--- /dev/null
+#include <assert.h>
+#include <stdlib.h>
+#include <sys/types.h>
+#include <libelf/gelf.h>
+#include <libelfu/libelfu.h>
+
+typedef enum Destsegment {
+ DS_UNKNOWN,
+ DS_TEXT,
+ DS_DATA,
+} Destsegment;
+
+
+static Destsegment destsegment(ElfuScn *ms)
+{
+ if (!(ms->shdr.sh_flags & SHF_ALLOC)) {
+ return DS_UNKNOWN;
+ }
+
+ if (!(ms->shdr.sh_flags & SHF_WRITE)
+ && (ms->shdr.sh_flags & SHF_EXECINSTR)) {
+ return DS_TEXT;
+ } else if ((ms->shdr.sh_flags & SHF_WRITE)
+ && !(ms->shdr.sh_flags & SHF_EXECINSTR)) {
+ return DS_DATA;
+ }
+
+ return DS_UNKNOWN;
+}
+
+
+
+static ElfuScn* insertSection(ElfuElf *me, ElfuElf *mrel, ElfuScn *ms)
+{
+ ElfuPhdr *mp;
+ ElfuPhdr *first = NULL;
+ ElfuPhdr *last = NULL;
+ ElfuScn *newscn = NULL;
+ ElfuPhdr *injAnchor;
+ int searchForCode = 0;
+
+ switch (destsegment(ms)) {
+ case DS_TEXT:
+ searchForCode = 1;
+ case DS_DATA:
+ newscn = elfu_mCloneScn(ms);
+ if (!newscn) {
+ return NULL;
+ }
+
+ /* Find first and last LOAD PHDRs. */
+ CIRCLEQ_FOREACH(mp, &me->phdrList, elem) {
+ if (mp->phdr.p_type != PT_LOAD) {
+ continue;
+ }
+
+ if (!first || mp->phdr.p_vaddr < first->phdr.p_vaddr) {
+ first = mp;
+ }
+ if (!last || mp->phdr.p_vaddr > last->phdr.p_vaddr) {
+ /* No need to check p_memsz as segments may not overlap in memory. */
+ last = mp;
+ }
+ }
+
+ if (searchForCode) {
+ if ((first->phdr.p_flags & PF_X) && !(first->phdr.p_flags & PF_W)) {
+ injAnchor = first;
+ } else if ((last->phdr.p_flags & PF_X) && !(last->phdr.p_flags & PF_W)) {
+ injAnchor = last;
+ } else {
+ injAnchor = NULL;
+ }
+ } else {
+ if ((first->phdr.p_flags & PF_W) && !(first->phdr.p_flags & PF_X)) {
+ injAnchor = first;
+ } else if ((last->phdr.p_flags & PF_W) && !(last->phdr.p_flags & PF_X)) {
+ injAnchor = last;
+ } else {
+ injAnchor = NULL;
+ }
+ }
+
+ if (!injAnchor) {
+ ELFU_WARN("insertSection: Could not find injection anchor.\n"
+ " It has to be the first or last segment in the memory image.\n");
+ } else {
+ GElf_Off injOffset;
+
+ /* If the anchor is first or last, insert before or after */
+ if (injAnchor == first) {
+ /* Find first section and inject before it */
+ ElfuScn *firstScn = elfu_mScnFirstInSegment(me, injAnchor);
+ if (!firstScn) {
+ ELFU_WARN("insertSection: mScnFirstInSegment failed.\n");
+
+ // TODO: Error handling
+ } else {
+ injOffset = firstScn->shdr.sh_offset;
+
+ /* Make space */
+ elfu_mInsertSpaceBefore(me, injOffset, ms->shdr.sh_size);
+
+ /* Update memory offset */
+ newscn->shdr.sh_addr = injAnchor->phdr.p_vaddr;
+
+ /* Insert into chain of sections */
+ elfu_mInsertScnInChainBefore(me, firstScn, newscn);
+ }
+ } else {
+ /* Find last section and inject after it */
+ ElfuScn *lastScn = elfu_mScnLastInSegment(me, injAnchor);
+ if (!lastScn) {
+ ELFU_WARN("insertSection: mScnLastInSegment failed.\n");
+
+ // TODO: Error handling
+ } else {
+ injOffset = lastScn->shdr.sh_offset + elfu_gScnSizeFile(&lastScn->shdr);
+
+ /* Expand NOBITS sections at injection site, if any. */
+ elfu_mExpandNobits(me, injOffset);
+
+ /* Recalculate injOffset in case we expanded a NOBITS section */
+ lastScn = elfu_mScnLastInSegment(me, injAnchor);
+ injOffset = lastScn->shdr.sh_offset + elfu_gScnSizeFile(&lastScn->shdr);
+
+ /* Make space */
+ elfu_mInsertSpaceAfter(me, injOffset, ms->shdr.sh_size);
+
+ /* Update memory offset */
+ newscn->shdr.sh_addr = injAnchor->phdr.p_vaddr + (injOffset - injAnchor->phdr.p_offset);
+
+ /* Insert into chain of sections */
+ elfu_mInsertScnInChainAfter(me, lastScn, newscn);
+ }
+ }
+
+ /* Update file offset in new section BEFORE we do anything else */
+ newscn->shdr.sh_offset = injOffset;
+
+ /* Inject name */
+ // TODO
+ newscn->shdr.sh_name = 0;
+
+ // TODO: Relocate
+
+ return newscn;
+ }
+ break;
+
+ case DS_UNKNOWN:
+ ELFU_WARN("insertSection: Don't know where to insert ' %s with flags %jd (type %d).\n",
+ elfu_mScnName(mrel, ms),
+ ms->shdr.sh_flags,
+ ms->shdr.sh_type);
+ default:
+ ELFU_WARN("insertSection: Skipping section %s with flags %jd (type %d).\n",
+ elfu_mScnName(mrel, ms),
+ ms->shdr.sh_flags,
+ ms->shdr.sh_type);
+ return NULL;
+ }
+
+ if (newscn) {
+ // TODO: Destroy newscn
+ }
+ return NULL;
+}
+
+
+
+void elfu_mReladd(ElfuElf *me, ElfuElf *mrel)
+{
+ ElfuScn *ms;
+
+ assert(me);
+ assert(mrel);
+
+
+ /* For each section in object file, guess how to insert it */
+ CIRCLEQ_FOREACH(ms, &mrel->scnList, elem) {
+ ElfuScn *newscn;
+
+ switch(ms->shdr.sh_type) {
+ case SHT_NULL: /* 0 */
+ continue;
+
+ case SHT_PROGBITS: /* 1 */
+ /* Find a place where it belongs and shove it in. */
+ newscn = insertSection(me, mrel, ms);
+ if (!newscn) {
+ ELFU_WARN("mReladd: Could not insert section %s (type %d), skipping.\n",
+ elfu_mScnName(mrel, ms),
+ ms->shdr.sh_type);
+ }
+ break;
+
+ case SHT_SYMTAB: /* 2 */
+ case SHT_DYNSYM: /* 11 */
+ /* Merge with the existing table. Take care of string tables also. */
+
+ case SHT_STRTAB: /* 3 */
+ /* May have to be merged with the existing string table for
+ * the symbol table. */
+
+ case SHT_RELA: /* 4 */
+ case SHT_REL: /* 9 */
+ /* Possibly append this in memory to the section model
+ * that it describes. */
+
+ case SHT_NOBITS: /* 8 */
+ /* Expand this to SHT_PROGBITS, then insert as such. */
+
+ case SHT_HASH: /* 5 */
+ case SHT_DYNAMIC: /* 6 */
+ case SHT_SHLIB: /* 10 */
+ case SHT_SYMTAB_SHNDX: /* 18 */
+
+ /* Don't care about the next ones yet. I've never seen
+ * them and they can be implemented when necessary. */
+ case SHT_NOTE: /* 7 */
+ case SHT_INIT_ARRAY: /* 14 */
+ case SHT_FINI_ARRAY: /* 15 */
+ case SHT_PREINIT_ARRAY: /* 16 */
+ case SHT_GROUP: /* 17 */
+ case SHT_NUM: /* 19 */
+ default:
+ ELFU_WARN("mReladd: Skipping section %s (type %d).\n",
+ elfu_mScnName(mrel, ms),
+ ms->shdr.sh_type);
+ }
+ }
+}
projects / centaur.git / blobdiff