Valgrind possibly lost message when checking for memory leaks - C

Question

I'm doing a course at the moment and one task is to create a program to resize 24 bit bitmap images by modifying some code they provide (which simply copies an image). The resizing itself was not a problem, but when I run a memory leak check with Valgrind I keep getting the message below. I can't for the life of me figure out where I'm going wrong and would appreciate some pointers (pun definitely intended) as to where the leak is, but nothing more.

Also, if you could let me know how good my code is, or ways I could improve at programming in general it would be greatly appreciated.

Here's my code:

#include <stdio.h>
#include <stdlib.h>

#include "bmp.h"

int main(int argc, char* argv[])
{
    // ensure proper usage
    if (argc != 4)
    {
        printf("Usage: ./copy n infile outfile\n");
        return 1;
    }

    // remember factor and filenames
    int n = atoi(argv[1]);
    char* infile = argv[2];
    char* outfile = argv[3];

    // check if scale factor is valid (i.e. between 1 and 100)
    if ((n < 1) || (n > 100))
    {
        printf("Invalid scale factor, enter value between 1 and 100 inclusive\n");
        return 2;
    }

    // open input file 
    FILE* inptr = fopen(infile, "r");
    if (inptr == NULL)
    {
        printf("Could not open %s.\n", infile);
        return 3;
    }

    // open output file
    FILE* outptr = fopen(outfile, "w");
    if (outptr == NULL)
    {
        fclose(inptr);
        fprintf(stderr, "Could not create %s.\n", outfile);
        return 4;
    }

    // read infile's BITMAPFILEHEADER
    BITMAPFILEHEADER bf;
    fread(&bf, sizeof(BITMAPFILEHEADER), 1, inptr);

    // read infile's BITMAPINFOHEADER
    BITMAPINFOHEADER bi;
    fread(&bi, sizeof(BITMAPINFOHEADER), 1, inptr);

    // create headers for outfile
    BITMAPFILEHEADER bfout = bf;
    BITMAPINFOHEADER biout = bi;

    // change output's header info w.r.t. n, the scale factor
    biout.biWidth *= n;
    biout.biHeight *= n;
    biout.biSizeImage *= n * n;
    bfout.bfSize = sizeof(BITMAPFILEHEADER) + 
                   sizeof(BITMAPINFOHEADER) + 
                   biout.biSizeImage;

    // ensure infile is (likely) a 24-bit uncompressed BMP 4.0
    if (bf.bfType != 0x4d42 || bf.bfOffBits != 54 || bi.biSize != 40 || 
        bi.biBitCount != 24 || bi.biCompression != 0)
    {
        fclose(outptr);
        fclose(inptr);
        fprintf(stderr, "Unsupported file format.\n");
        return 5;
    }

    // write outfile's BITMAPFILEHEADER
    fwrite(&bfout, sizeof(BITMAPFILEHEADER), 1, outptr);

    // write outfile's BITMAPINFOHEADER
    fwrite(&biout, sizeof(BITMAPINFOHEADER), 1, outptr);

    // determine padding for scanlines
    int paddingIn = (4 - (bi.biWidth * sizeof(RGBTRIPLE) % 4)) % 4;
    int paddingOut = (4 - (biout.biWidth * sizeof(RGBTRIPLE) % 4)) % 4;

    // iterate over infile's scanlines
    for (int i = 0, biHeight = abs(bi.biHeight); i < biHeight; i++)
    {
        //create buffer and set to row's pixels
        RGBTRIPLE* buffer = malloc(bi.biWidth * sizeof(RGBTRIPLE));
        fread(buffer, sizeof(RGBTRIPLE), bi.biWidth, inptr);

        // for each infile scanline, copy n times
        for (int j = 0; j < n; j++)
        {
            // iterate over pixels in scanline
            for (int k = 0; k < bi.biWidth; k++)
            {   
                // copy pixel n times
                for (int l = 0; l < n; l++)
                    fwrite(&buffer[k], sizeof(RGBTRIPLE), 1, outptr);

            }

            // then add padding to Outfile (if needed)
            for (int k = 0; k < paddingOut; k++)
                fputc(0x00, outptr);

        }

        // move past padding on infile
        fseek(inptr, paddingIn, SEEK_CUR);

        // free the buffer
        free(buffer);
    }

    // close infile
    fclose(inptr);

    // close outfile
    fclose(outptr);

    // that's all, folks
    return 0;
}

Answer 1

You are analysing resize , which is a binary executable on your system.

If you call a program without ./ in front of it, the shell will search for a program with this name in every directory which is entered in the PATH variable ( echo $PATH to see it), but not in the current directory.

You have to call your program with ./resize , so it will look in the . directory (your current directory) and will start your program.

The output Usage: resize [-u] [-c] [-s [rows cols]] does not match your code.