ElfLinker started. Dos/com & dos/sys formats converted
This commit is contained in:
László Molnár
+284
@@ -346,6 +346,290 @@ unsigned char *SimpleLinker::getLoader(int *llen)
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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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while (start < end)
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{
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char name[1024];
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unsigned offset, size;
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char *nextl = strchr(start, '\n');
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assert(nextl != NULL);
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if (sscanf(start, "%*d %1023s %x %*d %*d %x",
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name, &size, &offset) == 3)
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{
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char *n = strstr(start, name);
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n[strlen(name)] = 0;
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addSection(n, input + offset, size);
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printf("section %s preprocessed\n", n);
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}
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start = nextl + 1;
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}
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addSection("*ABS*", NULL, 0);
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addSection("*UND*", NULL, 0);
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}
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void ElfLinker::preprocessSymbols(char *start, const char *end)
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{
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nsymbols = 0;
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while (start < end)
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{
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char section[1024];
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char symbol[1024];
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unsigned offset;
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char *nextl = strchr(start, '\n');
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assert(nextl != NULL);
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if (sscanf(start, "%x%*8c %1024s %*x %1023s",
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&offset, section, symbol) == 3)
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{
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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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symbols[nsymbols++] = Symbol(s, findSection(section), offset);
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printf("symbol %s preprocessed\n", s);
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}
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start = nextl + 1;
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}
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}
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void ElfLinker::preprocessRelocations(char *start, const char *end)
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{
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char sect[1024];
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Section *section = NULL;
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nrelocations = 0;
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while (start < end)
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{
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if (sscanf(start, "RELOCATION RECORDS FOR [%[^]]", sect) == 1)
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section = findSection(sect);
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unsigned offset;
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char type[100];
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char symbol[1024];
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char *nextl = strchr(start, '\n');
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assert(nextl != NULL);
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if (sscanf(start, "%x %99s %1023s",
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&offset, type, symbol) == 3)
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{
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char *t = strstr(start, type);
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t[strlen(type)] = 0;
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assert(nrelocations < TABLESIZE(relocations));
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relocations[nrelocations++] = Relocation(section, offset, t,
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findSymbol(symbol));
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printf("relocation %s %x preprocessed\n", section->name, offset);
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}
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start = nextl + 1;
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}
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}
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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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printf("unknown section %s\n", name);
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abort();
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return NULL;
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}
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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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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)
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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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}
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void ElfLinker::init(const void *pdata, int plen, int)
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{
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unsigned char *i = new unsigned char[plen];
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memcpy(i, pdata, plen);
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input = i;
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inputlen = plen;
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output = new unsigned char[plen];
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outputlen = 0;
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int pos = find(input, plen, "Sections:", 9);
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assert(pos != -1);
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char *psections = pos + (char *) input;
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char *psymbols = strstr(psections, "SYMBOL TABLE:");
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assert(psymbols != NULL);
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char *prelocs = strstr(psymbols, "RELOCATION RECORDS FOR");
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assert(prelocs != NULL);
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preprocessSections(psections, psymbols);
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preprocessSymbols(psymbols, prelocs);
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preprocessRelocations(prelocs, (char*) input + inputlen);
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}
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void ElfLinker::setLoaderAlignOffset(int phase)
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{
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assert(phase & 0);
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}
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int ElfLinker::addSection(const char *sname)
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{
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assert(!frozen);
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if (sname[0] == 0)
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return outputlen;
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char *begin = strdup(sname);
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char *end = begin + strlen(begin);
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for (char *sect = begin; sect < end; )
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{
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for (char *tokend = sect; *tokend; tokend++)
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if (*tokend == ' ' || *tokend == ',')
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{
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*tokend = 0;
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break;
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}
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if (*sect == '+') // alignment
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printf("alignment skipped %s\n", sect);
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else
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{
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Section *section = findSection(sect);
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memcpy(output + outputlen, section->input, section->size);
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section->output = output + outputlen;
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outputlen += section->size;
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printf("section added: %s\n", sect);
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}
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sect += strlen(sect) + 1;
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}
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free(begin);
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return outputlen;
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}
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void ElfLinker::addSection(const char *sname, const void *sdata, int slen)
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{
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assert(nsections < TABLESIZE(sections));
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sections[nsections++] = Section(sname, sdata, slen);
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}
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void ElfLinker::freeze()
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{
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if (frozen)
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return;
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addSection("*UND*");
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findSection("*UND*")->output = output;
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frozen = true;
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}
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int ElfLinker::getSection(const char *sname, int *slen)
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{
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assert(frozen);
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Section *section = findSection(sname);
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if (slen)
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*slen = section->size;
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return section->output - output;
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}
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unsigned char *ElfLinker::getLoader(int *llen)
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{
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assert(frozen);
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if (llen)
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*llen = outputlen;
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return output;
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}
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void ElfLinker::relocate()
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{
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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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if (rel->section->output == NULL)
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continue;
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if (rel->value->section->output == NULL)
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{
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printf("can not apply reloc '%s:%x' without section '%s'\n",
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rel->section->name, rel->offset,
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rel->value->section->name);
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//abort();
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continue;
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}
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if (strcmp(rel->value->section->name, "*UND*") == 0 &&
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rel->value->offset == 0)
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{
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printf("undefined symbol '%s' referenced\n", rel->value->name);
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abort();
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}
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unsigned value = rel->value->section->output + rel->value->offset
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- output;
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unsigned char *location = rel->section->output + rel->offset;
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if (strcmp(rel->type, "R_386_PC8") == 0)
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{
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value -= location - output;
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*location += value;
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}
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else if (strcmp(rel->type, "R_386_PC16") == 0)
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{
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value -= location - output;
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set_le16(location, get_le16(location) + value);
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}
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else if (strcmp(rel->type, "R_386_32") == 0)
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{
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set_le32(location, get_le32(location) + value);
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}
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else if (strcmp(rel->type, "R_386_16") == 0)
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{
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set_le16(location, get_le16(location) + value);
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}
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else if (strcmp(rel->type, "R_386_8") == 0)
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{
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*location += value;
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}
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else
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{
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printf("unknown relocation type '%s\n", rel->type);
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abort();
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}
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}
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}
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void ElfLinker::defineSymbol(const char *name, unsigned value)
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{
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Symbol *symbol = findSymbol(name);
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if (strcmp(symbol->section->name, "*UND*") == 0)
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symbol->offset = value;
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else
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printf("symbol '%s' already defined\n", name);
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}
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/*
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vi:ts=4:et
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*/
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