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findMain will now return 0 on success, -1 on failure instead of asser…
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…ting.

	The visitor has been improved and should be able to recognize more
	false positives. Verbose debugging output has been converted to
	startup_printfs.
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John Detter committed Aug 3, 2016
1 parent 629db33 commit 1feabf5
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Showing 2 changed files with 62 additions and 30 deletions.
90 changes: 61 additions & 29 deletions dyninstAPI/src/image.C
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Expand Up @@ -410,8 +410,9 @@ class FindMainVisitor : public ASTVisitor

public:
bool resolved;
bool hardFault;
Address target;
FindMainVisitor() : resolved(false), target(0){}
FindMainVisitor() : resolved(false), hardFault(false), target(0) {}

virtual AST::Ptr visit(DataflowAPI::RoseAST * r)
{
Expand All @@ -431,8 +432,11 @@ class FindMainVisitor : public ASTVisitor
{
ConstantAST::Ptr c1 = ConstantAST::convert(newKids[0]);
ConstantAST::Ptr c2 = ConstantAST::convert(newKids[1]);
target = c1->val().val + c2->val().val;
resolved = true;
if(!hardFault)
{
target = c1->val().val + c2->val().val;
resolved = true;
}
return ConstantAST::create(
Constant(c1->val().val + c2->val().val));
}
Expand All @@ -447,22 +451,33 @@ class FindMainVisitor : public ASTVisitor

virtual ASTPtr visit(DataflowAPI::ConstantAST * c)
{
if(!target)
/* We can only handle constant values */
if(!target && !hardFault)
{
resolved = true;
target = c->val().val;
}

return c->ptr();
};

virtual ASTPtr visit(DataflowAPI::VariableAST* v)
{
/* If we visit a variable node, we can't do any analysis */
hardFault = true;
resolved = false;
target = 0;

return v->ptr();
}
};

/*
/**
* Search for the Main Symbols in the list of symbols, Only in case
* if the file is a shared object. If not present add them to the
* list
* list. Returns zero on success, nonzero otherwise.
*/
void image::findMain()
int image::findMain()
{
#if defined(ppc32_linux) || defined(ppc32_bgp) || defined(ppc64_linux)
using namespace Dyninst::InstructionAPI;
Expand All @@ -475,7 +490,7 @@ void image::findMain()
bool foundMain = false;
bool foundStart = false;
bool foundFini = false;
//check if 'main' is in allsymbols
// check if 'main' is in allsymbols
vector <SymtabAPI::Function *> funcs;
if (linkedFile->findFunctionsByName(funcs, "main") ||
linkedFile->findFunctionsByName(funcs, "_main"))
Expand All @@ -487,11 +502,11 @@ void image::findMain()

Region *eReg = NULL;
bool foundText = linkedFile->findRegion(eReg, ".text");
if (foundText == false) {
return;
}

if( !foundMain )
if (!foundText)
return -1;

if(!foundMain)
{
logLine("No main symbol found: attempting to create symbol for main\n");

Expand All @@ -507,15 +522,15 @@ void image::findMain()
scs.findRegions(eAddr,regions);
if(regions.empty()) {
// express puzzlement
return;
return -1;
}
SymtabCodeRegion * reg =
static_cast<SymtabCodeRegion*>(*regions.begin());
Function * func =
tco.findFuncByEntry(reg,eAddr);
if(!func) {
// again, puzzlement
return;
return -1;
}

Block * b = NULL;
Expand All @@ -530,16 +545,16 @@ void image::findMain()
startup_printf("%s[%d] _start has unexpected number (%d) of"
" call edges, bailing on findMain()\n",
FILE__,__LINE__,calls.size());
return;
return -1;
}
if (!b) return;
if (!b) return -1;

Address mainAddress = evaluate_main_address(linkedFile,func,b);
mainAddress = deref_opd(linkedFile, mainAddress);

if(0 == mainAddress || !scs.isValidAddress(mainAddress)) {
startup_printf("%s[%d] failed to find main\n",FILE__,__LINE__);
return;
return -1;
} else {
startup_printf("%s[%d] found main at %lx\n",
FILE__,__LINE__,mainAddress);
Expand All @@ -555,6 +570,7 @@ void image::findMain()
linkedFile->addSymbol(newSym);
}
}

#elif defined(i386_unknown_linux2_0) \
|| defined(x86_64_unknown_linux2_4) /* Blind duplication - Ray */ \
|| (defined(os_freebsd) \
Expand Down Expand Up @@ -585,12 +601,13 @@ void image::findMain()

Address eAddr = linkedFile->getEntryOffset();
Region *eReg = linkedFile->findEnclosingRegion(eAddr);
if (!eReg) {
return;
}

if (!eReg)
return -1;

Address eStart = eReg->getMemOffset();

if( !foundMain )
if(!foundMain)
{
logLine( "No main symbol found: creating symbol for main\n" );

Expand Down Expand Up @@ -622,8 +639,6 @@ void image::findMain()
break;
}

// instruction insn;
// insn.setInstruction( p );
Address mainAddress = 0;

// Create a temporary SymtabCodeSource that we can use for parsing.
Expand All @@ -634,7 +649,7 @@ void image::findMain()
CodeObject co(&scs);

#if !defined(os_freebsd)

/* Find the entry point, where we start our analysis */
Address entry_point = (Address)linkedFile->getEntryOffset();

/* Get the code regions we are looking at */
Expand All @@ -643,7 +658,11 @@ void image::findMain()

/* We should only get one region */
if(regions.size() != 1)
assert(!"Overlapping or non existant regions!");
{
startup_printf("%s[%u]: Overlapping or non existant regions!\n",
FILE__, __LINE__);
return -1;
}
CodeRegion* region = *regions.begin();
assert(region);

Expand All @@ -653,7 +672,12 @@ void image::findMain()
/* Get the parsed Function */
vector<ParseAPI::Function*> funcs;
Function* func = co.findFuncByEntry(region, entry_point);
assert(func); /* This should really exist now */
if(!func)
{
startup_printf("%s[%u]: No functions found in our region.\n",
FILE__, __LINE__);
return -1;
}

/* Use dataflow analysis here to determine the value of EDI */
const unsigned char* raw = p;
Expand All @@ -671,8 +695,10 @@ void image::findMain()

if(!last_insn) /* We cannot do analysis on this */
{
assert(!"findMain analysis has failed");
return;
startup_printf("%s[%u]: Our main analysis doesn't apply to "
"this compiler.\n",
FILE__, __LINE__);
return -1;
}

/* Calculate the address of the instruction */
Expand All @@ -694,7 +720,11 @@ void image::findMain()
assert(region->contains(insn_addr));
std::set<Block*> blocks;
co.findBlocks(region, insn_addr, blocks);
assert(blocks.size() == 1);
if(blocks.size() == 1)
{
startup_printf("%s[%u]: WARNING: overlapping blocks.\n",
FILE__, __LINE__);
}
Block* b = *blocks.begin();
assert(b);

Expand Down Expand Up @@ -899,6 +929,8 @@ void image::findMain()
}
}
#endif

return 0; /* Success */
}

/*
Expand Down
2 changes: 1 addition & 1 deletion dyninstAPI/src/image.h
View file
Expand Up @@ -448,7 +448,7 @@ class image : public codeRange {
// Platform-specific discovery of the "main" function
// FIXME There is a minor but fundamental design flaw that
// needs to be resolved wrt findMain returning void.
void findMain();
int findMain();

bool determineImageType();
bool addSymtabVariables();
Expand Down

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