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/**
* The 15-410 kernel project.
* @name loader.c
*
* Functions for the loading
* of user programs from binary
* files should be written in
* this file. The function
* elf_load_helper() is provided
* for your use.
*/
/* --- Includes --- */
#include <elf_410.h>
#include <exec2obj.h>
#include <loader.h>
#include <malloc.h>
#include <stdio.h>
#include <string.h>
/* --- Local function prototypes --- */
/**
* Copies data from a file into a buffer.
*
* @param filename the name of the file to copy data from
* @param offset the location in the file to begin copying from
* @param size the number of bytes to be copied
* @param buf the buffer to copy the data into
*
* @return returns the number of bytes copied on succes; -1 on failure
*/
int getbytes(const char* filename, int offset, int size, char* buf) {
file_t* f = find_file(filename);
if (f == NULL || offset > f->execlen) {
return -1;
}
return read_file(f, offset, size, buf);
}
int read_file(file_t* f, int offset, int size, char* buf) {
int src_size = size;
if (f->execlen - offset < size) {
src_size = f->execlen - offset;
}
memcpy(buf, f->execbytes + offset, src_size);
return src_size;
}
file_t* find_file(const char* name) {
int i;
for (i = 0; i < exec2obj_userapp_count; i++) {
if (strcmp(name, exec2obj_userapp_TOC[i].execname) == 0) {
return &exec2obj_userapp_TOC[i];
}
}
return NULL;
}
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