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https://github.com/upx/upx
synced 2025-10-26 23:36:41 +08:00
DF_1_PIE and calls_crt1() to handle part of -pie,-fPIE
https://github.com/upx/upx/issues/106 [partial] modified: p_elf_enum.h modified: p_lx_elf.cpp modified: p_lx_elf.h
This commit is contained in:
John Reiser
174
src/p_lx_elf.cpp
174
src/p_lx_elf.cpp
@@ -1481,6 +1481,34 @@ Elf64_Shdr const *PackLinuxElf64::elf_find_section_type(
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return 0;
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}
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bool PackLinuxElf64::calls_crt1(Elf64_Rela const *rela, int sz)
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{
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for (; 0 < sz; (sz -= sizeof(Elf64_Rela)), ++rela) {
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unsigned const symnum = get_te64(&rela->r_info) >> 32;
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char const *const symnam = get_te32(&dynsym[symnum].st_name) + dynstr;
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if (0==strcmp(symnam, "__libc_start_main") // glibc
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|| 0==strcmp(symnam, "__libc_init") // Android
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|| 0==strcmp(symnam, "__uClibc_main")
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|| 0==strcmp(symnam, "__uClibc_start_main"))
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return true;
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}
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return false;
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}
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bool PackLinuxElf32::calls_crt1(Elf32_Rel const *rel, int sz)
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{
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for (; 0 < sz; (sz -= sizeof(Elf32_Rel)), ++rel) {
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unsigned const symnum = get_te32(&rel->r_info) >> 8;
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char const *const symnam = get_te32(&dynsym[symnum].st_name) + dynstr;
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if (0==strcmp(symnam, "__libc_start_main") // glibc
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|| 0==strcmp(symnam, "__libc_init") // Android
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|| 0==strcmp(symnam, "__uClibc_main")
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|| 0==strcmp(symnam, "__uClibc_start_main"))
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return true;
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}
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return false;
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}
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bool PackLinuxElf32::canPack()
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{
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union {
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@@ -1600,23 +1628,14 @@ bool PackLinuxElf32::canPack()
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if (Elf32_Ehdr::ET_DYN==get_te16(&ehdr->e_type)) {
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memcpy(&ehdri, ehdr, sizeof(Elf32_Ehdr));
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// Modified 2009-10-10 to detect a ProgramLinkageTable relocation
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// which references the symbol, because DT_GNU_HASH contains only
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// defined symbols, and there might be no DT_HASH.
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Elf32_Rel const *
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jmprel= (Elf32_Rel const *)elf_find_dynamic(Elf32_Dyn::DT_JMPREL);
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for ( int sz = elf_unsigned_dynamic(Elf32_Dyn::DT_PLTRELSZ);
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0 < sz;
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(sz -= sizeof(Elf32_Rel)), ++jmprel
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) {
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unsigned const symnum = get_te32(&jmprel->r_info) >> 8;
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char const *const symnam = get_te32(&dynsym[symnum].st_name) + dynstr;
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if (0==strcmp(symnam, "__libc_start_main") // glibc
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|| 0==strcmp(symnam, "__libc_init") // Android
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|| 0==strcmp(symnam, "__uClibc_main")
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|| 0==strcmp(symnam, "__uClibc_start_main"))
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goto proceed;
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if (Elf32_Dyn::DF_1_PIE & elf_unsigned_dynamic(Elf32_Dyn::DT_FLAGS_1)) {
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goto proceed; // marked as main program
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}
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if (calls_crt1((Elf32_Rel const *)elf_find_dynamic(Elf32_Dyn::DT_REL),
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(int)elf_unsigned_dynamic(Elf32_Dyn::DT_RELSZ))
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|| calls_crt1((Elf32_Rel const *)elf_find_dynamic(Elf32_Dyn::DT_JMPREL),
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(int)elf_unsigned_dynamic(Elf32_Dyn::DT_PLTRELSZ))) {
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goto proceed; // calls C library init for main program
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}
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// Heuristic HACK for shared libraries (compare Darwin (MacOS) Dylib.)
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@@ -1763,7 +1782,7 @@ PackLinuxElf64ppcle::canPack()
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// Otherwise (no __libc_start_main as global undefined): skip it.
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// Also allow __uClibc_main and __uClibc_start_main .
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if (Elf32_Ehdr::ET_DYN==get_te16(&ehdr->e_type)) {
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if (Elf64_Ehdr::ET_DYN==get_te16(&ehdr->e_type)) {
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// The DT_SYMTAB has no designated length. Read the whole file.
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alloc_file_image(file_image, file_size);
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fi->seek(0, SEEK_SET);
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@@ -1793,37 +1812,16 @@ PackLinuxElf64ppcle::canPack()
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// which references the symbol, because DT_GNU_HASH contains only
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// defined symbols, and there might be no DT_HASH.
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Elf64_Rela const *
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rela= (Elf64_Rela const *)elf_find_dynamic(Elf64_Dyn::DT_RELA);
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Elf64_Rela const *
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jmprela= (Elf64_Rela const *)elf_find_dynamic(Elf64_Dyn::DT_JMPREL);
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for ( int sz = elf_unsigned_dynamic(Elf64_Dyn::DT_PLTRELSZ);
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0 < sz;
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(sz -= sizeof(Elf64_Rela)), ++jmprela
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) {
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unsigned const symnum = get_te64(&jmprela->r_info) >> 32;
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char const *const symnam = get_te32(&dynsym[symnum].st_name) + dynstr;
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if (0==strcmp(symnam, "__libc_start_main") // glibc
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|| 0==strcmp(symnam, "__libc_init") // Android
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|| 0==strcmp(symnam, "__uClibc_main")
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|| 0==strcmp(symnam, "__uClibc_start_main"))
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goto proceed;
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if (Elf64_Dyn::DF_1_PIE & elf_unsigned_dynamic(Elf64_Dyn::DT_FLAGS_1)) {
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goto proceed; // marked as main program
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}
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if (calls_crt1((Elf64_Rela const *)elf_find_dynamic(Elf64_Dyn::DT_RELA),
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(int)elf_unsigned_dynamic(Elf64_Dyn::DT_RELASZ))
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|| calls_crt1((Elf64_Rela const *)elf_find_dynamic(Elf64_Dyn::DT_JMPREL),
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(int)elf_unsigned_dynamic(Elf64_Dyn::DT_PLTRELSZ))) {
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goto proceed; // calls C library init for main program
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}
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// 2016-10-09 DT_JMPREL is no more (binutils-2.26.1)?
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// Check the general case, too.
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for ( int sz = elf_unsigned_dynamic(Elf64_Dyn::DT_RELASZ);
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0 < sz;
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(sz -= sizeof(Elf64_Rela)), ++rela
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) {
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unsigned const symnum = get_te64(&rela->r_info) >> 32;
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char const *const symnam = get_te32(&dynsym[symnum].st_name) + dynstr;
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if (0==strcmp(symnam, "__libc_start_main") // glibc
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|| 0==strcmp(symnam, "__libc_init") // Android
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|| 0==strcmp(symnam, "__uClibc_main")
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|| 0==strcmp(symnam, "__uClibc_start_main"))
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goto proceed;
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}
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// Heuristic HACK for shared libraries (compare Darwin (MacOS) Dylib.)
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// If there is an existing DT_INIT, and if everything that the dynamic
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// linker ld-linux needs to perform relocations before calling DT_INIT
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@@ -1985,44 +1983,14 @@ PackLinuxElf64amd::canPack()
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dynstr= (char const *)elf_find_dynamic(Elf64_Dyn::DT_STRTAB);
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dynsym= (Elf64_Sym const *)elf_find_dynamic(Elf64_Dyn::DT_SYMTAB);
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// Modified 2009-10-10 to detect a ProgramLinkageTable relocation
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// which references the symbol, because DT_GNU_HASH contains only
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// defined symbols, and there might be no DT_HASH.
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Elf64_Rela const *
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rela= (Elf64_Rela const *)elf_find_dynamic(Elf64_Dyn::DT_RELA);
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Elf64_Rela const *
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jmprela= (Elf64_Rela const *)elf_find_dynamic(Elf64_Dyn::DT_JMPREL);
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if (Elf64_Dyn::DF_1_PIE & elf_unsigned_dynamic(Elf64_Dyn::DT_FLAGS_1)) {
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goto proceed; // marked as main program
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}
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for ( int sz = elf_unsigned_dynamic(Elf64_Dyn::DT_PLTRELSZ);
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0 < sz;
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(sz -= sizeof(Elf64_Rela)), ++jmprela
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) {
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unsigned const symnum = get_te64(&jmprela->r_info) >> 32;
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char const *const symnam = get_te32(&dynsym[symnum].st_name) + dynstr;
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if (0==strcmp(symnam, "__libc_start_main") // glibc
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|| 0==strcmp(symnam, "__libc_init") // Android
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|| 0==strcmp(symnam, "__uClibc_main")
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|| 0==strcmp(symnam, "__uClibc_start_main"))
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goto proceed;
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}
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// 2016-10-09 DT_JMPREL is no more (binutils-2.26.1)?
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// Check the general case, too.
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for ( int sz = elf_unsigned_dynamic(Elf64_Dyn::DT_RELASZ);
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0 < sz;
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(sz -= sizeof(Elf64_Rela)), ++rela
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) {
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unsigned const symnum = get_te64(&rela->r_info) >> 32;
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char const *const symnam = get_te32(&dynsym[symnum].st_name) + dynstr;
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if (0==strcmp(symnam, "__libc_start_main") // glibc
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|| 0==strcmp(symnam, "__libc_init") // Android
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|| 0==strcmp(symnam, "__uClibc_main")
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|| 0==strcmp(symnam, "__uClibc_start_main"))
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goto proceed;
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if (calls_crt1((Elf64_Rela const *)elf_find_dynamic(Elf64_Dyn::DT_RELA),
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(int)elf_unsigned_dynamic(Elf64_Dyn::DT_RELASZ))
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|| calls_crt1((Elf64_Rela const *)elf_find_dynamic(Elf64_Dyn::DT_JMPREL),
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(int)elf_unsigned_dynamic(Elf64_Dyn::DT_PLTRELSZ))) {
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goto proceed; // calls C library init for main program
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}
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// Heuristic HACK for shared libraries (compare Darwin (MacOS) Dylib.)
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@@ -2160,7 +2128,7 @@ PackLinuxElf64arm::canPack()
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// Otherwise (no __libc_start_main as global undefined): skip it.
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// Also allow __uClibc_main and __uClibc_start_main .
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if (Elf32_Ehdr::ET_DYN==get_te16(&ehdr->e_type)) {
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if (Elf64_Ehdr::ET_DYN==get_te16(&ehdr->e_type)) {
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// The DT_SYMTAB has no designated length. Read the whole file.
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alloc_file_image(file_image, file_size);
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fi->seek(0, SEEK_SET);
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@@ -2186,40 +2154,14 @@ PackLinuxElf64arm::canPack()
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dynstr= (char const *)elf_find_dynamic(Elf64_Dyn::DT_STRTAB);
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dynsym= (Elf64_Sym const *)elf_find_dynamic(Elf64_Dyn::DT_SYMTAB);
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// Modified 2009-10-10 to detect a ProgramLinkageTable relocation
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// which references the symbol, because DT_GNU_HASH contains only
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// defined symbols, and there might be no DT_HASH.
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Elf64_Rela const *
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rela= (Elf64_Rela const *)elf_find_dynamic(Elf64_Dyn::DT_RELA);
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Elf64_Rela const *
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jmprela= (Elf64_Rela const *)elf_find_dynamic(Elf64_Dyn::DT_JMPREL);
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for ( int sz = elf_unsigned_dynamic(Elf64_Dyn::DT_PLTRELSZ);
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0 < sz;
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(sz -= sizeof(Elf64_Rela)), ++jmprela
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) {
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unsigned const symnum = get_te64(&jmprela->r_info) >> 32;
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char const *const symnam = get_te32(&dynsym[symnum].st_name) + dynstr;
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if (0==strcmp(symnam, "__libc_start_main") // glibc
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|| 0==strcmp(symnam, "__libc_init") // Android
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|| 0==strcmp(symnam, "__uClibc_main")
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|| 0==strcmp(symnam, "__uClibc_start_main"))
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goto proceed;
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if (Elf64_Dyn::DF_1_PIE & elf_unsigned_dynamic(Elf64_Dyn::DT_FLAGS_1)) {
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goto proceed; // marked as main program
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}
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// 2016-10-09 DT_JMPREL is no more (binutils-2.26.1)?
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// Check the general case, too.
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for ( int sz = elf_unsigned_dynamic(Elf64_Dyn::DT_RELASZ);
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0 < sz;
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(sz -= sizeof(Elf64_Rela)), ++rela
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) {
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unsigned const symnum = get_te64(&rela->r_info) >> 32;
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char const *const symnam = get_te32(&dynsym[symnum].st_name) + dynstr;
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if (0==strcmp(symnam, "__libc_start_main") // glibc
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|| 0==strcmp(symnam, "__libc_init") // Android
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|| 0==strcmp(symnam, "__uClibc_main")
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|| 0==strcmp(symnam, "__uClibc_start_main"))
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goto proceed;
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if (calls_crt1((Elf64_Rela const *)elf_find_dynamic(Elf64_Dyn::DT_RELA),
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(int)elf_unsigned_dynamic(Elf64_Dyn::DT_RELASZ))
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|| calls_crt1((Elf64_Rela const *)elf_find_dynamic(Elf64_Dyn::DT_JMPREL),
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(int)elf_unsigned_dynamic(Elf64_Dyn::DT_PLTRELSZ))) {
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goto proceed; // calls C library init for main program
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}
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// Heuristic HACK for shared libraries (compare Darwin (MacOS) Dylib.)
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