Directories constructed as a tree in C

#include<stdio.h>
#include <string.h>
int main()
{
 /*The output file*/
FILE *fo;

/*The input file*/
FILE *fi;

/*The current character we are on*/
char c[2];
c[1]=0;

/*The array to build the word we are on*/
char *s=malloc(900000);

/* Opens the file for reading */
fi=fopen("d.txt","r");
c[0]=getc(fi);
/* While loop responsible for reading current character,
 creating the string of directories linked to that character
 , and placing the word at the end*/
while(c[0]!=EOF)
{
strcat(s,"lib\\");
/*While loop that checks the current char for a space or a newline*/
    while((c[0]!=' '&&c[0]!='\n'))
    {


       strcat(s,c);

    strcat(s,"\\");
 c[0]=getc(fi);
    }
    printf(s);
    /*Makes the directory following the string of characters (IE: Character would be c\h\a\r\a\c\t\e\r)*/
    mkdir(s);

    s=malloc(9000);
c[0]=getc(fi);

}


return 0;
}

The new problem that I am encountering is most likely due to my allocation of memory, as when I get to the printf statement that prints out the composed string, I get lib\a\a\r\d\v\a\r\k\% where the % sign represents any ascii character, selected at random(probably due to some data that was at the ending of the string). How do I fix this problem?

>>26
For all intents and purposes we can assume that both the file system will not get bogged down, and that our disk space will not fill up. This is running on an array of 6 3tb HDDs