[syserror] Refactor abi/linux.Errno

PiperOrigin-RevId: 373265454

7 files changed, 158 insertions, 170 deletions

diff --git a/pkg/abi/linux/BUILD b/pkg/abi/linux/BUILD
index 064a54547..a461bb65e 100644
--- a/pkg/abi/linux/BUILD
+++ b/pkg/abi/linux/BUILD
@@ -85,6 +85,8 @@ go_library(
 go_test(
     name = "linux_test",
     size = "small",
-    srcs = ["netfilter_test.go"],
+    srcs = [
+        "netfilter_test.go",
+    ],
     library = ":linux",
 )
diff --git a/pkg/abi/linux/errors.go b/pkg/abi/linux/errors.go
index 93f85a864..b08b2687e 100644
--- a/pkg/abi/linux/errors.go
+++ b/pkg/abi/linux/errors.go
@@ -15,158 +15,149 @@
 package linux
 
 // Errno represents a Linux errno value.
-type Errno struct {
-	number int
-	name   string
-}
-
-// Number returns the errno number.
-func (e *Errno) Number() int {
-	return e.number
-}
-
-// String implements fmt.Stringer.String.
-func (e *Errno) String() string {
-	return e.name
-}
+type Errno int
 
 // Errno values from include/uapi/asm-generic/errno-base.h.
-var (
-	EPERM   = &Errno{1, "operation not permitted"}
-	ENOENT  = &Errno{2, "no such file or directory"}
-	ESRCH   = &Errno{3, "no such process"}
-	EINTR   = &Errno{4, "interrupted system call"}
-	EIO     = &Errno{5, "I/O error"}
-	ENXIO   = &Errno{6, "no such device or address"}
-	E2BIG   = &Errno{7, "argument list too long"}
-	ENOEXEC = &Errno{8, "exec format error"}
-	EBADF   = &Errno{9, "bad file number"}
-	ECHILD  = &Errno{10, "no child processes"}
-	EAGAIN  = &Errno{11, "try again"}
-	ENOMEM  = &Errno{12, "out of memory"}
-	EACCES  = &Errno{13, "permission denied"}
-	EFAULT  = &Errno{14, "bad address"}
-	ENOTBLK = &Errno{15, "block device required"}
-	EBUSY   = &Errno{16, "device or resource busy"}
-	EEXIST  = &Errno{17, "file exists"}
-	EXDEV   = &Errno{18, "cross-device link"}
-	ENODEV  = &Errno{19, "no such device"}
-	ENOTDIR = &Errno{20, "not a directory"}
-	EISDIR  = &Errno{21, "is a directory"}
-	EINVAL  = &Errno{22, "invalid argument"}
-	ENFILE  = &Errno{23, "file table overflow"}
-	EMFILE  = &Errno{24, "too many open files"}
-	ENOTTY  = &Errno{25, "not a typewriter"}
-	ETXTBSY = &Errno{26, "text file busy"}
-	EFBIG   = &Errno{27, "file too large"}
-	ENOSPC  = &Errno{28, "no space left on device"}
-	ESPIPE  = &Errno{29, "illegal seek"}
-	EROFS   = &Errno{30, "read-only file system"}
-	EMLINK  = &Errno{31, "too many links"}
-	EPIPE   = &Errno{32, "broken pipe"}
-	EDOM    = &Errno{33, "math argument out of domain of func"}
-	ERANGE  = &Errno{34, "math result not representable"}
+const (
+	NOERRNO = iota
+	EPERM
+	ENOENT
+	ESRCH
+	EINTR
+	EIO
+	ENXIO
+	E2BIG
+	ENOEXEC
+	EBADF
+	ECHILD // 10
+	EAGAIN
+	ENOMEM
+	EACCES
+	EFAULT
+	ENOTBLK
+	EBUSY
+	EEXIST
+	EXDEV
+	ENODEV
+	ENOTDIR // 20
+	EISDIR
+	EINVAL
+	ENFILE
+	EMFILE
+	ENOTTY
+	ETXTBSY
+	EFBIG
+	ENOSPC
+	ESPIPE
+	EROFS // 30
+	EMLINK
+	EPIPE
+	EDOM
+	ERANGE
+	// Errno values from include/uapi/asm-generic/errno.h.
+	EDEADLK
+	ENAMETOOLONG
+	ENOLCK
+	ENOSYS
+	ENOTEMPTY
+	ELOOP  //40
+	_      // Skip for EWOULDBLOCK = EAGAIN
+	ENOMSG //42
+	EIDRM
+	ECHRNG
+	EL2NSYNC
+	EL3HLT
+	EL3RST
+	ELNRNG
+	EUNATCH
+	ENOCSI
+	EL2HLT // 50
+	EBADE
+	EBADR
+	EXFULL
+	ENOANO
+	EBADRQC
+	EBADSLT
+	_ // Skip for EDEADLOCK = EDEADLK
+	EBFONT
+	ENOSTR // 60
+	ENODATA
+	ETIME
+	ENOSR
+	ENONET
+	ENOPKG
+	EREMOTE
+	ENOLINK
+	EADV
+	ESRMNT
+	ECOMM // 70
+	EPROTO
+	EMULTIHOP
+	EDOTDOT
+	EBADMSG
+	EOVERFLOW
+	ENOTUNIQ
+	EBADFD
+	EREMCHG
+	ELIBACC
+	ELIBBAD // 80
+	ELIBSCN
+	ELIBMAX
+	ELIBEXEC
+	EILSEQ
+	ERESTART
+	ESTRPIPE
+	EUSERS
+	ENOTSOCK
+	EDESTADDRREQ
+	EMSGSIZE // 90
+	EPROTOTYPE
+	ENOPROTOOPT
+	EPROTONOSUPPORT
+	ESOCKTNOSUPPORT
+	EOPNOTSUPP
+	EPFNOSUPPORT
+	EAFNOSUPPORT
+	EADDRINUSE
+	EADDRNOTAVAIL
+	ENETDOWN // 100
+	ENETUNREACH
+	ENETRESET
+	ECONNABORTED
+	ECONNRESET
+	ENOBUFS
+	EISCONN
+	ENOTCONN
+	ESHUTDOWN
+	ETOOMANYREFS
+	ETIMEDOUT // 110
+	ECONNREFUSED
+	EHOSTDOWN
+	EHOSTUNREACH
+	EALREADY
+	EINPROGRESS
+	ESTALE
+	EUCLEAN
+	ENOTNAM
+	ENAVAIL
+	EISNAM // 120
+	EREMOTEIO
+	EDQUOT
+	ENOMEDIUM
+	EMEDIUMTYPE
+	ECANCELED
+	ENOKEY
+	EKEYEXPIRED
+	EKEYREVOKED
+	EKEYREJECTED
+	EOWNERDEAD // 130
+	ENOTRECOVERABLE
+	ERFKILL
+	EHWPOISON
 )
 
-// Errno values from include/uapi/asm-generic/errno.h.
-var (
-	EDEADLK         = &Errno{35, "resource deadlock would occur"}
-	ENAMETOOLONG    = &Errno{36, "file name too long"}
-	ENOLCK          = &Errno{37, "no record locks available"}
-	ENOSYS          = &Errno{38, "invalid system call number"}
-	ENOTEMPTY       = &Errno{39, "directory not empty"}
-	ELOOP           = &Errno{40, "too many symbolic links encountered"}
-	EWOULDBLOCK     = &Errno{EAGAIN.number, "operation would block"}
-	ENOMSG          = &Errno{42, "no message of desired type"}
-	EIDRM           = &Errno{43, "identifier removed"}
-	ECHRNG          = &Errno{44, "channel number out of range"}
-	EL2NSYNC        = &Errno{45, "level 2 not synchronized"}
-	EL3HLT          = &Errno{46, "level 3 halted"}
-	EL3RST          = &Errno{47, "level 3 reset"}
-	ELNRNG          = &Errno{48, "link number out of range"}
-	EUNATCH         = &Errno{49, "protocol driver not attached"}
-	ENOCSI          = &Errno{50, "no CSI structure available"}
-	EL2HLT          = &Errno{51, "level 2 halted"}
-	EBADE           = &Errno{52, "invalid exchange"}
-	EBADR           = &Errno{53, "invalid request descriptor"}
-	EXFULL          = &Errno{54, "exchange full"}
-	ENOANO          = &Errno{55, "no anode"}
-	EBADRQC         = &Errno{56, "invalid request code"}
-	EBADSLT         = &Errno{57, "invalid slot"}
-	EDEADLOCK       = EDEADLK
-	EBFONT          = &Errno{59, "bad font file format"}
-	ENOSTR          = &Errno{60, "device not a stream"}
-	ENODATA         = &Errno{61, "no data available"}
-	ETIME           = &Errno{62, "timer expired"}
-	ENOSR           = &Errno{63, "out of streams resources"}
-	ENONET          = &Errno{64, "machine is not on the network"}
-	ENOPKG          = &Errno{65, "package not installed"}
-	EREMOTE         = &Errno{66, "object is remote"}
-	ENOLINK         = &Errno{67, "link has been severed"}
-	EADV            = &Errno{68, "advertise error"}
-	ESRMNT          = &Errno{69, "srmount error"}
-	ECOMM           = &Errno{70, "communication error on send"}
-	EPROTO          = &Errno{71, "protocol error"}
-	EMULTIHOP       = &Errno{72, "multihop attempted"}
-	EDOTDOT         = &Errno{73, "RFS specific error"}
-	EBADMSG         = &Errno{74, "not a data message"}
-	EOVERFLOW       = &Errno{75, "value too large for defined data type"}
-	ENOTUNIQ        = &Errno{76, "name not unique on network"}
-	EBADFD          = &Errno{77, "file descriptor in bad state"}
-	EREMCHG         = &Errno{78, "remote address changed"}
-	ELIBACC         = &Errno{79, "can not access a needed shared library"}
-	ELIBBAD         = &Errno{80, "accessing a corrupted shared library"}
-	ELIBSCN         = &Errno{81, ".lib section in a.out corrupted"}
-	ELIBMAX         = &Errno{82, "attempting to link in too many shared libraries"}
-	ELIBEXEC        = &Errno{83, "cannot exec a shared library directly"}
-	EILSEQ          = &Errno{84, "illegal byte sequence"}
-	ERESTART        = &Errno{85, "interrupted system call should be restarted"}
-	ESTRPIPE        = &Errno{86, "streams pipe error"}
-	EUSERS          = &Errno{87, "too many users"}
-	ENOTSOCK        = &Errno{88, "socket operation on non-socket"}
-	EDESTADDRREQ    = &Errno{89, "destination address required"}
-	EMSGSIZE        = &Errno{90, "message too long"}
-	EPROTOTYPE      = &Errno{91, "protocol wrong type for socket"}
-	ENOPROTOOPT     = &Errno{92, "protocol not available"}
-	EPROTONOSUPPORT = &Errno{93, "protocol not supported"}
-	ESOCKTNOSUPPORT = &Errno{94, "socket type not supported"}
-	EOPNOTSUPP      = &Errno{95, "operation not supported on transport endpoint"}
-	EPFNOSUPPORT    = &Errno{96, "protocol family not supported"}
-	EAFNOSUPPORT    = &Errno{97, "address family not supported by protocol"}
-	EADDRINUSE      = &Errno{98, "address already in use"}
-	EADDRNOTAVAIL   = &Errno{99, "cannot assign requested address"}
-	ENETDOWN        = &Errno{100, "network is down"}
-	ENETUNREACH     = &Errno{101, "network is unreachable"}
-	ENETRESET       = &Errno{102, "network dropped connection because of reset"}
-	ECONNABORTED    = &Errno{103, "software caused connection abort"}
-	ECONNRESET      = &Errno{104, "connection reset by peer"}
-	ENOBUFS         = &Errno{105, "no buffer space available"}
-	EISCONN         = &Errno{106, "transport endpoint is already connected"}
-	ENOTCONN        = &Errno{107, "transport endpoint is not connected"}
-	ESHUTDOWN       = &Errno{108, "cannot send after transport endpoint shutdown"}
-	ETOOMANYREFS    = &Errno{109, "too many references: cannot splice"}
-	ETIMEDOUT       = &Errno{110, "connection timed out"}
-	ECONNREFUSED    = &Errno{111, "connection refused"}
-	EHOSTDOWN       = &Errno{112, "host is down"}
-	EHOSTUNREACH    = &Errno{113, "no route to host"}
-	EALREADY        = &Errno{114, "operation already in progress"}
-	EINPROGRESS     = &Errno{115, "operation now in progress"}
-	ESTALE          = &Errno{116, "stale file handle"}
-	EUCLEAN         = &Errno{117, "structure needs cleaning"}
-	ENOTNAM         = &Errno{118, "not a XENIX named type file"}
-	ENAVAIL         = &Errno{119, "no XENIX semaphores available"}
-	EISNAM          = &Errno{120, "is a named type file"}
-	EREMOTEIO       = &Errno{121, "remote I/O error"}
-	EDQUOT          = &Errno{122, "quota exceeded"}
-	ENOMEDIUM       = &Errno{123, "no medium found"}
-	EMEDIUMTYPE     = &Errno{124, "wrong medium type"}
-	ECANCELED       = &Errno{125, "operation Canceled"}
-	ENOKEY          = &Errno{126, "required key not available"}
-	EKEYEXPIRED     = &Errno{127, "key has expired"}
-	EKEYREVOKED     = &Errno{128, "key has been revoked"}
-	EKEYREJECTED    = &Errno{129, "key was rejected by service"}
-	EOWNERDEAD      = &Errno{130, "owner died"}
-	ENOTRECOVERABLE = &Errno{131, "state not recoverable"}
-	ERFKILL         = &Errno{132, "operation not possible due to RF-kill"}
-	EHWPOISON       = &Errno{133, "memory page has hardware error"}
+// errnos derived from other errnos
+const (
+	EWOULDBLOCK = EAGAIN
+	EDEADLOCK   = EDEADLK
 )
diff --git a/pkg/sentry/socket/netlink/socket.go b/pkg/sentry/socket/netlink/socket.go
index d75a2879f..280563d09 100644
--- a/pkg/sentry/socket/netlink/socket.go
+++ b/pkg/sentry/socket/netlink/socket.go
@@ -656,7 +656,7 @@ func dumpErrorMesage(hdr linux.NetlinkMessageHeader, ms *MessageSet, err *syserr
 		Type: linux.NLMSG_ERROR,
 	})
 	m.Put(&linux.NetlinkErrorMessage{
-		Error:  int32(-err.ToLinux().Number()),
+		Error:  int32(-err.ToLinux()),
 		Header: hdr,
 	})
 }
diff --git a/pkg/sentry/socket/netstack/netstack.go b/pkg/sentry/socket/netstack/netstack.go
index 455a92e53..3fd22f936 100644
--- a/pkg/sentry/socket/netstack/netstack.go
+++ b/pkg/sentry/socket/netstack/netstack.go
@@ -851,7 +851,7 @@ func getSockOptSocket(t *kernel.Task, s socket.SocketOps, ep commonEndpoint, fam
 			return &optP, nil
 		}
 
-		optP := primitive.Int32(syserr.TranslateNetstackError(err).ToLinux().Number())
+		optP := primitive.Int32(syserr.TranslateNetstackError(err).ToLinux())
 		return &optP, nil
 
 	case linux.SO_PEERCRED:
diff --git a/pkg/sentry/socket/socket.go b/pkg/sentry/socket/socket.go
index 9e56487a6..353f4ade0 100644
--- a/pkg/sentry/socket/socket.go
+++ b/pkg/sentry/socket/socket.go
@@ -80,7 +80,7 @@ func sockErrCmsgToLinux(sockErr *tcpip.SockError) linux.SockErrCMsg {
 	}
 
 	ee := linux.SockExtendedErr{
-		Errno:  uint32(syserr.TranslateNetstackError(sockErr.Err).ToLinux().Number()),
+		Errno:  uint32(syserr.TranslateNetstackError(sockErr.Err).ToLinux()),
 		Origin: errOriginToLinux(sockErr.Cause.Origin()),
 		Type:   sockErr.Cause.Type(),
 		Code:   sockErr.Cause.Code(),
diff --git a/pkg/syserr/netstack.go b/pkg/syserr/netstack.go
index 79e564de6..90be24e15 100644
--- a/pkg/syserr/netstack.go
+++ b/pkg/syserr/netstack.go
@@ -38,7 +38,7 @@ var (
 	ErrPortInUse             = New((&tcpip.ErrPortInUse{}).String(), linux.EADDRINUSE)
 	ErrBadLocalAddress       = New((&tcpip.ErrBadLocalAddress{}).String(), linux.EADDRNOTAVAIL)
 	ErrClosedForSend         = New((&tcpip.ErrClosedForSend{}).String(), linux.EPIPE)
-	ErrClosedForReceive      = New((&tcpip.ErrClosedForReceive{}).String(), nil)
+	ErrClosedForReceive      = New((&tcpip.ErrClosedForReceive{}).String(), linux.NOERRNO)
 	ErrTimeout               = New((&tcpip.ErrTimeout{}).String(), linux.ETIMEDOUT)
 	ErrAborted               = New((&tcpip.ErrAborted{}).String(), linux.EPIPE)
 	ErrConnectStarted        = New((&tcpip.ErrConnectStarted{}).String(), linux.EINPROGRESS)
diff --git a/pkg/syserr/syserr.go b/pkg/syserr/syserr.go
index b5881ea3c..d70521f32 100644
--- a/pkg/syserr/syserr.go
+++ b/pkg/syserr/syserr.go
@@ -34,24 +34,19 @@ type Error struct {
 	// linux.Errno.
 	noTranslation bool
 
-	// errno is the linux.Errno this Error should be translated to. nil means
-	// that this Error should be translated to a nil linux.Errno.
-	errno *linux.Errno
+	// errno is the linux.Errno this Error should be translated to.
+	errno linux.Errno
 }
 
 // New creates a new Error and adds a translation for it.
 //
 // New must only be called at init.
-func New(message string, linuxTranslation *linux.Errno) *Error {
+func New(message string, linuxTranslation linux.Errno) *Error {
 	err := &Error{message: message, errno: linuxTranslation}
 
-	if linuxTranslation == nil {
-		return err
-	}
-
 	// TODO(b/34162363): Remove this.
-	errno := linuxTranslation.Number()
-	if errno <= 0 || errno >= len(linuxBackwardsTranslations) {
+	errno := linuxTranslation
+	if errno < 0 || int(errno) >= len(linuxBackwardsTranslations) {
 		panic(fmt.Sprint("invalid errno: ", errno))
 	}
 
@@ -74,7 +69,7 @@ func New(message string, linuxTranslation *linux.Errno) *Error {
 // NewDynamic should only be used sparingly and not be used for static error
 // messages. Errors with static error messages should be declared with New as
 // global variables.
-func NewDynamic(message string, linuxTranslation *linux.Errno) *Error {
+func NewDynamic(message string, linuxTranslation linux.Errno) *Error {
 	return &Error{message: message, errno: linuxTranslation}
 }
 
@@ -87,7 +82,7 @@ func NewWithoutTranslation(message string) *Error {
 	return &Error{message: message, noTranslation: true}
 }
 
-func newWithHost(message string, linuxTranslation *linux.Errno, hostErrno unix.Errno) *Error {
+func newWithHost(message string, linuxTranslation linux.Errno, hostErrno unix.Errno) *Error {
 	e := New(message, linuxTranslation)
 	addLinuxHostTranslation(hostErrno, e)
 	return e
@@ -119,10 +114,10 @@ func (e *Error) ToError() error {
 	if e.noTranslation {
 		panic(fmt.Sprintf("error %q does not support translation", e.message))
 	}
-	if e.errno == nil {
+	errno := int(e.errno)
+	if errno == linux.NOERRNO {
 		return nil
 	}
-	errno := e.errno.Number()
 	if errno <= 0 || errno >= len(linuxBackwardsTranslations) || !linuxBackwardsTranslations[errno].ok {
 		panic(fmt.Sprintf("unknown error %q (%d)", e.message, errno))
 	}
@@ -131,7 +126,7 @@ func (e *Error) ToError() error {
 
 // ToLinux converts the Error to a Linux ABI error that can be returned to the
 // application.
-func (e *Error) ToLinux() *linux.Errno {
+func (e *Error) ToLinux() linux.Errno {
 	if e.noTranslation {
 		panic(fmt.Sprintf("No Linux ABI translation available for %q", e.message))
 	}