Check for overflow in filename generation

The filename is defined as MAXPGPATH which can overflow on macOS
when 64 bit inodes are used,  since the dirent struct can hold 1023
character dir entries (Linux has a dirent64 struct instead of over-
loading dirent). Guard against possible overflow and ereport a
WARNING in case it happens. While perhaps not technically required
on other platforms it's good practice to check for overflow either
way so avoid ifdefing for only macOS.

src/backend/cdb/cdbsreh.c

@@ -896,10 +896,11 @@ ErrorLogDelete(Oid databaseId, Oid relationId)
 
 	if (!OidIsValid(relationId))
 	{
-		DIR	   *dir;
-		struct dirent *de;
-		char   *dirpath = ErrorLogDir;
-		char	prefix[MAXPGPATH];
+		DIR			   *dir;
+		struct dirent  *de;
+		char   		   *dirpath = ErrorLogDir;
+		char			prefix[MAXPGPATH];
+		int				len;
 
 		if (OidIsValid(databaseId))
 			snprintf(prefix, sizeof(prefix), "%u_", databaseId);
@@ -924,8 +925,16 @@ ErrorLogDelete(Oid databaseId, Oid relationId)
 			 */
 			if (!OidIsValid(databaseId))
 			{
+				len = snprintf(filename, MAXPGPATH, "%s/%s", dirpath, de->d_name);
+				if (len >= (MAXPGPATH - 1))
+				{
+					ereport(WARNING,
+						(errcode(ERRCODE_GP_INTERNAL_ERROR),
+						(errmsg("log filename truncation on \"%s\", unable to delete error log",
+								de->d_name))));
+					continue;
+				}
 				LWLockAcquire(ErrorLogLock, LW_EXCLUSIVE);
-				sprintf(filename, "%s/%s", dirpath, de->d_name);
 				unlink(filename);
 				LWLockRelease(ErrorLogLock);
 				continue;