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101 lines
2.4 KiB
101 lines
2.4 KiB
3 months ago
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/*
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* UCW Library -- Mapping of File Parts
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*
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* (c) 2003--2006 Martin Mares <mj@ucw.cz>
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* (c) 2003--2009 Robert Spalek <robert@ucw.cz>
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*
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* This software may be freely distributed and used according to the terms
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* of the GNU Lesser General Public License.
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*/
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#include <ucw/lib.h>
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#include <ucw/io.h>
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#include <ucw/partmap.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <fcntl.h>
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#include <unistd.h>
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#include <sys/stat.h>
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#include <sys/mman.h>
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#ifdef CONFIG_UCW_PARTMAP_IS_MMAP
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#define PARTMAP_WINDOW ~(size_t)0
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#else
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#ifdef TEST
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#define PARTMAP_WINDOW 4096
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#else
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#define PARTMAP_WINDOW 16777216
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#endif
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#endif
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struct partmap *
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partmap_open(char *name, int writeable)
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{
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struct partmap *p = xmalloc_zero(sizeof(struct partmap));
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p->fd = ucw_open(name, writeable ? O_RDWR : O_RDONLY);
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if (p->fd < 0)
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die("open(%s): %m", name);
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if ((p->file_size = ucw_seek(p->fd, 0, SEEK_END)) < 0)
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die("lseek(%s): %m", name);
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p->writeable = writeable;
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#ifdef CONFIG_UCW_PARTMAP_IS_MMAP
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partmap_load(p, 0, p->file_size);
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#endif
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return p;
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}
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ucw_off_t
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partmap_size(struct partmap *p)
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{
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return p->file_size;
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}
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void
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partmap_close(struct partmap *p)
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{
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if (p->start_map)
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munmap(p->start_map, p->end_off - p->start_off);
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close(p->fd);
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xfree(p);
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}
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void
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partmap_load(struct partmap *p, ucw_off_t start, uint size)
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{
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if (p->start_map)
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munmap(p->start_map, p->end_off - p->start_off);
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ucw_off_t end = start + size;
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ucw_off_t win_start = start/CPU_PAGE_SIZE * CPU_PAGE_SIZE;
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size_t win_len = PARTMAP_WINDOW;
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if (win_len > (size_t) (p->file_size - win_start))
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win_len = ALIGN_TO(p->file_size - win_start, CPU_PAGE_SIZE);
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if ((ucw_off_t) (win_start+win_len) < end)
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die("partmap_map: Window is too small for mapping %d bytes", size);
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if (win_len)
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{
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p->start_map = ucw_mmap(NULL, win_len, p->writeable ? (PROT_READ | PROT_WRITE) : PROT_READ, MAP_SHARED, p->fd, win_start);
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if (p->start_map == MAP_FAILED)
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die("mmap failed at position %lld: %m", (long long)win_start);
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}
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else
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p->start_map = NULL;
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p->start_off = win_start;
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p->end_off = win_start+win_len;
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madvise(p->start_map, win_len, MADV_SEQUENTIAL);
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}
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#ifdef TEST
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int main(int argc, char **argv)
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{
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struct partmap *p = partmap_open(argv[1], 0);
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uint l = partmap_size(p);
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uint i;
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for (i=0; i<l; i++)
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putchar(*(char *)partmap_map(p, i, 1));
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partmap_close(p);
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return 0;
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}
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#endif
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