Mercurial > hg > octave-nkf > gnulib-hg
changeset 4852:7f909e1de364
New module 'xsize'.
| author | Bruno Haible <bruno@clisp.org> |
|---|---|
| date | Tue, 04 Nov 2003 12:06:16 +0000 |
| parents | 992dd0324a2e |
| children | 5d25a00a8502 |
| files | ChangeLog lib/ChangeLog lib/xsize.h m4/ChangeLog m4/xsize.m4 modules/xsize |
| diffstat | 6 files changed, 141 insertions(+), 0 deletions(-) [+] |
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--- a/ChangeLog +++ b/ChangeLog @@ -1,3 +1,9 @@ +2003-11-04 Bruno Haible <bruno@clisp.org> + + * modules/xsize: New file. + * modules/linebreak: Depend on xsize. + * MODULES.html.sh (func_all_modules): Add xsize. + 2003-11-04 Jim Meyering <jim@meyering.net> * modules/sysexits: Use the `$(VAR)' notation for AC_SUBST'd
--- a/lib/ChangeLog +++ b/lib/ChangeLog @@ -1,3 +1,11 @@ +2003-11-04 Bruno Haible <bruno@clisp.org> + + * xsize.h: New file. + * linebreak.c: Include xsize.h. + (mbs_possible_linebreaks, mbs_width_linebreaks): Check malloc() + argument for overflow. + Suggested by Paul Eggert. + 2003-10-31 Bruno Haible <bruno@clisp.org> * wait-process.c (wait_process): Use waitid with WNOWAIT if available,
new file mode 100644 --- /dev/null +++ b/lib/xsize.h @@ -0,0 +1,89 @@ +/* xsize.h -- Checked size_t computations. + + Copyright (C) 2003 Free Software Foundation, Inc. + + 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 + the Free Software Foundation; either version 2, or (at your option) + any later version. + + This program is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + GNU General Public License for more details. + + You should have received a copy of the GNU General Public License + along with this program; if not, write to the Free Software Foundation, + Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */ + +#ifndef _XSIZE_H +#define _XSIZE_H + +/* Get size_t. */ +#include <stddef.h> + +/* Get SIZE_MAX. */ +#if HAVE_STDINT_H +# include <stdint.h> +#endif +#ifndef SIZE_MAX +# define SIZE_MAX ((size_t) -1) +#endif + +/* The size of memory objects is often computed through expressions of + type size_t. Example: + void* p = malloc (header_size + n * element_size). + These computations can lead to overflow. When this happens, malloc() + returns a piece of memory that is way too small, and the program then + crashes while attempting to fill the memory. + To avoid this, the functions and macros in this file check for overflow. + The convention is that SIZE_MAX represents overflow. + malloc (SIZE_MAX) is not guaranteed to fail -- think of a malloc + implementation that uses mmap --, it's recommended to use SIZE_OVERFLOW_P + before invoking malloc(). + The example thus becomes: + size_t size = xsum (header_size, xtimes (n, element_size)); + void *p = (!SIZE_OVERFLOW_P (size) ? malloc (size) : NULL); +*/ + +/* Convert an arbitrary value >= 0 to type size_t. */ +#define xcast_size_t(N) \ + ((N) <= SIZE_MAX ? (size_t) (N) : SIZE_MAX) + +/* Sum of two sizes, with overflow check. */ +static inline size_t +xsum (size_t size1, size_t size2) +{ + size_t sum = size1 + size2; + return (sum >= size1 ? sum : SIZE_MAX); +} + +/* Sum of three sizes, with overflow check. */ +static inline size_t +xsum3 (size_t size1, size_t size2, size_t size3) +{ + return xsum (xsum (size1, size2), size3); +} + +/* Sum of four sizes, with overflow check. */ +static inline size_t +xsum4 (size_t size1, size_t size2, size_t size3, size_t size4) +{ + return xsum (xsum (xsum (size1, size2), size3), size4); +} + +/* Multiplication of a count with an element size, with overflow check. + The count must be >= 0 and the element size must be > 0. + This is a macro, not an inline function, so that it works correctly even + when N is of a wider tupe and N > SIZE_MAX. */ +#define xtimes(N, ELSIZE) \ + ((N) <= SIZE_MAX / (ELSIZE) ? (size_t) (N) * (ELSIZE) : SIZE_MAX) + +/* Check for overflow. */ +#define size_overflow_p(SIZE) \ + ((SIZE) == SIZE_MAX) +/* Check against overflow. */ +#define size_in_bounds_p(SIZE) \ + ((SIZE) != SIZE_MAX) + +#endif /* _XSIZE_H */
--- a/m4/ChangeLog +++ b/m4/ChangeLog @@ -1,3 +1,7 @@ +2003-11-04 Bruno Haible <bruno@clisp.org> + + * xsize.m4: New file. + 2003-11-03 Bruno Haible <bruno@clisp.org> * wait-process.m4 (gl_WAIT_PROCESS): Also check for waitid.
new file mode 100644 --- /dev/null +++ b/m4/xsize.m4 @@ -0,0 +1,13 @@ +# xsize.m4 serial 1 +dnl Copyright (C) 2003 Free Software Foundation, Inc. +dnl This file is free software, distributed under the terms of the GNU +dnl General Public License. As a special exception to the GNU General +dnl Public License, this file may be distributed as part of a program +dnl that contains a configuration script generated by Autoconf, under +dnl the same distribution terms as the rest of that program. + +AC_DEFUN([gl_XSIZE], +[ + dnl Prerequisites of lib/xsize.h. + AC_CHECK_HEADERS(stdint.h) +])