C programming task Analyse pgmEcho.c to identify how it should be improved, then rewrite it so that it is more modular, more suitable for reuse, and properly defensive in terms of errors. Note that this should involve understanding the remaining tasks as well. Code Below: #include #include #define EXIT_NO_ERRORS 0 #define EXIT_WRONG_ARG_COUNT 1 #define EXIT_BAD_INPUT_FILE 2 #define EXIT_BAD_OUTPUT_FILE 3 #define MAGIC_NUMBER_RAW_PGM 0x3550 #define MAGIC_NUMBER_ASCII_PGM 0x3250 #define MIN_IMAGE_DIMENSION 1 #define MAX_IMAGE_DIMENSION 65536 #define MAX_COMMENT_LINE_LENGTH 128 int main(int argc, char **argv) {if (argc != 3) {printf("Usage: %s input_file output_file\n", argv[0]); return EXIT_WRONG_ARG_COUNT; } unsigned char magic_number[2] = {'0','0'}; unsigned short *magic_Number = (unsigned short *) magic_number; char *commentLine = NULL; unsigned int width = 0, height = 0; unsigned int maxGray = 255; unsigned char *imageData = NULL; FILE *inputFile = fopen(argv[1], "r"); if (inputFile == NULL) return EXIT_BAD_INPUT_FILE; magic_number[0] = getc(inputFile); magic_number[1] = getc(inputFile); if (*magic_Number != MAGIC_NUMBER_ASCII_PGM) { fclose(inputFile); printf("Error: Failed to read pgm image from file %s\n", argv[1]); return EXIT_BAD_INPUT_FILE; } int scanCount = fscanf(inputFile, " "); char nextChar = fgetc(inputFile); if (nextChar == '#') {commentLine = (char *) malloc(MAX_COMMENT_LINE_LENGTH); char *commentString = fgets(commentLine, MAX_COMMENT_LINE_LENGTH, inputFile); if (commentString == NULL) {free(commentLine); fclose(inputFile); printf("Error: Failed to read pgm image from file %s\n", argv[1]); return EXIT_BAD_INPUT_FILE; } }else { ungetc(nextChar, inputFile); } scanCount = fscanf(inputFile, " %u %u %u", &(width), &(height), &(maxGray)); if ( (scanCount != 3)|| (width < MIN_IMAGE_DIMENSION) || (width > MAX_IMAGE_DIMENSION) || (height < MIN_IMAGE_DIMENSION) || (height > MAX_IMAGE_DIMENSION) || (maxGray!= 255) ) { free(commentLine); fclose(inputFile); printf("Error: Failed to read pgm image from file %s\n", argv[1]); return EXIT_BAD_INPUT_FILE; } long nImageBytes = width * height * sizeof(unsigned char); imageData = (unsigned char *) malloc(nImageBytes); if (imageData == NULL) { free(commentLine); fclose(inputFile); printf("Error: Failed to read pgm image from file %s\n", argv[1]); return EXIT_BAD_INPUT_FILE; } for (unsigned char *nextGrayValue = imageData; nextGrayValue < imageData + nImageBytes; nextGrayValue++) {int grayValue = -1; int scanCount = fscanf(inputFile, " %u", &grayValue); if ((scanCount != 1) || (grayValue < 0) || (grayValue > 255)) { free(commentLine); free(imageData); fclose(inputFile); printf("Error: Failed to read pgm image from file %s\n", argv[1]); return EXIT_BAD_INPUT_FILE; } *nextGrayValue = (unsigned char) grayValue; } fclose(inputFile); FILE *outputFile = fopen(argv[2], "w"); if (outputFile == NULL) { free(commentLine); free(imageData); printf("Error: Failed to write pgm image to file %s\n", argv[2]); return EXIT_BAD_OUTPUT_FILE; } size_t nBytesWritten = fprintf(outputFile, "P2\n%d %d\n%d\n", width, height, maxGray); if (nBytesWritten < 0) { free(commentLine); free(imageData); printf("Error: Failed to write pgm image to file %s\n", argv[2]); return EXIT_BAD_OUTPUT_FILE; } for (unsigned char *nextGrayValue = imageData; nextGrayValue < imageData + nImageBytes; nextGrayValue++) { int nextCol = (nextGrayValue - imageData + 1) % width; nBytesWritten = fprintf(outputFile, "%d%c", *nextGrayValue, (nextCol ? ' ' : '\n') ); if (nBytesWritten < 0) {free(commentLine); free(imageData); printf("Error: Failed to write pgm image to file %s\n", argv[2]); return EXIT_BAD_OUTPUT_FILE; } } return EXIT_NO_ERRORS; } /* main() */
C programming task
Analyse pgmEcho.c to identify how it should be improved, then rewrite it so that it is more modular, more suitable for reuse, and properly defensive in terms of errors. Note that this should involve understanding the remaining tasks as well.
Code Below:
#include <stdio.h>
#include <stdlib.h>
#define EXIT_NO_ERRORS 0
#define EXIT_WRONG_ARG_COUNT 1
#define EXIT_BAD_INPUT_FILE 2
#define EXIT_BAD_OUTPUT_FILE 3
#define MAGIC_NUMBER_RAW_PGM 0x3550
#define MAGIC_NUMBER_ASCII_PGM 0x3250
#define MIN_IMAGE_DIMENSION 1
#define MAX_IMAGE_DIMENSION 65536
#define MAX_COMMENT_LINE_LENGTH 128
int main(int argc, char **argv)
{if (argc != 3)
{printf("Usage: %s input_file output_file\n", argv[0]);
return EXIT_WRONG_ARG_COUNT;
}
unsigned char magic_number[2] = {'0','0'};
unsigned short *magic_Number = (unsigned short *) magic_number;
char *commentLine = NULL;
unsigned int width = 0, height = 0;
unsigned int maxGray = 255;
unsigned char *imageData = NULL;
FILE *inputFile = fopen(argv[1], "r");
if (inputFile == NULL)
return EXIT_BAD_INPUT_FILE;
magic_number[0] = getc(inputFile);
magic_number[1] = getc(inputFile);
if (*magic_Number != MAGIC_NUMBER_ASCII_PGM)
{
fclose(inputFile);
printf("Error: Failed to read pgm image from file %s\n", argv[1]);
return EXIT_BAD_INPUT_FILE;
}
int scanCount = fscanf(inputFile, " ");
char nextChar = fgetc(inputFile);
if (nextChar == '#')
{commentLine = (char *) malloc(MAX_COMMENT_LINE_LENGTH);
char *commentString = fgets(commentLine, MAX_COMMENT_LINE_LENGTH, inputFile);
if (commentString == NULL)
{free(commentLine);
fclose(inputFile);
printf("Error: Failed to read pgm image from file %s\n", argv[1]);
return EXIT_BAD_INPUT_FILE;
}
}else
{
ungetc(nextChar, inputFile);
}
scanCount = fscanf(inputFile, " %u %u %u", &(width), &(height), &(maxGray));
if (
(scanCount != 3)||
(width < MIN_IMAGE_DIMENSION) ||
(width > MAX_IMAGE_DIMENSION) ||
(height < MIN_IMAGE_DIMENSION) ||
(height > MAX_IMAGE_DIMENSION) ||
(maxGray!= 255)
)
{
free(commentLine);
fclose(inputFile);
printf("Error: Failed to read pgm image from file %s\n", argv[1]);
return EXIT_BAD_INPUT_FILE;
}
long nImageBytes = width * height * sizeof(unsigned char);
imageData = (unsigned char *) malloc(nImageBytes);
if (imageData == NULL)
{
free(commentLine);
fclose(inputFile);
printf("Error: Failed to read pgm image from file %s\n", argv[1]);
return EXIT_BAD_INPUT_FILE;
}
for (unsigned char *nextGrayValue = imageData; nextGrayValue < imageData + nImageBytes; nextGrayValue++)
{int grayValue = -1;
int scanCount = fscanf(inputFile, " %u", &grayValue);
if ((scanCount != 1) || (grayValue < 0) || (grayValue > 255))
{
free(commentLine);
free(imageData);
fclose(inputFile);
printf("Error: Failed to read pgm image from file %s\n", argv[1]);
return EXIT_BAD_INPUT_FILE;
}
*nextGrayValue = (unsigned char) grayValue;
}
fclose(inputFile);
FILE *outputFile = fopen(argv[2], "w");
if (outputFile == NULL)
{
free(commentLine);
free(imageData);
printf("Error: Failed to write pgm image to file %s\n", argv[2]);
return EXIT_BAD_OUTPUT_FILE;
}
size_t nBytesWritten = fprintf(outputFile, "P2\n%d %d\n%d\n", width, height, maxGray);
if (nBytesWritten < 0)
{
free(commentLine);
free(imageData);
printf("Error: Failed to write pgm image to file %s\n", argv[2]);
return EXIT_BAD_OUTPUT_FILE;
}
for (unsigned char *nextGrayValue = imageData; nextGrayValue < imageData + nImageBytes; nextGrayValue++)
{
int nextCol = (nextGrayValue - imageData + 1) % width;
nBytesWritten = fprintf(outputFile, "%d%c", *nextGrayValue, (nextCol ? ' ' : '\n') );
if (nBytesWritten < 0)
{free(commentLine);
free(imageData);
printf("Error: Failed to write pgm image to file %s\n", argv[2]);
return EXIT_BAD_OUTPUT_FILE;
}
}
return EXIT_NO_ERRORS;
} /* main() */
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