Don't Insert() a VFD entry until it's fully built.

tglsfdc · tglsfdc · commit d02dbbadb7cc · 2020-11-16T20:32:35.000-05:00
Otherwise, if FDDEBUG is enabled, the debugging output fails because it tries to read the fileName, which isn't set up yet (and should in fact always be NULL). AFAICT, this has been wrong since Berkeley. Before 96bf88d, it would accidentally fail to crash on platforms where snprintf() is forgiving about being passed a NULL pointer for %s; but the file name intended to be included in the debug output wouldn't ever have shown up. Report and fix by Greg Nancarrow. Although this is only visibly broken in custom-made builds, it still seems worth back-patching to all supported branches, as the FDDEBUG code is pretty useless as it stands. Discussion: https://postgr.es/m/CAJcOf-cUDgm9qYtC_B6XrC6MktMPNRby2p61EtSGZKnfotMArw@mail.gmail.com
diff --git a/src/backend/storage/file/fd.c b/src/backend/storage/file/fd.c
@@ -1165,8 +1165,6 @@ PathNameOpenFile(FileName fileName, int fileFlags, int fileMode)
 	DO_DB(elog(LOG, "PathNameOpenFile: success %d",
 			   vfdP->fd));
 
-	Insert(file);
-
 	vfdP->fileName = fnamecopy;
 	/* Saved flags are adjusted to be OK for re-opening file */
 	vfdP->fileFlags = fileFlags & ~(O_CREAT | O_TRUNC | O_EXCL);
@@ -1176,6 +1174,8 @@ PathNameOpenFile(FileName fileName, int fileFlags, int fileMode)
 	vfdP->fdstate = 0x0;
 	vfdP->resowner = NULL;
 
+	Insert(file);
+
 	return file;
 }
 
