Update ELF parser. Sectionr eading implemented

elfpatch.c

@@ -2,47 +2,136 @@
 #include <patchelfcrc/reporting.h>
 #include <unistd.h>
 #include <stdio.h>
+#include <stdlib.h>
 #include <string.h>
 #include <fcntl.h>
 #include <sys/stat.h>
+#include <libelf.h>
+#include <gelf.h>
+#include <linklist-lib/singly-linked-list.h>
+
+struct elf_section {
+	GElf_Shdr section_header;
+	Elf_Scn *scn;
+	char *name;
+};
+
+struct elfpatch {
+	uint32_t magic;
+	int fd;
+	Elf *elf;
+	GElf_Ehdr ehdr;
+	int class;
+	SlList *sections;
+};
+
+#define ELFPATCH_MAGIC 0x8545637Aul
+
+#define is_elfpatch_struct(x) ((x) && (x)->magic == (ELFPATCH_MAGIC))
+
+#define ret_if_ep_err(ep) do { \
+	if (!is_elfpatch_struct((ep))) { \
+	return; \
+	} \
+	} while(0)
+
+#define ret_val_if_ep_err(ep, val) do { \
+	if (!is_elfpatch_struct((ep))) { \
+	return (val); \
+	} \
+	} while(0)
 
 #define print_err(fmt, ...) fprintf(stderr, (fmt), ## __VA_ARGS__);
 
-int elf_patch_open(struct elfpatch *ep, const char *path)
+static void free_elf_section_element(struct elf_section *sec)
 {
-	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;
+	if (sec) {
+		free(sec->name);
+		free(sec);
 	}
-	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)
+static const char *section_type_to_str(Elf64_Word type)
+{
+	switch (type) {
+	case SHT_NULL:
+		return "NULL";
+	case SHT_PROGBITS:
+		return "PROGBITS";
+	case SHT_SYMTAB:
+		return "SYMTAB";
+	case SHT_STRTAB:
+		return "STRTAB";
+	case SHT_NOBITS:
+		return "NOBITS";
+	case SHT_ARM_EXIDX:
+		return "ARM_EXIDX";
+	case SHT_INIT_ARRAY:
+		return "INIT_ARRAY";
+	case SHT_FINI_ARRAY:
+		return "FINI_ARRAY";
+	default:
+		break;
+	}
+	return "unknown";
+}
+
+static SlList *elf_patch_get_sections(elfpatch_handle_t *ep)
+{
+	SlList *ret = NULL;
+	Elf_Scn *scn;
+	struct elf_section *sec;
+	char *name;
+	size_t shstrndx;
+
+	ret_val_if_ep_err(ep, NULL);
+
+	if (ep->sections)
+		sl_list_free_full(ret, (void (*)(void *))free_elf_section_element);
+	ep->sections = NULL;
+
+	if (elf_getshdrstrndx (ep->elf , &shstrndx) != 0) {
+		print_err("ELF error: %s\n", elf_errmsg(-1));
+		goto ret_free_section_list;
+	}
+
+	scn = NULL;
+	while ((scn = elf_nextscn(ep->elf, scn)) != NULL) {
+		sec = (struct elf_section *)calloc(1u, sizeof(struct elf_section));
+		sec->name = NULL;
+		sec->scn = scn;
+		ret = sl_list_append(ret, sec);
+		if (gelf_getshdr(scn, &sec->section_header) != &sec->section_header) {
+			print_err("Error reading section header: %s\n", elf_errmsg(-1));
+			goto ret_free_section_list;
+		}
+		name = elf_strptr(ep->elf, shstrndx, sec->section_header.sh_name);
+		if (name) {
+			print_debug("[SEC] [%s] %s | %zu bytes at 0x%x (File offset: 0x%x) \n",
+				    section_type_to_str(sec->section_header.sh_type),
+				    name, (size_t)sec->section_header.sh_size,
+				    sec->section_header.sh_addr,
+				    sec->section_header.sh_offset);
+			sec->name = strdup(name);
+		}
+	}
+
+	ep->sections = ret;
+
+	return ret;
+
+ret_free_section_list:
+	sl_list_free_full(ret, (void (*)(void *))free_elf_section_element);
+	ret = NULL;
+	return ret;
+}
+
+static int elf_patch_update_info(elfpatch_handle_t *ep)
 {
 	Elf_Kind ek;
 	const char *type_string = "unrecognized";
 
-	if (!ep || !ep->elf)
-		return;
+	ret_val_if_ep_err(ep, -1001);
 
 	ek = elf_kind(ep->elf);
 
@@ -58,10 +147,83 @@ void elf_patch_print_stats(const struct elfpatch *ep)
 		break;
 	}
 	print_debug("ELF File Type: %s\n", type_string);
+
+	if (ek != ELF_K_ELF)
+		return -1;
+
+	gelf_getehdr(ep->elf, &ep->ehdr);
+	ep->class = gelf_getclass(ep->elf);
+
+	switch (ep->class) {
+	case ELFCLASS32:
+		print_debug("ELF class: 32 bit\n");
+		break;
+	case ELFCLASS64:
+		print_debug("ELF class: 64 bit\n");
+		break;
+	default:
+		print_err("Unsupported ELF class: %d\n", ep->class);
+		return -1;
+	}
+
+	if (!elf_patch_get_sections(ep)) {
+		print_err("No sections in file.\n");
+		return -1;
+	}
+
+
+
+	return 0;
 }
 
-void elf_patch_close(struct elfpatch *ep)
+elfpatch_handle_t *elf_patch_open(const char *path)
 {
+	struct elfpatch *ep;
+
+	if (!path) {
+		print_err("Internal error while opeing ELF file. No path specified\n");
+		return NULL;
+	}
+
+	ep = (struct elfpatch *)calloc(1u, sizeof(struct elfpatch));
+	ep->magic = ELFPATCH_MAGIC;
+
+	ep->fd = open(path, O_RDWR, 0);
+	if (ep->fd < 0) {
+		print_err("Error opening file: %s\n", path);
+		goto free_struct;
+	}
+	ep->elf = elf_begin(ep->fd, ELF_C_RDWR, NULL);
+	if (!ep->elf) {
+		print_err("[LIBELF] %s\n", elf_errmsg(-1));
+		goto close_fd;
+	}
+
+	if (elf_patch_update_info(ep)) {
+		print_err("File malformatted. Cannot use for CRC patching\n");
+		goto close_elf;
+	}
+
+	return (elfpatch_handle_t *)ep;
+close_elf:
+	if (ep->elf) {
+		elf_end(ep->elf);
+		ep->elf = NULL;
+	}
+close_fd:
+	if (ep->fd > 0) {
+		close(ep->fd);
+	}
+free_struct:
+	free(ep);
+	ep = NULL;
+	return (elfpatch_handle_t *)ep;
+}
+
+void elf_patch_close_and_free(elfpatch_handle_t *ep)
+{
+	ret_if_ep_err(ep);
+
 	if (!ep)
 		return;
 	if (ep->elf)
@@ -70,6 +232,12 @@ void elf_patch_close(struct elfpatch *ep)
 	if (ep->fd > 0)
 		close(ep->fd);
 
+	if (ep->sections)
+		sl_list_free_full(ep->sections, (void (*)(void *))free_elf_section_element);
+	ep->sections = NULL;
+
 	ep->elf = NULL;
 	ep->fd = 0;
+
+	free(ep);
 }

include/patchelfcrc/elfpatch.h

@@ -1,17 +1,12 @@
 #ifndef _ELFPATCH_H_
 #define _ELFPATCH_H_
 
-#include <libelf.h>
+#include <stdint.h>
 
-struct elfpatch {
-    int fd;
-    Elf *elf;
-};
+typedef struct elfpatch elfpatch_handle_t;
 
-int elf_patch_open(struct elfpatch *ep, const char *path);
+elfpatch_handle_t *elf_patch_open(const char *path);
 
-void elf_patch_print_stats(const struct elfpatch *ep);
-
-void elf_patch_close(struct elfpatch *ep);
+void elf_patch_close_and_free(elfpatch_handle_t *ep);
 
 #endif /* _ELFPATCH_H_ */

include/patchelfcrc/reporting.h

@@ -1,10 +1,14 @@
 #ifndef _REPORTING_H_
 #define _REPORTING_H_
 
+#include <stdbool.h>
+
 #define print_err(fmt, ...) fprintf(stderr, (fmt), ## __VA_ARGS__);
 
 void print_debug(const char *fmt, ...);
 
 void reporting_enable_verbose(void);
 
+bool reporting_get_verbosity(void);
+
 #endif /* _REPORTING_H_ */

main.c

@@ -242,7 +242,7 @@ int main(int argc, char **argv)
 {
 	struct crc_calc crc;
 	struct command_line_options cmd_opts;
-	struct elfpatch ep;
+	elfpatch_handle_t *ep;
 
 	prepare_default_opts(&cmd_opts);
 	parse_cmdline_options(&argc, &argv, &cmd_opts);
@@ -275,11 +275,9 @@ int main(int argc, char **argv)
 	elf_version(EV_CURRENT);
 
 	/* Open the ELF file */
-	elf_patch_open(&ep, cmd_opts.elf_path);
+	ep = elf_patch_open(cmd_opts.elf_path);
 
-	elf_patch_print_stats(&ep);
-
-	elf_patch_close(&ep);
+	elf_patch_close_and_free(ep);
 
 	crc_destroy(&crc);
 free_cmds:

reporting.c

@@ -20,3 +20,8 @@ void reporting_enable_verbose(void)
 {
 	global_verbosity_state = true;
 }
+
+bool reporting_get_verbosity(void)
+{
+	return global_verbosity_state;
+}