diff options
Diffstat (limited to 'source3/include/byteorder.h')
| -rw-r--r-- | source3/include/byteorder.h | 138 |
1 files changed, 115 insertions, 23 deletions
diff --git a/source3/include/byteorder.h b/source3/include/byteorder.h index 899cd6c499..1abf1854f3 100644 --- a/source3/include/byteorder.h +++ b/source3/include/byteorder.h @@ -1,8 +1,7 @@ /* - Unix SMB/Netbios implementation. - Version 1.9. + Unix SMB/CIFS implementation. SMB Byte handling - Copyright (C) Andrew Tridgell 1992-1995 + Copyright (C) Andrew Tridgell 1992-1998 This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by @@ -19,9 +18,79 @@ Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */ +#ifndef _BYTEORDER_H +#define _BYTEORDER_H + /* This file implements macros for machine independent short and int manipulation + +Here is a description of this file that I emailed to the samba list once: + +> I am confused about the way that byteorder.h works in Samba. I have +> looked at it, and I would have thought that you might make a distinction +> between LE and BE machines, but you only seem to distinguish between 386 +> and all other architectures. +> +> Can you give me a clue? + +sure. + +The distinction between 386 and other architectures is only there as +an optimisation. You can take it out completely and it will make no +difference. The routines (macros) in byteorder.h are totally byteorder +independent. The 386 optimsation just takes advantage of the fact that +the x86 processors don't care about alignment, so we don't have to +align ints on int boundaries etc. If there are other processors out +there that aren't alignment sensitive then you could also define +CAREFUL_ALIGNMENT=0 on those processors as well. + +Ok, now to the macros themselves. I'll take a simple example, say we +want to extract a 2 byte integer from a SMB packet and put it into a +type called uint16 that is in the local machines byte order, and you +want to do it with only the assumption that uint16 is _at_least_ 16 +bits long (this last condition is very important for architectures +that don't have any int types that are 2 bytes long) + +You do this: + +#define CVAL(buf,pos) (((unsigned char *)(buf))[pos]) +#define PVAL(buf,pos) ((unsigned)CVAL(buf,pos)) +#define SVAL(buf,pos) (PVAL(buf,pos)|PVAL(buf,(pos)+1)<<8) + +then to extract a uint16 value at offset 25 in a buffer you do this: + +char *buffer = foo_bar(); +uint16 xx = SVAL(buffer,25); + +We are using the byteoder independence of the ANSI C bitshifts to do +the work. A good optimising compiler should turn this into efficient +code, especially if it happens to have the right byteorder :-) + +I know these macros can be made a bit tidier by removing some of the +casts, but you need to look at byteorder.h as a whole to see the +reasoning behind them. byteorder.h defines the following macros: + +SVAL(buf,pos) - extract a 2 byte SMB value +IVAL(buf,pos) - extract a 4 byte SMB value +SVALS(buf,pos) signed version of SVAL() +IVALS(buf,pos) signed version of IVAL() + +SSVAL(buf,pos,val) - put a 2 byte SMB value into a buffer +SIVAL(buf,pos,val) - put a 4 byte SMB value into a buffer +SSVALS(buf,pos,val) - signed version of SSVAL() +SIVALS(buf,pos,val) - signed version of SIVAL() + +RSVAL(buf,pos) - like SVAL() but for NMB byte ordering +RSVALS(buf,pos) - like SVALS() but for NMB byte ordering +RIVAL(buf,pos) - like IVAL() but for NMB byte ordering +RIVALS(buf,pos) - like IVALS() but for NMB byte ordering +RSSVAL(buf,pos,val) - like SSVAL() but for NMB ordering +RSIVAL(buf,pos,val) - like SIVAL() but for NMB ordering +RSIVALS(buf,pos,val) - like SIVALS() but for NMB ordering + +it also defines lots of intermediate macros, just ignore those :-) + */ #undef CAREFUL_ALIGNMENT @@ -36,45 +105,68 @@ #define CAREFUL_ALIGNMENT 1 #endif -#define CVAL(buf,pos) (((unsigned char *)(buf))[pos]) -#define PVAL(buf,pos) ((unsigned)CVAL(buf,pos)) -#define SCVAL(buf,pos,val) (CVAL(buf,pos) = (val)) +#define CVAL(buf,pos) (((const unsigned char *)(buf))[pos]) +#define CVAL_NC(buf,pos) (((unsigned char *)(buf))[pos]) /* Non-const version of CVAL */ +#define PVAL(buf,pos) ((const unsigned)CVAL(buf,pos)) +#define PVAL_NC(buf,pos) ((unsigned)CVAL(buf,pos)) /* Non const version of PVAL */ +#define SCVAL(buf,pos,val) (CVAL_NC(buf,pos) = (val)) #if CAREFUL_ALIGNMENT + #define SVAL(buf,pos) (PVAL(buf,pos)|PVAL(buf,(pos)+1)<<8) #define IVAL(buf,pos) (SVAL(buf,pos)|SVAL(buf,(pos)+2)<<16) -#define SSVALX(buf,pos,val) (CVAL(buf,pos)=(val)&0xFF,CVAL(buf,pos+1)=(val)>>8) +#define SSVALX(buf,pos,val) (CVAL_NC(buf,pos)=(unsigned char)((val)&0xFF),CVAL_NC(buf,pos+1)=(unsigned char)((val)>>8)) #define SIVALX(buf,pos,val) (SSVALX(buf,pos,val&0xFFFF),SSVALX(buf,pos+2,val>>16)) -#define SVALS(buf,pos) ((int16)SVAL(buf,pos)) -#define IVALS(buf,pos) ((int32)IVAL(buf,pos)) -#define SSVAL(buf,pos,val) SSVALX((buf),(pos),((uint16)(val))) -#define SIVAL(buf,pos,val) SIVALX((buf),(pos),((uint32)(val))) -#define SSVALS(buf,pos,val) SSVALX((buf),(pos),((int16)(val))) -#define SIVALS(buf,pos,val) SIVALX((buf),(pos),((int32)(val))) -#else +#define SVALS(buf,pos) ((const int16)SVAL(buf,pos)) +#define IVALS(buf,pos) ((const int32)IVAL(buf,pos)) +#define SSVAL(buf,pos,val) SSVALX((buf),(pos),((const uint16)(val))) +#define SIVAL(buf,pos,val) SIVALX((buf),(pos),((const uint32)(val))) +#define SSVALS(buf,pos,val) SSVALX((buf),(pos),((const int16)(val))) +#define SIVALS(buf,pos,val) SIVALX((buf),(pos),((const int32)(val))) + +#else /* CAREFUL_ALIGNMENT */ + /* this handles things for architectures like the 386 that can handle alignment errors */ /* WARNING: This section is dependent on the length of int16 and int32 being correct */ -#define SVAL(buf,pos) (*(uint16 *)((char *)(buf) + (pos))) -#define IVAL(buf,pos) (*(uint32 *)((char *)(buf) + (pos))) -#define SVALS(buf,pos) (*(int16 *)((char *)(buf) + (pos))) -#define IVALS(buf,pos) (*(int32 *)((char *)(buf) + (pos))) -#define SSVAL(buf,pos,val) SVAL(buf,pos)=((uint16)(val)) -#define SIVAL(buf,pos,val) IVAL(buf,pos)=((uint32)(val)) -#define SSVALS(buf,pos,val) SVALS(buf,pos)=((int16)(val)) -#define SIVALS(buf,pos,val) IVALS(buf,pos)=((int32)(val)) -#endif +/* get single value from an SMB buffer */ +#define SVAL(buf,pos) (*(const uint16 *)((const char *)(buf) + (pos))) +#define SVAL_NC(buf,pos) (*(uint16 *)((char *)(buf) + (pos))) /* Non const version of above. */ +#define IVAL(buf,pos) (*(const uint32 *)((const char *)(buf) + (pos))) +#define IVAL_NC(buf,pos) (*(uint32 *)((char *)(buf) + (pos))) /* Non const version of above. */ +#define SVALS(buf,pos) (*(const int16 *)((const char *)(buf) + (pos))) +#define SVALS_NC(buf,pos) (*(int16 *)((char *)(buf) + (pos))) /* Non const version of above. */ +#define IVALS(buf,pos) (*(const int32 *)((const char *)(buf) + (pos))) +#define IVALS_NC(buf,pos) (*(int32 *)((char *)(buf) + (pos))) /* Non const version of above. */ + +/* store single value in an SMB buffer */ +#define SSVAL(buf,pos,val) SVAL_NC(buf,pos)=((const uint16)(val)) +#define SIVAL(buf,pos,val) IVAL_NC(buf,pos)=((const uint32)(val)) +#define SSVALS(buf,pos,val) SVALS_NC(buf,pos)=((const int16)(val)) +#define SIVALS(buf,pos,val) IVALS_NC(buf,pos)=((const int32)(val)) + +#endif /* CAREFUL_ALIGNMENT */ /* now the reverse routines - these are used in nmb packets (mostly) */ #define SREV(x) ((((x)&0xFF)<<8) | (((x)>>8)&0xFF)) #define IREV(x) ((SREV(x)<<16) | (SREV((x)>>16))) #define RSVAL(buf,pos) SREV(SVAL(buf,pos)) +#define RSVALS(buf,pos) SREV(SVALS(buf,pos)) #define RIVAL(buf,pos) IREV(IVAL(buf,pos)) +#define RIVALS(buf,pos) IREV(IVALS(buf,pos)) #define RSSVAL(buf,pos,val) SSVAL(buf,pos,SREV(val)) +#define RSSVALS(buf,pos,val) SSVALS(buf,pos,SREV(val)) #define RSIVAL(buf,pos,val) SIVAL(buf,pos,IREV(val)) +#define RSIVALS(buf,pos,val) SIVALS(buf,pos,IREV(val)) + +/* Alignment macros. */ +#define ALIGN4(p,base) ((p) + ((4 - (PTR_DIFF((p), (base)) & 3)) & 3)) +#define ALIGN2(p,base) ((p) + ((2 - (PTR_DIFF((p), (base)) & 1)) & 1)) + +#endif /* _BYTEORDER_H */ |