Add initial support for position-independent executables.

src/engines/ptrace.cc

@@ -7,6 +7,7 @@
 #include <phdr_data.h>
 
 #include <unistd.h>
+#include <sys/personality.h>
 #include <sys/ptrace.h>
 #include <sys/user.h>
 #include <sys/types.h>
@@ -487,8 +488,21 @@ class Ptrace : public IEngine
 
 		/* Executable exists, try to launch it */
 		if ((child = fork()) == 0) {
+			int persona;
 			int res;
 
+			/* Avoid address randomization */
+			persona = personality(0xffffffff);
+			if (persona < 0) {
+				perror("Can't get personality");
+				return false;
+			}
+			persona |= 0x0040000; /* ADDR_NO_RANDOMIZE */
+			if (personality(persona) < 0) {
+				perror("Can't set personality");
+				return false;
+			}
+
 			/* And launch the process */
 			res = ptrace(PTRACE_TRACEME, 0, 0, 0);
 			if (res < 0) {

src/engines/script-engine-base.hh

@@ -50,6 +50,11 @@ public:
 		return true;
 	}
 
+	bool setMainFileRelocation(unsigned long relocation)
+	{
+		return true;
+	}
+
 	void registerLineListener(ILineListener &listener)
 	{
 		m_lineListeners.push_back(&listener);

src/include/file-parser.hh

@@ -146,6 +146,22 @@ namespace kcov
 		 */
 		virtual bool addFile(const std::string &filename, struct phdr_data_entry *phdr_data = 0) = 0;
 
+		/**
+		 * Set the relocation of the main file for the position-independent executable (PIE) support
+		 *
+		 * PIEs have, like shared objects, an unknown load address which can only be
+		 * retrieved from the solib handler. Because of this the parser may defer
+		 * onFile and onLine notifications before this call.
+		 *
+		 * This method, if any, should be called after the initial parse call and
+		 * beefore the following addFile calls for solibs.
+		 *
+		 * @param relocation relocation offset
+		 *
+		 * @return true if the relocation is properly set, false otherwise
+		 */
+		virtual bool setMainFileRelocation(unsigned long relocation) = 0;
+
 		/**
 		 * Register a listener for source lines.
 		 *

src/include/phdr_data.h

@@ -27,6 +27,7 @@ struct phdr_data
 {
 	uint32_t magic;
 	uint32_t version;
+	unsigned long relocation; // for PIE
 	uint32_t n_entries;
 
 	struct phdr_data_entry entries[];

src/merge-file-parser.cc

@@ -95,6 +95,11 @@ class MergeParser :
 		return true;
 	}
 
+	virtual bool setMainFileRelocation(unsigned long relocation)
+	{
+		return true;
+	}
+
 	virtual void registerLineListener(IFileParser::ILineListener &listener)
 	{
 		m_lineListeners.push_back(&listener);

src/parsers/elf-parser.cc

@@ -40,6 +40,7 @@ class ElfInstance : public IFileParser
 		m_filename = "";
 		m_checksum = 0;
 		m_elfIs32Bit = true;
+		m_elfIsShared = false;
 		m_isMainFile = true;
 		m_initialized = false;
 		m_filter = NULL;
@@ -145,6 +146,7 @@ class ElfInstance : public IFileParser
 		if (m_isMainFile) {
 			char *raw;
 			size_t sz;
+			uint16_t e_type;
 
 			raw = elf_getident(elf, &sz);
 
@@ -159,6 +161,9 @@ class ElfInstance : public IFileParser
 					capabilities.addCapability("handle-solibs");
 			}
 
+			e_type = m_elfIs32Bit ? elf32_getehdr(elf)->e_type : elf64_getehdr(elf)->e_type;
+
+			m_elfIsShared = e_type == ET_DYN;
 			m_checksum = m_elfIs32Bit ? elf32_checksum(elf) : elf64_checksum(elf);
 		}
 
@@ -171,38 +176,71 @@ class ElfInstance : public IFileParser
 	}
 
 	bool parse()
+	{
+		// should defer until setMainFileRelocation
+		if (m_isMainFile && m_elfIsShared)
+			return true;
+
+		if (!doParse(0))
+			return false;
+
+		// After the first, all other are solibs
+		m_isMainFile = false;
+		return true;
+	}
+
+	bool doParse(unsigned long relocation)
 	{
 		struct stat st;
 
 		if (lstat(m_filename.c_str(), &st) < 0)
-			return 0;
+			return false;
 
 		parseOneElf();
 
 		// Gcov data?
 		if (IConfiguration::getInstance().keyAsInt("gcov") && !m_gcnoFiles.empty())
-			parseGcnoFiles();
+			parseGcnoFiles(relocation);
 		else
-			parseOneDwarf();
+			parseOneDwarf(relocation);
 
-		// After the first, all other are solibs
-		m_isMainFile = false;
+		return true;
+	}
+
+	bool setMainFileRelocation(unsigned long relocation)
+	{
+		if (!m_isMainFile)
+			return false;
+
+		kcov_debug(INFO_MSG, "main file relocation = %#lx", relocation);
+
+		if (m_elfIsShared) {
+			if (!doParse(relocation))
+				return false;
+		} else {
+			// this situation is probably problematic, as we have already notified
+			// segment informations to the listeners.
+			if (relocation != 0) {
+				warning("Got a static executable with relocation=%#lx, "
+					"probably the trace wouldn't work.", relocation);
+			}
+		}
 
 		return true;
 	}
 
-	void parseGcnoFiles()
+	void parseGcnoFiles(unsigned long relocation)
 	{
 		for (FileList_t::const_iterator it = m_gcnoFiles.begin();
 				it != m_gcnoFiles.end();
 				++it) {
 			const std::string &cur = *it;
 
-			parseOneGcno(cur);
+			parseOneGcno(cur, relocation);
 		}
 	}
 
-	void parseOneGcno(const std::string &filename)
+	void parseOneGcno(const std::string &filename, unsigned long relocation)
 	{
 		size_t sz;
 		void *data;
@@ -234,11 +272,11 @@ class ElfInstance : public IFileParser
 					it != m_lineListeners.end();
 					++it)
 				(*it)->onLine(cur.m_file, cur.m_line,
-						gcovGetAddress(cur.m_file, cur.m_function, cur.m_basicBlock, cur.m_index));
+						gcovGetAddress(cur.m_file, cur.m_function, cur.m_basicBlock, cur.m_index) + relocation);
 		}
 	}
 
-	bool parseOneDwarf()
+	bool parseOneDwarf(unsigned long relocation)
 	{
 		Dwarf_Off offset = 0;
 		Dwarf_Off last_offset = 0;
@@ -373,7 +411,7 @@ class ElfInstance : public IFileParser
 					for (LineListenerList_t::const_iterator it = m_lineListeners.begin();
 							it != m_lineListeners.end();
 							++it)
-						(*it)->onLine(file_path, line_nr, adjustAddressBySegment(addr));
+						(*it)->onLine(file_path, line_nr, adjustAddressBySegment(addr) + relocation);
 				}
 			}
 		}
@@ -605,6 +643,7 @@ class ElfInstance : public IFileParser
 
 	struct Elf *m_elf;
 	bool m_elfIs32Bit;
+	bool m_elfIsShared;
 	LineListenerList_t m_lineListeners;
 	FileListenerList_t m_fileListeners;
 	std::string m_filename;

src/solib-handler.cc

@@ -195,6 +195,8 @@ class SolibHandler : public ISolibHandler, ICollector::IEventTickListener
 		if (!p)
 			return;
 
+		m_parser->setMainFileRelocation(p->relocation);
+
 		for (unsigned int i = 0; i < p->n_entries; i++)
 		{
 			struct phdr_data_entry *cur = &p->entries[i];

src/solib-parser/lib.c

@@ -20,6 +20,12 @@ static struct phdr_data *phdr_data;
 
 static int phdrCallback(struct dl_phdr_info *info, size_t size, void *data)
 {
+	// the first entry is used to determine the executable's "base address"
+	// (which is actually the relocation for PIE)
+	if (phdr_data->n_entries == 0) {
+		phdr_data->relocation = info->dlpi_addr;
+	}
+
 	phdr_data_add(phdr_data, info);
 
 	return 0;

src/solib-parser/phdr_data.c

@@ -10,7 +10,7 @@
 #include <link.h>
 
 #define KCOV_MAGIC         0x6b636f76 /* "kcov" */
-#define KCOV_SOLIB_VERSION 2
+#define KCOV_SOLIB_VERSION 3
 
 static uint8_t data_area[4 * 1024 * 1024];
 
@@ -23,6 +23,7 @@ struct phdr_data *phdr_data_new(size_t allocSize)
 
 	p->magic = KCOV_MAGIC;
 	p->version = KCOV_SOLIB_VERSION;
+	p->relocation = 0;
 	p->n_entries = 0;
 
 	return p;