P/Invoking 时是否可以访问 C# 中的“errno”变量？这类似于 Win32 GetLastError()。
我相当确定有办法，但这可能是一个坏主意。您如何保证运行时在其内部处理期间没有调用某些影响
errno出于同样的原因，您也不应该直接致电
GetLastErrorDllImportAttributeSetLastErrorMarshal.GetLastWin32Error我认为在这种情况下，您可以做的最可靠的事情是创建一个 C DLL，它既执行实际的 C 工作，又执行捕获
errnoerrno解决方案是在
SetLastErrorDllImportMarshal.GetLastWin32Error直接调用
GetLastError是的，有可能 -
GetLastErrorSetLastErrorDllImporterrnoWin32Exception是的，这是可能的。
乍一看，errno 似乎很神奇。
但所有的魔法都是基于欺骗，errno 也是如此。
errno 不是变量，它是预处理器定义！
来自 FreeBSD 手册页：
extern int* __error();
#define errno (* __error())
查看我的 KDE-Neon Linux 上的源代码：
extern int *__errno_location (void) __THROW __attribute_const__;
# define errno (*__errno_location ())
（/usr/include/errno.h）
所以你可以像这样在 C# 中得到它：
（注意，我假设它在 Linux 上的工作原理相同，并且我还没有测试是否正确处理了指针）
namespace MonoReplacement
{
class MonoSux
{
private const string LIBC = "libc";
// [System.CLSCompliant(false)]
[System.Flags]
public enum AccessModes
:int
{
R_OK = 1,
W_OK = 2,
X_OK = 4,
F_OK = 8
}
public enum Errno
:int
{
EPERM = 1,
ENOENT = 2,
ESRCH = 3,
EINTR = 4,
EIO = 5,
ENXIO = 6,
E2BIG = 7,
ENOEXEC = 8,
EBADF = 9,
ECHILD = 10,
EAGAIN = 11,
EWOULDBLOCK = 11,
ENOMEM = 12,
EACCES = 13,
EFAULT = 14,
ENOTBLK = 15,
EBUSY = 16,
EEXIST = 17,
EXDEV = 18,
ENODEV = 19,
ENOTDIR = 20,
EISDIR = 21,
EINVAL = 22,
ENFILE = 23,
EMFILE = 24,
ENOTTY = 25,
ETXTBSY = 26,
EFBIG = 27,
ENOSPC = 28,
ESPIPE = 29,
EROFS = 30,
EMLINK = 31,
EPIPE = 32,
EDOM = 33,
ERANGE = 34,
EDEADLK = 35,
EDEADLOCK = 35,
ENAMETOOLONG = 36,
ENOLCK = 37,
ENOSYS = 38,
ENOTEMPTY = 39,
ELOOP = 40,
ENOMSG = 42,
EIDRM = 43,
ECHRNG = 44,
EL2NSYNC = 45,
EL3HLT = 46,
EL3RST = 47,
ELNRNG = 48,
EUNATCH = 49,
ENOCSI = 50,
EL2HLT = 51,
EBADE = 52,
EBADR = 53,
EXFULL = 54,
ENOANO = 55,
EBADRQC = 56,
EBADSLT = 57,
EBFONT = 59,
ENOSTR = 60,
ENODATA = 61,
ETIME = 62,
ENOSR = 63,
ENONET = 64,
ENOPKG = 65,
EREMOTE = 66,
ENOLINK = 67,
EADV = 68,
ESRMNT = 69,
ECOMM = 70,
EPROTO = 71,
EMULTIHOP = 72,
EDOTDOT = 73,
EBADMSG = 74,
EOVERFLOW = 75,
ENOTUNIQ = 76,
EBADFD = 77,
EREMCHG = 78,
ELIBACC = 79,
ELIBBAD = 80,
ELIBSCN = 81,
ELIBMAX = 82,
ELIBEXEC = 83,
EILSEQ = 84,
ERESTART = 85,
ESTRPIPE = 86,
EUSERS = 87,
ENOTSOCK = 88,
EDESTADDRREQ = 89,
EMSGSIZE = 90,
EPROTOTYPE = 91,
ENOPROTOOPT = 92,
EPROTONOSUPPORT = 93,
ESOCKTNOSUPPORT = 94,
EOPNOTSUPP = 95,
EPFNOSUPPORT = 96,
EAFNOSUPPORT = 97,
EADDRINUSE = 98,
EADDRNOTAVAIL = 99,
ENETDOWN = 100,
ENETUNREACH = 101,
ENETRESET = 102,
ECONNABORTED = 103,
ECONNRESET = 104,
ENOBUFS = 105,
EISCONN = 106,
ENOTCONN = 107,
ESHUTDOWN = 108,
ETOOMANYREFS = 109,
ETIMEDOUT = 110,
ECONNREFUSED = 111,
EHOSTDOWN = 112,
EHOSTUNREACH = 113,
EALREADY = 114,
EINPROGRESS = 115,
ESTALE = 116,
EUCLEAN = 117,
ENOTNAM = 118,
ENAVAIL = 119,
EISNAM = 120,
EREMOTEIO = 121,
EDQUOT = 122,
ENOMEDIUM = 123,
EMEDIUMTYPE = 124,
ECANCELED = 125,
ENOKEY = 126,
EKEYEXPIRED = 127,
EKEYREVOKED = 128,
EKEYREJECTED = 129,
EOWNERDEAD = 130,
ENOTRECOVERABLE = 131,
EPROCLIM = 1067,
EBADRPC = 1072,
ERPCMISMATCH = 1073,
EPROGUNAVAIL = 1074,
EPROGMISMATCH = 1075,
EPROCUNAVAIL = 1076,
EFTYPE = 1079,
EAUTH = 1080,
ENEEDAUTH = 1081,
EPWROFF = 1082,
EDEVERR = 1083,
EBADEXEC = 1085,
EBADARCH = 1086,
ESHLIBVERS = 1087,
EBADMACHO = 1088,
ENOATTR = 1093,
ENOPOLICY = 1103
}
// int access(const char *pathname, int mode);
// https://linux.die.net/man/2/access
[System.Security.SuppressUnmanagedCodeSecurity]
[System.Runtime.InteropServices.DllImport(LIBC, CallingConvention = System.Runtime.InteropServices.CallingConvention.Cdecl, EntryPoint = "access", SetLastError=true)]
#if USE_LPUTF8Str
internal static extern int access([System.Runtime.InteropServices.MarshalAs(System.Runtime.InteropServices.UnmanagedType.LPUTF8Str)] string path, AccessModes mode);
#else
internal static extern int access([System.Runtime.InteropServices.MarshalAs(System.Runtime.InteropServices.UnmanagedType.CustomMarshaler, MarshalTypeRef = typeof(libACL.Unix.FileNameMarshaler))] string path, AccessModes mode);
#endif
// char *strerror(int errnum);
// https://man7.org/linux/man-pages/man3/strerror.3.html
[System.Security.SuppressUnmanagedCodeSecurity]
[System.Runtime.InteropServices.DllImport(LIBC, CallingConvention = System.Runtime.InteropServices.CallingConvention.Cdecl, EntryPoint = "strerror")]
internal static extern string strerror(Errno errnum);
[System.Security.SuppressUnmanagedCodeSecurity]
[System.Runtime.InteropServices.DllImport(LIBC, EntryPoint = "__errno_location", CallingConvention = System.Runtime.InteropServices.CallingConvention.Cdecl)]
internal static extern System.IntPtr __errno_location();
/// <summary>
/// access() checks whether the calling process can access the file pathname. If pathname is a symbolic link, it is dereferenced.
/// </summary>
/// <param name="pathmame"></param>
/// <param name="mode"></param>
/// <returns>On success (all requested permissions granted), zero is returned. On error (at least one bit in mode asked for a permission that is denied, or some other error occurred), -1 is returned, and errno is set appropriately.</returns>
public static bool Access(string pathmame, AccessModes mode)
{
int ret = access(pathmame, mode);
if (ret == -1)
{
// return null;
System.Console.Error.WriteLine("Error on Access");
// https://github.com/mono/mono/blob/master/mcs/class/Mono.Posix/Mono.Unix.Native/Stdlib.cs
// https://stackoverflow.com/questions/2485648/access-c-global-variable-errno-from-c-sharp
// Errno errno = error();
System.IntPtr errorptr = __errno_location();
Errno errno = (Errno)System.Runtime.InteropServices.Marshal.ReadInt32(errorptr);
string message = strerror(errno);
// throw ACLManagerException(Glib::locale_to_utf8(strerror(errno)));
throw new System.InvalidOperationException(message);
} // End if (ret == -1)
return ret == 0;
} // End Function Access
}
}
注：
正如 Jason Kresowaty 所提到的，以这种方式获取 errorno 是一个坏主意，因为 CLR 可能会同时调用函数。
但根据 developers.redhat.com，您也可以在 Linux 上使用 Marshal.GetLastWin32Error。
示例：
[DllImport("libc", SetLastError = true))]
public static extern int kill(int pid, int sig);
SetLastError 表示函数使用 errno 来指示发生了什么 错误的。 Marshal.GetLastWin32Error 可用于检索 errno。
这也是 Tmds.LibC 所做的（这里，属性 errorno 取代了神奇的预处理器定义）：
using System.Runtime.InteropServices;
namespace Tmds.Linux
{
public static partial class LibC
{
public static unsafe int errno
// use the value captured by DllImport
=> Marshal.GetLastWin32Error();
}
}
因此，为了在 C# 中模拟这种行为，我们使用属性来代替：
public static Errno errno
{
get
{
// How would you guarantee that the runtime has not called some CRT function
// during its internal processing that has affected the errno?
// For the same reason, you should not call GetLastError directly either.
// The DllImportAttribute provides a SetLastError property so the runtime knows
// to immediately capture the last error and store it in a place that the managed code
// can read using Marshal.GetLastWin32Error.
// this work on Linux !
// Marshal.GetLastWin32Error can be used to retrieve errno.
return (Errno)System.Runtime.InteropServices.Marshal.GetLastWin32Error();
}
}
string message = strerror(errorno);
我相信你可以
throw new Win32Exception()它适用于 Windows、Linux 和 macOS（尽管名称令人困惑）。