Implement ELF file opening

CMakeLists.txt

@@ -10,6 +10,8 @@ set (CFILES
 	version.c
 	named_crcs.c
 	crc.c
+	elfpatch.c
+	reporting.c
 )
 
 set(GEN_HEADER_PATH "${CMAKE_CURRENT_BINARY_DIR}/include/generated")

elfpatch.c

@@ -0,0 +1,75 @@
+#include <patchelfcrc/elfpatch.h>
+#include <patchelfcrc/reporting.h>
+#include <unistd.h>
+#include <stdio.h>
+#include <string.h>
+#include <fcntl.h>
+#include <sys/stat.h>
+
+#define print_err(fmt, ...) fprintf(stderr, (fmt), ## __VA_ARGS__);
+
+int elf_patch_open(struct elfpatch *ep, const char *path)
+{
+	int fd;
+	Elf *elf;
+
+	if (!ep || !path)
+		return -1000;
+
+	memset(ep, 0, sizeof(struct elfpatch));
+
+	fd = open(path, O_RDWR, 0);
+	if (fd < 0) {
+		print_err("Error opening file: %s\n", path);
+		return -1;
+	}
+	elf = elf_begin(fd, ELF_C_RDWR, NULL);
+	if (!elf) {
+		close(fd);
+		print_err("[LIBELF] %s\n", elf_errmsg(-1));
+		return -1;
+	}
+
+	ep->fd = fd;
+	ep->elf = elf;
+
+	return 0;
+}
+
+void elf_patch_print_stats(const struct elfpatch *ep)
+{
+	Elf_Kind ek;
+	const char *type_string = "unrecognized";
+
+	if (!ep || !ep->elf)
+		return;
+
+	ek = elf_kind(ep->elf);
+
+	switch (ek) {
+	case ELF_K_AR:
+		type_string = "archive";
+		break;
+	case ELF_K_ELF:
+		type_string = "elf object";
+		break;
+	default:
+		/* Unrecognized is the default. Do nothing */
+		break;
+	}
+	print_debug("ELF File Type: %s\n", type_string);
+}
+
+void elf_patch_close(struct elfpatch *ep)
+{
+	if (!ep)
+		return;
+	if (ep->elf)
+		elf_end(ep->elf);
+
+	if (ep->fd > 0)
+		close(ep->fd);
+
+	ep->elf = NULL;
+	ep->fd = 0;
+}

include/patchelfcrc/elfpatch.h

@@ -0,0 +1,17 @@
+#ifndef _ELFPATCH_H_
+#define _ELFPATCH_H_
+
+#include <libelf.h>
+
+struct elfpatch {
+    int fd;
+    Elf *elf;
+};
+
+int elf_patch_open(struct elfpatch *ep, const char *path);
+
+void elf_patch_print_stats(const struct elfpatch *ep);
+
+void elf_patch_close(struct elfpatch *ep);
+
+#endif /* _ELFPATCH_H_ */

include/patchelfcrc/reporting.h

@@ -0,0 +1,10 @@
+#ifndef _REPORTING_H_
+#define _REPORTING_H_
+
+#define print_err(fmt, ...) fprintf(stderr, (fmt), ## __VA_ARGS__);
+
+void print_debug(const char *fmt, ...);
+
+void reporting_enable_verbose(void);
+
+#endif /* _REPORTING_H_ */

main.c

@@ -25,13 +25,8 @@
 #include <patchelfcrc/crc.h>
 #include <patchelfcrc/version.h>
 #include <linklist-lib/singly-linked-list.h>
-
-#define print_err(fmt, ...) fprintf(stderr, (fmt), ## __VA_ARGS__);
-#define print_debug(fmt, ...) do { \
-				if (verbose) { \
-					printf("[DBG] "fmt, ## __VA_ARGS__); \
-				} \
-				} while (0)
+#include <patchelfcrc/reporting.h>
+#include <patchelfcrc/elfpatch.h>
 
 const char *argp_program_bug_address = "<mario.huettel@linux.com>";
 
@@ -64,6 +59,7 @@ struct command_line_options {
 	uint32_t end_magic;
 	bool list;
 	SlList *section_list;
+	const char *elf_path;
 };
 
 static error_t parse_opt(int key, char *arg, struct argp_state *state)
@@ -117,6 +113,12 @@ static error_t parse_opt(int key, char *arg, struct argp_state *state)
 		else if  (!strcmp(arg, "word"))
 			args->granularity = GRANULARITY_32BIT;
 		break;
+	case ARGP_KEY_ARG:
+		if (state->arg_num >= 1)
+			argp_usage(state);
+		else
+			args->elf_path = arg;
+		break;
 	default:
 		return ARGP_ERR_UNKNOWN;
 	}
@@ -155,7 +157,7 @@ static int parse_cmdline_options(int *argc, char ***argv, struct command_line_op
 	static struct argp arg_parser = {
 		options,
 		parse_opt,
-		NULL,
+		"ELF",
 		NULL,
 		0, 0, 0
 	};
@@ -180,11 +182,11 @@ static void prepare_default_opts(struct command_line_options *opts)
 	opts->has_start_magic = false;
 	opts->list = false;
 	opts->section_list = NULL;
+	opts->elf_path = NULL;
 }
 
 static void print_verbose_start_info(const struct command_line_options *cmd_opts)
 {
-	bool verbose = cmd_opts->verbose;
 	int i;
 	SlList *list_iter;
 	const struct named_crc *predef_crc;
@@ -209,6 +211,10 @@ static void print_verbose_start_info(const struct command_line_options *cmd_opts
 		print_debug("CRC length: %d\n", crc_len_from_poly(cmd_opts->crc.polynomial));
 	}
 
+	if (cmd_opts->elf_path) {
+		print_debug("ELF file: %s\n", cmd_opts->elf_path);
+	}
+
 	if (cmd_opts->section_list) {
 		for (list_iter = cmd_opts->section_list, i = 1; list_iter; list_iter = sl_list_next(list_iter), i++) {
 			print_debug("Input section [%d]: \"%s\"\n", i, (const char *)list_iter->data);
@@ -234,28 +240,46 @@ static void free_cmd_args(struct command_line_options *opts)
 
 int main(int argc, char **argv)
 {
-	bool verbose;
 	struct crc_calc crc;
 	struct command_line_options cmd_opts;
+	struct elfpatch ep;
 
 	prepare_default_opts(&cmd_opts);
 	parse_cmdline_options(&argc, &argv, &cmd_opts);
 
-	verbose = cmd_opts.verbose || cmd_opts.dry_run;
+	if (cmd_opts.verbose || cmd_opts.dry_run)
+		reporting_enable_verbose();
 	print_verbose_start_info(&cmd_opts);
 
+	/* Check if file has been supplied */
+	if (!cmd_opts.elf_path) {
+		print_err("No ELF file specified. Exiting...\n");
+		return -1;
+	}
+
 	if (cmd_opts.list) {
 		list_predefined_crcs();
 		goto free_cmds;
 	}
 
+	/* Do error printing if using a reversed polynomial. It is not implemented yet! */
+	if (cmd_opts.crc.rev) {
+		print_err("Reversed polynomials are not supported yet\nExiting...\n");
+		goto free_cmds;
+	}
+
 	/* Build the CRC */
 	crc_init(&crc, &cmd_opts.crc);
 
-	/* Perform the check test */
-	crc_push_bytes(&crc, "123456789", 9u);
-	crc_finish_calc(&crc);
-	printf("CRC Check value: 0x%08x\n", crc_get_value(&crc));
+	/* Prepare libelf for use with the latest ELF version */
+	elf_version(EV_CURRENT);
+
+	/* Open the ELF file */
+	elf_patch_open(&ep, cmd_opts.elf_path);
+
+	elf_patch_print_stats(&ep);
+
+	elf_patch_close(&ep);
 
 	crc_destroy(&crc);
 free_cmds:

reporting.c

@@ -0,0 +1,22 @@
+#include <patchelfcrc/reporting.h>
+#include <stdarg.h>
+#include <stdio.h>
+#include <stdbool.h>
+
+static bool global_verbosity_state = false;
+
+void print_debug(const char *fmt, ...)
+{
+	va_list va;
+
+	if (global_verbosity_state) {
+		va_start(va, fmt);
+		(void)vprintf(fmt, va);
+		va_end(va);
+	}
+}
+
+void reporting_enable_verbose(void)
+{
+	global_verbosity_state = true;
+}