Initial commit

p1-check/elf.h

@@ -0,0 +1,57 @@
+#ifndef __CS261_ELF__
+#define __CS261_ELF__
+
+#include <stdio.h>
+#include <stdint.h>
+
+/*
+   Mini-ELF file format (byte 0 = first byte of the file)
+   +----------------------------------------------+
+   | header (elf_hdr_t) - 16 bytes                |
+   +----------------------------------------------+
+   | program headers (elf_phdr_t) - 20 bytes each |
+   +----------------------------------------------+
+   | program segments - variable length of bytes  |
+   +----------------------------------------------+
+   | symbol table - each entry is 4 bytes each    |
+   +----------------------------------------------+
+   | string table - variable length of strings    |
+   +----------------------------------------------+
+
+   ELF header structure:
+   +----------------------------------------------------------------------------+
+   |  0   1  |  2   3  |  4   5  |  6   7  |  8   9  | 10  11  | 12  13  14  15 |
+   | version | entry   | phdr    | numphdr | symtab  | strtab  | magic number   |
+   +----------------------------------------------------------------------------+
+
+   Sample ELF header (all entries in hex, format is little endian):
+   +----------------------------------------------------------------------------+
+   |  01  00 |  00  01 |  10  00 |  02  00 |  58  00 |  70  00 | 45  4c  46  00 |
+   | version | entry   | phdr    | numphdr | symtab  | strtab  | magic number   |
+   +----------------------------------------------------------------------------+
+
+   version = 0x0001     entry = 0x0100      phdr = 0x0010     numphdr = 0x0002
+   symtab = 0x0058      strtab = 0x0070     magic = "ELF\0"
+
+   Interpretation:
+
+   This file was created under version 1 of this format. When the program is
+   loaded into memory, the instruct at address 0x100 (256) will be executed
+   first. The first program header (which indicates segments in this file)
+   starts at offset 0x10 (16) into the file, and there are 2 program headers
+   total. The symbol table starts at offset 0x58 (88) into this file, and the
+   string table starts at offset 0x70 (112). The magic number is the string
+   "ELF\0", stored in the elf_hdr_t format as a 4-byte integer 0x00464c45
+   (4607045) and is used for checking the validity of the header.
+*/
+typedef struct __attribute__((__packed__)) elf {
+    uint16_t e_version;     /* version should be 1 */
+    uint16_t e_entry;       /* entry point of program */
+    uint16_t e_phdr_start;  /* start of program headers */
+    uint16_t e_num_phdr;    /* number of program headers */
+    uint16_t e_symtab;      /* start of symbol table */
+    uint16_t e_strtab;      /* start of string table */
+    uint32_t magic;         /* ELF */
+} elf_hdr_t;
+
+#endif