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

9 files changed, 283 insertions, 36 deletions

diff --git a/src/client/linux/Makefile b/src/client/linux/Makefile
index 6f1c24f5..9116fe6f 100644
--- a/src/client/linux/Makefile
+++ b/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))
diff --git a/src/client/linux/minidump_writer/linux_dumper.cc b/src/client/linux/minidump_writer/linux_dumper.cc
index 28729b34..d752608d 100644
--- a/src/client/linux/minidump_writer/linux_dumper.cc
+++ b/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];
diff --git a/src/client/linux/minidump_writer/linux_dumper.h b/src/client/linux/minidump_writer/linux_dumper.h
index d8e5e783..3e8869b5 100644
--- a/src/client/linux/minidump_writer/linux_dumper.h
+++ b/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
diff --git a/src/client/linux/minidump_writer/linux_dumper_unittest.cc b/src/client/linux/minidump_writer/linux_dumper_unittest.cc
index f5ed914b..e060e53e 100644
--- a/src/client/linux/minidump_writer/linux_dumper_unittest.cc
+++ b/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]);
+}
diff --git a/src/client/linux/minidump_writer/minidump_writer.cc b/src/client/linux/minidump_writer/minidump_writer.cc
index 09f23723..166b8e5c 100644
--- a/src/client/linux/minidump_writer/minidump_writer.cc
+++ b/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);
diff --git a/src/common/linux/file_id.cc b/src/common/linux/file_id.cc
index 34c9e508..8fae273a 100644
--- a/src/common/linux/file_id.cc
+++ b/src/common/linux/file_id.cc
@@ -33,6 +33,8 @@
 //
 
 #include "common/linux/file_id.h"
+#include "common/linux/linux_libc_support.h"
+#include "common/linux/linux_syscall_support.h"
 
 #include <arpa/inet.h>
 #include <elf.h>
@@ -42,6 +44,7 @@
 #include <sys/mman.h>
 #include <unistd.h>
 
+#include <algorithm>
 #include <cassert>
 #include <cstdio>
 
@@ -51,33 +54,94 @@ FileID::FileID(const char* path) {
   strncpy(path_, path, sizeof(path_));
 }
 
+// These two functions are also used inside the crashed process, so be safe
+// and use the syscall/libc wrappers instead of direct syscalls or libc.
+  static bool FindElfTextSection(const void *elf_mapped_base,
+                                 const void **text_start,
+                                 int *text_size) {
+  assert(elf_mapped_base);
+  assert(text_start);
+  assert(text_size);
+
+  const char* elf_base =
+    static_cast<const char*>(elf_mapped_base);
+  const ElfW(Ehdr)* elf_header =
+    reinterpret_cast<const ElfW(Ehdr)*>(elf_base);
+  if (my_strncmp(elf_base, ELFMAG, SELFMAG) != 0)
+    return false;
+#if __ELF_NATIVE_CLASS == 32
+#define ELFCLASS ELFCLASS32
+#else
+#define ELFCLASS ELFCLASS64
+#endif
+  //TODO: support dumping 32-bit binaries from a 64-bit dump_syms?
+  if (elf_header->e_ident[EI_CLASS] != ELFCLASS)
+    return false;
+  *text_start = NULL;
+  *text_size = 0;
+  const ElfW(Shdr)* sections =
+    reinterpret_cast<const ElfW(Shdr)*>(elf_base + elf_header->e_shoff);
+  const char* text_section_name = ".text";
+  int name_len = my_strlen(text_section_name);
+  const ElfW(Shdr)* string_section = sections + elf_header->e_shstrndx;
+  const ElfW(Shdr)* text_section = NULL;
+  for (int i = 0; i < elf_header->e_shnum; ++i) {
+    if (sections[i].sh_type == SHT_PROGBITS) {
+      const char* section_name = (char*)(elf_base +
+                                         string_section->sh_offset +
+                                         sections[i].sh_name);
+      if (!my_strncmp(section_name, text_section_name, name_len)) {
+        text_section = &sections[i];
+        break;
+      }
+    }
+  }
+  if (text_section != NULL && text_section->sh_size > 0) {
+    *text_start = elf_base + text_section->sh_offset;
+    *text_size = text_section->sh_size;
+  }
+  return true;
+}
+
+// static
+bool FileID::ElfFileIdentifierFromMappedFile(void* base,
+                                             uint8_t identifier[kMDGUIDSize])
+{
+  const void* text_section = NULL;
+  int text_size = 0;
+  bool success = false;
+  if (FindElfTextSection(base, &text_section, &text_size) && (text_size > 0)) {
+    my_memset(identifier, 0, kMDGUIDSize);
+    const uint8_t* ptr = reinterpret_cast<const uint8_t*>(text_section);
+    const uint8_t* ptr_end = ptr + std::min(text_size, 4096);
+    while (ptr < ptr_end) {
+      for (unsigned i = 0; i < kMDGUIDSize; i++)
+        identifier[i] ^= ptr[i];
+      ptr += kMDGUIDSize;
+    }
+    success = true;
+  }
+  return success;
+}
+
 bool FileID::ElfFileIdentifier(uint8_t identifier[kMDGUIDSize]) {
-  const ssize_t mapped_len = 4096;  // Page size (matches WriteMappings())
   int fd = open(path_, O_RDONLY);
   if (fd < 0)
     return false;
   struct stat st;
-  if (fstat(fd, &st) != 0 || st.st_size <= mapped_len) {
+  if (fstat(fd, &st) != 0) {
     close(fd);
     return false;
   }
-  void* base = mmap(NULL, mapped_len,
+  void* base = mmap(NULL, st.st_size,
                     PROT_READ | PROT_WRITE, MAP_PRIVATE, fd, 0);
   close(fd);
   if (base == MAP_FAILED)
     return false;
 
-  memset(identifier, 0, kMDGUIDSize);
-  uint8_t* ptr = reinterpret_cast<uint8_t*>(base);
-  uint8_t* ptr_end = ptr + mapped_len;
-  while (ptr < ptr_end) {
-    for (unsigned i = 0; i < kMDGUIDSize; i++)
-      identifier[i] ^= ptr[i];
-    ptr += kMDGUIDSize;
-  }
-
-  munmap(base, mapped_len);
-  return true;
+  bool success = ElfFileIdentifierFromMappedFile(base, identifier);
+  munmap(base, st.st_size);
+  return success;
 }
 
 // static
diff --git a/src/common/linux/file_id.h b/src/common/linux/file_id.h
index 31bb5e4a..2cd4953e 100644
--- a/src/common/linux/file_id.h
+++ b/src/common/linux/file_id.h
@@ -49,10 +49,16 @@ class FileID {
   // Load the identifier for the elf file path specified in the constructor into
   // |identifier|.  Return false if the identifier could not be created for the
   // file.
-  // The current implementation will XOR the first page of data to generate an
-  // identifier.
+  // The current implementation will XOR the first 4096 bytes of the
+  // .text section to generate an identifier.
   bool ElfFileIdentifier(uint8_t identifier[kMDGUIDSize]);
 
+  // Load the identifier for the elf file mapped into memory at |base| into
+  // |identifier|.  Return false if the identifier could not be created for the
+  // file.
+  static bool ElfFileIdentifierFromMappedFile(void* base,
+                                              uint8_t identifier[kMDGUIDSize]);
+
   // Convert the |identifier| data to a NULL terminated string.  The string will
   // be formatted as a UUID (e.g., 22F065BB-FC9C-49F7-80FE-26A7CEBD7BCE).
   // The |buffer| should be at least 37 bytes long to receive all of the data
diff --git a/src/common/linux/file_id_unittest.cc b/src/common/linux/file_id_unittest.cc
new file mode 100644
index 00000000..e15d39fb
--- /dev/null
+++ b/src/common/linux/file_id_unittest.cc
@@ -0,0 +1,76 @@
+// Copyright (c) 2009, Google Inc.
+// All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+// Unit tests for FileID
+
+#include <stdlib.h>
+
+#include "common/linux/file_id.h"
+#include "breakpad_googletest_includes.h"
+
+using namespace google_breakpad;
+
+
+namespace {
+typedef testing::Test FileIDTest;
+}
+
+TEST(FileIDTest, FileIDStrip) {
+  // Calculate the File ID of our binary using
+  // FileID::ElfFileIdentifier, then make a copy of our binary,
+  // strip it, and ensure that we still get the same result.
+  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';
+
+  // copy our binary to a temp file, and strip it
+  char templ[] = "/tmp/file-id-unittest-XXXXXX";
+  mktemp(templ);
+  char cmdline[4096];
+  sprintf(cmdline, "cp \"%s\" \"%s\"", exe_name, templ);
+  ASSERT_EQ(system(cmdline), 0);
+  sprintf(cmdline, "strip \"%s\"", templ);
+  ASSERT_EQ(system(cmdline), 0);
+
+  uint8_t identifier1[sizeof(MDGUID)];
+  uint8_t identifier2[sizeof(MDGUID)];
+  FileID fileid1(exe_name);
+  EXPECT_TRUE(fileid1.ElfFileIdentifier(identifier1));
+  FileID fileid2(templ);
+  EXPECT_TRUE(fileid2.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);
+  unlink(templ);
+}
diff --git a/src/tools/linux/dump_syms/Makefile b/src/tools/linux/dump_syms/Makefile
index a0424c05..94871da7 100644
--- a/src/tools/linux/dump_syms/Makefile
+++ b/src/tools/linux/dump_syms/Makefile
@@ -113,6 +113,22 @@ stabs_reader_unittest.o: override CPPFLAGS += $(GTEST_CPPFLAGS) \
 clean::
 	rm -f stabs_reader_unittest
 
+### Unit tests for google_breakpad::FileID.
+check: check-file_id_unittest
+check-file_id_unittest: file_id_unittest
+file_id_unittest:				\
+	gmock-all.o				\
+	gtest-all.o				\
+	gtest_main.o				\
+	file_id.o				\
+	$(empty)
+CPP_EXECUTABLES += file_id_unittest
+file_id_unittest.o: file_id_unittest.cc
+file_id_unittest.o: override CPPFLAGS += $(GTEST_CPPFLAGS) \
+				         $(GMOCK_CPPFLAGS)
+clean::
+	rm -f file_id_unittest
+
 
 ### Generic compilation rules.