Strip Windows newlines from extension script files manually.

Revert commit 924e039 in favor of adding code to convert \r\n to \n
explicitly, on Windows only.  The idea of letting text mode do the
work fails for a couple of reasons:

* Per Microsoft documentation, text mode also causes control-Z to be
interpreted as end-of-file.  While it may be unlikely that extension
scripts contain control-Z, we've historically allowed it, and breaking
the case doesn't seem wise.

* Apparently, on some Windows configurations, "r" mode is interpreted
as binary not text mode.  We could force it with "rt" but that would
be inconsistent with our code elsewhere, and it would still require
Windows-specific coding.

Thanks to Alexander Lakhin for investigation.

Discussion: https://postgr.es/m/79284195-4993-7b00-f6df-8db28ca60fa3@gmail.com

Author: tglsfdc

src/backend/commands/extension.c

@@ -724,6 +724,10 @@ script_error_callback(void *arg)
 			 * certainly possible to fool this with semicolon-newline embedded
 			 * in a string literal, but it seems better to do this than to
 			 * show the entire extension script.
+			 *
+			 * Notice we cope with Windows-style newlines (\r\n) regardless of
+			 * platform.  This is because there might be such newlines in
+			 * script files on other platforms.
 			 */
 			int			slen = strlen(query);
 
@@ -3618,7 +3622,8 @@ ExecAlterExtensionContentsRecurse(AlterExtensionContentsStmt *stmt,
  * Read the whole of file into memory.
  *
  * The file contents are returned as a single palloc'd chunk. For convenience
- * of the callers, an extra \0 byte is added to the end.
+ * of the callers, an extra \0 byte is added to the end.  That is not counted
+ * in the length returned into *length.
  */
 static char *
 read_whole_file(const char *filename, int *length)
@@ -3639,15 +3644,15 @@ read_whole_file(const char *filename, int *length)
 				 errmsg("file \"%s\" is too large", filename)));
 	bytes_to_read = (size_t) fst.st_size;
 
-	if ((file = AllocateFile(filename, "r")) == NULL)
+	if ((file = AllocateFile(filename, PG_BINARY_R)) == NULL)
 		ereport(ERROR,
 				(errcode_for_file_access(),
 				 errmsg("could not open file \"%s\" for reading: %m",
 						filename)));
 
 	buf = (char *) palloc(bytes_to_read + 1);
 
-	*length = fread(buf, 1, bytes_to_read, file);
+	bytes_to_read = fread(buf, 1, bytes_to_read, file);
 
 	if (ferror(file))
 		ereport(ERROR,
@@ -3656,6 +3661,31 @@ read_whole_file(const char *filename, int *length)
 
 	FreeFile(file);
 
-	buf[*length] = '\0';
+	buf[bytes_to_read] = '\0';
+
+	/*
+	 * On Windows, manually convert Windows-style newlines (\r\n) to the Unix
+	 * convention of \n only.  This avoids gotchas due to script files
+	 * possibly getting converted when being transferred between platforms.
+	 * Ideally we'd do this by using text mode to read the file, but that also
+	 * causes control-Z to be treated as end-of-file.  Historically we've
+	 * allowed control-Z in script files, so breaking that seems unwise.
+	 */
+#ifdef WIN32
+	{
+		char	   *s,
+				   *d;
+
+		for (s = d = buf; *s; s++)
+		{
+			if (!(*s == '\r' && s[1] == '\n'))
+				*d++ = *s;
+		}
+		*d = '\0';
+		bytes_to_read = d - buf;
+	}
+#endif
+
+	*length = bytes_to_read;
 	return buf;
 }