Issue 357: New Linux file_id code doesn't persist across strip. r=agl,nealsid at http://breakpad.appspot.com/49008

git-svn-id: http://google-breakpad.googlecode.com/svn/trunk@461 4c0a9323-5329-0410-9bdc-e9ce6186880e

src/client/linux/Makefile

@@ -39,6 +39,7 @@ TEST_CC_SRC=handler/exception_handler_unittest.cc \
 	    minidump_writer/line_reader_unittest.cc \
 	    minidump_writer/linux_dumper_unittest.cc \
 	    minidump_writer/minidump_writer_unittest.cc \
+	    ../../common/linux/file_id.cc \
 	    $(GOOGLETEST_CC_SRC)
 
 TEST_CC_OBJ=$(patsubst %.cc, $(OBJ_DIR)/%.o,$(TEST_CC_SRC))

src/client/linux/minidump_writer/linux_dumper.cc

@@ -42,15 +42,20 @@
 #include <string.h>
 
 #include <unistd.h>
+#include <elf.h>
 #include <errno.h>
 #include <fcntl.h>
+#include <link.h>
 
 #include <sys/types.h>
 #include <sys/ptrace.h>
 #include <sys/wait.h>
 
+#include <algorithm>
+
 #include "client/linux/minidump_writer/directory_reader.h"
 #include "client/linux/minidump_writer/line_reader.h"
+#include "common/linux/file_id.h"
 #include "common/linux/linux_libc_support.h"
 #include "common/linux/linux_syscall_support.h"
 
@@ -156,6 +161,30 @@ LinuxDumper::BuildProcPath(char* path, pid_t pid, const char* node) const {
   memcpy(path + total_length, "\0", 1);
 }
 
+bool
+LinuxDumper::ElfFileIdentifierForMapping(unsigned int mapping_id,
+                                         uint8_t identifier[sizeof(MDGUID)])
+{
+  assert(mapping_id < mappings_.size());
+  const MappingInfo* mapping = mappings_[mapping_id];
+  int fd = sys_open(mapping->name, O_RDONLY, 0);
+  if (fd < 0)
+    return false;
+  struct kernel_stat st;
+  if (sys_fstat(fd, &st) != 0) {
+    sys_close(fd);
+    return false;
+  }
+  void* base = sys_mmap2(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
+  sys_close(fd);
+  if (base == MAP_FAILED)
+    return false;
+
+  bool success = FileID::ElfFileIdentifierFromMappedFile(base, identifier);
+  sys_munmap(base, st.st_size);
+  return success;
+}
+
 void*
 LinuxDumper::FindBeginningOfLinuxGateSharedLibrary(const pid_t pid) const {
   char auxv_path[80];

src/client/linux/minidump_writer/linux_dumper.h

@@ -37,6 +37,7 @@
 #include <sys/user.h>
 
 #include "common/linux/memory.h"
+#include "google_breakpad/common/minidump_format.h"
 
 namespace google_breakpad {
 
@@ -122,6 +123,10 @@ class LinuxDumper {
   // without any slashes.
   void BuildProcPath(char* path, pid_t pid, const char* node) const;
 
+  // Generate a File ID from the .text section of a mapped entry
+  bool ElfFileIdentifierForMapping(unsigned int mapping_id,
+                                   uint8_t identifier[sizeof(MDGUID)]);
+
   // Utility method to find the location of where the kernel has
   // mapped linux-gate.so in memory(shows up in /proc/pid/maps as
   // [vdso], but we can't guarantee that it's the only virtual dynamic

src/client/linux/minidump_writer/linux_dumper_unittest.cc

@@ -27,13 +27,25 @@
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
+#include <limits.h>
 #include <unistd.h>
 
 #include "client/linux/minidump_writer/linux_dumper.h"
+#include "common/linux/file_id.h"
 #include "breakpad_googletest_includes.h"
 
 using namespace google_breakpad;
 
+// This provides a wrapper around system calls which may be
+// interrupted by a signal and return EINTR. See man 7 signal.
+#define HANDLE_EINTR(x) ({ \
+  typeof(x) __eintr_result__; \
+  do { \
+    __eintr_result__ = x; \
+  } while (__eintr_result__ == -1 && errno == EINTR); \
+  __eintr_result__;\
+})
+
 namespace {
 typedef testing::Test LinuxDumperTest;
 }
@@ -116,3 +128,56 @@ TEST(LinuxDumperTest, MappingsIncludeLinuxGate) {
     EXPECT_EQ(0, memcmp(linux_gate_loc, ELFMAG, SELFMAG));
   }
 }
+
+TEST(LinuxDumperTest, FileIDsMatch) {
+  // Calculate the File ID of our binary using both
+  // FileID::ElfFileIdentifier and LinuxDumper::ElfFileIdentifierForMapping
+  // and ensure that we get the same result from both.
+  char exe_name[PATH_MAX];
+  ssize_t len = readlink("/proc/self/exe", exe_name, PATH_MAX - 1);
+  ASSERT_NE(len, -1);
+  exe_name[len] = '\0';
+
+  int fds[2];
+  ASSERT_NE(-1, pipe(fds));
+
+  // fork a child so we can ptrace it
+  const pid_t child = fork();
+  if (child == 0) {
+    close(fds[1]);
+    // now wait forever for the parent
+    char b;
+    HANDLE_EINTR(read(fds[0], &b, sizeof(b)));
+    close(fds[0]);
+    syscall(__NR_exit);
+  }
+  close(fds[0]);
+
+  LinuxDumper dumper(child);
+  ASSERT_TRUE(dumper.Init());
+  const wasteful_vector<MappingInfo*> mappings = dumper.mappings();
+  bool found_exe = false;
+  unsigned i;
+  for (i = 0; i < mappings.size(); ++i) {
+    const MappingInfo* mapping = mappings[i];
+    if (!strcmp(mapping->name, exe_name)) {
+      found_exe = true;
+      break;
+    }
+  }
+  ASSERT_TRUE(found_exe);
+
+  uint8_t identifier1[sizeof(MDGUID)];
+  uint8_t identifier2[sizeof(MDGUID)];
+  EXPECT_TRUE(dumper.ElfFileIdentifierForMapping(i, identifier1));
+  FileID fileid(exe_name);
+  EXPECT_TRUE(fileid.ElfFileIdentifier(identifier2));
+  char identifier_string1[37];
+  char identifier_string2[37];
+  FileID::ConvertIdentifierToString(identifier1, identifier_string1,
+                                    37);
+  FileID::ConvertIdentifierToString(identifier2, identifier_string2,
+                                    37);
+  EXPECT_STREQ(identifier_string1, identifier_string2);
+  close(fds[1]);
+}

src/client/linux/minidump_writer/minidump_writer.cc

@@ -547,26 +547,11 @@ class MinidumpWriter {
       const uint32_t cv_signature = MD_CVINFOPDB70_SIGNATURE;
       memcpy(cv_ptr, &cv_signature, sizeof(cv_signature));
       cv_ptr += sizeof(cv_signature);
-
-      {
-        // We XOR the first page of the file to get a signature for it.
-        uint8_t xor_buf[sizeof(MDGUID)];
-        size_t done = 0;
-        uint8_t* signature = cv_ptr;
-        cv_ptr += sizeof(xor_buf);
-
-        my_memset(signature, 0, sizeof(xor_buf));
-        while (done < 4096) {
-          dumper_.CopyFromProcess(xor_buf, crashing_tid_,
-                                  (void *) (mod.base_of_image + done),
-                                  sizeof(xor_buf));
-          for (unsigned i = 0; i < sizeof(xor_buf); ++i)
-            signature[i] ^= xor_buf[i];
-          done += sizeof(xor_buf);
-        }
-        my_memset(cv_ptr, 0, sizeof(uint32_t));  // Set age to 0 on Linux.
-        cv_ptr += sizeof(uint32_t);
-      }
+      uint8_t* signature = cv_ptr;
+      cv_ptr += sizeof(MDGUID);
+      dumper_.ElfFileIdentifierForMapping(i, signature);
+      my_memset(cv_ptr, 0, sizeof(uint32_t));  // Set age to 0 on Linux.
+      cv_ptr += sizeof(uint32_t);
 
       // Write pdb_file_name
       memcpy(cv_ptr, filename_ptr, filename_len + 1);