locs2.c

/**
 * Find starts of LaunchController::decideLaunchMode and
 * AccountList::anyAccountIsValid (for prism launcher 11.x)
 */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/stat.h>

#include <elf.h>

typedef struct Data {
	union {
		void *pointer;
		size_t offset;
	};
	size_t size;
} Data;

int read_file(const char *path, Data *info_out) {
	/**
	 * Read a file into a buffer
	 */
	
	FILE *f = fopen(path, "rb");
	
	if (!f) {
		return 0;
	}
	
	struct stat file_status;
	
	if (fstat(fileno(f), &file_status)) {
		fclose(f);
		return 0;
	}
	
	void *buffer = malloc(file_status.st_size);
	
	if (!buffer) {
		fclose(f);
		return 0;
	}
	
	if (fread(buffer, file_status.st_size, 1, f) != 1) {
		fclose(f);
		free(buffer);
		return 0;
	}
	
	info_out->pointer = buffer;
	info_out->size = file_status.st_size;
	
	return 1;
}

int main(int argc, char *argv[]) {
	if (argc < 2) {
		fprintf(stderr, "Usage: %s <elf file>\n", argv[0]);
		return 127;
	}
	
	Data elf_data;
	
	if (!read_file(argv[1], &elf_data)) {
		fprintf(stderr, "Could not load file %s\n", argv[1]);
		return 1;
	}
	
	// Main ELF header
	Elf64_Ehdr *header = elf_data.pointer;
	
	// Section headers
	Elf64_Shdr *shdrs = elf_data.pointer + header->e_shoff;
	
	// String table location
	const char *shstrtab = elf_data.pointer + shdrs[header->e_shstrndx].sh_offset;
	
	// Let's find the symbol table
	Elf64_Sym *symbols = NULL;
	size_t num_symbols = 0;
	
	const char *strtab = NULL;
	
	for (size_t i = 0; i < header->e_shnum; i++) {
		if (!strcmp(shstrtab + shdrs[i].sh_name, ".symtab")) {
			symbols = elf_data.pointer + shdrs[i].sh_offset;
			num_symbols = shdrs[i].sh_size / shdrs[i].sh_entsize;
		}
		else if (!strcmp(shstrtab + shdrs[i].sh_name, ".strtab")) {
			strtab = elf_data.pointer + shdrs[i].sh_offset;
		}
	}
	
	if (!symbols) {
		fprintf(stderr, "Could not find .symtab section\n");
		return 1;
	}
	
	// print symbol names
	for (size_t i = 0; i < num_symbols; i++) {
		const char *name = strtab + symbols[i].st_name;
		Elf64_Shdr *section = &shdrs[symbols[i].st_shndx];
		
		if ((  (strstr(name, "AccountList") && strstr(name, "anyAccountIsValid"))
			|| (strstr(name, "LaunchController") && strstr(name, "decideLaunchMode")))
			&& (!strstr(name, ".cold"))) {
			printf("[%zu] name=%s shndx=%d value=%p\n", i, name, symbols[i].st_shndx, symbols[i].st_value);
		}
	}
	
	return 0;
}