From 13b621d944766f19db762c0fd79e359e824a5f83 Mon Sep 17 00:00:00 2001
From: norly <ny-git@enpas.org>
Date: Thu, 27 Jun 2013 03:20:54 +0100
Subject: [PATCH] Allocate .symtab during Reladd if none present

---
 include/libelfu/modelops.h    |  2 ++
 src/libelfu/model/section.c   | 24 +++++++++++++++++++
 src/libelfu/model/symtab.c    | 45 +++++++++++++++++++++++++++++++++++
 src/libelfu/modelops/reladd.c | 44 +++++++---------------------------
 4 files changed, 79 insertions(+), 36 deletions(-)

diff --git a/include/libelfu/modelops.h b/include/libelfu/modelops.h
index e9ea9ee..538e97a 100644
--- a/include/libelfu/modelops.h
+++ b/include/libelfu/modelops.h
@@ -15,6 +15,7 @@
  ElfuSym* elfu_mSymtabIndexToSym(ElfuScn *msst, GElf_Word entry);
 GElf_Addr elfu_mSymtabLookupAddrByName(ElfuElf *me, ElfuScn *msst, char *name);
      void elfu_mSymtabFlatten(ElfuElf *me);
+     void elfu_mSymtabAddGlobalDymtabIfNotPresent(ElfuElf *me);
 
 
 typedef void* (PhdrHandlerFunc)(ElfuElf *me, ElfuPhdr *mp, void *aux1, void *aux2);
@@ -39,6 +40,7 @@ typedef void* (SectionHandlerFunc)(ElfuElf *me, ElfuScn *ms, void *aux1, void *a
  ElfuScn* elfu_mScnByOldscn(ElfuElf *me, ElfuScn *oldscn);
     char* elfu_mScnName(ElfuElf *me, ElfuScn *ms);
 ElfuScn** elfu_mScnSortedByOffset(ElfuElf *me, size_t *count);
+      int elfu_mScnAppendData(ElfuScn *ms, void *buf, size_t len);
  ElfuScn* elfu_mScnAlloc();
      void elfu_mScnDestroy(ElfuScn* ms);
 
diff --git a/src/libelfu/model/section.c b/src/libelfu/model/section.c
index 9ef6fd8..74fbc3a 100644
--- a/src/libelfu/model/section.c
+++ b/src/libelfu/model/section.c
@@ -198,6 +198,30 @@ ElfuScn** elfu_mScnSortedByOffset(ElfuElf *me, size_t *count)
 
 
 
+int elfu_mScnAppendData(ElfuScn *ms, void *buf, size_t len)
+{
+  char *newbuf;
+
+  assert(ms);
+  assert(ms->shdr.sh_type != SHT_NOBITS);
+  assert(ms->databuf);
+
+  newbuf = realloc(ms->databuf, ms->shdr.sh_size + len);
+  if (!newbuf) {
+    ELFU_WARN("elfu_mScnAppendData: malloc() failed for newbuf.\n");
+    return -1;
+  }
+
+  ms->databuf = newbuf;
+  memcpy(newbuf + ms->shdr.sh_size, buf, len);
+  ms->shdr.sh_size += len;
+  assert(ms->shdr.sh_size == ms->shdr.sh_size);
+
+  return 0;
+}
+
+
+
 /*
  * Allocation, destruction
  */
diff --git a/src/libelfu/model/symtab.c b/src/libelfu/model/symtab.c
index 0cf107b..439c4d3 100644
--- a/src/libelfu/model/symtab.c
+++ b/src/libelfu/model/symtab.c
@@ -198,3 +198,48 @@ void elfu_mSymtabFlatten(ElfuElf *me)
 
   elfu_mLayoutAuto(me);
 }
+
+
+
+void elfu_mSymtabAddGlobalDymtabIfNotPresent(ElfuElf *me)
+{
+  assert(me);
+
+  if (!me->symtab) {
+    ElfuScn *symtab;
+    ElfuScn *strtab;
+
+    symtab = elfu_mScnAlloc();
+    assert(symtab);
+    strtab = elfu_mScnAlloc();
+    assert(strtab);
+
+    symtab->linkptr = strtab;
+    symtab->shdr.sh_entsize = me->elfclass == ELFCLASS32 ? sizeof(Elf32_Sym) : sizeof(Elf64_Sym);
+    symtab->shdr.sh_addralign = 4;
+    strtab->shdr.sh_addralign = 1;
+    symtab->shdr.sh_type = SHT_SYMTAB;
+    strtab->shdr.sh_type = SHT_STRTAB;
+
+    strtab->databuf = malloc(1);
+    assert(strtab->databuf);
+    strtab->databuf[0] = 0;
+
+    CIRCLEQ_INSERT_TAIL(&me->orphanScnList, symtab, elemChildScn);
+    CIRCLEQ_INSERT_TAIL(&me->orphanScnList, strtab, elemChildScn);
+
+    me->symtab = symtab;
+
+    if (me->shstrtab) {
+      symtab->shdr.sh_name = me->shstrtab->shdr.sh_size;
+      if (elfu_mScnAppendData(me->shstrtab, ".symtab", 8)) {
+        symtab->shdr.sh_name = 0;
+      }
+
+      strtab->shdr.sh_name = me->shstrtab->shdr.sh_size;
+      if (elfu_mScnAppendData(me->shstrtab, ".strtab", 8)) {
+        strtab->shdr.sh_name = 0;
+      }
+    }
+  }
+}
diff --git a/src/libelfu/modelops/reladd.c b/src/libelfu/modelops/reladd.c
index fc0adc3..1980c76 100644
--- a/src/libelfu/modelops/reladd.c
+++ b/src/libelfu/modelops/reladd.c
@@ -36,28 +36,6 @@ static ElfuScn* cloneScn(ElfuScn *ms)
 }
 
 
-static int appendData(ElfuScn *ms, void *buf, size_t len)
-{
-  char *newbuf;
-
-  assert(ms);
-  assert(ms->shdr.sh_type != SHT_NOBITS);
-  assert(ms->databuf);
-
-  newbuf = realloc(ms->databuf, ms->shdr.sh_size + len);
-  if (!newbuf) {
-    ELFU_WARN("appendData: malloc() failed for newbuf.\n");
-    return 1;
-  }
-
-  ms->databuf = newbuf;
-  memcpy(newbuf + ms->shdr.sh_size, buf, len);
-  ms->shdr.sh_size += len;
-  assert(ms->shdr.sh_size == ms->shdr.sh_size);
-
-  return 0;
-}
-
 
 static ElfuScn* insertSection(ElfuElf *me, ElfuElf *mrel, ElfuScn *oldscn)
 {
@@ -128,7 +106,6 @@ static ElfuScn* insertSection(ElfuElf *me, ElfuElf *mrel, ElfuScn *oldscn)
 
     /* Inject name */
     if (me->shstrtab) {
-      char *newname;
       size_t newnamelen;
 
       newnamelen = strlen("reladd") + 1;
@@ -136,21 +113,15 @@ static ElfuScn* insertSection(ElfuElf *me, ElfuElf *mrel, ElfuScn *oldscn)
         newnamelen += strlen(elfu_mScnName(mrel, oldscn));
       }
 
-      newname = malloc(newnamelen);
+      char newname[newnamelen];
+
       strcpy(newname, "reladd");
       strcat(newname, elfu_mScnName(mrel, oldscn));
 
-      if (!newname) {
-        ELFU_WARN("insertSection: malloc() failed for newname. Leaving section name empty.\n");
-        newscn->shdr.sh_name = 0;
-      } else {
-        size_t offset = me->shstrtab->shdr.sh_size;
-
-        if (!appendData(me->shstrtab, newname, newnamelen)) {
-          newscn->shdr.sh_name = offset;
-        }
+      newscn->shdr.sh_name = me->shstrtab->shdr.sh_size;
 
-        free(newname);
+      if (elfu_mScnAppendData(me->shstrtab, newname, newnamelen)) {
+        newscn->shdr.sh_name = 0;
       }
     }
 
@@ -262,8 +233,9 @@ static void insertSymClone(ElfuElf *me, const ElfuScn *oldmsst, const ElfuSym *o
     }
   }
 
-  // TODO: Allocate symtab if none present
-  assert(me->symtab);
+  /* If we don't have a symbol table, create one so we have somewhere to
+   * write our new symbols to. */
+  elfu_mSymtabAddGlobalDymtabIfNotPresent(me);
 
   /* Allocate memory for the cloned symbol */
   newsym = malloc(sizeof(*newsym));
-- 
2.30.2