strerror_r-posix: fixes for MSVC 14

[Bruno Haible]

This patch fixes two problems with MSVC 14 support in module 'strerror_r-posix':

1) The function local_snprintf uses va_list, va_start, va_end, without including
the required header <stdarg.h>.

2) Test failures of strerror_r-posix and perror, reported in
https://lists.gnu.org/archive/html/bug-gnulib/2016-12/msg00112.html
The cause is that MSVC's <errno.h> now defines ETIMEDOUT and other errno
values in the range 100..140, but without adding them to the _sys_errlist
array. _sys_nerr still is = 43.


2017-04-29  Bruno Haible  <address@hidden>

        strerror_r-posix: Fixes for MSVC 14.
        * lib/strerror_r.c: Include <stdarg.h>.
        (strerror_r): Provide error messages for errno values 100...140.
        * doc/posix-functions/strerror_r.texi: Mention the MSVC 14 problem.

diff --git a/doc/posix-functions/strerror_r.texi 
b/doc/posix-functions/strerror_r.texi
index 06fdfd2..8554a29 100644
--- a/doc/posix-functions/strerror_r.texi
+++ b/doc/posix-functions/strerror_r.texi
@@ -39,6 +39,10 @@ glibc 2.12 with @code{-D_POSIX_C_SOURCE=200112L}, AIX 6.1, 
OSF/1 5.1.
 When this function fails, it corrupts @code{errno}, on some platforms:
 Solaris 10.
 @item
+This function does not support many error values defined in @code{<errno.h>} on
+some platforms:
+MSVC 14.
address@hidden
 This function does not support the error values that are specified by POSIX
 but not defined by the system, on some platforms:
 OpenBSD 4.0, OSF/1 5.1, NonStop Kernel, Cygwin 1.5.x.
diff --git a/lib/strerror_r.c b/lib/strerror_r.c
index d7b0f77..650751f 100644
--- a/lib/strerror_r.c
+++ b/lib/strerror_r.c
@@ -28,6 +28,9 @@
 #include <errno.h>
 #include <stdio.h>
 #include <stdlib.h>
+#if !HAVE_SNPRINTF
+# include <stdarg.h>
+#endif
 
 #include "strerror-override.h"
 
@@ -329,6 +332,115 @@ strerror_r (int errnum, char *buf, size_t buflen)
 
 #endif
 
+#if (defined _WIN32 || defined __WIN32__) && !defined __CYGWIN__
+    /* MSVC 14 defines names for many error codes in the range 100..140,
+       but _sys_errlist contains strings only for the error codes
+       < _sys_nerr = 43.  */
+    if (ret == EINVAL)
+      {
+        const char *errmsg;
+
+        switch (errnum)
+          {
+          case 100 /* EADDRINUSE */:
+            errmsg = "Address already in use";
+            break;
+          case 101 /* EADDRNOTAVAIL */:
+            errmsg = "Cannot assign requested address";
+            break;
+          case 102 /* EAFNOSUPPORT */:
+            errmsg = "Address family not supported by protocol";
+            break;
+          case 103 /* EALREADY */:
+            errmsg = "Operation already in progress";
+            break;
+          case 105 /* ECANCELED */:
+            errmsg = "Operation canceled";
+            break;
+          case 106 /* ECONNABORTED */:
+            errmsg = "Software caused connection abort";
+            break;
+          case 107 /* ECONNREFUSED */:
+            errmsg = "Connection refused";
+            break;
+          case 108 /* ECONNRESET */:
+            errmsg = "Connection reset by peer";
+            break;
+          case 109 /* EDESTADDRREQ */:
+            errmsg = "Destination address required";
+            break;
+          case 110 /* EHOSTUNREACH */:
+            errmsg = "No route to host";
+            break;
+          case 112 /* EINPROGRESS */:
+            errmsg = "Operation now in progress";
+            break;
+          case 113 /* EISCONN */:
+            errmsg = "Transport endpoint is already connected";
+            break;
+          case 114 /* ELOOP */:
+            errmsg = "Too many levels of symbolic links";
+            break;
+          case 115 /* EMSGSIZE */:
+            errmsg = "Message too long";
+            break;
+          case 116 /* ENETDOWN */:
+            errmsg = "Network is down";
+            break;
+          case 117 /* ENETRESET */:
+            errmsg = "Network dropped connection on reset";
+            break;
+          case 118 /* ENETUNREACH */:
+            errmsg = "Network is unreachable";
+            break;
+          case 119 /* ENOBUFS */:
+            errmsg = "No buffer space available";
+            break;
+          case 123 /* ENOPROTOOPT */:
+            errmsg = "Protocol not available";
+            break;
+          case 126 /* ENOTCONN */:
+            errmsg = "Transport endpoint is not connected";
+            break;
+          case 128 /* ENOTSOCK */:
+            errmsg = "Socket operation on non-socket";
+            break;
+          case 129 /* ENOTSUP */:
+            errmsg = "Not supported";
+            break;
+          case 130 /* EOPNOTSUPP */:
+            errmsg = "Operation not supported";
+            break;
+          case 132 /* EOVERFLOW */:
+            errmsg = "Value too large for defined data type";
+            break;
+          case 133 /* EOWNERDEAD */:
+            errmsg = "Owner died";
+            break;
+          case 134 /* EPROTO */:
+            errmsg = "Protocol error";
+            break;
+          case 135 /* EPROTONOSUPPORT */:
+            errmsg = "Protocol not supported";
+            break;
+          case 136 /* EPROTOTYPE */:
+            errmsg = "Protocol wrong type for socket";
+            break;
+          case 138 /* ETIMEDOUT */:
+            errmsg = "Connection timed out";
+            break;
+          case 140 /* EWOULDBLOCK */:
+            errmsg = "Operation would block";
+            break;
+          default:
+            errmsg = NULL;
+            break;
+          }
+        if (errmsg != NULL)
+          ret = safe_copy (buf, buflen, errmsg);
+      }
+#endif
+
     if (ret == EINVAL && !*buf)
       snprintf (buf, buflen, "Unknown error %d", errnum);