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#
#
# Nim's Runtime Library
# (c) Copyright 2022 Nim contributors
#
# See the file "copying.txt", included in this
# distribution, for details about the copyright.
#
## The `std/oserrors` module implements OS error reporting.
type
OSErrorCode* = distinct int32 ## Specifies an OS Error Code.
when not defined(nimscript):
when defined(windows):
import winlean
when defined(nimPreviewSlimSystem):
import std/widestrs
else:
var errno {.importc, header: "<errno.h>".}: cint
proc c_strerror(errnum: cint): cstring {.
importc: "strerror", header: "<string.h>".}
proc `==`*(err1, err2: OSErrorCode): bool {.borrow.}
proc `$`*(err: OSErrorCode): string {.borrow.}
proc osErrorMsg*(errorCode: OSErrorCode): string =
## Converts an OS error code into a human readable string.
##
## The error code can be retrieved using the `osLastError proc`_.
##
## If conversion fails, or `errorCode` is `0` then `""` will be
## returned.
##
## See also:
## * `raiseOSError proc`_
## * `osLastError proc`_
runnableExamples:
when defined(linux):
assert osErrorMsg(OSErrorCode(0)) == ""
assert osErrorMsg(OSErrorCode(1)) == "Operation not permitted"
assert osErrorMsg(OSErrorCode(2)) == "No such file or directory"
result = ""
when defined(nimscript):
discard
elif defined(windows):
if errorCode != OSErrorCode(0'i32):
var msgbuf: WideCString
if formatMessageW(0x00000100 or 0x00001000 or 0x00000200,
nil, errorCode.int32, 0, addr(msgbuf), 0, nil) != 0'i32:
result = $msgbuf
if msgbuf != nil: localFree(cast[pointer](msgbuf))
else:
if errorCode != OSErrorCode(0'i32):
result = $c_strerror(errorCode.int32)
proc newOSError*(
errorCode: OSErrorCode, additionalInfo = ""
): owned(ref OSError) {.noinline.} =
## Creates a new `OSError exception <system.html#OSError>`_.
##
## The `errorCode` will determine the
## message, `osErrorMsg proc`_ will be used
## to get this message.
##
## The error code can be retrieved using the `osLastError proc`_.
##
## If the error code is `0` or an error message could not be retrieved,
## the message `unknown OS error` will be used.
##
## See also:
## * `osErrorMsg proc`_
## * `osLastError proc`_
result = (ref OSError)(errorCode: errorCode.int32, msg: osErrorMsg(errorCode))
if additionalInfo.len > 0:
if result.msg.len > 0 and result.msg[^1] != '\n': result.msg.add '\n'
result.msg.add "Additional info: "
result.msg.add additionalInfo
# don't add trailing `.` etc, which negatively impacts "jump to file" in IDEs.
if result.msg == "":
result.msg = "unknown OS error"
proc raiseOSError*(errorCode: OSErrorCode, additionalInfo = "") {.noinline.} =
## Raises an `OSError exception <system.html#OSError>`_.
##
## Read the description of the `newOSError proc`_ to learn
## how the exception object is created.
raise newOSError(errorCode, additionalInfo)
{.push stackTrace:off.}
proc osLastError*(): OSErrorCode {.sideEffect.} =
## Retrieves the last operating system error code.
##
## This procedure is useful in the event when an OS call fails. In that case
## this procedure will return the error code describing the reason why the
## OS call failed. The `OSErrorMsg` procedure can then be used to convert
## this code into a string.
##
## .. warning:: The behaviour of this procedure varies between Windows and POSIX systems.
## On Windows some OS calls can reset the error code to `0` causing this
## procedure to return `0`. It is therefore advised to call this procedure
## immediately after an OS call fails. On POSIX systems this is not a problem.
##
## See also:
## * `osErrorMsg proc`_
## * `raiseOSError proc`_
when defined(nimscript):
discard
elif defined(windows):
result = cast[OSErrorCode](getLastError())
else:
result = OSErrorCode(errno)
{.pop.}
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