From 9514abc2da3525ef4314a8fcf70982ad07319e51 Mon Sep 17 00:00:00 2001 From: Roberto Ierusalimschy Date: Tue, 19 May 2020 12:42:20 -0300 Subject: [PATCH] Cleaner definition for 'TString' Use a variable-sized array to store string contents at the end of a structure 'TString', instead of raw memory. --- lobject.h | 7 +++---- lstring.h | 6 +++++- 2 files changed, 8 insertions(+), 5 deletions(-) diff --git a/lobject.h b/lobject.h index 2d63c001..04a81d3d 100644 --- a/lobject.h +++ b/lobject.h @@ -356,7 +356,7 @@ typedef struct GCObject { /* -** Header for string value; string bytes follow the end of this structure. +** Header for a string value. */ typedef struct TString { CommonHeader; @@ -367,16 +367,15 @@ typedef struct TString { size_t lnglen; /* length for long strings */ struct TString *hnext; /* linked list for hash table */ } u; + char contents[1]; } TString; /* ** Get the actual string (array of bytes) from a 'TString'. -** (Access to 'extra' ensures that value is really a 'TString'.) */ -#define getstr(ts) \ - check_exp(sizeof((ts)->extra), cast_charp((ts)) + sizeof(TString)) +#define getstr(ts) ((ts)->contents) /* get the actual string (array of bytes) from a Lua value */ diff --git a/lstring.h b/lstring.h index 56896867..a413a9d3 100644 --- a/lstring.h +++ b/lstring.h @@ -19,7 +19,11 @@ #define MEMERRMSG "not enough memory" -#define sizelstring(l) (sizeof(TString) + ((l) + 1) * sizeof(char)) +/* +** Size of a TString: Size of the header plus space for the string +** itself (including final '\0'). +*/ +#define sizelstring(l) (offsetof(TString, contents) + ((l) + 1) * sizeof(char)) #define luaS_newliteral(L, s) (luaS_newlstr(L, "" s, \ (sizeof(s)/sizeof(char))-1))