1 files changed, 57 insertions, 0 deletions
diff --git a/src/loader/elf.c b/src/loader/elf.c
new file mode 100644
index 0000000..3f5aea3
--- /dev/null
+++ b/src/loader/elf.c
@@ -0,0 +1,57 @@
+// MIT License, Copyright (c) 2021 Marvin Borner
+
+#include <elf.h>
+#include <pnc.h>
+
+u32 elf_load(struct dev *dev, const char *path)
+{
+	assert(dev->type == DEV_DISK);
+
+	struct elf_header header = { 0 };
+	s32 rd = dev->p.disk.fs.read(path, &header, 0, sizeof(header), dev);
+	if (rd < 0)
+		panic("File couldn't be found\n");
+	if (rd != sizeof(header))
+		panic("File too small\n");
+
+	// Valid?
+	u8 *magic = header.ident;
+	u8 valid_magic = magic[ELF_IDENT_MAG0] == ELF_MAG0 && magic[ELF_IDENT_MAG1] == ELF_MAG1 &&
+			 magic[ELF_IDENT_MAG2] == ELF_MAG2 && magic[ELF_IDENT_MAG3] == ELF_MAG3 &&
+			 magic[ELF_IDENT_CLASS] == ELF_IDENT_CLASS_32 &&
+			 magic[ELF_IDENT_DATA] == ELF_IDENT_DATA_LSB;
+	if (!valid_magic || (header.type != ELF_ETYPE_REL && header.type != ELF_ETYPE_EXEC) ||
+	    header.version != 1 || header.machine != ELF_MACHINE_386)
+		panic("File is not valid ELF\n");
+
+	// Loop through programs
+	for (u32 i = 0; i < header.phnum; i++) {
+		struct elf_program program = { 0 };
+
+		if (dev->p.disk.fs.read(path, &program, header.phoff + header.phentsize * i,
+					sizeof(program), dev) != sizeof(program))
+			panic("Couldn't read program\n");
+
+		if (program.type == ELF_PROGRAM_TYPE_INTERP)
+			panic("Program interpreters aren't supported\n");
+
+		if (program.vaddr == 0 || program.type != ELF_PROGRAM_TYPE_LOAD)
+			continue;
+
+		if ((u32)dev->p.disk.fs.read(path, (void *)program.vaddr, program.offset,
+					     program.filesz, dev) != program.filesz)
+			panic("Couldn't load program\n");
+	}
+
+	// Find section string table
+	struct elf_section section_strings = { 0 };
+	if (dev->p.disk.fs.read(path, &section_strings,
+				header.shoff + header.shentsize * header.shstrndx,
+				sizeof(section_strings), dev) != sizeof(section_strings))
+		panic("Couldn't find string section\n");
+
+	if (section_strings.type != ELF_SECTION_TYPE_STRTAB)
+		panic("Invalid string section\n");
+
+	return header.entry;
+}