Sending file directory from one function to another - c

Question

In this programme I want to ask the user to enter the file path of the image, this takes place in the main function. However the open file takes place in another function.
To get the variable (location) to communicate between both functions, I declared it as a global variable, however, when the programme is executed no file path can be found.
Here is a snippet from the main function:
#define _CRT_SECURE_NO_DEPRECATE
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdint.h>
char * scale = "8Xoi?;`. ";
int numScale;
char * location;
typedef struct
{
size_t width;
size_t height;
unsigned char * data;
} image;
unsigned char luminanceFromRGB(unsigned char r, unsigned char g, unsigned char b)
{
return (unsigned char) (0.2126 * r + 0.7152 * g + 0.0722 * b);
}
//Loads image and saves it to img as an image pointer.
long loadImage(image ** img, char * location)
{
FILE *f = fopen(location, "rb");
if (f == NULL)
{
puts("Opening failed...");
return 0;
}
unsigned char * result;
fseek(f, 0, SEEK_END);
long size = ftell(f);
fseek(f, 0, SEEK_SET);
result = (unsigned char *) malloc((size_t) size);
if (size != fread(result, sizeof(unsigned char), (size_t) size, f))
{
free(result);
puts("Reading failed...");
fclose(f);
return 0;
}
fclose (f);
if (size < 54)
{
free(result);
puts("Invalid file...");
return 0;
}
size_t pdOffset = result[10] | result[11] << 8 | result[12] << 16 | result[13] << 24;
unsigned long width = result[18] | result[19] << 8 | result[20] << 16 | result[21] << 24;
unsigned long height = result[22] | result[23] << 8 | result[24] << 16 | result[25] << 24;
unsigned long bpp = result[28] | result[29] << 8;
int noCompression = result[30] == 0 && result[31] == 0 && result[32] == 0 && result[33] == 0;
if (bpp != 24 || !noCompression || width < 1 || height < 1 || width > 64000 || height > 64000)
{
free(result);
puts("Unsupported BMP format, only 24 bits per pixel are supported...");
return 0;
}
int bytesPerPixel = (int) (bpp / 8);
size_t rowBytes = (width * bytesPerPixel + 3) / 4 * 4;
printf("Bytes per row: %zu\n", rowBytes);
size_t usedRowBytes = width * bytesPerPixel;
size_t imageBytes = rowBytes * height;
*img = malloc(sizeof(image));
(*img)->height = height;
(*img)->width = width;
size_t imgSize = width * height;
(*img)->data = (unsigned char *) malloc(imgSize);
printf("Offset: %zu\n", pdOffset);
unsigned char * ptr = (*img)->data;
unsigned char * srcPtr = &result[pdOffset];
for (size_t i = 0; i < imgSize; ++i)
{
unsigned char r = *srcPtr;
unsigned char g = *(srcPtr + 1);
unsigned char b = *(srcPtr + 2);
*ptr = luminanceFromRGB(r, g, b);
ptr++;
srcPtr += bytesPerPixel;
if (i % width == 0)
{
srcPtr += rowBytes - usedRowBytes;
}
}
free(result);
return size;
}
//Assigns a ASCII character (scale) depending on the images brightness
void sprintchar(char *dst, image *img) {
for (size_t y = img->height - 1; y > 0; --y) {
for (size_t x = 0; x < img->width; ++x) {
unsigned char c = *(img->data + x + img->width * y);
int rescaled = c * numScale / 256;
*dst++ = scale[numScale - rescaled];
}
*dst++ = '\n';
}
*dst++ = 0;
}
void release(image * img)
{
if (img)
{
if (img->data)
free(img->data);
free(img);
}
}
int main(int argc, char ** argv)
{
char filepath [99];
printf("Enter file path: \n");
scanf_s("%s", &filepath);
location = filepath;
if (argc != 2)
{
puts("Argument needed: filename.");
return 1;
}
puts(argv[1]);
setbuf(stdout, 0);
numScale = strlen(scale) - 1;
printf("ASCII Brightness Scale: %d\n", numScale);
image *img = NULL;
if (loadImage(&img, argv[1]))
{
printf("Image dimensions: %zux%zu\n", img->width, img->height);
//Prints ASCII characters in terminal
char buf[1000000]; // 1M should be enough
sprintchar(buf, img);
//printf("%s", buf); // or whatever
release(img);
}
return 0;
}