1 files changed, 135 insertions, 0 deletions
diff --git a/mld/seg.c b/mld/seg.c
new file mode 100644
index 0000000..a720720
--- /dev/null
+++ b/mld/seg.c
@@ -0,0 +1,135 @@
+#include <merror.h>
+#include <melf.h>
+#include <elf.h>
+#include <sys/mman.h>
+
+#include "link.h"
+
+/**
+ * Read the phdr for this segment
+ */
+static int load_phdr(struct object *obj, struct segment *seg, size_t index)
+{
+	if (index >= obj->phdr_len) {
+		ERROR("phdr index [%d] out of bounds", index);
+		return M_ERROR;
+	}
+
+	seg->phdr = &obj->phdr[index];
+	seg->phdr_idx = index;
+	return M_SUCCESS;
+}
+
+/**
+ * Read the shdr for this segment
+ */
+static int load_shdr(struct object *obj, struct segment *seg, size_t index)
+{
+	bool found = false;
+
+	for (size_t i = 0; i < obj->shdr_len; i++) {
+		Elf32_Shdr *hdr = &obj->shdr[i];
+
+		// find shdr that matches  the offset in phdr
+		if (seg->phdr->p_offset != hdr->sh_offset)
+			continue;
+
+
+		// get name
+		uint32_t name = B32(hdr->sh_name);
+		if (name >= obj->shstrtab->len) {
+			ERROR("section name index [%d] out of bounds", name);
+			return M_ERROR;
+		}
+		seg->name = &obj->shstrtab->data[name];
+
+		// map bytes
+		uint32_t len = B32(hdr->sh_size);
+		uint32_t off = B32(hdr->sh_offset);
+		seg->bytes = (unsigned char *) (obj->mapped + off);
+
+		if (BOUND_CHK(obj, len, off)) {
+			ERROR("cannot map seg %s:%d", seg->name, index);
+			return M_ERROR;
+		}
+
+		found = true;
+		seg->shdr = hdr;
+		seg->shdr_idx = i;
+		break;
+	}
+
+	if (!found) {
+		ERROR("cannot find shdr for segment [%d]", index);
+		return M_ERROR;
+	}
+
+	return M_SUCCESS;
+}
+
+/**
+ * Read the relocation table for this segment (if one exists)
+ */
+static int load_reltab(struct object *obj, struct segment *seg)
+{
+	// default to none
+	seg->reltab.len = 0;
+
+	for (size_t i = 0; i < obj->shdr_len; i++) {
+		Elf32_Shdr *hdr = &obj->shdr[i];
+		uint32_t type = B32(hdr->sh_type);
+
+		if (type != SHT_REL && type != SHT_RELA)
+			continue;
+
+		if (B32(hdr->sh_info) != seg->shdr_idx)
+			continue;
+
+		uint32_t symtab_idx = B32(hdr->sh_link);
+		if (symtab_idx >= obj->shdr_len) {
+			ERROR("reltab [%d] symtab index [%d] out of bounds",
+				i, symtab_idx);
+			return M_ERROR;
+		}
+
+		struct symbol_table *symtab = &obj->symtabs[symtab_idx];
+		if (symtab->len < 1) {
+			ERROR("reltab [%d] symtab is empty or invalid", i);
+			return M_ERROR;
+		}
+
+		uint32_t len = B32(hdr->sh_size);
+		uint32_t off = B32(hdr->sh_offset);
+
+
+		seg->reltab.symtab = symtab;
+		seg->reltab.len = len;
+		seg->reltab.raw = obj->mapped + off;
+		seg->reltab.type = type;
+
+		if (BOUND_CHK(obj, len, off)) {
+			ERROR("cannot map reltab [%d] for %s",
+				i, seg->name);
+			return M_ERROR;
+		}
+
+		break;
+	}
+
+	return M_SUCCESS;
+}
+
+int segment_load(struct object *obj, struct segment *seg, size_t index)
+{
+
+	if (load_phdr(obj, seg, index))
+		return M_ERROR;
+
+	if (load_shdr(obj, seg, index))
+		return M_ERROR;
+
+	if (load_reltab(obj, seg))
+		return M_ERROR;
+
+	return M_SUCCESS;
+}