From dcccbfdc799d174901c29d82874457367231fec5 Mon Sep 17 00:00:00 2001 From: James M Snell Date: Mon, 2 May 2016 10:27:12 -0700 Subject: [PATCH] src: refactor require('constants') The require('constants') module is currently undocumented and mashes together unrelated constants. This refactors the require('constants') in favor of distinct os.constants, fs.constants, and crypto.constants that are specific to the modules for which they are relevant. The next step is to document those within the specific modules. PR-URL: https://github.com/nodejs/node/pull/6534 Reviewed-By: Anna Henningsen Reviewed-By: Robert Lindstaedt --- doc/api/crypto.md | 379 ++++++++- doc/api/fs.md | 275 ++++++- doc/api/os.md | 770 ++++++++++++++++++ lib/_tls_common.js | 6 +- lib/child_process.js | 2 +- lib/constants.js | 10 +- lib/crypto.js | 8 +- lib/dgram.js | 4 +- lib/fs.js | 8 +- lib/internal/child_process.js | 2 +- lib/internal/process.js | 6 +- lib/os.js | 6 + lib/tls.js | 4 +- src/node.cc | 2 +- src/node_constants.cc | 30 +- src/node_constants.h | 2 +- test/parallel/test-constants.js | 12 + test/parallel/test-crypto-binary-default.js | 4 +- test/parallel/test-crypto-dh.js | 18 +- test/parallel/test-crypto-rsa-dsa.js | 2 +- test/parallel/test-fs-open-flags.js | 15 +- test/parallel/test-fs-open-numeric-flags.js | 3 +- test/parallel/test-fs-write.js | 3 +- .../test-https-agent-session-eviction.js | 4 +- .../test-process-constants-noatime.js | 6 +- .../test-tls-async-cb-after-socket-end.js | 4 +- test/parallel/test-tls-cipher-list.js | 4 +- test/parallel/test-tls-ocsp-callback.js | 5 +- test/parallel/test-tls-server-verify.js | 6 +- 29 files changed, 1484 insertions(+), 116 deletions(-) create mode 100644 test/parallel/test-constants.js diff --git a/doc/api/crypto.md b/doc/api/crypto.md index e84c10dfa4..aac0c6eed6 100644 --- a/doc/api/crypto.md +++ b/doc/api/crypto.md @@ -856,6 +856,12 @@ thrown. ## `crypto` module methods and properties +## crypto.constants + +Returns an object containing commonly used constants for crypto and security +related operations. The specific constants currently defined are described in +[Crypto Constants][]. + ### crypto.DEFAULT_ENCODING The default encoding to use for functions that can take either strings @@ -1205,11 +1211,11 @@ keys: * `key` : {String} - PEM encoded private key * `passphrase` : {String} - Optional passphrase for the private key * `padding` : An optional padding value, one of the following: - * `constants.RSA_NO_PADDING` - * `constants.RSA_PKCS1_PADDING` - * `constants.RSA_PKCS1_OAEP_PADDING` + * `crypto.constants.RSA_NO_PADDING` + * `crypto.constants.RSA_PKCS1_PADDING` + * `crypto.constants.RSA_PKCS1_OAEP_PADDING` -All paddings are defined in the `constants` module. +All paddings are defined in `crypto.constants`. ### crypto.privateEncrypt(private_key, buffer) @@ -1223,11 +1229,11 @@ keys: * `key` : {String} - PEM encoded private key * `passphrase` : {String} - Optional passphrase for the private key * `padding` : An optional padding value, one of the following: - * `constants.RSA_NO_PADDING` - * `constants.RSA_PKCS1_PADDING` - * `constants.RSA_PKCS1_OAEP_PADDING` + * `crypto.constants.RSA_NO_PADDING` + * `crypto.constants.RSA_PKCS1_PADDING` + * `crypto.constants.RSA_PKCS1_OAEP_PADDING` -All paddings are defined in the `constants` module. +All paddings are defined in `crypto.constants`. ### crypto.publicDecrypt(public_key, buffer) @@ -1241,14 +1247,14 @@ keys: * `key` : {String} - PEM encoded public key * `passphrase` : {String} - Optional passphrase for the private key * `padding` : An optional padding value, one of the following: - * `constants.RSA_NO_PADDING` - * `constants.RSA_PKCS1_PADDING` - * `constants.RSA_PKCS1_OAEP_PADDING` + * `crypto.constants.RSA_NO_PADDING` + * `crypto.constants.RSA_PKCS1_PADDING` + * `crypto.constants.RSA_PKCS1_OAEP_PADDING` Because RSA public keys can be derived from private keys, a private key may be passed instead of a public key. -All paddings are defined in the `constants` module. +All paddings are defined in `crypto.constants`. ### crypto.publicEncrypt(public_key, buffer) @@ -1262,14 +1268,14 @@ keys: * `key` : {String} - PEM encoded public key * `passphrase` : {String} - Optional passphrase for the private key * `padding` : An optional padding value, one of the following: - * `constants.RSA_NO_PADDING` - * `constants.RSA_PKCS1_PADDING` - * `constants.RSA_PKCS1_OAEP_PADDING` + * `crypto.constants.RSA_NO_PADDING` + * `crypto.constants.RSA_PKCS1_PADDING` + * `crypto.constants.RSA_PKCS1_OAEP_PADDING` Because RSA public keys can be derived from private keys, a private key may be passed instead of a public key. -All paddings are defined in the `constants` module. +All paddings are defined in `crypto.constants`. ### crypto.randomBytes(size[, callback]) @@ -1313,22 +1319,22 @@ Load and set the `engine` for some or all OpenSSL functions (selected by flags). `engine` could be either an id or a path to the engine's shared library. The optional `flags` argument uses `ENGINE_METHOD_ALL` by default. The `flags` -is a bit field taking one of or a mix of the following flags (defined in the -`constants` module): +is a bit field taking one of or a mix of the following flags (defined in +`crypto.constants`): -* `ENGINE_METHOD_RSA` -* `ENGINE_METHOD_DSA` -* `ENGINE_METHOD_DH` -* `ENGINE_METHOD_RAND` -* `ENGINE_METHOD_ECDH` -* `ENGINE_METHOD_ECDSA` -* `ENGINE_METHOD_CIPHERS` -* `ENGINE_METHOD_DIGESTS` -* `ENGINE_METHOD_STORE` -* `ENGINE_METHOD_PKEY_METHS` -* `ENGINE_METHOD_PKEY_ASN1_METHS` -* `ENGINE_METHOD_ALL` -* `ENGINE_METHOD_NONE` +* `crypto.constants.ENGINE_METHOD_RSA` +* `crypto.constants.ENGINE_METHOD_DSA` +* `crypto.constants.ENGINE_METHOD_DH` +* `crypto.constants.ENGINE_METHOD_RAND` +* `crypto.constants.ENGINE_METHOD_ECDH` +* `crypto.constants.ENGINE_METHOD_ECDSA` +* `crypto.constants.ENGINE_METHOD_CIPHERS` +* `crypto.constants.ENGINE_METHOD_DIGESTS` +* `crypto.constants.ENGINE_METHOD_STORE` +* `crypto.constants.ENGINE_METHOD_PKEY_METHS` +* `crypto.constants.ENGINE_METHOD_PKEY_ASN1_METHS` +* `crypto.constants.ENGINE_METHOD_ALL` +* `crypto.constants.ENGINE_METHOD_NONE` ## Notes @@ -1380,6 +1386,316 @@ Based on the recommendations of [NIST SP 800-131A][]: See the reference for other recommendations and details. +## Crypto Constants + +The following constants exported by `crypto.constants` apply to various uses of +the `crypto`, `tls`, and `https` modules and are generally specific to OpenSSL. + +### OpenSSL Options + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +
ConstantDescription
SSL_OP_ALLApplies multiple bug workarounds within OpenSSL. See + https://www.openssl.org/docs/manmaster/ssl/SSL_CTX_set_options.html for + detail.
SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATIONAllows legacy insecure renegotiation between OpenSSL and unpatched + clients or servers. See + https://www.openssl.org/docs/manmaster/ssl/SSL_CTX_set_options.html.
SSL_OP_CIPHER_SERVER_PREFERENCEUses the server's preferences instead of the clients when selecting a + cipher. See + https://www.openssl.org/docs/manmaster/ssl/SSL_CTX_set_options.html.
SSL_OP_CISCO_ANYCONNECTInstructs OpenSSL to use Cisco's "speshul" version of DTLS_BAD_VER.
SSL_OP_COOKIE_EXCHANGEInstructs OpenSSL to turn on cookie exchange.
SSL_OP_CRYPTOPRO_TLSEXT_BUGInstructs OpenSSL to add server-hello extension from an early version + of the cryptopro draft.
SSL_OP_DONT_INSERT_EMPTY_FRAGMENTSInstructs OpenSSL to disable a SSL 3.0/TLS 1.0 vulnerability + workaround added in OpenSSL 0.9.6d.
SSL_OP_EPHEMERAL_RSAInstructs OpenSSL to always use the tmp_rsa key when performing RSA + operations.
SSL_OP_LEGACY_SERVER_CONNECTAllow initial connection to servers that do not support RI.
SSL_OP_MICROSOFT_BIG_SSLV3_BUFFER
SSL_OP_MICROSOFT_SESS_ID_BUG
SSL_OP_MSIE_SSLV2_RSA_PADDINGInstructs OpenSSL to disable the workaround for a man-in-the-middle + protocol-version vulnerability in the SSL 2.0 server implementation.
SSL_OP_NETSCAPE_CA_DN_BUG
SSL_OP_NETSCAPE_CHALLENGE_BUG
SSL_OP_NETSCAPE_DEMO_CIPHER_CHANGE_BUG
SSL_OP_NETSCAPE_REUSE_CIPHER_CHANGE_BUG
SSL_OP_NO_COMPRESSIONInstructs OpenSSL to disable support for SSL/TLS compression.
SSL_OP_NO_QUERY_MTU
SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATIONInstructs OpenSSL to always start a new session when performing + renegotiation.
SSL_OP_NO_SSLv2Instructs OpenSSL to turn off SSL v2
SSL_OP_NO_SSLv3Instructs OpenSSL to turn off SSL v3
SSL_OP_NO_TICKETInstructs OpenSSL to disable use of RFC4507bis tickets.
SSL_OP_NO_TLSv1Instructs OpenSSL to turn off TLS v1
SSL_OP_NO_TLSv1_1Instructs OpenSSL to turn off TLS v1.1
SSL_OP_NO_TLSv1_2Instructs OpenSSL to turn off TLS v1.2
SSL_OP_PKCS1_CHECK_1
SSL_OP_PKCS1_CHECK_2
SSL_OP_SINGLE_DH_USEInstructs OpenSSL to always create a new key when using + temporary/ephemeral DH parameters.
SSL_OP_SINGLE_ECDH_USEInstructs OpenSSL to always create a new key when using + temporary/ephemeral ECDH parameters.
SSL_OP_SSLEAY_080_CLIENT_DH_BUG
SSL_OP_SSLREF2_REUSE_CERT_TYPE_BUG
SSL_OP_TLS_BLOCK_PADDING_BUG
SSL_OP_TLS_D5_BUG
SSL_OP_TLS_ROLLBACK_BUGInstructs OpenSSL to disable version rollback attack detection.
+ +### OpenSSL Engine Constants + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +
ConstantDescription
ENGINE_METHOD_RSALimit engine usage to RSA
ENGINE_METHOD_DSALimit engine usage to DSA
ENGINE_METHOD_DHLimit engine usage to DH
ENGINE_METHOD_RANDLimit engine usage to RAND
ENGINE_METHOD_ECDHLimit engine usage to ECDH
ENGINE_METHOD_ECDSALimit engine usage to ECDSA
ENGINE_METHOD_CIPHERSLimit engine usage to CIPHERS
ENGINE_METHOD_DIGESTSLimit engine usage to DIGESTS
ENGINE_METHOD_STORELimit engine usage to STORE
ENGINE_METHOD_PKEY_METHSLimit engine usage to PKEY_METHDS
ENGINE_METHOD_PKEY_ASN1_METHSLimit engine usage to PKEY_ASN1_METHS
ENGINE_METHOD_ALL
ENGINE_METHOD_NONE
+ +### Other OpenSSL Constants + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +
ConstantDescription
DH_CHECK_P_NOT_SAFE_PRIME
DH_CHECK_P_NOT_PRIME
DH_UNABLE_TO_CHECK_GENERATOR
DH_NOT_SUITABLE_GENERATOR
NPN_ENABLED
ALPN_ENABLED
RSA_PKCS1_PADDING
RSA_SSLV23_PADDING
RSA_NO_PADDING
RSA_PKCS1_OAEP_PADDING
RSA_X931_PADDING
RSA_PKCS1_PSS_PADDING
POINT_CONVERSION_COMPRESSED
POINT_CONVERSION_UNCOMPRESSED
POINT_CONVERSION_HYBRID
+ +### Node.js Crypto Constants + + + + + + + + + + + + + + +
ConstantDescription
defaultCoreCipherListSpecifies the built-in default cipher list used by Node.js.
defaultCipherListSpecifies the active default cipher list used by the current Node.js + process.
+ + [`Buffer`]: buffer.html [`cipher.final()`]: #crypto_cipher_final_output_encoding [`cipher.update()`]: #crypto_cipher_update_data_input_encoding_output_encoding @@ -1423,3 +1739,4 @@ See the reference for other recommendations and details. [RFC 3526]: https://www.rfc-editor.org/rfc/rfc3526.txt [stream]: stream.html [stream-writable-write]: stream.html#stream_writable_write_chunk_encoding_callback +[Crypto Constants]: #crypto_crypto_constants diff --git a/doc/api/fs.md b/doc/api/fs.md index f3c74d3885..9ecd61b1b6 100644 --- a/doc/api/fs.md +++ b/doc/api/fs.md @@ -266,13 +266,13 @@ optional integer that specifies the accessibility checks to be performed. The following constants define the possible values of `mode`. It is possible to create a mask consisting of the bitwise OR of two or more values. -- `fs.F_OK` - File is visible to the calling process. This is useful for -determining if a file exists, but says nothing about `rwx` permissions. +- `fs.constants.F_OK` - File is visible to the calling process. This is useful +for determining if a file exists, but says nothing about `rwx` permissions. Default if no `mode` is specified. -- `fs.R_OK` - File can be read by the calling process. -- `fs.W_OK` - File can be written by the calling process. -- `fs.X_OK` - File can be executed by the calling process. This has no effect -on Windows (will behave like `fs.F_OK`). +- `fs.constants.R_OK` - File can be read by the calling process. +- `fs.constants.W_OK` - File can be written by the calling process. +- `fs.constants.X_OK` - File can be executed by the calling process. This has no +effect on Windows (will behave like `fs.constants.F_OK`). The final argument, `callback`, is a callback function that is invoked with a possible error argument. If any of the accessibility checks fail, the error @@ -280,7 +280,7 @@ argument will be populated. The following example checks if the file `/etc/passwd` can be read and written by the current process. ```js -fs.access('/etc/passwd', fs.R_OK | fs.W_OK, (err) => { +fs.access('/etc/passwd', fs.constants.R_OK | fs.constants.W_OK, (err) => { console.log(err ? 'no access!' : 'can read/write'); }); ``` @@ -290,8 +290,8 @@ fs.access('/etc/passwd', fs.R_OK | fs.W_OK, (err) => { * `path` {String | Buffer} * `mode` {Integer} -Synchronous version of [`fs.access()`][]. This throws if any accessibility checks -fail, and does nothing otherwise. +Synchronous version of [`fs.access()`][]. This throws if any accessibility +checks fail, and does nothing otherwise. ## fs.appendFile(file, data[, options], callback) @@ -384,6 +384,12 @@ to the completion callback. Synchronous close(2). Returns `undefined`. +## fs.constants + +Returns an object containing commonly used constants for file system +operations. The specific constants currently defined are described in +[FS Constants][]. + ## fs.createReadStream(path[, options]) * `path` {String | Buffer} @@ -419,9 +425,9 @@ the file instead of the entire file. Both `start` and `end` are inclusive and start at 0. The `encoding` can be any one of those accepted by [`Buffer`][]. If `fd` is specified, `ReadStream` will ignore the `path` argument and will use -the specified file descriptor. This means that no `'open'` event will be emitted. -Note that `fd` should be blocking; non-blocking `fd`s should be passed to -[`net.Socket`][]. +the specified file descriptor. This means that no `'open'` event will be +emitted. Note that `fd` should be blocking; non-blocking `fd`s should be passed +to [`net.Socket`][]. If `autoClose` is false, then the file descriptor won't be closed, even if there's an error. It is your responsibility to close it and make sure @@ -468,7 +474,8 @@ Returns a new [`WriteStream`][] object. (See [Writable Stream][]). `options` may also include a `start` option to allow writing data at some position past the beginning of the file. Modifying a file rather than replacing it may require a `flags` mode of `r+` rather than the -default mode `w`. The `defaultEncoding` can be any one of those accepted by [`Buffer`][]. +default mode `w`. The `defaultEncoding` can be any one of those accepted by +[`Buffer`][]. If `autoClose` is set to true (default behavior) on `error` or `end` the file descriptor will be closed automatically. If `autoClose` is false, @@ -507,7 +514,8 @@ non-existent. ## fs.existsSync(path) - Stability: 0 - Deprecated: Use [`fs.statSync()`][] or [`fs.accessSync()`][] instead. + Stability: 0 - Deprecated: Use [`fs.statSync()`][] or [`fs.accessSync()`][] + instead. * `path` {String | Buffer} @@ -789,7 +797,7 @@ to a non-existent file. The exclusive flag may or may not work with network file systems. `flags` can also be a number as documented by open(2); commonly used constants -are available from `require('constants')`. On Windows, flags are translated to +are available from `fs.constants`. On Windows, flags are translated to their equivalent ones where applicable, e.g. `O_WRONLY` to `FILE_GENERIC_WRITE`, or `O_EXCL|O_CREAT` to `CREATE_NEW`, as accepted by CreateFileW. @@ -1038,11 +1046,11 @@ Synchronous stat(2). Returns an instance of [`fs.Stats`][]. * `callback` {Function} Asynchronous symlink(2). No arguments other than a possible exception are given -to the completion callback. -The `type` argument can be set to `'dir'`, `'file'`, or `'junction'` (default -is `'file'`) and is only available on Windows (ignored on other platforms). -Note that Windows junction points require the destination path to be absolute. When using -`'junction'`, the `target` argument will automatically be normalized to absolute path. +to the completion callback. The `type` argument can be set to `'dir'`, +`'file'`, or `'junction'` (default is `'file'`) and is only available on +Windows (ignored on other platforms). Note that Windows junction points require +the destination path to be absolute. When using `'junction'`, the `target` +argument will automatically be normalized to absolute path. Here is an example below: @@ -1255,9 +1263,9 @@ _Note: when an `fs.watchFile` operation results in an `ENOENT` error, it will of zero. If the file is created later on, the listener will be called again, with the latest stat objects. This is a change in functionality since v0.10._ -_Note: [`fs.watch()`][] is more efficient than `fs.watchFile` and `fs.unwatchFile`. -`fs.watch` should be used instead of `fs.watchFile` and `fs.unwatchFile` -when possible._ +_Note: [`fs.watch()`][] is more efficient than `fs.watchFile` and +`fs.unwatchFile`. `fs.watch` should be used instead of `fs.watchFile` and +`fs.unwatchFile` when possible._ ## fs.write(fd, buffer, offset, length[, position], callback) @@ -1387,6 +1395,226 @@ The synchronous version of [`fs.writeFile()`][]. Returns `undefined`. Synchronous versions of [`fs.write()`][]. Returns the number of bytes written. +## FS Constants + +The following constants are exported by `fs.constants`. **Note:** Not every +constant will be available on every operating system. + +### File Access Constants + +The following constants are meant for use with [`fs.access()`][]. + + + + + + + + + + + + + + + + + + + + + + +
ConstantDescription
F_OKFlag indicating that the file is visible to the calling process.
R_OKFlag indicating that the file can be read by the calling process.
W_OKFlag indicating that the file can be written by the calling + process.
X_OKFlag indicating that the file can be executed by the calling + process.
+ +### File Open Constants + +The following constants are meant for use with `fs.open()`. + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +
ConstantDescription
O_RDONLYFlag indicating to open a file for read-only access.
O_WRONLYFlag indicating to open a file for write-only access.
O_RDWRFlag indicating to open a file for read-write access.
O_CREATFlag indicating to create the file if it does not already exist.
O_EXCLFlag indicating that opening a file should fail if the + O_CREAT flag is set and the file already exists.
O_NOCTTYFlag indicating that if path identifies a terminal device, opening the + path shall not cause that terminal to become the controlling terminal for + the process (if the process does not already have one).
O_TRUNCFlag indicating that if the file exists and is a regular file, and the + file is opened successfully for write access, its length shall be truncated + to zero.
O_APPENDFlag indicating that data will be appended to the end of the file.
O_DIRECTORYFlag indicating that the open should fail if the path is not a + directory.
O_NOATIMEFlag indicating reading accesses to the file system will no longer + result in an update to the `atime` information associated with the file. + This flag is available on Linux operating systems only.
O_NOFOLLOWFlag indicating that the open should fail if the path is a symbolic + link.
O_SYNCFlag indicating that the file is opened for synchronous I/O.
O_SYMLINKFlag indicating to open the symbolic link itself rather than the + resource it is pointing to.
O_DIRECTWhen set, an attempt will be made to minimize caching effects of file + I/O.
O_NONBLOCKFlag indicating to open the file in nonblocking mode when possible.
+ +### File Type Constants + +The following constants are meant for use with the [`fs.Stats`][] object's +`mode` property for determining a file's type. + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +
ConstantDescription
S_IFMTBit mask used to extract the file type code.
S_IFREGFile type constant for a regular file.
S_IFDIRFile type constant for a directory.
S_IFCHRFile type constant for a character-oriented device file.
S_IFBLKFile type constant for a block-oriented device file.
S_IFIFOFile type constant for a FIFO/pipe.
S_IFLNKFile type constant for a symbolic link.
S_IFSOCKFile type constant for a socket.
+ +### File Mode Constants + +The following constants are meant for use with the [`fs.Stats`][] object's +`mode` property for determining the access permissions for a file. + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +
ConstantDescription
S_IRWXUFile mode indicating readable, writable and executable by owner.
S_IRUSRFile mode indicating readable by owner.
S_IWUSRFile mode indicating writable by owner.
S_IXUSRFile mode indicating executable by owner.
S_IRWXGFile mode indicating readable, writable and executable by group.
S_IRGRPFile mode indicating readable by group.
S_IWGRPFile mode indicating writable by group.
S_IXGRPFile mode indicating executable by group.
S_IRWXOFile mode indicating readable, writable and executable by others.
S_IROTHFile mode indicating readable by others.
S_IWOTHFile mode indicating writable by others.
S_IXOTHFile mode indicating executable by others.
+ [`Buffer.byteLength`]: buffer.html#buffer_class_method_buffer_bytelength_string_encoding [`Buffer`]: buffer.html#buffer_buffer [Caveats]: #fs_caveats @@ -1418,3 +1646,4 @@ Synchronous versions of [`fs.write()`][]. Returns the number of bytes written. [Readable Stream]: stream.html#stream_class_stream_readable [Writable Stream]: stream.html#stream_class_stream_writable [inode]: http://www.linux.org/threads/intro-to-inodes.4130 +[FS Constants]: #fs_fs_constants diff --git a/doc/api/os.md b/doc/api/os.md index 7e92f2bf43..59ed110666 100644 --- a/doc/api/os.md +++ b/doc/api/os.md @@ -22,6 +22,12 @@ added: v0.5.0 Returns the operating system CPU architecture. Possible values are `'x64'`, `'arm'` and `'ia32'`. Returns the value of [`process.arch`][]. +## os.constants + +Returns an object containing commonly used operating system specific constants +for error codes, process signals, and so on. The specific constants currently +defined are described in [OS Constants][]. + ## os.cpus()