/* zpipe.c: example of proper use of zlib's inflate() and deflate()+
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   Not copyrighted -- provided to the public domain+
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   Version 1.2  9 November 2004  Mark Adler */+
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+
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/* Version history:+
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   1.0  30 Oct 2004  First version+
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   1.1   8 Nov 2004  Add void casting for unused return values+
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                     Use switch statement for inflate() return values+
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   1.2   9 Nov 2004  Add assertions to document zlib guarantees+
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   1.3   6 Apr 2005  Remove incorrect assertion in inf()+
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 */+
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+
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#include <stdio.h>+
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#include <string.h>+
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#include <assert.h>+
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#include "zlib.h"+
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+
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#define CHUNK 16384+
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+
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/* Compress from file source to file dest until EOF on source.+
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   def() returns Z_OK on success, Z_MEM_ERROR if memory could not be+
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   allocated for processing, Z_STREAM_ERROR if an invalid compression+
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   level is supplied, Z_VERSION_ERROR if the version of zlib.h and the+
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   version of the library linked do not match, or Z_ERRNO if there is+
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   an error reading or writing the files. */+
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int def(FILE *source, FILE *dest, int level)+
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{+
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    int ret, flush;+
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    unsigned have;+
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    z_stream strm;+
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    char in[CHUNK];+
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    char out[CHUNK];+
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+
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    /* allocate deflate state */+
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    strm.zalloc = Z_NULL;+
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    strm.zfree = Z_NULL;+
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    strm.opaque = Z_NULL;+
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    ret = deflateInit(&strm, level);+
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    if (ret != Z_OK)+
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        return ret;+
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+
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    /* compress until end of file */+
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    do {+
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        strm.avail_in = fread(in, 1, CHUNK, source);+
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        if (ferror(source)) {+
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            (void)deflateEnd(&strm);+
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            return Z_ERRNO;+
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        }+
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        flush = feof(source) ? Z_FINISH : Z_NO_FLUSH;+
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        strm.next_in = in;+
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+
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        /* run deflate() on input until output buffer not full, finish+
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           compression if all of source has been read in */+
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        do {+
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            strm.avail_out = CHUNK;+
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            strm.next_out = out;+
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            ret = deflate(&strm, flush);    /* no bad return value */+
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            assert(ret != Z_STREAM_ERROR);  /* state not clobbered */+
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            have = CHUNK - strm.avail_out;+
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            if (fwrite(out, 1, have, dest) != have || ferror(dest)) {+
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                (void)deflateEnd(&strm);+
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                return Z_ERRNO;+
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            }+
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        } while (strm.avail_out == 0);+
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        assert(strm.avail_in == 0);     /* all input will be used */+
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+
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        /* done when last data in file processed */+
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    } while (flush != Z_FINISH);+
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    assert(ret == Z_STREAM_END);        /* stream will be complete */+
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+
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    /* clean up and return */+
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    (void)deflateEnd(&strm);+
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    return Z_OK;+
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}+
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+
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/* Decompress from file source to file dest until stream ends or EOF.+
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   inf() returns Z_OK on success, Z_MEM_ERROR if memory could not be+
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   allocated for processing, Z_DATA_ERROR if the deflate data is+
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   invalid or incomplete, Z_VERSION_ERROR if the version of zlib.h and+
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   the version of the library linked do not match, or Z_ERRNO if there+
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   is an error reading or writing the files. */+
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int inf(FILE *source, FILE *dest)+
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{+
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    int ret;+
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    unsigned have;+
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    z_stream strm;+
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    char in[CHUNK];+
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    char out[CHUNK];+
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+
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    /* allocate inflate state */+
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    strm.zalloc = Z_NULL;+
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    strm.zfree = Z_NULL;+
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    strm.opaque = Z_NULL;+
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    strm.avail_in = 0;+
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    strm.next_in = Z_NULL;+
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    ret = inflateInit(&strm);+
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    if (ret != Z_OK)+
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        return ret;+
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+
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    /* decompress until deflate stream ends or end of file */+
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    do {+
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        strm.avail_in = fread(in, 1, CHUNK, source);+
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        if (ferror(source)) {+
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            (void)inflateEnd(&strm);+
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            return Z_ERRNO;+
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        }+
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        if (strm.avail_in == 0)+
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            break;+
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        strm.next_in = in;+
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+
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        /* run inflate() on input until output buffer not full */+
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        do {+
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            strm.avail_out = CHUNK;+
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            strm.next_out = out;+
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            ret = inflate(&strm, Z_NO_FLUSH);+
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            assert(ret != Z_STREAM_ERROR);  /* state not clobbered */+
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            switch (ret) {+
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            case Z_NEED_DICT:+
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                ret = Z_DATA_ERROR;     /* and fall through */+
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            case Z_DATA_ERROR:+
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            case Z_MEM_ERROR:+
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                (void)inflateEnd(&strm);+
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                return ret;+
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            }+
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            have = CHUNK - strm.avail_out;+
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            if (fwrite(out, 1, have, dest) != have || ferror(dest)) {+
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                (void)inflateEnd(&strm);+
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                return Z_ERRNO;+
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            }+
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        } while (strm.avail_out == 0);+
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+
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        /* done when inflate() says it's done */+
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    } while (ret != Z_STREAM_END);+
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+
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    /* clean up and return */+
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    (void)inflateEnd(&strm);+
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    return ret == Z_STREAM_END ? Z_OK : Z_DATA_ERROR;+
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}+
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+
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/* report a zlib or i/o error */+
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void zerr(int ret)+
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{+
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    fputs("zpipe: ", stderr);+
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    switch (ret) {+
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    case Z_ERRNO:+
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        if (ferror(stdin))+
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            fputs("error reading stdin\n", stderr);+
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        if (ferror(stdout))+
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            fputs("error writing stdout\n", stderr);+
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        break;+
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    case Z_STREAM_ERROR:+
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        fputs("invalid compression level\n", stderr);+
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        break;+
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    case Z_DATA_ERROR:+
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        fputs("invalid or incomplete deflate data\n", stderr);+
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        break;+
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    case Z_MEM_ERROR:+
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        fputs("out of memory\n", stderr);+
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        break;+
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    case Z_VERSION_ERROR:+
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        fputs("zlib version mismatch!\n", stderr);+
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    }+
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}+
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+
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/* compress or decompress from stdin to stdout */+
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int main(int argc, char **argv)+
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{+
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    int ret;+
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+
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    /* do compression if no arguments */+
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    if (argc == 1) {+
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        ret = def(stdin, stdout, Z_DEFAULT_COMPRESSION);+
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        if (ret != Z_OK)+
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            zerr(ret);+
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        return ret;+
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    }+
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+
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    /* do decompression if -d specified */+
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    else if (argc == 2 && strcmp(argv[1], "-d") == 0) {+
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        ret = inf(stdin, stdout);+
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        if (ret != Z_OK)+
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            zerr(ret);+
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        return ret;+
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    }+
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+
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    /* otherwise, report usage */+
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    else {+
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        fputs("zpipe usage: zpipe [-d] < source > dest\n", stderr);+
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        return 1;+
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    }+
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}+
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