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.gitignore

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+# Created by https://www.toptal.com/developers/gitignore/api/cmake,c
+# Edit at https://www.toptal.com/developers/gitignore?templates=cmake,c
+
+### C ###
+# Prerequisites
+*.d
+
+# Object files
+*.o
+*.ko
+*.obj
+*.elf
+
+# Linker output
+*.ilk
+*.map
+*.exp
+
+# Precompiled Headers
+*.gch
+*.pch
+
+# Libraries
+*.lib
+*.a
+*.la
+*.lo
+
+# Shared objects (inc. Windows DLLs)
+*.dll
+*.so
+*.so.*
+*.dylib
+
+# Executables
+*.exe
+*.out
+*.app
+*.i*86
+*.x86_64
+*.hex
+
+# Debug files
+*.dSYM/
+*.su
+*.idb
+*.pdb
+
+# Kernel Module Compile Results
+*.mod*
+*.cmd
+.tmp_versions/
+modules.order
+Module.symvers
+Mkfile.old
+dkms.conf
+
+### CMake ###
+CMakeLists.txt.user
+CMakeCache.txt
+CMakeFiles
+CMakeScripts
+Testing
+Makefile
+cmake_install.cmake
+install_manifest.txt
+compile_commands.json
+CTestTestfile.cmake
+_deps
+
+### CMake Patch ###
+# External projects
+*-prefix/
+
+# End of https://www.toptal.com/developers/gitignore/api/cmake,c

CMakeLists.txt

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+cmake_minimum_required(VERSION 3.5)
+
+project(patchelfcrc LANGUAGES C)
+
+find_package(PkgConfig REQUIRED)
+pkg_check_modules(ELF REQUIRED libelf)
+
+set (CFILES
+	main.c
+)
+
+add_executable(${PROJECT_NAME} ${CFILES})
+target_link_libraries(${PROJECT_NAME} ${ELF_LIBRARIES})
+target_link_directories(${PROJECT_NAME} PRIVATE ${ELF_LIBRARY_DIRS})
+target_include_directories(${PROJECT_NAME} PRIVATE ${ELF_INCLUDE_DIRS})
+
+
+
+

main.c

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+#include <stdio.h>
+#include <libelf.h>
+#include <argp.h>
+#include <stdbool.h>
+
+#define print_err(fmt, ...) fprintf(stderr, (fmt), ## __VA_ARGS__);
+#define print_debug(fmt, ...) do { \
+				if (verbose) { \
+					printf("[DBG] "fmt, ## __VA_ARGS__); \
+				} \
+				} while (0)
+
+enum granularity {
+	GRANULARITY_BYTE = 1,
+	GRANULARITY_16BIT,
+	GRANULARITY_32BIT,
+};
+
+struct command_line_options {
+	bool little_endian;
+	enum granularity granularity;
+};
+
+static error_t parse_opt(int key, char *arg, struct argp_state *state)
+{
+	struct command_line_options *args = (struct command_line_options *)state->input;
+	switch (key) {
+	case 'l':
+		args->little_endian = true;
+		break;
+	default:
+		return ARGP_ERR_UNKNOWN;
+	}
+}
+
+static int parse_cmdline_options(int *argc, char ***argv, struct command_line_options *cmd_opts)
+{
+	if (!argc || !argv)
+		return -1000;
+
+	static struct argp_option options[] = {
+		{"little-endian", 'l', 0, 0, "Memory image is little endian. Only relevant if granularity is greater than a single byte"},
+		/* Sentinel */
+		{NULL, 0, 0, 0, NULL}
+	};
+
+	static struct argp arg_parser = {
+		options,
+		parse_opt,
+		NULL,
+		NULL,
+		0, 0, 0
+	};
+
+	argp_parse(&arg_parser, *argc, *argv, 0, 0, cmd_opts);
+
+}
+
+int main(int argc, char **argv)
+{
+	bool verbose = true;
+	struct command_line_options cmd_opts;
+
+	cmd_opts.little_endian = false;
+	cmd_opts.granularity = GRANULARITY_BYTE;
+
+	parse_cmdline_options(&argc, &argv, &cmd_opts);
+
+	print_debug("Start CRC patching\n");
+	print_debug("Endianess: %s endian\n", (cmd_opts.little_endian ? "little" : "big"));
+
+	return 0;
+}