Databases
StackOverflow2013
Postsdbo
PO
 

Note that there are some explanatory texts on larger screens.

plurals
  1. PO
    primarykey
    data
    text
    <p>Not sure if I completely understand your needs (for example, don't you need the decompressed file on disk?).</p> <p>I was looking at <strong>LZMA SDK 9.20</strong> and its <strong>lzma.txt</strong> readme file, and there are plenty of hints that decompression to memory is possible - you may just need to use the C API rather than the C++ interface. Check out, for example, the section called <code>Single-call Decompressing</code>: </p> <pre><code>When to use: RAM-&gt;RAM decompressing Compile files: LzmaDec.h + LzmaDec.c + Types.h Compile defines: no defines Memory Requirements: - Input buffer: compressed size - Output buffer: uncompressed size - LZMA Internal Structures: state_size (16 KB for default settings) </code></pre> <p>Also, there is this function: </p> <pre><code>SRes LzmaDec_DecodeToBuf(CLzmaDec *p, Byte *dest, SizeT *destLen, const Byte *src, SizeT *srcLen, ELzmaFinishMode finishMode, ELzmaStatus *status); </code></pre> <p>You can utilize these by memory-mapping the archive file. To the best of my knowledge, if your process creates a memory-mapped file with exclusive access (so no other process can access it) and does no explicit flushing, all changes to the file will be kept in memory until the mapping is destroyed or the file closed. Alternatively, you could just load the archive contents in memory.</p> <p>For the sake of completeness, I hacked together several examples into a demo of using memory mapping in Windows. </p> <pre><code>#include &lt;stdio.h&gt; #include &lt;time.h&gt; #include &lt;Windows.h&gt; #include &lt;WinNT.h&gt; // This demo will limit the file to 4KiB #define FILE_SIZE_MAX_LOWER_DW 4096 #define FILE_SIZE_MAX_UPPER_DW 0 #define MAP_OFFSET_LOWER_DW 0 #define MAP_OFFSET_UPPER_DW 0 #define TEST_ITERATIONS 1000 #define INT16_SIZE 2 typedef short int int16; // NOTE: This will not work for Windows less than XP or 2003 Server! int main() { HANDLE hFile, hFileMapping; PBYTE mapViewStartAddress; // Note: with no explicit security attributes, the process needs to have // the necessary rights (e.g. read, write) to this location. LPCSTR path = "C:\\Users\\mcmlxxxvi\\Desktop\\test.dat"; // First, open a file handle. hFile = CreateFile(path, GENERIC_READ | GENERIC_WRITE, // The file is created with Read/Write permissions FILE_SHARE_READ, // Set this to 0 for exclusive access NULL, // Optional security attributes CREATE_ALWAYS, // File is created if not found, overwritten otherwise FILE_ATTRIBUTE_TEMPORARY, // This affects the caching behaviour 0); // Attributes template, can be left NULL if ((hFile) == INVALID_HANDLE_VALUE) { fprintf(stderr, "Unable to open file"); return 1; } // Then, create a memory mapping for the opened file. hFileMapping = CreateFileMapping(hFile, // Handle for an opened file NULL, // Optional security attributes PAGE_READWRITE, // File can be mapped for Read/Write access FILE_SIZE_MAX_UPPER_DW, // Maximum file size split in DWORDs. FILE_SIZE_MAX_LOWER_DW, // NOTE: I may have these two mixed up! NULL); // Optional name if (hFileMapping == 0) { CloseHandle(hFile); fprintf(stderr, "Unable to open file for mapping."); return 1; } // Next, map a view (a continuous portion of the file) to a memory region // The view must start and end at an offset that is a multiple of // the allocation granularity (roughly speaking, the machine page size). mapViewStartAddress = (PBYTE)MapViewOfFile(hFileMapping, // Handle to a memory-mapped file FILE_MAP_READ | FILE_MAP_WRITE, // Maps the view for Read/Write access MAP_OFFSET_UPPER_DW, // Offset in the file from which MAP_OFFSET_LOWER_DW, // the view starts, split in DWORDs. FILE_SIZE_MAX_LOWER_DW); // Size of the view (here, entire file) if (mapViewStartAddress == 0) { CloseHandle(hFileMapping); CloseHandle(hFile); fprintf(stderr, "Couldn't map a view of the file."); return 1; } // This is where actual business stuff belongs. // This example application does iterations of reading and writing // random numbers for the entire length of the file. int16 value; errno_t result = 0; srand((int)time(NULL)); for (int i = 0; i &lt; TEST_ITERATIONS; i++) { // Write for (int j = 0; j &lt; FILE_SIZE_MAX_LOWER_DW / INT16_SIZE; j++) { value = rand(); result = memcpy_s(mapViewStartAddress + j * INT16_SIZE, INT16_SIZE, &amp;value, INT16_SIZE); if (result != 0) { CloseHandle(hFileMapping); CloseHandle(hFile); fprintf(stderr, "File write error during iteration #%d, error %d", i, GetLastError()); return 1; } } // Read SetFilePointer(hFileMapping, 0, 0, FILE_BEGIN); for (int j = 0; j &lt; FILE_SIZE_MAX_LOWER_DW / sizeof(int); j++) { result = memcpy_s(&amp;value, INT16_SIZE, mapViewStartAddress + j * INT16_SIZE, INT16_SIZE); if (result != 0) { CloseHandle(hFileMapping); CloseHandle(hFile); fprintf(stderr, "File read error during iteration #%d, error %d", i, GetLastError()); return 1; } } } // End business stuff CloseHandle(hFileMapping); CloseHandle(hFile); return 0; } </code></pre>
    singulars
    1. This table or related slice is empty.
    1. POC++ using 7zip.dll
      singulars
      1. PTQuestion
    1. PTAnswer
    1. USmcmlxxxvi
    1. USmcmlxxxvi
    plurals
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. This table or related slice is empty.
 

Querying!

 
Guidance
A row detail

Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.

SQuiL has stopped working due to an internal error.

If you are curious you may find further information in the browser console, which is accessible through the devtools (F12).

Reload