diff options
author | Bruno Haible <bruno@clisp.org> | 2005-03-03 14:07:04 +0000 |
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committer | Bruno Haible <bruno@clisp.org> | 2005-03-03 14:07:04 +0000 |
commit | c49424557579cb46914ba4f080720d8b94abab39 (patch) | |
tree | d82b363ac80c448e58b8ff89c5c08b82be6dab7b /lib/pagealign_alloc.c | |
parent | cd3bee968885a85671cad267e142aad74076b5e2 (diff) | |
download | gnulib-c49424557579cb46914ba4f080720d8b94abab39.tar.gz |
New module 'pagealign_alloc'.
Diffstat (limited to 'lib/pagealign_alloc.c')
-rw-r--r-- | lib/pagealign_alloc.c | 164 |
1 files changed, 164 insertions, 0 deletions
diff --git a/lib/pagealign_alloc.c b/lib/pagealign_alloc.c new file mode 100644 index 0000000000..e848b06065 --- /dev/null +++ b/lib/pagealign_alloc.c @@ -0,0 +1,164 @@ +/* Memory allocation aligned to system page boundaries. + + Copyright (C) 2005 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. */ + +/* Written by Derek R. Price <derek@ximbiot.com>. */ + +#ifdef HAVE_CONFIG_H +# include <config.h> +#endif + +#include "pagealign_alloc.h" + +#include <errno.h> +#include <stdlib.h> + +#if HAVE_FCNTL_H +# include <fcntl.h> +#endif + +#if HAVE_UNISTD_H +# include <unistd.h> +#endif + +#if HAVE_MMAP +# include <sys/mman.h> +#endif + +#include "error.h" +#include "exit.h" +#include "getpagesize.h" +#include "xalloc.h" + + +#if HAVE_MMAP || ! HAVE_POSIX_MEMALIGN + +# if HAVE_MMAP +/* For each memory region, we store its size. */ +typedef size_t info_t; +# else +/* For each memory region, we store the original pointer returned by + malloc(). */ +typedef void * info_t; +# endif + +/* A simple linked list of allocated memory regions. It is probably not the + most efficient way to store these, but anyway... */ +typedef struct memnode_s memnode_t; +struct memnode_s +{ + void *aligned_ptr; + info_t info; + memnode_t *next; +}; + +/* The list of currently allocated memory regions. */ +static memnode_t *memnode_table = NULL; + + +static void +new_memnode (void *aligned_ptr, info_t info) +{ + memnode_t *new_node = (memnode_t *) xmalloc (sizeof (memnode_t)); + new_node->aligned_ptr = aligned_ptr; + new_node->info = info; + new_node->next = memnode_table; + memnode_table = new_node; +} + + +/* Dispose of the memnode containing a map for the ALIGNED_PTR in question + and return the content of the node's INFO field. */ +static info_t +get_memnode (void *aligned_ptr) +{ + info_t ret; + memnode_t *c; + memnode_t **p_next = &memnode_table; + + for (c = *p_next; c != NULL; p_next = &c->next, c = c->next) + if (c->aligned_ptr == aligned_ptr) + break; + + if (!c) + /* An attempt to free untracked memory. A wrong pointer was passed + to pagealign_free(). */ + abort (); + + /* Remove this entry from the list, save the return value, and free it. */ + *p_next = c->next; + ret = c->info; + free (c); + + return ret; +} + +#endif /* HAVE_MMAP || !HAVE_POSIX_MEMALIGN */ + + +void * +pagealign_alloc (size_t size) +{ + void *ret; +#if HAVE_MMAP + int flags; + static int fd = -1; /* Only open /dev/zero once in order to avoid limiting + the amount of memory we may allocate based on the + number of open file descriptors. */ +# ifdef HAVE_MAP_ANONYMOUS + flags = MAP_ANONYMOUS | MAP_PRIVATE; + fd = -1; +# else /* !HAVE_MAP_ANONYMOUS */ + flags = MAP_FILE | MAP_PRIVATE; + if (fd == -1) + { + fd = open ("/dev/zero", O_RDONLY, 0666); + if (fd < 0) + error (EXIT_FAILURE, errno, "Failed to open /dev/zero for read"); + } +# endif /* HAVE_MAP_ANONYMOUS */ + ret = mmap (NULL, size, PROT_READ | PROT_WRITE, flags, fd, 0); + if (!ret) + error (EXIT_FAILURE, errno, "mmap to /dev/zero failed"); + new_memnode (ret, size); +#elif HAVE_POSIX_MEMALIGN + int status = posix_memalign (&ret, getpagesize (), size); + if (status) + error (EXIT_FAILURE, status, "posix_memalign failed"); +#else /* !HAVE_MMAP && !HAVE_POSIX_MEMALIGN */ + size_t pagesize = getpagesize (); + void *unaligned_ptr = xmalloc (size + pagesize - 1); + ret = (char *) unaligned_ptr + + ((- (unsigned long) unaligned_ptr) & (pagesize - 1)); + new_memnode (ret, unaligned_ptr); +#endif /* HAVE_MMAP && HAVE_POSIX_MEMALIGN */ + return ret; +} + + +void +pagealign_free (void *aligned_ptr) +{ +#if HAVE_MMAP + munmap (aligned_ptr, get_memnode (aligned_ptr)); +#elif HAVE_POSIX_MEMALIGN + free (aligned_ptr); +#else + free (get_memnode (aligned_ptr)); +#endif +} |