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https://github.com/upx/upx
synced 2025-09-28 19:06:07 +08:00
ElfLinker improvements
Sections/symbols/relocations are allocated dynamically Sections use an internal copy of their input data
This commit is contained in:
László Molnár
parent
67a282f19f
commit
3d3c20e507
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@ -346,6 +346,42 @@ unsigned char *SimpleLinker::getLoader(int *llen)
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}
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/*************************************************************************
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//
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**************************************************************************/
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ElfLinker::Section::Section(const char *n, const void *i, unsigned s) :
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name(strdup(n)), output(NULL), size(s), offset(0), next(NULL)
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{
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assert(name);
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input = malloc(s + 1);
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assert(input);
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memcpy(input, i, s);
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}
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ElfLinker::Section::~Section()
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{
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free(name);
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free(input);
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}
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ElfLinker::Symbol::Symbol(const char *n, Section *s, unsigned o) :
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name(strdup(n)), section(s), offset(o)
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{
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assert(name);
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}
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ElfLinker::Symbol::~Symbol()
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{
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free(name);
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}
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ElfLinker::Relocation::Relocation(Section *s, unsigned o, const char *t,
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Symbol *v, unsigned a) :
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section(s), offset(o), type(t), value(v), add(a)
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{}
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void ElfLinker::preprocessSections(char *start, const char *end)
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{
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nsections = 0;
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@ -390,10 +426,9 @@ void ElfLinker::preprocessSymbols(char *start, const char *end)
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char *s = strstr(start, symbol);
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s[strlen(symbol)] = 0;
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assert(nsymbols < TABLESIZE(symbols));
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if (strcmp(section, "*UND*") == 0)
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offset = 0xdeaddead;
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symbols[nsymbols++] = Symbol(s, findSection(section), offset);
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addSymbol(s, section, offset);
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//printf("symbol %s preprocessed o=%x\n", s, offset);
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}
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@ -433,9 +468,7 @@ void ElfLinker::preprocessRelocations(char *start, const char *end)
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sscanf(p + 3, "%x", &add);
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}
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assert(nrelocations < TABLESIZE(relocations));
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relocations[nrelocations++] = Relocation(section, offset, t,
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findSymbol(symbol), add);
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addRelocation(section->name, offset, t, symbol, add);
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//printf("relocation %s %x preprocessed\n", section->name, offset);
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}
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@ -447,8 +480,8 @@ void ElfLinker::preprocessRelocations(char *start, const char *end)
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ElfLinker::Section *ElfLinker::findSection(const char *name)
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{
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for (unsigned ic = 0; ic < nsections; ic++)
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if (strcmp(sections[ic].name, name) == 0)
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return sections + ic;
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if (strcmp(sections[ic]->name, name) == 0)
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return sections[ic];
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printf("unknown section %s\n", name);
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abort();
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@ -458,21 +491,54 @@ ElfLinker::Section *ElfLinker::findSection(const char *name)
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ElfLinker::Symbol *ElfLinker::findSymbol(const char *name)
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{
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for (unsigned ic = 0; ic < nsymbols; ic++)
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if (strcmp(symbols[ic].name, name) == 0)
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return symbols + ic;
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if (strcmp(symbols[ic]->name, name) == 0)
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return symbols[ic];
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printf("unknown symbol %s\n", name);
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abort();
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return NULL;
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}
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ElfLinker::ElfLinker() : input(NULL), output(NULL), head(NULL), tail(NULL)
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void ElfLinker::addSymbol(const char *name, const char *section,
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unsigned offset)
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{
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symbols = static_cast<Symbol **>(realloc(symbols, (nsymbols + 1)
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* sizeof(Symbol *)));
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assert(symbols);
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symbols[nsymbols++] = new Symbol(name, findSection(section), offset);
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}
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void ElfLinker::addRelocation(const char *section, unsigned off,
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const char *type, const char *symbol,
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unsigned add)
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{
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relocations = static_cast<Relocation **>(realloc(relocations,
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(nrelocations + 1)
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* sizeof(Relocation *)));
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assert(relocations);
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relocations[nrelocations++] = new Relocation(findSection(section), off,
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type, findSymbol(symbol), add);
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}
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ElfLinker::ElfLinker() : input(NULL), output(NULL), head(NULL), tail(NULL),
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sections(NULL), symbols(NULL), relocations(NULL)
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{}
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ElfLinker::~ElfLinker()
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{
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delete [] input;
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delete [] output;
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unsigned ic;
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for (ic = 0; ic < nsections; ic++)
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delete sections[ic];
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free(sections);
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for (ic = 0; ic < nsymbols; ic++)
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delete symbols[ic];
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free(symbols);
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for (ic = 0; ic < nrelocations; ic++)
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delete relocations[ic];
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free(relocations);
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}
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void ElfLinker::init(const void *pdata, int plen, int)
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@ -562,8 +628,10 @@ int ElfLinker::addSection(const char *sname)
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void ElfLinker::addSection(const char *sname, const void *sdata, int slen)
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{
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assert(!frozen);
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assert(nsections < TABLESIZE(sections));
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sections[nsections++] = Section(sname, sdata, slen);
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sections = static_cast<Section **>(realloc(sections, (nsections + 1)
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* sizeof(Section *)));
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assert(sections);
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sections[nsections++] = new Section(sname, sdata, slen);
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}
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void ElfLinker::freeze()
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@ -598,7 +666,7 @@ void ElfLinker::relocate()
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for (unsigned ic = 0; ic < nrelocations; ic++)
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{
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Relocation *rel = relocations + ic;
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Relocation *rel = relocations[ic];
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if (rel->section->output == NULL)
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continue;
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if (rel->value->section->output == NULL)
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96
src/linker.h
96
src/linker.h
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@ -151,52 +151,18 @@ typedef TSimpleLinker<NBELE::BEPolicy> SimpleBELinker;
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typedef TSimpleLinker<NBELE::LEPolicy> SimpleLELinker;
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class ElfLinker : public Linker
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/*************************************************************************
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// ElfLinker
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**************************************************************************/
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class ElfLinker : public Linker, private nocopy
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{
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typedef Linker super;
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protected:
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struct Section
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{
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const char *name;
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const void *input;
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upx_byte *output;
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unsigned size;
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unsigned offset;
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Section *next;
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Section(){}
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Section(const char *n, const void *i, unsigned s) :
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name(n), input(i), output(NULL), size(s), offset(0), next(NULL)
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{}
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};
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struct Symbol
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{
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const char *name;
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Section *section;
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unsigned offset;
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Symbol(){}
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Symbol(const char *n, Section *s, unsigned o) :
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name(n), section(s), offset(o)
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{}
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};
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struct Relocation
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{
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Section *section;
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unsigned offset;
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const char *type;
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Symbol *value;
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unsigned add; // used in .rela relocations
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Relocation(){}
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Relocation(Section *s, unsigned o, const char *t,
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Symbol *v, unsigned a) :
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section(s), offset(o), type(t), value(v), add(a)
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{}
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};
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struct Section;
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struct Symbol;
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struct Relocation;
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upx_byte *input;
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int inputlen;
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@ -206,9 +172,9 @@ protected:
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Section *head;
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Section *tail;
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Section sections[550];
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Symbol symbols[1000];
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Relocation relocations[2000];
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Section **sections;
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Symbol **symbols;
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Relocation **relocations;
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unsigned nsections;
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unsigned nsymbols;
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@ -220,6 +186,10 @@ protected:
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Section *findSection(const char *name);
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Symbol *findSymbol(const char *name);
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void addSymbol(const char *name, const char *section, unsigned offset);
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void addRelocation(const char *section, unsigned off, const char *type,
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const char *symbol, unsigned add);
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public:
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ElfLinker();
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@ -248,6 +218,42 @@ protected:
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unsigned value, const char *type);
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};
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struct ElfLinker::Section : private nocopy
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{
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char *name;
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void *input;
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upx_byte *output;
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unsigned size;
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unsigned offset;
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Section *next;
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Section(const char *n, const void *i, unsigned s);
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~Section();
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};
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struct ElfLinker::Symbol : private nocopy
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{
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char *name;
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Section *section;
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unsigned offset;
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Symbol(const char *n, Section *s, unsigned o);
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~Symbol();
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};
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struct ElfLinker::Relocation : private nocopy
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{
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Section *section;
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unsigned offset;
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const char *type;
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Symbol *value;
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unsigned add; // used in .rela relocations
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Relocation(Section *s, unsigned o, const char *t,
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Symbol *v, unsigned a);
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};
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class ElfLinkerX86 : public ElfLinker
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{
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typedef ElfLinker super;
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