Implement ELF loading ; arrange so that user processes run.

2 files changed, 78 insertions, 0 deletions

diff --git a/src/kernel/user/elf.c b/src/kernel/user/elf.c
new file mode 100644
index 0000000..905577d
--- /dev/null
+++ b/src/kernel/user/elf.c
@@ -0,0 +1,70 @@
+#include <string.h>
+
+#include <elf.h>
+
+
+bool is_elf(fs_handle_t *f) {
+	elf_ehdr_t h;
+	if (file_read(f, 0, sizeof(elf_ehdr_t), (char*)&h) != sizeof(elf_ehdr_t)) return false;
+
+	return (h.e_ident[0] == 0x7F && h.e_ident[1] == 'E'
+		  && h.e_ident[2] == 'L' && h.e_ident[3] == 'F');
+}
+
+proc_entry_t elf_load(fs_handle_t *f, process_t* process) {
+	if (!is_elf(f)) return 0;
+
+	elf_ehdr_t ehdr;
+	if (file_read(f, 0, sizeof(elf_ehdr_t), (char*)&ehdr) != sizeof(elf_ehdr_t)) return 0;
+
+	elf_phdr_t phdr;
+	int i;
+
+	pagedir_t *r = get_current_pagedir();
+	switch_pagedir(proc_pagedir(process));
+
+	// TODO : when we fail, free ressources ?
+
+	for (i = 0; i < ehdr.e_phnum; i++) {
+		size_t read_phdr_r = 
+			file_read(f,
+					ehdr.e_phoff + i * sizeof(elf_phdr_t),
+					sizeof(elf_phdr_t),
+					(char*)&phdr);
+		if (read_phdr_r != sizeof(elf_phdr_t)) goto error;
+
+		if (phdr.p_type == PT_LOAD) {
+			if (phdr.p_flags & PF_W) {
+				mmap(process, (void*)phdr.p_vaddr, phdr.p_memsz,
+						((phdr.p_flags & PF_R) ? MM_READ : 0) | MM_WRITE);
+
+				size_t read_r = file_read(f, phdr.p_offset, phdr.p_filesz, (char*)phdr.p_vaddr);
+				if (read_r != phdr.p_filesz) goto error;
+
+				if (phdr.p_memsz > phdr.p_filesz) {
+					memset((char*)phdr.p_vaddr + phdr.p_filesz, 0, phdr.p_memsz - phdr.p_filesz);
+				}
+			} else {
+				if (phdr.p_filesz != phdr.p_memsz) {
+					dbg_printf("Strange ELF file...\n");
+					goto error;
+				}
+
+				mmap_file(process,
+						f, phdr.p_offset,
+						(void*)phdr.p_vaddr, phdr.p_memsz,
+						((phdr.p_flags & PF_R) ? MM_READ : 0) | ((phdr.p_flags & PF_X) ? MM_EXEC : 0));
+			}
+		}
+	}
+
+	switch_pagedir(r);
+
+	return (proc_entry_t)ehdr.e_entry;
+
+error:
+	switch_pagedir(r);
+	return 0;
+}
+
+/* vim: set ts=4 sw=4 tw=0 noet :*/
diff --git a/src/kernel/user/process.c b/src/kernel/user/process.c
index b8b0c23..0f4892d 100644
--- a/src/kernel/user/process.c
+++ b/src/kernel/user/process.c
@@ -114,6 +114,10 @@ bool start_process(process_t *p, void* entry) {
 	return true;
 }
 
+pagedir_t *proc_pagedir(process_t *p) {
+	return p->pd;
+}
+
 // ================================== //
 // MANAGING FILESYSTEMS FOR PROCESSES //
 // ================================== //
@@ -224,6 +228,10 @@ bool munmap(process_t *proc, void* addr) {
 		}
 	}
 
+	// TODO : write modified pages back to file!
+
+	if (r->file != 0) unref_file(r->file);
+
 	free(r);
 
 	return true;