From 147edc30e5afb3fa0b17727fde972a0c1a9b275f Mon Sep 17 00:00:00 2001
From: norly <ny-git@enpas.org>
Date: Mon, 27 May 2013 04:57:46 +0100
Subject: Abstract model more - break 'make check'

Sections are now sorted by file offset and sh_link dependencies between
them as well as PHDR-SHDR dependencies are deduced as much as possible.

The downside is that while the output should still work just fine, 'make
check' fails to establish binary equivalence of input and output if the
section table is reordered. Thankfully, in normal GCC binaries it is
already ordered so we don't have to worry about this.

Unfortunately the ELF spec is very lax in this regard so we have to draw
a line ourselves.
---
 src/model/fromFile.c | 114 ++++++++++++++++++++++++++++++++++++++++++++-------
 1 file changed, 99 insertions(+), 15 deletions(-)

(limited to 'src/model/fromFile.c')

diff --git a/src/model/fromFile.c b/src/model/fromFile.c
index bcdb91a..125ea77 100644
--- a/src/model/fromFile.c
+++ b/src/model/fromFile.c
@@ -7,6 +7,51 @@
 #include <libelfu/libelfu.h>
 
 
+static int cmpScnOffs(const void *ms1, const void *ms2)
+{
+  assert(ms1);
+  assert(ms2);
+
+  ElfuScn *s1 = *(ElfuScn**)ms1;
+  ElfuScn *s2 = *(ElfuScn**)ms2;
+
+  assert(s1);
+  assert(s2);
+
+
+  if (s1->shdr.sh_offset < s2->shdr.sh_offset) {
+    return -1;
+  } else if (s1->shdr.sh_offset == s2->shdr.sh_offset) {
+    return 0;
+  } else /* if (s1->shdr.sh_offset > s2->shdr.sh_offset) */ {
+    return 1;
+  }
+}
+
+
+
+static ElfuPhdr* parentPhdr(ElfuElf *me, ElfuScn *ms)
+{
+  ElfuPhdr *mp;
+
+  assert(me);
+  assert(ms);
+
+  CIRCLEQ_FOREACH(mp, &me->phdrList, elem) {
+    if (ms->shdr.sh_addr >= mp->phdr.p_vaddr
+        && OFFS_END(ms->shdr.sh_addr, ms->shdr.sh_size) <= OFFS_END(mp->phdr.p_vaddr, mp->phdr.p_memsz)) {
+      return mp;
+    } else if (ms->shdr.sh_offset >= mp->phdr.p_offset
+               && OFFS_END(ms->shdr.sh_offset, SCNFILESIZE(&ms->shdr)) <= OFFS_END(mp->phdr.p_offset, mp->phdr.p_filesz)
+               && OFFS_END(ms->shdr.sh_offset, ms->shdr.sh_size) <= OFFS_END(mp->phdr.p_offset, mp->phdr.p_memsz)) {
+      return mp;
+    }
+  }
+
+  return NULL;
+}
+
+
 static ElfuPhdr* modelFromPhdr(GElf_Phdr *phdr)
 {
   ElfuPhdr *mp;
@@ -21,6 +66,8 @@ static ElfuPhdr* modelFromPhdr(GElf_Phdr *phdr)
 
   mp->phdr = *phdr;
 
+  CIRCLEQ_INIT(&mp->phdrToScnList);
+
   return mp;
 }
 
@@ -77,6 +124,8 @@ static ElfuScn* modelFromSection(Elf_Scn *scn)
     }
   }
 
+  ms->link = NULL;
+
 
   return ms;
 
@@ -95,6 +144,7 @@ ElfuElf* elfu_mFromElf(Elf *e)
   ElfuElf *me;
   size_t shstrndx;
   size_t i, numPhdr, numShdr;
+  ElfuScn **secArray = NULL;
 
   assert(e);
   if (elfu_eCheck(e)) {
@@ -143,39 +193,73 @@ ElfuElf* elfu_mFromElf(Elf *e)
 
   /* Load sections */
   assert(!elf_getshdrnum(e, &numShdr));
-  for (i = 1; i < numShdr; i++) {
-    Elf_Scn *scn;
-    ElfuScn *ms;
+  if (numShdr > 1) {
+    secArray = malloc((numShdr - 1) * sizeof(*secArray));
+    if (!secArray) {
+      ELFU_WARN("elfu_mFromElf: malloc() failed for secArray.\n");
+      goto ERROR;
+    }
 
-    scn = elf_getscn(e, i);
-    assert(scn);
+    for (i = 1; i < numShdr; i++) {
+      Elf_Scn *scn;
+      ElfuScn *ms;
 
-    ms = modelFromSection(scn);
-    if (!ms) {
-      goto ERROR;
+      scn = elf_getscn(e, i);
+      assert(scn);
+
+      ms = modelFromSection(scn);
+      if (!ms) {
+        goto ERROR;
+      }
+
+      secArray[i-1] =  ms;
+
+      if (i == shstrndx) {
+        me->shstrtab = ms;
+      }
     }
 
-    CIRCLEQ_INSERT_TAIL(&me->scnList, ms, elem);
-    if (i == shstrndx) {
-      me->shstrtab = ms;
+
+    /* Find sh_link dependencies */
+    for (i = 0; i < numShdr - 1; i++) {
+      ElfuScn *ms = secArray[i];
+
+      if (ms->shdr.sh_link > 0) {
+        ms->link = secArray[ms->shdr.sh_link - 1];
+      }
     }
-  }
 
 
-  /* Find sh_link dependencies */
+    /* Sort sections by file offset */
+    qsort(secArray, numShdr - 1, sizeof(*secArray), cmpScnOffs);
+
 
+    /* Find PHDR -> Section dependencies (needs sorted sections) */
+    for (i = 0; i < numShdr - 1; i++) {
+      ElfuScn *ms = secArray[i];
 
-  /* Sort sections by offset */
+      ElfuPhdr *parent = parentPhdr(me, ms);
 
+      if (parent) {
+        CIRCLEQ_INSERT_TAIL(&parent->phdrToScnList, ms, elemPhdrToScn);
+      }
+    }
 
-  /* Find PHDR -> Section dependencies */
 
+    /* Put sections into list of all sections */
+    for (i = 0; i < numShdr - 1; i++) {
+      CIRCLEQ_INSERT_TAIL(&me->scnList, secArray[i], elem);
+    }
+  }
 
 
   return me;
 
 
   ERROR:
+  if (secArray) {
+    free(secArray);
+  }
   if (me) {
     // TODO: Free data structures
   }
-- 
cgit v1.2.3