Add shstrtab

1 files changed, 66 insertions, 79 deletions

diff --git a/write_elf.c b/write_elf.c
index 62b6cd3..adb11a8 100644
--- a/write_elf.c
+++ b/write_elf.c
@@ -1,18 +1,9 @@
-#include "instructions.h"
-#include "registers.h"
 #include <elf.h>
 #include <err.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 
-unsigned char some_opcodes[]  = {MOVDI(REG_EAX, 0x3c),
-                                 // 0xb8, 0x3c, 0x00, 0x00, 0x00,
-                                 MOVDI(REG_EDI, 0x41),
-                                 // 0xbf, 0x41, 0x00, 0x00, 0x00,
-                                 SYSCALL};
-unsigned int some_opcodes_len = sizeof(some_opcodes) / sizeof(some_opcodes[0]);
-
 int
 write_elf(char* restrict file, size_t opcodes_len, char* restrict opcodes) {
   int error                   = 0;
@@ -29,83 +20,70 @@ write_elf(char* restrict file, size_t opcodes_len, char* restrict opcodes) {
     //  .p_align  = 0x1000, /* Segment alignment */
     //},
     {
-     .p_type  = PT_LOAD,
-     .p_flags = PF_X | PF_R,
-     .p_offset =
-        sizeof(Elf64_Ehdr) + sizeof(Elf64_Phdr), /* Segment file offset */
-      .p_vaddr  = 0x400000 + sizeof(Elf64_Ehdr) +
-                  sizeof(Elf64_Phdr), /* Segment virtual address */
-      .p_paddr  = 0x400000 + sizeof(Elf64_Ehdr) +
-                  sizeof(Elf64_Phdr), /* Segment physical address */
-      .p_filesz = opcodes_len,        /* Segment size in file */
-      .p_memsz  = opcodes_len,        /* Segment size in memory */
-      .p_align  = 0x1,                /* Segment alignment */
+      .p_type   = PT_LOAD,
+      .p_flags  = PF_X | PF_R,
+      .p_offset = 0x1000,            /* Segment file offset */
+      .p_vaddr  = 0x400000 + 0x1000, /* Segment virtual address */
+      .p_paddr  = 0x400000 + 0x1000, /* Segment physical address */
+      .p_filesz = opcodes_len,       /* Segment size in file */
+      .p_memsz  = opcodes_len,       /* Segment size in memory */
+      .p_align  = 0x1,               /* Segment alignment */
     },
   };
 
-  Elf64_Shdr header_section[] = {
-    {
-     // .init
-     // Index in section header string table
-     .sh_name      = 0,
-     .sh_type      = 0,
-     .sh_flags     = 0,
-     .sh_addr      = 0,
-     .sh_offset    = 0,
-     .sh_size      = 0,
-     .sh_link      = 0,
-     .sh_info      = 0,
-     .sh_addralign = 0,
-     .sh_entsize   = 0,
-     },
+  unsigned char string_header_table[] = {0,   '.', 'i', 'n', 'i', 't',
+                                         0,   '.', 's', 'h', 's', 't',
+                                         'r', 't', 'a', 'b', 0};
+
+  Elf64_Shdr header_section[]         = {
+    {0}, // NULL
     {
-     // .init
-     // Index in section header string table
-     .sh_name   = 0,
-     .sh_type   = SHT_PROGBITS,
-     .sh_flags  = SHF_ALLOC | SHF_EXECINSTR,
-     .sh_addr   = 0x401000,
-     .sh_offset = 0x1000,
-     .sh_size   = opcodes_len,
-     /* todo: deps on type */
-     .sh_link = 0,
-     /* todo: deps on type */
-     .sh_info      = 0,
-     .sh_addralign = 4,
-     .sh_entsize   = 0,
-     },
+      // .init
+      // Index in section header string table
+      .sh_name   = 1,
+      .sh_type   = SHT_PROGBITS,
+      .sh_flags  = SHF_ALLOC | SHF_EXECINSTR,
+      .sh_addr   = 0x401000,
+      .sh_offset = 0x1000,
+      .sh_size   = opcodes_len,
+      /* todo: deps on type */
+      .sh_link = 0,
+      /* todo: deps on type */
+      .sh_info      = 0,
+      .sh_addralign = 4,
+      .sh_entsize   = 0,
+    },
     {
-     // .shstrtab Section Header String Table
-     // Index in section header string table
-     .sh_name   = 1,
-     .sh_type   = SHT_STRTAB,
-     .sh_flags  = 0,
-     .sh_addr   = 0x100,
-     .sh_offset = 0x2000,
-     .sh_size   = opcodes_len,
-     /* todo: deps on type */
-     .sh_link = 0,
-     /* todo: deps on type */
-     .sh_info      = 0,
-     .sh_addralign = 1,
-     .sh_entsize   = 0,
-     },
+      // .shstrtab Section Header String Table
+      // Index in section header string table
+      .sh_name   = 7,
+      .sh_type   = SHT_STRTAB,
+      .sh_flags  = 0,
+      .sh_addr   = 0x0,
+      .sh_offset = 0x2000,
+      .sh_size   = sizeof(string_header_table) / sizeof(string_header_table[0]),
+      /* todo: deps on type */
+      .sh_link = 0,
+      /* todo: deps on type */
+      .sh_info      = 0,
+      .sh_addralign = 1,
+      .sh_entsize   = 0,
+    },
   };
 
-  unsigned char string_header_table[] = {0, '.', 'i', 'n', 'i', 't', 0};
-
-  Elf64_Ehdr header                   = {
+  Elf64_Ehdr header = {
     // memset(&header, 0, sizeof(Elf64_Ehdr));
     .e_ident   = {ELFMAG0, ELFMAG1, ELFMAG2, ELFMAG3, ELFCLASS64, ELFDATA2LSB,
                   EV_CURRENT, ELFOSABI_SYSV},
     .e_type    = ET_EXEC,
     .e_machine = EM_X86_64,
     .e_version = EV_CURRENT,
-    .e_entry   = 0x400000 + sizeof(Elf64_Ehdr) +
-                 sizeof(Elf64_Phdr), // point to VIRTUAL address of _start
-    .e_phoff   = sizeof(Elf64_Ehdr)  /* Program header table offset */,
-    .e_shoff   = 0, //  sizeof(Elf64_Ehdr) + sizeof(header_program)  /* Section
-  // header table offset */,
+    // point to VIRTUAL address of _start
+    .e_entry = 0x400000 + 0x1000,
+    // Program header table offset
+    .e_phoff = sizeof(Elf64_Ehdr),
+    // Section header table offset
+    .e_shoff     = sizeof(Elf64_Ehdr) + sizeof(header_program),
     .e_flags     = 0,
     .e_ehsize    = sizeof(Elf64_Ehdr),
     .e_phentsize = sizeof(Elf64_Phdr),
@@ -115,11 +93,12 @@ write_elf(char* restrict file, size_t opcodes_len, char* restrict opcodes) {
     .e_shentsize = sizeof(header_section[0]),
     // If larger than SHN_LORESERVE, then set to 0 and store real number in
     // sh_size of first section header entry
-    .e_shnum = 0, //  sizeof(header_section) / sizeof(header_section[0]),
-    // If larger than SHN_LORESERVE, then set to SHN_XINDEX and store real index
-    // in
-    // sh_link of first section header entry
-    .e_shstrndx = 0,
+    .e_shnum = sizeof(header_section) / sizeof(header_section[0]),
+    // If larger than SHN_LORESERVE, then set to SHN_XINDEX and store real
+    // index
+    // in sh_link of first section header entry
+    // "Section Header string-table-index
+    .e_shstrndx = 2,
   };
 
   size_t bytes_written = 0;
@@ -128,11 +107,19 @@ write_elf(char* restrict file, size_t opcodes_len, char* restrict opcodes) {
   fwrite(&header, sizeof(Elf64_Ehdr), 1, fd);
   fwrite(&header_program, sizeof(Elf64_Phdr),
          sizeof(header_program) / sizeof(header_program[0]), fd);
-  // fseek(fd, 0x1000, SEEK_SET);
+  fwrite(&header_section, sizeof(Elf64_Shdr),
+         sizeof(header_section) / sizeof(header_section[0]), fd);
+
+  fseek(fd, 0x1000, SEEK_SET);
 
   do {
     bytes_written += fwrite(opcodes, sizeof(char), opcodes_len, fd);
   } while (bytes_written != opcodes_len);
+
+  fseek(fd, 0x2000, SEEK_SET);
+  fwrite(string_header_table, sizeof(char),
+         sizeof(string_header_table) / sizeof(string_header_table[0]), fd);
+
   error = fclose(fd);
   if (error) {
     err(EXIT_FAILURE, "no way");