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ULP filesize function caches values

Former Member

Can anyone make filesize return the size of the file given as its parameter? There seems to be a bug that returns the size of the previous call if the file doesn't exist. Here is some sample code that demonstrates this on my machine (7.5.0).

 

// Simple ULP to show flaw in filesize function

 

void displayFileSize(string fileName)

{

  string fSize = "";  // Initialize to empty string (size == 1?)

  fSize[0] = '\0';    // Strings are zero terminated; erase this way too!

  sprintf(fSize, "%d", filesize(fileName));

  dlgMessageBox("displayFileSize: " + fileName + "\tSize: " + fSize + ".");

}

 

void main(void)

{

  // Verify that filesize can return '0' when file doesn't exist

  // Result: displayFileSize: file.txt Size: 0.

  displayFileSize("file.txt");

 

  // Write a string to a file so it exists and has non-zero size

  output("file.txt", "wt")

  {

    printf("Here is some text to write.");

  }

 

  // Verify that this new file has a valid size

  // Result: displayFileSize: file.txt Size: 27.

  displayFileSize("file.txt");

 

  // Demonstrate that a file that doesn't exist 'has the same size' as the last

  // file that filesize() processed.

  // Result: displayFileSize: f_a_k_e__F_i_l_e.txt Size: 27.

  displayFileSize("f_a_k_e__F_i_l_e.txt");

}

Parents
  • 0

    A work around output a null file.

     

    // Write a null string to a file so it exists and has zero size

    output("null.txt", "wt")

      {

        printf("");

      }

    displayFileSize("null.txt");

     

    Then you should get the correct results.

    Clem

  • 0 in reply to clem57

    Thanks. That works inserted into my trivial example, but for my real code I need to call it a bunch, so I tried throwing the workaround into a function. The results are very interesting! During debugging I created two workaround functions identical other than their names. If I call the one defined first, it works. If I call the one defined second, the workaround doesn't work. Code:

    // Simple ULP to show flaw in filesize function

     

    // Set to zero to fail, non-zero to function correctly

    int correct = 0;

     

    void displayFileSize(string fileName)

    {

      string fSize = "";  // Initialize to empty string (size == 1?)

      fSize[0] = '\0';    // Strings are zero terminated; erase this way too!

      sprintf(fSize, "%d", filesize(fileName));

      dlgMessageBox("displayFileSize: " + fileName + "\tSize: " + fSize + ".\n"

        + fileerror());

    }

     

    void displayFileSize2(string fileName)

    {

      string fSize = "";  // Initialize to empty string (size == 1?)

      fSize[0] = '\0';    // Strings are zero terminated; erase this way too!

      sprintf(fSize, "%d", filesize(fileName));

      dlgMessageBox("displayFileSize: " + fileName + "\tSize: " + fSize + ".\n"

        + fileerror());

    }

     

    // Create a zero byte file to get the size of

    void workAround(void)

    {

      fileerror();

      output("null.txt", "wtD")

      {

        printf("");

      }

      if (fileerror())

      {

        exit(1);

      }

     

      if (correct)

      {

        displayFileSize("null.txt");

      }

      else

      {

        displayFileSize2("null.txt");

        //filesize("null.txt"); // Call filesize to try & make last return value 0

      }

      dlgMessageBox("Workaround finished.");

    }

     

    void main(void)

    {

      // Verify that filesize can return '0' when file doesn't exist

      // Result: displayFileSize: file.txt Size: 0.

      displayFileSize("file.txt");

     

      // Write a string to a file so it exists and has non-zero size

      fileerror();

      output("file.txt", "wtD")

      {

        printf("Here is some text to write.");

      }

     

      // Verify that this new file has a valid size

      // Result: displayFileSize: file.txt Size: 27.

      displayFileSize("file.txt");

     

      // Try and clear 'cache'

      workAround();

     

      // Demonstrate that a file that doesn't exist 'has the same size' as the last

      // file that filesize() processed.

      // Result: displayFileSize: f_a_k_e__F_i_l_e.txt Size: 27.

      displayFileSize("f_a_k_e__F_i_l_e.txt");

    }

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