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93 lines
2.4 KiB
93 lines
2.4 KiB
/* Compute CRC32 checksum of file contents.
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Copyright (C) 2006 Red Hat, Inc.
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This file is part of elfutils.
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This file is free software; you can redistribute it and/or modify
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it under the terms of either
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* the GNU Lesser General Public License as published by the Free
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Software Foundation; either version 3 of the License, or (at
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your option) any later version
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or
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* the GNU General Public License as published by the Free
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Software Foundation; either version 2 of the License, or (at
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your option) any later version
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or both in parallel, as here.
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elfutils is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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General Public License for more details.
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You should have received copies of the GNU General Public License and
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the GNU Lesser General Public License along with this program. If
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not, see <http://www.gnu.org/licenses/>. */
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#ifdef HAVE_CONFIG_H
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# include <config.h>
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#endif
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#include "libeu.h"
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#include <errno.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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#include "system.h"
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int
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crc32_file (int fd, uint32_t *resp)
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{
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unsigned char buffer[1024 * 8];
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uint32_t crc = 0;
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off_t off = 0;
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ssize_t count;
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struct stat st;
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if (fstat (fd, &st) == 0)
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{
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/* Try mapping in the file data. */
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size_t mapsize = st.st_size;
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void *mapped = mmap (NULL, mapsize, PROT_READ, MAP_PRIVATE, fd, 0);
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if (mapped == MAP_FAILED && errno == ENOMEM)
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{
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const size_t pagesize = sysconf (_SC_PAGESIZE);
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mapsize = ((mapsize / 2) + pagesize - 1) & -pagesize;
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while (mapsize >= pagesize
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&& (mapped = mmap (NULL, mapsize, PROT_READ, MAP_PRIVATE,
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fd, 0)) == MAP_FAILED && errno == ENOMEM)
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mapsize /= 2;
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}
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if (mapped != MAP_FAILED)
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{
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do
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{
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if (st.st_size <= (off_t) mapsize)
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{
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*resp = crc32 (crc, mapped, st.st_size);
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munmap (mapped, mapsize);
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return 0;
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}
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crc = crc32 (crc, mapped, mapsize);
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off += mapsize;
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st.st_size -= mapsize;
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} while (mmap (mapped, mapsize, PROT_READ, MAP_FIXED|MAP_PRIVATE,
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fd, off) == mapped);
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munmap (mapped, mapsize);
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}
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}
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while ((count = TEMP_FAILURE_RETRY (pread (fd, buffer, sizeof buffer,
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off))) > 0)
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{
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off += count;
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crc = crc32 (crc, buffer, count);
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}
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*resp = crc;
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return count == 0 ? 0 : -1;
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}
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