diff options
Diffstat (limited to 'cpukit/libdl/rtl-obj-cache.c')
| -rw-r--r-- | cpukit/libdl/rtl-obj-cache.c | 197 |
1 files changed, 197 insertions, 0 deletions
diff --git a/cpukit/libdl/rtl-obj-cache.c b/cpukit/libdl/rtl-obj-cache.c new file mode 100644 index 0000000000..23d7d07c43 --- /dev/null +++ b/cpukit/libdl/rtl-obj-cache.c @@ -0,0 +1,197 @@ +/* + * COPYRIGHT (c) 2012 Chris Johns <chrisj@rtems.org> + * + * The license and distribution terms for this file may be + * found in the file LICENSE in this distribution or at + * http://www.rtems.com/license/LICENSE. + */ +/** + * @file + * + * @ingroup rtems_rtl + * + * @brief RTEMS Run-Time Linker Object File cache buffers a section of the + * object file in a buffer to localise read performance. + */ + +#if HAVE_CONFIG_H +#include "config.h" +#endif + +#include <errno.h> +#include <string.h> +#include <unistd.h> + +#include <rtems/rtl/rtl-allocator.h> +#include "rtl-obj-cache.h" +#include "rtl-error.h" + +bool +rtems_rtl_obj_cache_open (rtems_rtl_obj_cache_t* cache, size_t size) +{ + cache->fd = -1; + cache->file_size = 0; + cache->offset = 0; + cache->size = size; + cache->level = 0; + cache->buffer = rtems_rtl_alloc_new (RTEMS_RTL_ALLOC_OBJECT, size, false); + if (!cache->buffer) + { + rtems_rtl_set_error (ENOMEM, "no memory for cache buffer"); + return false; + } + return true; +} + +void +rtems_rtl_obj_cache_close (rtems_rtl_obj_cache_t* cache) +{ + rtems_rtl_alloc_del (RTEMS_RTL_ALLOC_OBJECT, cache->buffer); + cache->fd = -1; + cache->file_size = 0; + cache->level = 0; +} + +void +rtems_rtl_obj_cache_flush (rtems_rtl_obj_cache_t* cache) +{ + cache->fd = -1; + cache->file_size = 0; + cache->level = 0; +} + +bool +rtems_rtl_obj_cache_read (rtems_rtl_obj_cache_t* cache, + int fd, + off_t offset, + void** buffer, + size_t* length) +{ + struct stat sb; + + if (*length > cache->size) + { + rtems_rtl_set_error (EINVAL, "read size larger than cache size"); + return false; + } + + if (cache->fd == fd) + { + if (offset > cache->file_size) + { + rtems_rtl_set_error (EINVAL, "offset past end of file: offset=%i size=%i", + (int) offset, (int) cache->file_size); + return false; + } + + if ((offset + *length) > cache->file_size) + *length = cache->file_size - offset; + } + + while (true) + { + size_t buffer_offset = 0; + size_t buffer_read = cache->size; + + /* + * Is the data in the cache for this file ? + */ + if (fd == cache->fd) + { + /* + * Is any part of the data in the cache ? + */ + if ((offset >= cache->offset) && + (offset < (cache->offset + cache->level))) + { + buffer_offset = offset - cache->offset; + + /* + * Return the location of the data in the cache. + */ + *buffer = cache->buffer + buffer_offset; + + /* + * Is all the data in the cache or just a part ? + */ + if (*length <= (cache->level - buffer_offset)) + { + return true; + } + + /* + * Copy down the data in the buffer and then fill the remaining + * space with as much data we are able to read. + */ + memmove (cache->buffer, + cache->buffer + buffer_offset, + cache->size - buffer_offset); + + buffer_read = buffer_offset; + buffer_offset = cache->size - buffer_offset; + } + } + + if (lseek (fd, offset + buffer_offset, SEEK_SET) < 0) + { + rtems_rtl_set_error (errno, "file seek failed"); + return false; + } + + /* + * Loop reading the data from the file until either an error or 0 is + * returned and if data has been read check if the amount is what we + * want. If not it is an error. A POSIX read can read data in fragments. + */ + cache->level = buffer_read; + while (buffer_read) + { + int r = read (fd, cache->buffer + buffer_offset, buffer_read); + if (r < 0) + { + rtems_rtl_set_error (errno, "file read failed"); + return false; + } + if ((r == 0) && buffer_read) + { + cache->level = cache->level - buffer_read; + buffer_read = 0; + } + else + { + buffer_read -= r; + buffer_offset += r; + } + } + + cache->fd = fd; + cache->offset = offset; + + if (fstat (cache->fd, &sb) < 0) + { + rtems_rtl_set_error (errno, "file stat failed"); + return false; + } + + cache->file_size = sb.st_size; + } + + return false; +} + +bool +rtems_rtl_obj_cache_read_byval (rtems_rtl_obj_cache_t* cache, + int fd, + off_t offset, + void* buffer, + size_t length) +{ + void* cbuffer = 0; + size_t len = length; + bool ok = rtems_rtl_obj_cache_read (cache, fd, offset, &cbuffer, &len); + if (ok && (len != length)) + ok = false; + if (ok) + memcpy (buffer, cbuffer, length); + return ok; +} |