Starting to write a little ELF Loader that is not working for now

.vscode/settings.json

@@ -23,5 +23,6 @@
         "paging.h": "c",
         "syscalls.h": "c",
         "ata.h": "c"
-    }
+    },
+    "C_Cpp.errorSquiggles": "disabled"
 }

apps/hello_asm/build.sh

@@ -0,0 +1,6 @@
+CC="gcc"
+ASM="nasm"
+LD="ld"
+
+$ASM -f elf32 main.asm -o main.o
+$LD -m elf_i386 main.o -o hello_asm

apps/hello_asm/main.asm

@@ -0,0 +1,17 @@
+section .data
+    hello db "Hello from assembler!", 10
+    hello_len equ $ - hello
+
+section .text
+    global _start
+
+_start:
+    mov eax, 4
+    mov ebx, 1
+    mov ecx, hello
+    mov edx, hello_len
+    int 0x80
+
+    mov eax, 1
+    mov ebx, 0
+    int 0x80

include/sys/elf.h

@@ -0,0 +1,138 @@
+#ifndef ELF_H
+#define ELF_H
+
+/* ELF Types */
+typedef unsigned short Elf32_Half;
+typedef unsigned short Elf64_Half;
+
+typedef unsigned int   Elf32_Word;
+typedef	int            Elf32_Sword;
+typedef unsigned int   Elf64_Word;
+typedef	int            Elf64_Sword;
+
+typedef unsigned long  Elf32_Xword;
+typedef	long           Elf32_Sxword;
+typedef unsigned long  Elf64_Xword;
+typedef	long           Elf64_Sxword;
+
+typedef unsigned int   Elf32_Addr;
+typedef unsigned long  Elf64_Addr;
+
+typedef unsigned int   Elf32_Off;
+typedef unsigned long  Elf64_Off;
+
+typedef unsigned short Elf32_Section;
+typedef unsigned short Elf64_Section;
+
+typedef Elf32_Half     Elf32_Versym;
+typedef Elf64_Half     Elf64_Versym;
+
+/* ELF Headers */
+
+#define EI_NIDENT (16)
+
+typedef struct __elf32_ehdr_t {
+  unsigned char	e_ident[EI_NIDENT];	/* Magic number and other info */
+  Elf32_Half	e_type;			          /* Object file type */
+  Elf32_Half	e_machine;		        /* Architecture */
+  Elf32_Word	e_version;		        /* Object file version */
+  Elf32_Addr	e_entry;		          /* Entry point virtual address */
+  Elf32_Off	  e_phoff;		          /* Program header table file offset */
+  Elf32_Off	  e_shoff;		          /* Section header table file offset */
+  Elf32_Word	e_flags;		          /* Processor-specific flags */
+  Elf32_Half	e_ehsize;		          /* ELF header size in bytes */
+  Elf32_Half	e_phentsize;		      /* Program header table entry size */
+  Elf32_Half	e_phnum;		          /* Program header table entry count */
+  Elf32_Half	e_shentsize;		      /* Section header table entry size */
+  Elf32_Half	e_shnum;		          /* Section header table entry count */
+  Elf32_Half	e_shstrndx;		        /* Section header string table index */
+} elf32_ehdr_t;
+
+
+/* Magic number */
+enum Elf_Ident {
+    EI_MAG0		= 0, // 0x7F
+    EI_MAG1		= 1, // 'E'
+    EI_MAG2		= 2, // 'L'
+    EI_MAG3		= 3, // 'F'
+    EI_CLASS	= 4, // Architecture (32/64)
+    EI_DATA		= 5, // Byte Order
+    EI_VERSION	= 6, // ELF Version
+    EI_OSABI	= 7, // OS Specific
+    EI_ABIVERSION	= 8, // OS Specific
+    EI_PAD		= 9  // Padding
+};
+
+#define ELFMAG0		0x7f    /* Magic number byte 0 */
+#define ELFMAG1		'E'		/* Magic number byte 1 */
+#define ELFMAG2		'L'		/* Magic number byte 2 */
+#define ELFMAG3		'F'		/* Magic number byte 3 */
+
+#define ELFCLASSNONE	0   /* Invalid class */
+#define ELFCLASS32	1		  /* 32-bit objects */
+#define ELFCLASS64	2		  /* 64-bit objects */
+#define ELFCLASSNUM	3
+
+#define ELFOSABI_NONE		0	/* UNIX System V ABI */
+#define ELFOSABI_SYSV		0	/* Alias.  */
+#define ELFOSABI_HPUX		1	/* HP-UX */
+#define ELFOSABI_NETBSD		2	/* NetBSD.  */
+#define ELFOSABI_GNU		3	/* Object uses GNU ELF extensions.  */
+#define ELFOSABI_LINUX		ELFOSABI_GNU /* Compatibility alias.  */
+#define ELFOSABI_SOLARIS	6	/* Sun Solaris.  */
+#define ELFOSABI_AIX		7	/* IBM AIX.  */
+#define ELFOSABI_IRIX		8	/* SGI Irix.  */
+#define ELFOSABI_FREEBSD	9	/* FreeBSD.  */
+#define ELFOSABI_TRU64		10	/* Compaq TRU64 UNIX.  */
+#define ELFOSABI_MODESTO	11	/* Novell Modesto.  */
+#define ELFOSABI_OPENBSD	12	/* OpenBSD.  */
+#define ELFOSABI_ARM_AEABI	64	/* ARM EABI */
+#define ELFOSABI_ARM		97	/* ARM */
+#define ELFOSABI_STANDALONE	255	/* Standalone (embedded) application */
+
+/* e_types values  */
+#define ET_NONE		0		    /* No file type */
+#define ET_REL		1		    /* Relocatable file */
+#define ET_EXEC		2		    /* Executable file */
+#define ET_DYN		3		    /* Shared object file */
+#define ET_CORE		4		    /* Core file */
+#define	ET_NUM		5		    /* Number of defined types */
+#define ET_LOOS		0xfe00		/* OS-specific range start */
+#define ET_HIOS		0xfeff		/* OS-specific range end */
+#define ET_LOPROC	0xff00		/* Processor-specific range start */
+#define ET_HIPROC	0xffff		/* Processor-specific range end */
+
+/* e_machine values (only 2 because we don't need all of them) */
+#define EM_NONE		 0	/* No machine */
+#define EM_386		 3	/* Intel 80386 */
+
+/* EI_DATA value in magic number */
+#define ELFDATA2LSB   1
+
+/* e_version value (only correct one that we support) */
+#define EV_CURRENT 1
+
+typedef struct __elf32_phdr_t {
+  Elf32_Word	p_type;			/* Segment type */
+  Elf32_Off	  p_offset;		/* Segment file offset */
+  Elf32_Addr	p_vaddr;		/* Segment virtual address */
+  Elf32_Addr	p_paddr;		/* Segment physical address */
+  Elf32_Word	p_filesz;		/* Segment size in file */
+  Elf32_Word	p_memsz;		/* Segment size in memory */
+  Elf32_Word	p_flags;		/* Segment flags */
+  Elf32_Word	p_align;		/* Segment alignment */
+} elf32_phdr_t;
+
+/* correct values of p_type */
+#define PT_LOAD 1
+
+#define INVALID_ELF  -1
+#define NCORRECT_ELF -2
+
+int load_elf(char* data, elf32_ehdr_t* header);
+
+int is_elf_correct(elf32_ehdr_t* header);
+
+int is_elf_magic(elf32_ehdr_t* header);
+
+#endif

include/sys/memory.h

@@ -31,6 +31,7 @@ void *krealloc(void *__address, int __nsize);
 
 void *kmemcpy(void *__dest, const void *__src, unsigned int __n);
 void *kmemset(void *__dest, char __c, unsigned int __n);
+void *memset(void *__dest, char __c, unsigned int __n);
 int   kmemcmp(char *m1, char *m2, int n);
 
 void kfree(void *__address);

kernel/memory.c

@@ -256,6 +256,18 @@ void *kmemset(void *__dest, char __c, unsigned int __n)
     return __dest;
 }
 
+void *memset(void *__dest, char __c, unsigned int __n)
+{
+    char *__tmp = __dest;
+
+    for (; __n != 0; __n--)
+    {
+        *__tmp++ = __c;
+    }
+
+    return __dest;
+}
+
 int kmemcmp(char *m1, char *m2, int n)
 {
     for (int i = 0; i < n; i++)

sys/elf.c

@@ -3,4 +3,68 @@
  *  - Solindek <[email protected]>
  */
 
-#include <sys/elf.h>
+#include <sys/elf.h>
+
+#include <quantum/init.h>
+#include <core/stdlib.h>
+
+int is_elf_magic(elf32_ehdr_t* header)
+{
+    if (!(header->e_ident[0] == ELFMAG0 && header->e_ident[1] == ELFMAG1 &&
+          header->e_ident[2] == ELFMAG2 && header->e_ident[3] == ELFMAG3)) 
+        return 0;
+}
+
+int is_elf_correct(elf32_ehdr_t* header)
+{
+    if (header->e_ident[EI_CLASS] != ELFCLASS32) {
+        quantum_info(1, " ELF    ", "Unsupported ELF File Class");
+		return 0;
+	}
+	else if (header->e_ident[EI_DATA] != ELFDATA2LSB) {
+        quantum_info(1, " ELF    ", "Unsupported ELF File byte order");
+		return 0;
+	}
+	else if (header->e_machine != EM_386) {
+        quantum_info(1, " ELF    ", "Unsupported ELF File target");
+		return 0;
+	}
+	else if (header->e_ident[EI_VERSION] != EV_CURRENT) {
+        quantum_info(1, " ELF    ", "Unsupported ELF File version");
+		return 0;
+	}
+	else if (header->e_type != ET_REL && header->e_type != ET_EXEC) {
+        quantum_info(1, " ELF    ", "Unsupported ELF File type");
+		return 0;
+	}
+}
+
+int load_elf(char* data, elf32_ehdr_t* header)
+{
+    header = (elf32_ehdr_t*)data;
+
+    if (!is_elf_magic(header))
+    {
+        quantum_info(1, " ELF    ", "This is not an ELF File");
+        return INVALID_ELF;
+    }
+
+    if (!is_elf_correct(header))
+    {
+        quantum_info(1, " ELF    ", "This is not an correct ELF File");
+        return NCORRECT_ELF;
+    }
+
+    quantum_info(0, " ELF    ", "Fully correct file");
+
+    // Load this program better please :)
+    for (int i = 0; i < header->e_phnum; i++) {
+        elf32_phdr_t* program_header;
+        program_header = (elf32_phdr_t*)(data + (header->e_phoff + (i * header->e_phentsize)));
+
+        if (program_header->p_type == PT_LOAD) {
+            unsigned char* mem = (unsigned char*)program_header->p_paddr;
+            kmemcpy(mem, data + program_header->p_offset, program_header->p_memsz);
+        }
+    }
+}