Error handling#

In libuv errors are negative numbered constants. As a rule of thumb, whenever there is a status parameter, or an API functions returns an integer, a negative number will imply an error.

When a function which takes a callback returns an error, the callback will never be called.

Note

Implementation detail: on Unix error codes are the negated errno (or -errno), while on Windows they are defined by libuv to arbitrary negative numbers.

Error constants#

UV_E2BIG#: argument list too long

UV_EACCES#: permission denied

UV_EADDRINUSE#: address already in use

UV_EADDRNOTAVAIL#: address not available

UV_EAFNOSUPPORT#: address family not supported

UV_EAGAIN#: resource temporarily unavailable

UV_EAI_ADDRFAMILY#: address family not supported

UV_EAI_AGAIN#: temporary failure

UV_EAI_BADFLAGS#: bad ai_flags value

UV_EAI_BADHINTS#: invalid value for hints

UV_EAI_CANCELED#: request canceled

UV_EAI_FAIL#: permanent failure

UV_EAI_FAMILY#: ai_family not supported

UV_EAI_MEMORY#: out of memory

UV_EAI_NODATA#: no address

UV_EAI_NONAME#: unknown node or service

UV_EAI_OVERFLOW#: argument buffer overflow

UV_EAI_PROTOCOL#: resolved protocol is unknown

UV_EAI_SERVICE#: service not available for socket type

UV_EAI_SOCKTYPE#: socket type not supported

UV_EALREADY#: connection already in progress

UV_EBADF#: bad file descriptor

UV_EBUSY#: resource busy or locked

UV_ECANCELED#: operation canceled

UV_ECHARSET#: invalid Unicode character

UV_ECONNABORTED#: software caused connection abort

UV_ECONNREFUSED#: connection refused

UV_ECONNRESET#: connection reset by peer

UV_EDESTADDRREQ#: destination address required

UV_EEXIST#: file already exists

UV_EFAULT#: bad address in system call argument

UV_EFBIG#: file too large

UV_EHOSTUNREACH#: host is unreachable

UV_EINTR#: interrupted system call

UV_EINVAL#: invalid argument

UV_EIO#: i/o error

UV_EISCONN#: socket is already connected

UV_EISDIR#: illegal operation on a directory

UV_ELOOP#: too many symbolic links encountered

UV_EMFILE#: too many open files

UV_EMSGSIZE#: message too long

UV_ENAMETOOLONG#: name too long

UV_ENETDOWN#: network is down

UV_ENETUNREACH#: network is unreachable

UV_ENFILE#: file table overflow

UV_ENOBUFS#: no buffer space available

UV_ENODEV#: no such device

UV_ENOENT#: no such file or directory

UV_ENOMEM#: not enough memory

UV_ENONET#: machine is not on the network

UV_ENOPROTOOPT#: protocol not available

UV_ENOSPC#: no space left on device

UV_ENOSYS#: function not implemented

UV_ENOTCONN#: socket is not connected

UV_ENOTDIR#: not a directory

UV_ENOTEMPTY#: directory not empty

UV_ENOTSOCK#: socket operation on non-socket

UV_ENOTSUP#: operation not supported on socket

UV_EOVERFLOW#: value too large for defined data type

UV_EPERM#: operation not permitted

UV_EPIPE#: broken pipe

UV_EPROTO#: protocol error

UV_EPROTONOSUPPORT#: protocol not supported

UV_EPROTOTYPE#: protocol wrong type for socket

UV_ERANGE#: result too large

UV_EROFS#: read-only file system

UV_ESHUTDOWN#: cannot send after transport endpoint shutdown

UV_ESPIPE#: invalid seek

UV_ESRCH#: no such process

UV_ETIMEDOUT#: connection timed out

UV_ETXTBSY#: text file is busy

UV_EXDEV#: cross-device link not permitted

UV_UNKNOWN#: unknown error

UV_EOF#: end of file

UV_ENXIO#: no such device or address

UV_EMLINK#: too many links

UV_ENOTTY#: inappropriate ioctl for device

UV_EFTYPE#: inappropriate file type or format

UV_EILSEQ#: illegal byte sequence

UV_ESOCKTNOSUPPORT#: socket type not supported

UV_EUNATCH#: protocol driver not attached

API#

UV_ERRNO_MAP(iter_macro)#: Macro that expands to a series of invocations of iter_macro for each of the error constants above. iter_macro is invoked with two arguments: the name of the error constant without the UV_ prefix, and the error message string literal.

const char *uv_strerror(int err)#: Returns the error message for the given error code. Leaks a few bytes of memory when you call it with an unknown error code.

char *uv_strerror_r(int err, char *buf, size_t buflen)#: Returns the error message for the given error code. The zero-terminated message is stored in the user-supplied buffer buf of at most buflen bytes.

New in version 1.22.0.

const char *uv_err_name(int err)#: Returns the error name for the given error code. Leaks a few bytes of memory when you call it with an unknown error code.

char *uv_err_name_r(int err, char *buf, size_t buflen)#: Returns the error name for the given error code. The zero-terminated name is stored in the user-supplied buffer buf of at most buflen bytes.

New in version 1.22.0.

int uv_translate_sys_error(int sys_errno)#

Returns the libuv error code equivalent to the given platform dependent error code: POSIX error codes on Unix (the ones stored in errno), and Win32 error codes on Windows (those returned by GetLastError() or WSAGetLastError()).

If sys_errno is already a libuv error, it is simply returned.

Changed in version 1.10.0: function declared public.