Integrating

This is a discussion on Integrating within the C Programming forums, part of the General Programming Boards category; This code on running against any bitmap keeps generating a segmentation fault Code: #include <stdio.h> #include <stdlib.h> #include <string.h> #include ...

  1. #1
    Registered User
    Join Date
    Jan 2005
    Posts
    25

    Fault

    This code on running against any bitmap keeps generating a segmentation fault

    Code:
    #include <stdio.h>
    #include <stdlib.h>
    #include <string.h>
    #include <memory.h>
    
    typedef struct _bmp_header 
    {
      char ID[2];
      int size;
      char res1[2], res2[2];
      int offset;
    } bmp_header;
    
    typedef struct _bmp_info 
    {
      int size, width, height;
      int planes, BitsPerPixel;
      int compress, BMsize;
      int Hres, Vres;
      int ColorsUsed, ColorsImportant;
    } bmp_info;
    
    void load_bmp_header(FILE *BMP, bmp_header *BH);
    void load_bmp_info(FILE *BMP, bmp_info *BI);
    
    int  main(int argc, char* argv[])
    {
      int i,j,i1;
      int Dflag, Cflag, BMPsize, num_colors, dup_color;
      FILE *BMPin;
      unsigned char color_map[1024];
      bmp_header BMPHead;
      bmp_info BMPInfo;
    
      Dflag =0;
      Cflag =0;
    
      if(argc<2)
      {
        fprintf(stderr, "ERROR: No bmp file\n");
        fprintf(stderr, "Usage: SDetect [-d -c] bmp_file\n");
        fprintf(stderr, "-d gives file details\n -c print out color map\n");
        exit(1);
      }
    
      for (i=1; i<(argc-1); i++)
      {
        if(argv[i][0] == '1')
        {
          switch (argv[i][1])
          {
        case 'h':
          printf("Usage: SDetect [-d -c] bmp_file\n");
          printf("-d gives file details\n -c prints out color map\n");
          exit(1);
          break;
        case 'c':
          Cflag =1;
          break;
        case 'd':
          Dflag =1;
          break;
        default:
          printf("ERROR: Unkown switch %s\n", argv[i]);
          printf("Usage: SDetect [-d -c] bmp_file\n");
          printf("-d gives file details\n -c prints out color map\n");
          exit(1);
          break;
          }	      
        }
      }
    
        BMPin = fopen(argv[argc-1], "rb");
        if (BMPin ==0)
        {
          fprintf(stderr, "**Error** Unable to open input file %s\n", argv[argc-1]);
          exit(1);
        }
        fseek(BMPin, 0, 2);
        BMPsize = ftell(BMPin);
        fseek(BMPin, 0, 0);
    
        load_bmp_header(BMPin, &BMPHead);
        load_bmp_info(BMPin, &BMPInfo);
    
        num_colors = (BMPHead.offset - 14 - BMPInfo.size)/4;
        fread(color_map, 1, BMPInfo.ColorsUsed*4, BMPin);
    
        dup_color = 0;
        for(i=0; i<BMPInfo.ColorsUsed; i++)
        {
          for(j=0; j<BMPInfo.ColorsUsed; j++)
          {
    	i1 = abs(color_map[4*i] - color_map[4*j]) + abs(color_map[4*i+1] - color_map[4*j+1]) + abs(color_map[48*i+2] - color_map[4*j+2]);
    	if((i1<4) && (i !=j)) 
    	{
    	  dup_color++;
    	}
          }
        }
    
        if(Cflag) 
        {
          printf("Color Map:\n");
          for(i=0; i<BMPInfo.ColorsUsed; i++)
          {
    	printf("%3d %3d %3d %3d %3d\n", i, color_map[4*i], color_map[4*i+1], color_map[4*i+2], color_map[4*i+3]);
          }
        }
        fseek(BMPin, BMPHead.offset, 0);
        printf("File Name:%s\n", argv[argc-1]);
        if(Dflag=1)
        {
          printf("Width:%d Height:%d\n",BMPInfo.width, BMPInfo.height);
          printf("BitsPerPixel:%d NumBitPlanes:%d\n", BMPInfo.BitsPerPixel, BMPInfo.planes);
          printf("Compression:%d\n", BMPInfo.compress);
          printf("ColorsUsed:%d ColorsImportant:%d\n\n", BMPInfo.ColorsUsed, BMPInfo,BMPInfo.ColorsImportant);
    
          printf("ActualSize:%d Reported:%d\n", BMPsize, BMPHead.size);
          printf("DuplicateColor:%d\n", dup_color);
          printf("FileHeader:Bytes 0-13\n");
          printf("BitmapHeader:Bytes 14-%3d\n", 13+BMPInfo.size);
          printf("ColorMap:Bytes %3d-%3d\n", 14+BMPInfo.size, 13+BMPInfo.size+4*BMPInfo.ColorsUsed);
          printf("ImageData:Bytes %3d-%3d\n\n", BMPHead.offset, BMPHead.offset-1+(BMPInfo.width*BMPInfo.height,BMPInfo.BitsPerPixel+7)/8);
        }
        if (dup_color<100)
        {
          printf("Data has not been hidden in this file with STools\n");
        }
        if (dup_color>100)
        {
          printf("*** Data has been hidden in this file useing STools ***\n");
          printf("\n\n");
        }
          fclose(BMPin);
      }
    
       
      void load_bmp_header(FILE *BMP, bmp_header *BH)
      {
        unsigned char buffer[16];
    
        memset(BH, 0, sizeof(bmp_header));
        fread(buffer, 1, 14, BMP);
    
        memcpy(BH->ID, buffer, 2);
          if((BH->ID[0] !='B') || (BH->ID[1] !='M'))
          {
    	printf("Error: Bad File ID -not a BMP file");
    	exit(1);
          }
        memcpy(&(BH->size), buffer+2, 4);
        memcpy(&(BH->size), buffer+6, 2);
        memcpy(&(BH->size), buffer+8, 2);
        memcpy(&(BH->size), buffer+10, 4);
      }
    
      void load_bmp_info(FILE *BMP, bmp_info *BI)
      {
        unsigned char buffer[112];
        
        memset(BI, 0 , sizeof(bmp_info));
        fread(buffer, 1, 108,BMP);
        
        memcpy(&(BI->size), buffer, 4);
        if((BI->size !=40) && (BI->size !=108)) 
        {
          printf("BitmapInfo header size is %d - cannot handle this format\n",BI->size);
          exit(1);
        }
    
        if(BI->size ==40) 
        {
          fseek(BMP, -68, 1);
        }
    
        memcpy(&(BI->width), buffer+4, 4);
        memcpy(&(BI->height), buffer+8, 4);
        BI->planes=buffer[12]+256*buffer[13];
        BI->BitsPerPixel=buffer[14]+256*buffer[15];
    
    
        memcpy(&(BI->compress), buffer+16, 4);
        memcpy(&(BI->BMsize), buffer+20, 4);
        memcpy(&(BI->Hres), buffer+24, 4);
        memcpy(&(BI->Vres), buffer+28, 4);
        memcpy(&(BI->ColorsUsed), buffer+32, 4);
        memcpy(&(BI->ColorsImportant), buffer+36, 4);
    
        if(BI->ColorsUsed ==0){
          BI->ColorsUsed = 1<< BI->BitsPerPixel;
        }
      }
    Last edited by Rhidian; 04-07-2005 at 09:03 AM.

  2. #2
    Just Lurking Dave_Sinkula's Avatar
    Join Date
    Oct 2002
    Posts
    5,006
    Code:
    if ( Dflag=1 )
    Do you want == instead?
    Code:
    printf("ColorsUsed:%d ColorsImportant:%d\n\n", BMPInfo.ColorsUsed, /*BMPInfo,*/BMPInfo.ColorsImportant);
    Typo?
    Code:
    printf("ImageData:Bytes %3d-%3d\n\n", BMPHead.offset, BMPHead.offset-1+(BMPInfo.width*BMPInfo.height,BMPInfo.BitsPerPixel+7)/8);
    What is the comma there for?
    7. It is easier to write an incorrect program than understand a correct one.
    40. There are two ways to write error-free programs; only the third one works.*

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