njn | 16eeb4e | 2005-06-16 03:56:58 +0000 | [diff] [blame] | 1 | |
| 2 | /*--------------------------------------------------------------------*/ |
| 3 | /*--- Redirections, etc. pub_tool_redir.h ---*/ |
| 4 | /*--------------------------------------------------------------------*/ |
| 5 | |
| 6 | /* |
| 7 | This file is part of Valgrind, a dynamic binary instrumentation |
| 8 | framework. |
| 9 | |
| 10 | Copyright (C) 2000-2005 Julian Seward |
| 11 | jseward@acm.org |
| 12 | |
| 13 | This program is free software; you can redistribute it and/or |
| 14 | modify it under the terms of the GNU General Public License as |
| 15 | published by the Free Software Foundation; either version 2 of the |
| 16 | License, or (at your option) any later version. |
| 17 | |
| 18 | This program is distributed in the hope that it will be useful, but |
| 19 | WITHOUT ANY WARRANTY; without even the implied warranty of |
| 20 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| 21 | General Public License for more details. |
| 22 | |
| 23 | You should have received a copy of the GNU General Public License |
| 24 | along with this program; if not, write to the Free Software |
| 25 | Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA |
| 26 | 02111-1307, USA. |
| 27 | |
| 28 | The GNU General Public License is contained in the file COPYING. |
| 29 | */ |
| 30 | |
njn | 4a164d0 | 2005-06-18 18:49:40 +0000 | [diff] [blame] | 31 | #ifndef __PUB_TOOL_REDIR_H |
| 32 | #define __PUB_TOOL_REDIR_H |
njn | 16eeb4e | 2005-06-16 03:56:58 +0000 | [diff] [blame] | 33 | |
| 34 | /* The following macros facilitate function replacement, which is one form |
| 35 | of code replacement. |
| 36 | |
| 37 | The general idea is: you can write a function like this: |
| 38 | |
| 39 | ret_type VG_REPLACE_FUNCTION(zEncodedSoname, fnname) ( ... args ... ) |
| 40 | { |
| 41 | ... body ... |
| 42 | } |
| 43 | |
| 44 | zEncodedSoname should be a Z-encoded soname (see below for Z-encoding |
| 45 | details) and fnname should be an unencoded fn name. The resulting name is |
| 46 | |
| 47 | _vgi_zEncodedSoname_fnname |
| 48 | |
| 49 | The "_vgi_" is a prefix that gets discarded upon decoding. |
| 50 | |
| 51 | When it sees this name, the core's symbol-table reading machinery |
| 52 | and redirection machinery will conspire to cause calls to the function |
| 53 | 'fnname' in object with soname 'zEncodedSoname' to actually be routed to |
| 54 | the function written here. We use this below to define dozens of |
| 55 | replacements of malloc, free, etc. |
| 56 | |
| 57 | The soname must be a Z-encoded bit of text because sonames can |
| 58 | contain dots etc which are not valid symbol names. But don't Z-encode |
| 59 | the function name, since it will already be a valid symbol name, and the |
| 60 | Z-encoding might screw up the C++ demangling. |
| 61 | |
| 62 | Note that the soname can contain '*' as a wildcard meaning "match |
| 63 | anything". |
| 64 | |
| 65 | Note also that the replacement function should probably (must be?) in |
| 66 | client space, so it runs on the simulated CPU. So it must be in |
| 67 | either vg_preload_<tool>.so or vg_preload_core.so. |
| 68 | |
| 69 | It is important that the Z-encoded soname contains no unencoded |
| 70 | underscores, since the intercept-handlers in vg_symtab2.c detect |
| 71 | the end of the soname by looking for the first trailing underscore. |
| 72 | |
| 73 | Z-encoding details: the scheme is like GHC's. It is just about |
| 74 | readable enough to make a preprocessor unnecessary. First the "_vgi_" |
| 75 | prefix is added, and then the following characters are transformed. |
| 76 | |
| 77 | * --> Za ('a' for "asterisk") |
| 78 | + --> Zp |
| 79 | : --> Zc |
| 80 | . --> Zd |
| 81 | _ --> Zu |
| 82 | - --> Zh ('h' for "hyphen") |
| 83 | (space) --> Zs |
| 84 | Z --> ZZ |
| 85 | |
| 86 | Everything else is left unchanged. |
| 87 | */ |
| 88 | |
| 89 | #define VG_REPLACE_FUNCTION(soname, fnname) _vgi_##soname##_##fnname |
| 90 | #define VG_REPLACE_FUNCTION_PREFIX "_vgi_" |
| 91 | #define VG_REPLACE_FUNCTION_PREFIX_LEN 5 |
| 92 | |
njn | 4a164d0 | 2005-06-18 18:49:40 +0000 | [diff] [blame] | 93 | #endif // __PUB_TOOL_REDIR_H |
njn | 16eeb4e | 2005-06-16 03:56:58 +0000 | [diff] [blame] | 94 | |
| 95 | /*--------------------------------------------------------------------*/ |
| 96 | /*--- end ---*/ |
| 97 | /*--------------------------------------------------------------------*/ |