Implemented and tested ELF header structure.

2 files changed, 143 insertions, 0 deletions

diff --git a/elf/elf.h b/elf/elf.h
index feadf661..eaa0f0c8 100644
--- a/elf/elf.h
+++ b/elf/elf.h
@@ -3,4 +3,62 @@
 #ifndef ELF_H_
 #define ELF_H_
 
+// ELF data types
+typedef unsigned long 	Elf32_Addr;
+typedef unsigned short 	Elf32_Half;
+typedef unsigned long 	Elf32_Off;
+typedef long			Elf32_Sword;
+typedef unsigned long	Elf32_Word;
+
+// Size of the magic section
+#define EI_NIDENT  16
+
+// Object file types
+enum e_type_enum {
+	ET_NONE 	= 0, // No type
+	ET_REL		= 1, // Relocatable
+	ET_EXEC		= 2, // Executable
+	ET_DYN		= 3, // Shared object
+	ET_CORE		= 4, // Core
+};
+
+// Machine types
+enum e_machine_enum {
+	EM_NONE			= 0, // No machine
+	EM_M32			= 1, // AT&T WE 32100
+	EM_SPARC		= 2, // SPARC
+	EM_386			= 3, // Intel 80386
+	EM_68K			= 4, // Motorola 68000
+	EM_88K			= 5, // Motorola 88000
+	EM_860 			= 7, // Intel 80860
+	EM_MIPS			= 8, // MIPS RS3000 Big Endian
+	EM_MIPS_RS4_BE  = 10 // MIPS RS4000 Big Endian
+};
+
+// Object version
+enum e_version_enum {
+	EV_NONE			= 0, 	// Invalid version
+	EV_CURRENT		= 1		// Current version
+};
+
+// The ELF header
+typedef struct {
+	unsigned char 	e_ident[EI_NIDENT]; // Magic
+	Elf32_Half		e_type; 			// Object file type
+	Elf32_Half		e_machine; 			// Machine type
+	Elf32_Word		e_version;			// Object file version
+	Elf32_Addr		e_entry;			// Program entry point
+	Elf32_Off		e_phoff;			// Program Header Table (PHT) offset
+	Elf32_Off		e_shoff;			// Section Header Table (SHT) offset
+	Elf32_Word		e_flags;			// Processor specific flags
+	Elf32_Half		e_ehsize;			// ELF header size
+	Elf32_Half		e_phentsize;		// Size of an entry in PHT
+	Elf32_Half		e_phnum;			// Number of entries in PHT
+	Elf32_Half		e_shentsize;		// Size of an header in SHT
+	Elf32_Half		e_shnum;			// Number of entries in SHT
+	Elf32_Half		shstrndx;			// Section name string table index
+} Elf32_Ehdr;
+
+
+
 #endif /*ELF_H_*/
diff --git a/elf/elftest.c b/elf/elftest.c
index 10ef2308..154708d6 100644
--- a/elf/elftest.c
+++ b/elf/elftest.c
@@ -1,5 +1,90 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <sys/mman.h>
+#include <fcntl.h>
+#include <unistd.h>
+
 #include "elf.h"
 
+void print_usage() {
+	fprintf(stderr, "Usage:\n");
+	fprintf(stderr, "\telftest objfile\n");
+}
+
+void print_elf_info(const char *file_name) {
+	int elf_fd = open(file_name, O_RDONLY);
+	void *elf_addr = NULL;
+	Elf32_Ehdr *elf_header;
+	struct stat elf_stat;
+	int i;
+	
+	if (elf_fd < 0) {
+		perror("Could not open object file");
+		goto error;
+	}
+	
+	if (fstat(elf_fd, &elf_stat) < 0) {
+		perror("Could not get file information");
+		goto error;
+	}
+	
+	elf_addr = mmap(NULL, elf_stat.st_size, PROT_READ, MAP_PRIVATE, elf_fd, 0);
+	
+	if (elf_addr == NULL) {
+		perror("Could not map the file into memory");
+		goto error;
+	}
+	
+	elf_header = (Elf32_Ehdr*)elf_addr;
+	
+	printf("Magic:\t\t");
+	for (i=0; i < EI_NIDENT; i++) {
+		printf("%d ", elf_header->e_ident[i]);
+	}
+	printf("\n");
+	printf("Type:\t\t%u\n", elf_header->e_type);
+	printf("Machine:\t%u\n", elf_header->e_machine);
+	printf("Version:\t%lu\n", elf_header->e_version);
+	printf("Entry:\t\t0x%08lx\n", elf_header->e_entry);
+	printf("PHT Offset:\t0x%08lx\n", elf_header->e_phoff);
+	printf("SHT Offset:\t0x%08lx\n", elf_header->e_shoff);
+	printf("Flags:\t\t%lu\n", elf_header->e_flags);
+	printf("Header size:\t%u (Structure size: %u)\n", elf_header->e_ehsize,
+			sizeof(Elf32_Ehdr));
+	
+	
+	munmap(elf_addr, elf_stat.st_size);
+	close(elf_fd);
+	
+	return;
+	
+error:
+	if (elf_addr != NULL)
+		munmap(elf_addr, elf_stat.st_size);
+	
+	if (elf_fd >= 0)
+		close(elf_fd);
+	exit(2);
+}
+
 int main(int argc, char **argv) {
+	const char *file_name = NULL;
+	
+	// Skip program name
+	argc--;
+	argv++;
+	
+	if (argc != 1) {
+		print_usage();
+		return 1;
+	}
+	
+	file_name = argv[0];
+	
+	print_elf_info(file_name);
+	
 	return 0;
 }