frep | Generate file using template from environment arguments | YAML Processing library

This question is split into 3 parts : 'The Idea', 'Assumptions' and 'Code MRE', so that you may help point my follies clearly, quickly and with least hassle, and also since, in descending order of frequency, most mistakes lie in the algorithm, the assumptions made during implementation and then in the actual code.

The Idea :

• Parse through file, at every blank space char (' ' or '\t' or '\n' or '\0', increment iand store the blank space char in an int arr EOW[i] (so that even \0 can be read).
• rewind FILE *. int q =1;
• for int q < i:
• fscanf() every word (word = sequence of chars seperated by blank space chars) and store to buffer[].
• if strcmp(buffer, target)==0 then strcpy(buffer, replacement).
• fprintf() buffer followed immediately by char at EOW[q] to temp file.
• remove original file and rename temp file.

Assumptions :

• fscanf(%s) will scan and store character until encountering ' ', '\t', '\n', and '\0' chars.
• char when stored to int arr is stored as its ASCII val, and element of int arr when stored to char is stored as its ASCII character.
• Usage & incrementation of counters i and q as well as usage for accessing array elements is correct, even if a tad bit twisted.

Code M.R.E :