Fix endianness issues for powerpc PIE

Previously when running `patchelf --set-rpath "/usr/sbin" my_bin` on a
PIE ppc32 binary that had no RPATH a few issues were encountered.

This commit fixes:

1. The PT_PHDR being sorted improperly due to the type being read in
   incorrect endianness

2. The aligment being set to default 0x1000 due to the machine arch
   being read in incorrect endianness

3. The interpreter being clobbered due to the replace sections routine
   reading sh_offset and sh_size in incorrect endianness

4. The PHDR segment having an incorrect virt and phys address due to
   reading the e_phoff in the incorrect endianness

This also fixes a read of the shdr.sh_type in writeReplacedSections but
this was not encountered during testing.

src/patchelf.cc

@@ -136,8 +136,8 @@ class ElfFile
         bool operator ()(const Elf_Phdr & x, const Elf_Phdr & y)
         {
             // A PHDR comes before everything else.
-            if (y.p_type == PT_PHDR) return false;
-            if (x.p_type == PT_PHDR) return true;
+            if (elfFile->rdi(y.p_type) == PT_PHDR) return false;
+            if (elfFile->rdi(x.p_type) == PT_PHDR) return true;
 
             // Sort non-PHDRs by address.
             return elfFile->rdi(x.p_paddr) < elfFile->rdi(y.p_paddr);
@@ -453,7 +453,7 @@ unsigned int ElfFile<ElfFileParamNames>::getPageSize() const
     // Architectures (and ABIs) can have different minimum section alignment
     // requirements. There is no authoritative list of these values. The
     // current list is extracted from GNU gold's source code (abi_pagesize).
-    switch (hdr->e_machine) {
+    switch (rdi(hdr->e_machine)) {
       case EM_SPARC:
       case EM_MIPS:
       case EM_PPC:
@@ -665,7 +665,7 @@ void ElfFile<ElfFileParamNames>::writeReplacedSections(Elf_Off & curOff,
     for (auto & i : replacedSections) {
         std::string sectionName = i.first;
         Elf_Shdr & shdr = findSection(sectionName);
-        if (shdr.sh_type != SHT_NOBITS)
+        if (rdi(shdr.sh_type) != SHT_NOBITS)
             memset(contents + rdi(shdr.sh_offset), 'X', rdi(shdr.sh_size));
     }
 
@@ -778,9 +778,9 @@ void ElfFile<ElfFileParamNames>::rewriteSectionsLibrary()
     /* Some sections may already be replaced so account for that */
     unsigned int i = 1;
     Elf_Addr pht_size = sizeof(Elf_Ehdr) + (phdrs.size() + num_notes + 1)*sizeof(Elf_Phdr);
-    while( shdrs[i].sh_offset <= pht_size && i < rdi(hdr->e_shnum) ) {
+    while( rdi(shdrs[i].sh_offset) <= pht_size && i < rdi(hdr->e_shnum) ) {
         if (not haveReplacedSection(getSectionName(shdrs[i])))
-            replaceSection(getSectionName(shdrs[i]), shdrs[i].sh_size);
+            replaceSection(getSectionName(shdrs[i]), rdi(shdrs[i].sh_size));
         i++;
     }
 
@@ -835,7 +835,7 @@ void ElfFile<ElfFileParamNames>::rewriteSectionsLibrary()
     assert(curOff == startOffset + neededSpace);
 
     /* Write out the updated program and section headers */
-    rewriteHeaders(hdr->e_phoff);
+    rewriteHeaders(rdi(hdr->e_phoff));
 }