBUFS",
+	Errno:   "ENOBUFS",
+	Failure: "NoBufferSpace",
 }, {
-	Errno: "ENOPROTOOPT",
+	Errno:   "ENOPROTOOPT",
+	Failure: "NoProtocolOption",
 }, {
-	Errno: "ENOTSOCK",
+	Errno:   "ENOTSOCK",
+	Failure: "NotASocket",
 }, {
-	Errno: "ENOTCONN",
+	Errno:   "ENOTCONN",
+	Failure: "NotConnected",
 }, {
-	Errno: "EWOULDBLOCK",
+	Errno:   "EWOULDBLOCK",
+	Failure: "OperationWouldBlock",
 }, {
-	Errno: "EACCES",
+	Errno:   "EACCES",
+	Failure: "PermissionDenied",
 }, {
-	Errno: "EPROTONOSUPPORT",
+	Errno:   "EPROTONOSUPPORT",
+	Failure: "ProtocolNotSupported",
 }, {
-	Errno: "EPROTOTYPE",
+	Errno:   "EPROTOTYPE",
+	Failure: "WrongProtocolType",
 }}
 
 func fileCreate(filename string) *os.File {
@@ -143,6 +164,19 @@ func writeGenericFile() {
 	fileWrite(filep, "\t\"errors\"\n")
 	fileWrite(filep, "\t\"syscall\"\n")
 	fileWrite(filep, ")\n\n")
+
+	fileWrite(filep, "// This enumeration lists the syscall-derived failures defined at\n")
+	fileWrite(filep, "// https://github.com/ooni/spec/blob/master/data-formats/df-007-errors.md\n")
+	fileWrite(filep, "//\n")
+	fileWrite(filep, "// See also the enumeration at failures.go for the failures that\n")
+	fileWrite(filep, "// DO NOT derive from system call errors.\n")
+	fileWrite(filep, "const (\n")
+	for _, spec := range Specs {
+		filePrintf(filep, "\tFailure%s = \"%s\"\n", spec.Failure,
+			strcase.ToSnake(spec.Failure))
+	}
+	fileWrite(filep, ")\n\n")
+
 	fileWrite(filep, "// toSyscallErr converts a syscall error to the\n")
 	fileWrite(filep, "// proper OONI error. Returns the OONI error string\n")
 	fileWrite(filep, "// on success, an empty string otherwise.\n")
@@ -164,6 +198,40 @@ func writeGenericFile() {
 	fileWrite(filep, "\t}\n")
 	fileWrite(filep, "\treturn \"\"\n")
 	fileWrite(filep, "}\n\n")
+
+	fileClose(filep)
+	gofmt(filename)
+}
+
+func writeGenericTestFile() {
+	filename := "errno_test.go"
+	filep := fileCreate(filename)
+
+	fileWrite(filep, "// Code generated by go generate; DO NOT EDIT.\n")
+	filePrintf(filep, "// Generated: %+v\n\n", time.Now())
+	fileWrite(filep, "package errorsx\n\n")
+	fileWrite(filep, "import (\n")
+	fileWrite(filep, "\t\"io\"\n")
+	fileWrite(filep, "\t\"syscall\"\n")
+	fileWrite(filep, "\t\"testing\"\n")
+	fileWrite(filep, ")\n\n")
+
+	fileWrite(filep, "func TestToSyscallErr(t *testing.T) {\n")
+	fileWrite(filep, "\tif v := toSyscallErr(io.EOF); v != \"\" {\n")
+	fileWrite(filep, "\t\tt.Fatalf(\"expected empty string, got '%s'\", v)\n")
+	fileWrite(filep, "\t}\n")
+
+	for _, spec := range Specs {
+		filePrintf(filep, "\tif v := toSyscallErr(%s); v != Failure%s {\n", spec.Errno, spec.Failure)
+		filePrintf(filep, "\t\tt.Fatalf(\"expected '%%s', got '%%s'\", Failure%s, v)\n", spec.Failure)
+		fileWrite(filep, "\t}\n")
+	}
+
+	fileWrite(filep, "\tif v := toSyscallErr(syscall.Errno(0)); v != \"\" {\n")
+	fileWrite(filep, "\t\tt.Fatalf(\"expected empty string, got '%s'\", v)\n")
+	fileWrite(filep, "\t}\n")
+	fileWrite(filep, "}\n")
+
 	fileClose(filep)
 	gofmt(filename)
 }
@@ -172,4 +240,5 @@ func main() {
 	writeSystemSpecificFile("unix")
 	writeSystemSpecificFile("windows")
 	writeGenericFile()
+	writeGenericTestFile()
 }