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ext/zstd/contrib/seekable_format/zstdseek_decompress.c  view on Meta::CPAN

#    define _LARGE_FILES                              /* Large file support on 32-bits AIX and HP-UX */
#  endif
#endif

/* ************************************************************
* Avoid fseek()'s 2GiB barrier with MSVC, macOS, *BSD, MinGW
***************************************************************/
#if defined(_MSC_VER) && _MSC_VER >= 1400
#   define LONG_SEEK _fseeki64
#elif !defined(__64BIT__) && (PLATFORM_POSIX_VERSION >= 200112L) /* No point defining Large file for 64 bit */
#  define LONG_SEEK fseeko
#elif defined(__MINGW32__) && !defined(__STRICT_ANSI__) && !defined(__NO_MINGW_LFS) && defined(__MSVCRT__)
#   define LONG_SEEK fseeko64
#elif defined(_WIN32) && !defined(__DJGPP__)
#   include <windows.h>
    static int LONG_SEEK(FILE* file, __int64 offset, int origin) {
        LARGE_INTEGER off;
        DWORD method;
        off.QuadPart = offset;
        if (origin == SEEK_END)
            method = FILE_END;
        else if (origin == SEEK_CUR)
            method = FILE_CURRENT;
        else
            method = FILE_BEGIN;

        if (SetFilePointerEx((HANDLE) _get_osfhandle(_fileno(file)), off, NULL, method))
            return 0;
        else
            return -1;
    }
#else
#   define LONG_SEEK fseek
#endif

#include <stdlib.h>  /* malloc, free */
#include <stdio.h>   /* FILE* */
#include <limits.h>  /* UNIT_MAX */
#include <assert.h>

#define XXH_STATIC_LINKING_ONLY
#define XXH_NAMESPACE ZSTD_
#include "xxhash.h"

#define ZSTD_STATIC_LINKING_ONLY
#include "zstd.h"
#include "zstd_errors.h"
#include "mem.h"
#include "zstd_seekable.h"

#undef ERROR
#define ERROR(name) ((size_t)-ZSTD_error_##name)

#define CHECK_IO(f) { int const errcod = (f); if (errcod < 0) return ERROR(seekableIO); }

#undef MIN
#undef MAX
#define MIN(a, b) ((a) < (b) ? (a) : (b))
#define MAX(a, b) ((a) > (b) ? (a) : (b))

/* Special-case callbacks for FILE* and in-memory modes, so that we can treat
 * them the same way as the advanced API */
static int ZSTD_seekable_read_FILE(void* opaque, void* buffer, size_t n)
{
    size_t const result = fread(buffer, 1, n, (FILE*)opaque);
    if (result != n) {
        return -1;
    }
    return 0;
}

static int ZSTD_seekable_seek_FILE(void* opaque, long long offset, int origin)
{
    int const ret = LONG_SEEK((FILE*)opaque, offset, origin);
    if (ret) return ret;
    return fflush((FILE*)opaque);
}

typedef struct {
    const void *ptr;
    size_t size;
    size_t pos;
} buffWrapper_t;

static int ZSTD_seekable_read_buff(void* opaque, void* buffer, size_t n)
{
    buffWrapper_t* buff = (buffWrapper_t*) opaque;
    if (buff->pos + n > buff->size) return -1;
    memcpy(buffer, (const BYTE*)buff->ptr + buff->pos, n);
    buff->pos += n;
    return 0;
}

static int ZSTD_seekable_seek_buff(void* opaque, long long offset, int origin)
{
    buffWrapper_t* const buff = (buffWrapper_t*) opaque;
    unsigned long long newOffset;
    switch (origin) {
    case SEEK_SET:
        newOffset = offset;
        break;
    case SEEK_CUR:
        newOffset = (unsigned long long)buff->pos + offset;
        break;
    case SEEK_END:
        newOffset = (unsigned long long)buff->size + offset;
        break;
    default:
        assert(0);  /* not possible */
    }
    if (newOffset > buff->size) {
        return -1;
    }
    buff->pos = newOffset;
    return 0;
}

typedef struct {
    U64 cOffset;
    U64 dOffset;
    U32 checksum;