Re: AC_FUNC_MMAP lacks <unistd.h> include?
Paul Eggert <[email protected]>
| Newsgroups | gmane.comp.sysutils.autoconf.bugs |
|---|---|
| Organization | UCLA Computer Science Department |
| Message-ID | <[email protected]> |
On 2023-05-10 21:06, Matt Turner wrote: > We're mmap'ing a 1-byte file, and since the pagesize on amd64 is 4096 > bytes, only the first 4096 byte page (of two) is mapped. Accessing the > second page triggers the SIGBUS. Ouch, I misread that part of the test. Thanks for reporting that. I suppose we should go back to invoking getpagesize despite the hassle of configuring it. I installed the attached further patch; please give it a try.
0001-Fix-port-of-AC_FUNC_MMAP.patch
(text/x-patch, 2.8 KB)
From 33c26d2700f927432c756ccf7a4fc89403d35b95 Mon Sep 17 00:00:00 2001 From: Paul Eggert <[email protected]> Date: Wed, 10 May 2023 22:57:27 -0700 Subject: [PATCH] Fix port of AC_FUNC_MMAP MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Problem reported by Matt Turner in: https://lists.gnu.org/r/bug-autoconf/2023-05/msg00005.html * lib/autoconf/functions.m4 (AC_FUNC_MMAP): Go back to getting the page size, since the zero-fill test needs this after all. However, prefer sysconf (_SC_PAGESIZE) or sysconf (_SC_PAGE_SIZE) to getpagesize (), and use ‘long’ not ‘int’ to store the page size. Also, declare getpagesize if it is used as a function. --- lib/autoconf/functions.m4 | 41 ++++++++++++++++++++++++++++++++++----- 1 file changed, 36 insertions(+), 5 deletions(-) diff --git a/lib/autoconf/functions.m4 b/lib/autoconf/functions.m4 index 5a0f0185..3d6e4aca 100644 --- a/lib/autoconf/functions.m4 +++ b/lib/autoconf/functions.m4 @@ -1283,7 +1283,6 @@ AU_ALIAS([AM_FUNC_MKTIME], [AC_FUNC_MKTIME]) AN_FUNCTION([mmap], [AC_FUNC_MMAP]) AC_DEFUN([AC_FUNC_MMAP], [AC_REQUIRE([AC_CANONICAL_HOST])dnl for cross-compiles -dnl FIXME: Remove the unnecessary checks for unistd.h, sys/param.h, getpagesize. AC_CHECK_HEADERS_ONCE([unistd.h sys/param.h]) AC_CHECK_FUNCS_ONCE([getpagesize]) AC_CACHE_CHECK([for working mmap], [ac_cv_func_mmap_fixed_mapped], @@ -1311,17 +1310,49 @@ AC_CACHE_CHECK([for working mmap], [ac_cv_func_mmap_fixed_mapped], #include <fcntl.h> #include <sys/mman.h> +#ifndef getpagesize +# ifdef _SC_PAGESIZE +# define getpagesize() sysconf (_SC_PAGESIZE) +# elif defined _SC_PAGE_SIZE +# define getpagesize() sysconf (_SC_PAGE_SIZE) +# elif HAVE_GETPAGESIZE +int getpagesize (); +# else +# ifdef HAVE_SYS_PARAM_H +# include <sys/param.h> +# ifdef EXEC_PAGESIZE +# define getpagesize() EXEC_PAGESIZE +# else /* no EXEC_PAGESIZE */ +# ifdef NBPG +# define getpagesize() NBPG * CLSIZE +# ifndef CLSIZE +# define CLSIZE 1 +# endif /* no CLSIZE */ +# else /* no NBPG */ +# ifdef NBPC +# define getpagesize() NBPC +# else /* no NBPC */ +# ifdef PAGESIZE +# define getpagesize() PAGESIZE +# endif /* PAGESIZE */ +# endif /* no NBPC */ +# endif /* no NBPG */ +# endif /* no EXEC_PAGESIZE */ +# else /* no HAVE_SYS_PARAM_H */ +# define getpagesize() 8192 /* punt totally */ +# endif /* no HAVE_SYS_PARAM_H */ +# endif +#endif + int main (void) { char *data, *data2, *data3; const char *cdata2; - int i, pagesize; + long i, pagesize; int fd, fd2; - /* The "page size" need not equal the system page size, - and need not even be a power of 2. */ - pagesize = 8192; + pagesize = getpagesize (); /* First, make a file with some known garbage in it. */ data = (char *) malloc (pagesize); -- 2.39.2