Initial work on copying an ELF file

11 files changed, 419 insertions, 0 deletions

diff --git a/Makefile b/Makefile
index df5f59f..726b92a 100644
--- a/Makefile
+++ b/Makefile
@@ -21,6 +21,10 @@ LDFLAGS  := -lelf
 default: $(EXE)
 
 
+.PHONY: debug
+debug: $(EXE)
+	gdb $(EXE) $(shell ps -e | sed "s/^ *\([0-9]\+\) .*$(PROJ).*$$/\1/g;te;d;:e")
+
 
 $(EXE): $(OBJS)
 	@if [ ! -d $(BUILDDIR) ] ; then echo "Error: Build dir '$(BUILDDIR)' does not exist." ; false ; fi
diff --git a/include/libelfu/copy.h b/include/libelfu/copy.h
new file mode 100644
index 0000000..341df88
--- /dev/null
+++ b/include/libelfu/copy.h
@@ -0,0 +1,9 @@
+#ifndef __LIBELFU_COPY_H_
+#define __LIBELFU_COPY_H_
+
+#include <libelf.h>
+#include <gelf.h>
+
+void elfu_copyElf(Elf *eo, Elf *ei);
+
+#endif
diff --git a/include/libelfu/fixup.h b/include/libelfu/fixup.h
new file mode 100644
index 0000000..6fb6620
--- /dev/null
+++ b/include/libelfu/fixup.h
@@ -0,0 +1,9 @@
+#ifndef __LIBELFU_FIXUP_H__
+#define __LIBELFU_FIXUP_H__
+
+#include <libelf.h>
+#include <gelf.h>
+
+void elfu_fixupPhdrSelfRef(Elf *e);
+
+#endif
diff --git a/include/libelfu/libelfu.h b/include/libelfu/libelfu.h
index 1c40541..ac9812b 100644
--- a/include/libelfu/libelfu.h
+++ b/include/libelfu/libelfu.h
@@ -5,6 +5,8 @@
 #include <libelfu/types.h>
 
 #include <libelfu/analysis.h>
+#include <libelfu/copy.h>
+#include <libelfu/fixup.h>
 #include <libelfu/lookup.h>
 
 
diff --git a/src/copy/ehdr.c b/src/copy/ehdr.c
new file mode 100644
index 0000000..b7c6232
--- /dev/null
+++ b/src/copy/ehdr.c
@@ -0,0 +1,52 @@
+#include <stdio.h>
+
+#include <libelf.h>
+#include <gelf.h>
+
+#include <libelfu/libelfu.h>
+
+
+void elfu_copyEhdr(Elf *eo, Elf *ei)
+{
+  int elfclass;
+  GElf_Ehdr ehdr, ehdrOut;
+
+  elfclass = gelf_getclass(ei);
+  if (elfclass == ELFCLASSNONE) {
+    fprintf(stderr, "getclass() failed: %s\n", elf_errmsg(-1));
+  }
+
+  if (!gelf_getehdr(ei, &ehdr)) {
+    fprintf(stderr, "gelf_getehdr() failed: %s\n", elf_errmsg(-1));
+    return;
+  }
+
+  if (!gelf_newehdr(eo, elfclass)) {
+    fprintf(stderr, "gelf_newehdr() failed: %s\n", elf_errmsg(-1));
+  }
+
+  if (!gelf_getehdr(ei, &ehdrOut)) {
+    fprintf(stderr, "gelf_getehdr() failed: %s\n", elf_errmsg(-1));
+    return;
+  }
+
+  ehdrOut.e_ident[EI_DATA] = ehdr.e_ident[EI_DATA];
+  ehdrOut.e_type = ehdr.e_type;
+  ehdrOut.e_machine = ehdr.e_machine;
+  ehdrOut.e_version = ehdr.e_version;
+  ehdrOut.e_entry = ehdr.e_entry; // FIXME
+  /* e_phoff */
+  /* e_shoff */
+  ehdrOut.e_flags = ehdr.e_flags;
+  /* e_ehsize */
+  /* e_phentsize */
+  /* e_phnum */
+  /* e_shentsize */
+  /* s_shnum */
+  ehdrOut.e_shstrndx = ehdr.e_shstrndx; // FIXME
+
+
+  if (!gelf_update_ehdr(eo, &ehdrOut)) {
+    fprintf(stderr, "gelf_update_ehdr() failed: %s\n", elf_errmsg(-1));
+  }
+}
diff --git a/src/copy/elf.c b/src/copy/elf.c
new file mode 100644
index 0000000..445f98c
--- /dev/null
+++ b/src/copy/elf.c
@@ -0,0 +1,30 @@
+#include <stdio.h>
+
+#include <libelf.h>
+#include <gelf.h>
+
+#include <libelfu/libelfu.h>
+
+
+void elfu_copyEhdr(Elf *eo, Elf *ei);
+void elfu_copySections(Elf *eo, Elf *ei);
+void elfu_copySegments1(Elf *eo, Elf *ei);
+void elfu_copySegments2(Elf *eo, Elf *ei);
+
+
+void elfu_copyElf(Elf *eo, Elf *ei)
+{
+  elfu_copyEhdr(eo, ei);
+  elfu_copySections(eo, ei);
+  elfu_copySegments1(eo, ei);
+
+  /* Calculate file structure so we have section offsets */
+  if (elf_update(eo, ELF_C_NULL) < 0) {
+    fprintf(stderr, "elf_update(NULL) failed: %s\n", elf_errmsg(-1));
+  }
+
+  /* Update the segment offsets and lengths */
+  elfu_copySegments2(eo, ei);
+
+  elfu_fixupPhdrSelfRef(eo);
+}
diff --git a/src/copy/section.c b/src/copy/section.c
new file mode 100644
index 0000000..5a62593
--- /dev/null
+++ b/src/copy/section.c
@@ -0,0 +1,75 @@
+#include <stdio.h>
+
+#include <libelf.h>
+#include <gelf.h>
+
+#include <libelfu/libelfu.h>
+
+
+void elfu_copySection(Elf *eo, Elf_Scn *scn)
+{
+  Elf_Scn *scnOut;
+  Elf_Data *data;
+  GElf_Shdr shdr, shdrOut;
+
+  scnOut = elf_newscn(eo);
+  if (!scnOut) {
+    fprintf(stderr, "elf_newscn() failed: %s\n", elf_errmsg(-1));
+    return;
+  }
+
+  if (gelf_getshdr(scn, &shdr) != &shdr) {
+    fprintf(stderr, "gelf_getshdr() failed: %s\n", elf_errmsg(-1));
+  }
+
+
+  /* Copy section header */
+  if (gelf_getshdr(scnOut, &shdrOut) != &shdrOut) {
+    fprintf(stderr, "gelf_getshdr() failed: %s\n", elf_errmsg(-1));
+  }
+
+  shdrOut.sh_name = shdr.sh_name;
+  shdrOut.sh_type = shdr.sh_type;
+  shdrOut.sh_flags = shdr.sh_flags;
+  /* sh_addr */
+  shdrOut.sh_addr = shdr.sh_addr;
+  /* sh_offset */
+  /* sh_size */
+  shdrOut.sh_link = shdr.sh_link;
+  shdrOut.sh_info = shdr.sh_info;
+  shdrOut.sh_addralign = shdr.sh_addralign;
+  //shdrOut.sh_entsize = shdr.sh_entsize;
+
+  if (!gelf_update_shdr(scnOut, &shdrOut)) {
+    fprintf(stderr, "gelf_update_shdr() failed: %s\n", elf_errmsg(-1));
+  }
+
+
+  //elf_flagshdr(scnOut, ELF_C_SET, ELF_F_DIRTY);
+  //elf_flagscn(scnOut, ELF_C_SET, ELF_F_DIRTY);
+
+
+  /* Copy each data part in source segment */
+  data = elf_rawdata(scn, NULL);
+  while (data) {
+    Elf_Data *dataOut = elf_newdata(scnOut);
+    if (!dataOut) {
+      fprintf(stderr, "elf_newdata() failed: %s\n", elf_errmsg(-1));
+    }
+
+    dataOut->d_align = data->d_align;
+    dataOut->d_buf  = data->d_buf;
+    /* dataOut->d_off  = data->d_off; */
+    dataOut->d_type = data->d_type;
+    dataOut->d_size = data->d_size;
+    dataOut->d_version = data->d_version;
+
+    //elf_flagdata(dataOut, ELF_C_SET, ELF_F_DIRTY);
+
+    data = elf_rawdata(scn, data);
+  }
+
+  // ehf_newdata() should flag the entire section dirty
+  //elf_flagshdr(scnOut, ELF_C_SET, ELF_F_DIRTY);
+  //elf_flagscn(scnOut, ELF_C_SET, ELF_F_DIRTY);
+}
diff --git a/src/copy/sections.c b/src/copy/sections.c
new file mode 100644
index 0000000..046b590
--- /dev/null
+++ b/src/copy/sections.c
@@ -0,0 +1,25 @@
+#include <stdio.h>
+
+#include <libelf.h>
+#include <gelf.h>
+
+#include <libelfu/libelfu.h>
+
+
+
+void elfu_copySection(Elf *eo, Elf_Scn *scn);
+
+
+
+void elfu_copySections(Elf *eo, Elf *ei)
+{
+  Elf_Scn *scn;
+
+  scn = elf_getscn(ei, 1);
+
+  while (scn) {
+    elfu_copySection(eo, scn);
+
+    scn = elf_nextscn(ei, scn);
+  }
+}
diff --git a/src/copy/segments.c b/src/copy/segments.c
new file mode 100644
index 0000000..0928de6
--- /dev/null
+++ b/src/copy/segments.c
@@ -0,0 +1,167 @@
+#include <stdio.h>
+
+#include <libelf.h>
+#include <gelf.h>
+
+#include <libelfu/libelfu.h>
+
+
+
+void elfu_copySegments1(Elf *eo, Elf *ei)
+{
+  size_t i, n;
+
+  if (elf_getphdrnum(ei, &n)) {
+    fprintf(stderr, "elf_getphdrnum() failed: %s\n", elf_errmsg(-1));
+  }
+
+  if (!gelf_newphdr(eo, n)) {
+    fprintf(stderr, "gelf_newphdr() failed: %s\n", elf_errmsg(-1));
+  }
+
+  for (i = 0; i < n; i++) {
+    GElf_Phdr phdr, phdrOut;
+
+    if (gelf_getphdr(ei, i, &phdr) != &phdr) {
+      fprintf(stderr, "gelf_getphdr() failed for #%d: %s\n", i, elf_errmsg(-1));
+      break;
+    }
+
+    if (gelf_getphdr(eo, i, &phdrOut) != &phdrOut) {
+      fprintf(stderr, "gelf_getphdr() failed for #%d: %s\n", i, elf_errmsg(-1));
+      break;
+    }
+
+    phdrOut.p_type = phdr.p_type;
+    /* p_offset */
+    phdrOut.p_vaddr = phdr.p_vaddr;
+    phdrOut.p_paddr = phdr.p_paddr;
+    /* p_filesz */
+    /* p_memsz */
+    phdrOut.p_flags = phdr.p_flags;
+    phdrOut.p_align = phdr.p_align;
+
+    if (!gelf_update_phdr (eo, i, &phdrOut)) {
+      fprintf(stderr, "gelf_update_ehdr() failed: %s\n", elf_errmsg(-1));
+    }
+  }
+
+  /* Tell libelf that phdrs have changed */
+  elf_flagphdr(eo, ELF_C_SET, ELF_F_DIRTY);
+}
+
+
+void elfu_copySegments2(Elf *eo, Elf *ei)
+{
+  size_t i, n;
+
+  if (elf_getphdrnum(ei, &n)) {
+    fprintf(stderr, "elf_getphdrnum() failed: %s\n", elf_errmsg(-1));
+  }
+
+  for (i = 0; i < n; i++) {
+    GElf_Phdr phdr, phdrOut;
+
+    if (gelf_getphdr(ei, i, &phdr) != &phdr) {
+      fprintf(stderr, "gelf_getphdr() failed for #%d: %s\n", i, elf_errmsg(-1));
+      break;
+    }
+
+    if (gelf_getphdr(eo, i, &phdrOut) != &phdrOut) {
+      fprintf(stderr, "gelf_getphdr() failed for #%d: %s\n", i, elf_errmsg(-1));
+      break;
+    }
+
+    /* Start of segment */
+    if (phdr.p_type == PT_PHDR) {
+      /* Skip PHDR entries and fix them up later */
+    }
+    else if (phdr.p_offset == 0) {
+      /* The text segment usually loads the whole ELF header */
+      phdrOut.p_offset = 0;
+    } else {
+      /* Try to guess the start of the segment */
+      Elf_Scn *scn, *scnOut;
+      GElf_Shdr shdr, shdrOut;
+
+      scn = elfu_firstSectionInSegment(ei, &phdr);
+      if (!scn) {
+        fprintf(stderr, "elfu_firstSectionInSegment() failed for segment #%d\n", i);
+        continue;
+      }
+
+      if (gelf_getshdr(scn, &shdr) != &shdr) {
+        fprintf(stderr, "gelf_getshdr() failed: %s\n", elf_errmsg(-1));
+      }
+
+      if (phdr.p_offset < shdr.sh_offset) {
+        fprintf(stderr, "elfu_copySegments2: Segment #%d starts before first contained section.\n", i);
+      }
+
+      scnOut = elf_getscn(eo, elf_ndxscn(scn));
+      if (!scnOut) {
+        fprintf(stderr, "elf_getscn() failed: %s\n", elf_errmsg(-1));
+      }
+
+      if (gelf_getshdr(scnOut, &shdrOut) != &shdrOut) {
+        fprintf(stderr, "gelf_getshdr() failed: %s\n", elf_errmsg(-1));
+      }
+
+      phdrOut.p_offset = shdrOut.sh_offset;
+    }
+
+    /* File length of segment */
+    if (phdr.p_type == PT_PHDR) {
+      /* Skip PHDR entries and fix them up later */
+    }
+    else if (phdr.p_filesz == 0) {
+      phdrOut.p_filesz = 0;
+    } else {
+      /* Try to guess the end of the segment */
+      Elf_Scn *scn, *scnOut;
+      GElf_Shdr shdr, shdrOut;
+
+      scn = elfu_lastSectionInSegment(ei, &phdr);
+      if (!scn) {
+        fprintf(stderr, "elfu_lastSectionInSegment() failed for segment #%d\n", i);
+        continue;
+      }
+
+      if (gelf_getshdr(scn, &shdr) != &shdr) {
+        fprintf(stderr, "gelf_getshdr() failed: %s\n", elf_errmsg(-1));
+      }
+
+      if (phdr.p_offset + phdr.p_filesz > shdr.sh_offset + shdr.sh_size) {
+        fprintf(stderr, "elfu_copySegments2: Segment #%d ends after last contained section.\n", i);
+      }
+
+      scnOut = elf_getscn(eo, elf_ndxscn(scn));
+      if (!scnOut) {
+        fprintf(stderr, "elf_getscn() failed: %s\n", elf_errmsg(-1));
+      }
+
+      if (gelf_getshdr(scnOut, &shdrOut) != &shdrOut) {
+        fprintf(stderr, "gelf_getshdr() failed: %s\n", elf_errmsg(-1));
+      }
+
+      phdrOut.p_filesz = shdrOut.sh_offset - phdrOut.p_offset + shdrOut.sh_size;
+    }
+
+    if (phdr.p_type == PT_PHDR) {
+      /* Skip PHDR entries and fix them up later */
+    }
+    else if (phdr.p_memsz == 0) {
+      phdrOut.p_memsz = 0;
+    } else {
+      // TODO: Calculate memory size (depends on .bss, etc.)
+      phdrOut.p_memsz = phdrOut.p_filesz; // FIXME
+    }
+
+    if (!gelf_update_phdr (eo, i, &phdrOut)) {
+      fprintf(stderr, "gelf_update_ehdr() failed: %s\n", elf_errmsg(-1));
+    }
+  }
+
+  /* Tell libelf that phdrs have changed */
+  elf_flagphdr(eo, ELF_C_SET, ELF_F_DIRTY);
+}
diff --git a/src/fixup/phdr.c b/src/fixup/phdr.c
new file mode 100644
index 0000000..ccdc021
--- /dev/null
+++ b/src/fixup/phdr.c
@@ -0,0 +1,41 @@
+#include <stdio.h>
+
+#include <libelf.h>
+#include <gelf.h>
+
+void elfu_fixupPhdrSelfRef(Elf *e)
+{
+  GElf_Ehdr ehdr;
+  size_t i, n;
+
+  if (!gelf_getehdr(e, &ehdr)) {
+    fprintf(stderr, "gelf_getehdr() failed: %s.", elf_errmsg(-1));
+    return;
+  }
+
+  if (elf_getphdrnum(e, &n)) {
+    fprintf(stderr, "elf_getphdrnum() failed: %s\n", elf_errmsg(-1));
+  }
+
+  for (i = 0; i < n; i++) {
+    GElf_Phdr phdr;
+
+    if (gelf_getphdr(e, i, &phdr) != &phdr) {
+      fprintf(stderr, "gelf_getphdr() failed for #%d: %s\n", i, elf_errmsg(-1));
+      continue;
+    }
+
+    if (phdr.p_type == PT_PHDR) {
+      phdr.p_offset = ehdr.e_phoff;
+      phdr.p_filesz = elf32_fsize(ELF_T_PHDR, n, EV_CURRENT);
+      phdr.p_memsz = phdr.p_filesz;
+
+      if (!gelf_update_phdr (e, i, &phdr)) {
+        fprintf(stderr, "gelf_update_ehdr() failed: %s\n", elf_errmsg(-1));
+      }
+    }
+  }
+
+  /* Tell libelf that phdrs have changed */
+  elf_flagphdr(e, ELF_C_SET, ELF_F_DIRTY);
+}
diff --git a/src/main.c b/src/main.c
index 9791feb..4ed0059 100644
--- a/src/main.c
+++ b/src/main.c
@@ -56,6 +56,11 @@ int main(int argc, char **argv)
     printSections(hIn.e);
   }
 
+  /* Copy the input ELF to the output file */
+  if (opts.fnOutput) {
+    elfu_copyElf(hOut.e, hIn.e);
+  }
+
 
 
 EXIT: