diff options
Diffstat (limited to 'lib/pagealign_alloc.c')
| -rw-r--r-- | lib/pagealign_alloc.c | 198 |
1 files changed, 198 insertions, 0 deletions
diff --git a/lib/pagealign_alloc.c b/lib/pagealign_alloc.c new file mode 100644 index 0000000..28e8209 --- /dev/null +++ b/lib/pagealign_alloc.c @@ -0,0 +1,198 @@ +/* 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, + 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> + +#include <fcntl.h> + +#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" +#include "gettext.h" + +#define _(str) gettext (str) + +#if HAVE_MMAP +/* Define MAP_FILE when it isn't otherwise. */ +# ifndef MAP_FILE +# define MAP_FILE 0 +# endif +/* Define MAP_FAILED for old systems which neglect to. */ +# ifndef MAP_FAILED +# define MAP_FAILED ((void *)-1) +# endif +#endif + + +#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 == NULL) + /* 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 +# ifdef HAVE_MAP_ANONYMOUS + const int fd = -1; + const int flags = MAP_ANONYMOUS | MAP_PRIVATE; +# else /* !HAVE_MAP_ANONYMOUS */ + 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. */ + const int 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 == MAP_FAILED) + return NULL; + new_memnode (ret, size); +#elif HAVE_POSIX_MEMALIGN + int status = posix_memalign (&ret, getpagesize (), size); + if (status) + { + errno = status; + return NULL; + } +#else /* !HAVE_MMAP && !HAVE_POSIX_MEMALIGN */ + size_t pagesize = getpagesize (); + void *unaligned_ptr = malloc (size + pagesize - 1); + if (unaligned_ptr == NULL) + { + /* Set errno. We don't know whether malloc already set errno: some + implementations of malloc do, some don't. */ + errno = ENOMEM; + return NULL; + } + 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_xalloc (size_t size) +{ + void *ret; + + ret = pagealign_alloc (size); + if (ret == NULL) + xalloc_die (); + return ret; +} + + +void +pagealign_free (void *aligned_ptr) +{ +#if HAVE_MMAP + if (munmap (aligned_ptr, get_memnode (aligned_ptr)) < 0) + error (EXIT_FAILURE, errno, "Failed to unmap memory"); +#elif HAVE_POSIX_MEMALIGN + free (aligned_ptr); +#else + free (get_memnode (aligned_ptr)); +#endif +} |