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Add ability to add and replace DT_NEEDED entries

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This commit is contained in:
Jonas Kuemmerlin
2013-04-28 16:42:01 +02:00
parent 7c8c47bf7a
commit ae5c6775e4
2 changed files with 121 additions and 1 deletions
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10
README
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@@ -26,6 +26,16 @@ libraries. In particular, it can do the following:
This option can be given multiple times.
* Add a declared dependency on a dynamic library (DT_NEEDED):
$ patchelf --add-needed libfoo.so.1 my-program
This option can be give multiple times.
* Replace a declared dependency on a dynamic library with another one (DT_NEEDED):
$ patchelf --replace-needed liboriginal.so.1 libreplacement.so.1 my-program
This option can be give multiple times.
AUTHOR

112
src/patchelf.cc
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@@ -150,7 +150,11 @@ public:
void modifyRPath(RPathOp op, string newRPath);
void addNeeded(set<string> libs);
void removeNeeded(set<string> libs);
void replaceNeeded(map<string, string>& libs);
private:
@@ -1079,6 +1083,98 @@ void ElfFile<ElfFileParamNames>::removeNeeded(set<string> libs)
memset(last, 0, sizeof(Elf_Dyn) * (dyn - last));
}
template<ElfFileParams>
void ElfFile<ElfFileParamNames>::replaceNeeded(map<string, string>& libs)
{
if (libs.empty()) return;
Elf_Shdr & shdrDynamic = findSection(".dynamic");
Elf_Shdr & shdrDynStr = findSection(".dynstr");
char * strTab = (char *) contents + rdi(shdrDynStr.sh_offset);
Elf_Dyn * dyn = (Elf_Dyn *) (contents + rdi(shdrDynamic.sh_offset));
unsigned int dynStrAddedBytes = 0;
for ( ; rdi(dyn->d_tag) != DT_NULL; dyn++) {
if (rdi(dyn->d_tag) == DT_NEEDED) {
char * name = strTab + rdi(dyn->d_un.d_val);
if (libs.find(name) != libs.end()) {
const string & replacement = libs[name];
debug("replacing DT_NEEDED entry `%s' with `%s'\n", name, replacement.c_str());
// technically, the string referred by d_val could be used otherwise, too (although unlikely)
// we'll therefore add a new string
debug("resizing .dynstr ...");
string & newDynStr = replaceSection(".dynstr",
rdi(shdrDynStr.sh_size) + replacement.size() + 1 + dynStrAddedBytes);
setSubstr(newDynStr, rdi(shdrDynStr.sh_size) + dynStrAddedBytes, replacement + '\0');
dyn->d_un.d_val = shdrDynStr.sh_size + dynStrAddedBytes;
dynStrAddedBytes += replacement.size() + 1;
changed = true;
} else {
debug("keeping DT_NEEDED entry `%s'\n", name);
}
}
}
}
template<ElfFileParams>
void ElfFile<ElfFileParamNames>::addNeeded(set<string> libs)
{
if (libs.empty()) return;
Elf_Shdr & shdrDynamic = findSection(".dynamic");
Elf_Shdr & shdrDynStr = findSection(".dynstr");
char * strTab = (char *) contents + rdi(shdrDynStr.sh_offset);
Elf_Dyn * dyn = (Elf_Dyn *) (contents + rdi(shdrDynamic.sh_offset));
/* add all new libs to the dynstr string table */
unsigned int length = 0;
for (set<string>::iterator it = libs.begin(); it != libs.end(); it++) {
length += it->size() + 1;
}
string & newDynStr = replaceSection(".dynstr",
rdi(shdrDynStr.sh_size) + length + 1);
set<Elf64_Xword> libStrings;
unsigned int pos = 0;
for (set<string>::iterator it = libs.begin(); it != libs.end(); it++) {
setSubstr(newDynStr, rdi(shdrDynStr.sh_size) + pos, *it + '\0');
libStrings.insert(rdi(shdrDynStr.sh_size) + pos);
pos += it->size() + 1;
}
/* add all new needed entries to the dynamic section */
string & newDynamic = replaceSection(".dynamic",
rdi(shdrDynamic.sh_size) + sizeof(Elf_Dyn) * libs.size());
unsigned int idx = 0;
for ( ; rdi(((Elf_Dyn *) newDynamic.c_str())[idx].d_tag) != DT_NULL; idx++) ;
debug("DT_NULL index is %d\n", idx);
/* Shift all entries down by the number of new entries. */
setSubstr(newDynamic, sizeof(Elf_Dyn) * libs.size(),
string(newDynamic, 0, sizeof(Elf_Dyn) * (idx + 1)));
/* Add the DT_NEEDED entries at the top. */
unsigned int i = 0;
for (set<Elf64_Xword>::iterator it = libStrings.begin(); it != libStrings.end(); it++, i++) {
Elf_Dyn newDyn;
wri(newDyn.d_tag, DT_NEEDED);
wri(newDyn.d_un.d_val, *it);
setSubstr(newDynamic, i * sizeof(Elf_Dyn), string((char *) &newDyn, sizeof(Elf_Dyn)));
}
changed = true;
}
static bool printInterpreter = false;
static string newInterpreter;
@@ -1088,7 +1184,8 @@ static bool setRPath = false;
static bool printRPath = false;
static string newRPath;
static set<string> neededLibsToRemove;
static map<string, string> neededLibsToReplace;
static set<string> neededLibsToAdd;
template<class ElfFile>
static void patchElf2(ElfFile & elfFile, mode_t fileMode)
@@ -1110,6 +1207,8 @@ static void patchElf2(ElfFile & elfFile, mode_t fileMode)
elfFile.modifyRPath(elfFile.rpSet, newRPath);
elfFile.removeNeeded(neededLibsToRemove);
elfFile.replaceNeeded(neededLibsToReplace);
elfFile.addNeeded(neededLibsToAdd);
if (elfFile.isChanged()){
elfFile.rewriteSections();
@@ -1161,7 +1260,9 @@ void showHelp(const string & progName)
[--shrink-rpath]\n\
[--print-rpath]\n\
[--force-rpath]\n\
[--add-needed LIBRARY]\n\
[--remove-needed LIBRARY]\n\
[--replace-needed LIBRARY NEW_LIBRARY]\n\
[--debug]\n\
[--version]\n\
FILENAME\n", progName.c_str());
@@ -1212,10 +1313,19 @@ int main(int argc, char * * argv)
added. */
forceRPath = true;
}
else if (arg == "--add-needed") {
if (++i == argc) error("missing argument");
neededLibsToAdd.insert(argv[i]);
}
else if (arg == "--remove-needed") {
if (++i == argc) error("missing argument");
neededLibsToRemove.insert(argv[i]);
}
else if (arg == "--replace-needed") {
if (i+2 >= argc) error("missing argument(s)");
neededLibsToReplace[ argv[i+1] ] = argv[i+2];
i += 2;
}
else if (arg == "--debug") {
debugMode = true;
}