[syserror] Refactor linuxerr and error package.

Move Error struct to pkg/errors package for use in multiple places.
Move linuxerr static definitions under pkg/errors/linuxerr.
Add a lookup list for quick lookup of *errors.Error by errno. This is useful
when converting syserror errors and unix.Errno/syscall.Errrno values to
*errors.Error.
Update benchmarks routines to include conversions.

The below benchmarks show *errors.Error usage to be comparable to using
unix.Errno.

BenchmarkAssignUnix
BenchmarkAssignUnix-32                 	787875022	         1.284 ns/op
BenchmarkAssignLinuxerr
BenchmarkAssignLinuxerr-32             	1000000000	         1.209 ns/op
BenchmarkAssignSyserror
BenchmarkAssignSyserror-32             	759269229	         1.429 ns/op
BenchmarkCompareUnix
BenchmarkCompareUnix-32                	1000000000	         1.310 ns/op
BenchmarkCompareLinuxerr
BenchmarkCompareLinuxerr-32            	1000000000	         1.241 ns/op
BenchmarkCompareSyserror
BenchmarkCompareSyserror-32            	147196165	         8.248 ns/op
BenchmarkSwitchUnix
BenchmarkSwitchUnix-32                 	373233556	         3.664 ns/op
BenchmarkSwitchLinuxerr
BenchmarkSwitchLinuxerr-32             	476323929	         3.294 ns/op
BenchmarkSwitchSyserror
BenchmarkSwitchSyserror-32             	39293408	        29.62 ns/op
BenchmarkReturnUnix
BenchmarkReturnUnix-32                 	1000000000	         0.5042 ns/op
BenchmarkReturnLinuxerr
BenchmarkReturnLinuxerr-32             	1000000000	         0.8152 ns/op
BenchmarkConvertUnixLinuxerr
BenchmarkConvertUnixLinuxerr-32        	739948875	         1.547 ns/op
BenchmarkConvertUnixLinuxerrZero
BenchmarkConvertUnixLinuxerrZero-32    	977733974	         1.489 ns/op

PiperOrigin-RevId: 379806801

2 files changed, 174 insertions, 0 deletions

diff --git a/pkg/abi/linux/errno/BUILD b/pkg/abi/linux/errno/BUILD
new file mode 100644
index 000000000..d003342d5
--- /dev/null
+++ b/pkg/abi/linux/errno/BUILD
@@ -0,0 +1,9 @@
+load("//tools:defs.bzl", "go_library")
+
+package(licenses = ["notice"])
+
+go_library(
+    name = "errno",
+    srcs = ["errno.go"],
+    visibility = ["//visibility:public"],
+)
diff --git a/pkg/abi/linux/errno/errno.go b/pkg/abi/linux/errno/errno.go
new file mode 100644
index 000000000..5a09c6605
--- /dev/null
+++ b/pkg/abi/linux/errno/errno.go
@@ -0,0 +1,165 @@
+// Copyright 2018 The gVisor Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// Package errno holds errno codes for abi/linux.
+package errno
+
+// Errno represents a Linux errno value.
+type Errno uint32
+
+// Errno values from include/uapi/asm-generic/errno-base.h.
+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
+	_ // Skip for ENOENT = 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
+)
+
+// errnos derived from other errnos
+const (
+	EWOULDBLOCK = EAGAIN
+	EDEADLOCK   = EDEADLK
+	ENONET      = ENOENT
+)