SRT: Build SRT from source by SRS. 4.0.115

trunk/3rdparty/srt-1-fit/srtcore/srt_compat.c

@@ -0,0 +1,140 @@
+/*
+ * SRT - Secure, Reliable, Transport
+ * Copyright (c) 2018 Haivision Systems Inc.
+ * 
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ * 
+ */
+
+// Implementation file for srt_compat.h
+/*****************************************************************************
+written by
+   Haivision Systems Inc.
+ *****************************************************************************/
+
+// Prevents from misconfiguration through preprocessor.
+
+#include <srt_compat.h>
+
+#include <string.h>
+#include <stdio.h>
+#include <errno.h>
+#if defined(__unix__) && !defined(BSD)
+#include <features.h>
+#endif
+
+#if defined(_WIN32)
+#define WIN32_LEAN_AND_MEAN
+#include <windows.h>
+#endif
+
+
+static const char* SysStrError_Fallback(int errnum, char* buf, size_t buflen)
+{
+#if defined(_MSC_VER) && _MSC_VER < 1900
+    _snprintf(buf, buflen - 1, "ERROR CODE %d", errnum);
+    buf[buflen - 1] = '\0';
+#else
+    snprintf(buf, buflen, "ERROR CODE %d", errnum);
+#endif
+    return buf;
+}
+
+// This function is a portable and thread-safe version of `strerror`.
+// It requires a user-supplied buffer to store the message. The returned
+// value is always equal to the given buffer pointer. If the system
+// error message is longer than the given buflen, it will be trimmed.
+// When the error code is incorrect for the given error message function,
+// a fallback message will be returned, either as returned by the underlying
+// function, or crafted by this function as a response to error in an
+// underlying function. 
+extern const char * SysStrError(int errnum, char * buf, size_t buflen)
+{
+    if (buf == NULL || buflen < 4) // Required to put ??? into it as a fallback
+    {
+        errno = EFAULT;
+        return buf;
+    }
+
+    buf[0] = '\0';
+
+#if defined(_WIN32)
+    const char* lpMsgBuf;
+
+    // Note: Intentionally the "fixed char size" types are used despite using
+    // character size dependent FormatMessage (instead of FormatMessageA) so that
+    // your compilation fails when you use wide characters.
+    // The problem is that when TCHAR != char, then the buffer written this way
+    // would have to be converted to ASCII, not just copied by strncpy.
+    FormatMessage(0
+            | FORMAT_MESSAGE_ALLOCATE_BUFFER
+            | FORMAT_MESSAGE_FROM_SYSTEM
+            | FORMAT_MESSAGE_IGNORE_INSERTS,
+            NULL, // no lpSource
+            errnum, // dwMessageId (as controlled by FORMAT_MESSAGE_FROM_SYSTEM)
+            MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),
+            // This below parameter normally should contain a pointer to an allocated buffer,
+            // and this way it's LPTSTR. But when FORMAT_MESSAGE_ALLOCATE_BUFFER, then it is
+            // expected to be a the value of LPTSTR* type, converted to LPTSTR, that designates
+            // a pointer to a variable of type LPTSTR, to which the newly allocated buffer is
+            // assigned. This buffer should be freed afterwards using LocalFree().
+            (LPSTR)&lpMsgBuf,
+            0, NULL);
+
+    if (lpMsgBuf)
+    {
+        strncpy(buf, lpMsgBuf, buflen-1);
+        buf[buflen-1] = 0;
+        LocalFree((HLOCAL)lpMsgBuf);
+    }
+    else
+    {
+        SysStrError_Fallback(errnum, buf, buflen);
+    }
+
+    return buf;
+
+#elif (!defined(__GNU_LIBRARY__) && !defined(__GLIBC__) )  \
+    || (( (_POSIX_C_SOURCE >= 200112L) || (_XOPEN_SOURCE >= 600)) && ! _GNU_SOURCE )
+    // POSIX/XSI-compliant version.
+    // Overall general POSIX version: returns status.
+    // 0 for success, otherwise it's:
+    // - possibly -1 and the error code is in ::errno
+    // - possibly the error code itself
+    // The details of the errror are not interesting; simply
+    // craft a fallback message in this case.
+    if (strerror_r(errnum, buf, buflen) != 0)
+    {
+        return SysStrError_Fallback(errnum, buf, buflen);
+    }
+    return buf;
+#else
+    // GLIBC is non-standard under these conditions.
+    // GNU version: returns the pointer to the message.
+    // This is either equal to the local buffer (buf)
+    // or some system-wide (constant) storage. To maintain
+    // stability of the API, this overall function shall
+    // always return the local buffer and the message in
+    // this buffer - so these cases should be distinguished
+    // and the internal storage copied to the buffer.
+
+    char * gnu_buffer = strerror_r(errnum, buf, buflen);
+    if (!gnu_buffer)
+    {
+        // This should never happen, so just a paranoid check
+        return SysStrError_Fallback(errnum, buf, buflen);
+    }
+
+    // If they are the same, the message is already copied
+    // (and it's usually a "fallback message" for an error case).
+    if (gnu_buffer != buf)
+    {
+        strncpy(buf, gnu_buffer, buflen-1);
+        buf[buflen-1] = 0; // guarantee what strncpy doesn't
+    }
+
+    return buf;
+#endif
+}