elf.c

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/*
# _____     ___ ____     ___ ____
#  ____|   |    ____|   |        | |____|
# |     ___|   |____ ___|    ____| |    \    PS2DEV Open Source Project.
#-----------------------------------------------------------------------
# (c) 2020 Francisco Javier Trujillo Mata <fjtrujy@gmail.com>
# Licenced under Academic Free License version 2.0
# Review ps2sdk README & LICENSE files for further details.
*/
 
#include <string.h>
#include <sifrpc.h>
#include <kernel.h>
#include <sys/stat.h>
#include <stdbool.h>
#include <malloc.h>
 
#include "elf.h"
 
// Loader ELF variables
extern u8 loader_elf[];
extern int size_loader_elf;
 
// ELF-loading stuff
#define ELF_MAGIC 0x464c457f
#define ELF_PT_LOAD 1
 
static bool file_exists(const char *filename) {
        struct stat   buffer;   
        return (stat (filename, &buffer) == 0);
}
 
int LoadELFFromFile(const char *filename, int argc, char *argv[])
{
        u8 *boot_elf;
        elf_header_t *eh;
        elf_pheader_t *eph;
        void *pdata;
        int i;
        int new_argc = argc + 1;
        
        // We need to check that the ELF file before continue
        if (!file_exists(filename)) {
                return -1; // ELF file doesn't exists
        }
        // ELF Exists
        char *new_argv[new_argc];
 
        new_argv[0] = (char *)filename;
        for (i = 0; i < argc; i++) {
                new_argv[i + 1] = argv[i];
        }
        
        /* NB: LOADER.ELF is embedded  */
        boot_elf = (u8 *)loader_elf;
        eh = (elf_header_t *)boot_elf;
        if (_lw((u32)&eh->ident) != ELF_MAGIC)
                asm volatile("break\n");
 
        eph = (elf_pheader_t *)(boot_elf + eh->phoff);
 
        /* Scan through the ELF's program headers and copy them into RAM, then zero out any non-loaded regions.  */
        for (i = 0; i < eh->phnum; i++) {
                if (eph[i].type != ELF_PT_LOAD)
                        continue;
 
                pdata = (void *)(boot_elf + eph[i].offset);
                memcpy(eph[i].vaddr, pdata, eph[i].filesz);
 
                if (eph[i].memsz > eph[i].filesz)
                        memset(eph[i].vaddr + eph[i].filesz, 0, eph[i].memsz - eph[i].filesz);
        }
 
        /* Let's go.  */
        SifExitRpc();
        FlushCache(0);
        FlushCache(2);
        
        return ExecPS2((void *)eh->entry, NULL, new_argc, new_argv);
}