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macho_loader.c
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macho_loader.c
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/*
* Copyright 2013, winocm. <winocm@icloud.com>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without modification,
* are permitted provided that the following conditions are met:
*
* Redistributions of source code must retain the above copyright notice, this
* list of conditions and the following disclaimer.
*
* Redistributions in binary form must reproduce the above copyright notice, this
* list of conditions and the following disclaimer in the documentation and/or
* other materials provided with the distribution.
*
* If you are going to use this software in any form that does not involve
* releasing the source to this project or improving it, let me know beforehand.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR
* ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
* ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
/*
* Main guts of the Mach-O loader for Neo-BootX.
*/
#include "genboot.h"
#define add_ptr2(x, y) ((uintptr_t)((uintptr_t)x + (uintptr_t)y))
#define add_ptr3(x, y, z) ((uintptr_t)((uintptr_t)x + (uintptr_t)y + (uintptr_t)z))
#define for_each_lc(lcp, head) for (uint32_t XXi = 0; XXi < head->ncmds; XXi++, lcp = (struct load_command*)add_ptr2(lcp, lcp->cmdsize))
#define for_each_section(sect, seg) sect = (struct section*)((uintptr_t)seg + sizeof(struct segment_command)); \
for (uint32_t XXi = 0; XXi < seg->nsects; XXi++, sect++)
/**
* macho_initialize
*
* Initialize the basic loader context and verify that the file
* is indeed a Mach-O executable.
*/
loader_return_t macho_initialize(loader_context_t * ctx, void *file)
{
mach_header_t *header = (mach_header_t *) file;
/* We want to always perform this if a loader context is here. */
if ((!ctx) || (!file)) {
return kLoadInvalidParameter;
}
/* Verify the type of Mach-O we're about to load. */
if (header->magic != kMachMagic) {
return kLoadBadImage;
}
/* Only executables are supported. */
if (header->filetype != kMachExecute) {
return kLoadBadImage;
}
ctx->source = (uint8_t *) file;
return kLoadSuccess;
}
/**
* macho_set_vm_bias
*
* Set the virtual address bias for the specified context.
*/
loader_return_t macho_set_vm_bias(loader_context_t * ctx, uint32_t vmaddr)
{
if (!ctx) {
return kLoadInvalidParameter;
}
ctx->vm_bias = vmaddr;
return kLoadSuccess;
}
/**
* macho_get_entrypoint
*
* Get the address of the entrypoint for a specified context.
*/
loader_return_t macho_get_entrypoint(loader_context_t * ctx, uint32_t * ep)
{
if (!ctx || !ep) {
return kLoadInvalidParameter;
}
*ep = ctx->entry;
return kLoadSuccess;
}
/**
* macho_file_map
*
* Copy all of the mach-o segments to the proper addresses.
*/
loader_return_t macho_file_map(loader_context_t * ctx, uint32_t loadaddr)
{
mach_header_t *mh = (mach_header_t *) ctx->source;
struct load_command *lc = (struct load_command *)((mach_header_t *) mh + 1);
uint32_t vmsize_count = 0;
uint32_t vm_bias = ctx->vm_bias;
for_each_lc(lc, mh) {
/* Only segments for mapping */
if (lc->cmd == kLoadCommandSegment) {
struct segment_command *sc = (struct segment_command *)lc;
uint32_t our_vmaddr;
/* Add up the vm size */
vmsize_count += sc->vmsize;
/* Get the load address */
our_vmaddr = sc->vmaddr - vm_bias;
/* Map the binary now */
if (sc->filesize) {
bcopy((void *)
add_ptr2(ctx->source, sc->fileoff),
(void *)add_ptr2(loadaddr, our_vmaddr), sc->filesize);
}
} else if (lc->cmd == kLoadCommandUnixThread) {
/* UnixThread has the entrypoint. */
thread_command_t *tc = (thread_command_t *) lc;
ctx->entry = tc->state.pc;
}
}
return kLoadSuccess;
}
/**
* macho_get_vmsize
*
* Copy all of the mach-o segments to the proper addresses.
*/
uint32_t macho_get_vmsize(loader_context_t * ctx)
{
mach_header_t *mh = (mach_header_t *) ctx->source;
struct load_command *lc = (struct load_command *)((mach_header_t *) mh + 1);
uint32_t vmsize_count = 0;
for_each_lc(lc, mh) {
/* Only segments for mapping */
if (lc->cmd == kLoadCommandSegment) {
struct segment_command *sc = (struct segment_command *)lc;
vmsize_count += sc->vmsize;
}
}
return vmsize_count;
}