.. _errors:
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
---------------
.. c:macro:: UV_E2BIG
argument list too long
.. c:macro:: UV_EACCES
permission denied
.. c:macro:: UV_EADDRINUSE
address already in use
.. c:macro:: UV_EADDRNOTAVAIL
address not available
.. c:macro:: UV_EAFNOSUPPORT
address family not supported
.. c:macro:: UV_EAGAIN
resource temporarily unavailable
.. c:macro:: UV_EAI_ADDRFAMILY
address family not supported
.. c:macro:: UV_EAI_AGAIN
temporary failure
.. c:macro:: UV_EAI_BADFLAGS
bad ai_flags value
.. c:macro:: UV_EAI_BADHINTS
invalid value for hints
.. c:macro:: UV_EAI_CANCELED
request canceled
.. c:macro:: UV_EAI_FAIL
permanent failure
.. c:macro:: UV_EAI_FAMILY
ai_family not supported
.. c:macro:: UV_EAI_MEMORY
out of memory
.. c:macro:: UV_EAI_NODATA
no address
.. c:macro:: UV_EAI_NONAME
unknown node or service
.. c:macro:: UV_EAI_OVERFLOW
argument buffer overflow
.. c:macro:: UV_EAI_PROTOCOL
resolved protocol is unknown
.. c:macro:: UV_EAI_SERVICE
service not available for socket type
.. c:macro:: UV_EAI_SOCKTYPE
socket type not supported
.. c:macro:: UV_EALREADY
connection already in progress
.. c:macro:: UV_EBADF
bad file descriptor
.. c:macro:: UV_EBUSY
resource busy or locked
.. c:macro:: UV_ECANCELED
operation canceled
.. c:macro:: UV_ECHARSET
invalid Unicode character
.. c:macro:: UV_ECONNABORTED
software caused connection abort
.. c:macro:: UV_ECONNREFUSED
connection refused
.. c:macro:: UV_ECONNRESET
connection reset by peer
.. c:macro:: UV_EDESTADDRREQ
destination address required
.. c:macro:: UV_EEXIST
file already exists
.. c:macro:: UV_EFAULT
bad address in system call argument
.. c:macro:: UV_EFBIG
file too large
.. c:macro:: UV_EHOSTUNREACH
host is unreachable
.. c:macro:: UV_EINTR
interrupted system call
.. c:macro:: UV_EINVAL
invalid argument
.. c:macro:: UV_EIO
i/o error
.. c:macro:: UV_EISCONN
socket is already connected
.. c:macro:: UV_EISDIR
illegal operation on a directory
.. c:macro:: UV_ELOOP
too many symbolic links encountered
.. c:macro:: UV_EMFILE
too many open files
.. c:macro:: UV_EMSGSIZE
message too long
.. c:macro:: UV_ENAMETOOLONG
name too long
.. c:macro:: UV_ENETDOWN
network is down
.. c:macro:: UV_ENETUNREACH
network is unreachable
.. c:macro:: UV_ENFILE
file table overflow
.. c:macro:: UV_ENOBUFS
no buffer space available
.. c:macro:: UV_ENODEV
no such device
.. c:macro:: UV_ENOENT
no such file or directory
.. c:macro:: UV_ENOMEM
not enough memory
.. c:macro:: UV_ENONET
machine is not on the network
.. c:macro:: UV_ENOPROTOOPT
protocol not available
.. c:macro:: UV_ENOSPC
no space left on device
.. c:macro:: UV_ENOSYS
function not implemented
.. c:macro:: UV_ENOTCONN
socket is not connected
.. c:macro:: UV_ENOTDIR
not a directory
.. c:macro:: UV_ENOTEMPTY
directory not empty
.. c:macro:: UV_ENOTSOCK
socket operation on non-socket
.. c:macro:: UV_ENOTSUP
operation not supported on socket
.. c:macro:: UV_EPERM
operation not permitted
.. c:macro:: UV_EPIPE
broken pipe
.. c:macro:: UV_EPROTO
protocol error
.. c:macro:: UV_EPROTONOSUPPORT
protocol not supported
.. c:macro:: UV_EPROTOTYPE
protocol wrong type for socket
.. c:macro:: UV_ERANGE
result too large
.. c:macro:: UV_EROFS
read-only file system
.. c:macro:: UV_ESHUTDOWN
cannot send after transport endpoint shutdown
.. c:macro:: UV_ESPIPE
invalid seek
.. c:macro:: UV_ESRCH
no such process
.. c:macro:: UV_ETIMEDOUT
connection timed out
.. c:macro:: UV_ETXTBSY
text file is busy
.. c:macro:: UV_EXDEV
cross-device link not permitted
.. c:macro:: UV_UNKNOWN
unknown error
.. c:macro:: UV_EOF
end of file
.. c:macro:: UV_ENXIO
no such device or address
.. c:macro:: UV_EMLINK
too many links
API
---
.. c:function:: 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.
.. c:function:: 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.
.. c:function:: 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.
.. versionadded:: 1.22.0
.. c:function:: 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.
.. c:function:: 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.
.. versionadded:: 1.22.0
.. c:function:: 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.
.. versionchanged:: 1.10.0 function declared public.