diff options
Diffstat (limited to 'lib/libc/gen/getpagesizes.c')
-rw-r--r-- | lib/libc/gen/getpagesizes.c | 85 |
1 files changed, 85 insertions, 0 deletions
diff --git a/lib/libc/gen/getpagesizes.c b/lib/libc/gen/getpagesizes.c new file mode 100644 index 0000000..534fe9e --- /dev/null +++ b/lib/libc/gen/getpagesizes.c @@ -0,0 +1,85 @@ +/*- + * Copyright (c) 2009 Alan L. Cox <alc@cs.rice.edu> + * All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * + * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND + * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE + * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE + * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL + * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS + * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) + * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT + * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY + * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF + * SUCH DAMAGE. + */ + +#include <sys/cdefs.h> +__FBSDID("$FreeBSD$"); + +#include <sys/param.h> +#include <sys/mman.h> +#include <sys/sysctl.h> + +#include <errno.h> +#include <link.h> + +#include "libc_private.h" + +/* + * Retrieves page size information from the system. Specifically, returns the + * number of distinct page sizes that are supported by the system, if + * "pagesize" is NULL and "nelem" is 0. Otherwise, assigns up to "nelem" of + * the system-supported page sizes to consecutive elements of the array + * referenced by "pagesize", and returns the number of such page sizes that it + * assigned to the array. These page sizes are expressed in bytes. + * + * The implementation of this function does not directly or indirectly call + * malloc(3) or any other dynamic memory allocator that may itself call this + * function. + */ +int +getpagesizes(size_t pagesize[], int nelem) +{ + static u_long ps[MAXPAGESIZES]; + static int nops; + size_t size; + int error, i; + + if (nelem < 0 || (nelem > 0 && pagesize == NULL)) { + errno = EINVAL; + return (-1); + } + /* Cache the result of the sysctl(2). */ + if (nops == 0) { + error = _elf_aux_info(AT_PAGESIZES, ps, sizeof(ps)); + size = sizeof(ps); + if (error != 0 || ps[0] == 0) { + if (sysctlbyname("hw.pagesizes", ps, &size, NULL, 0) + == -1) + return (-1); + } + /* Count the number of page sizes that are supported. */ + nops = size / sizeof(ps[0]); + while (nops > 0 && ps[nops - 1] == 0) + nops--; + } + if (pagesize == NULL) + return (nops); + /* Return up to "nelem" page sizes from the cached result. */ + if (nelem > nops) + nelem = nops; + for (i = 0; i < nelem; i++) + pagesize[i] = ps[i]; + return (nelem); +} |