commit f5917f499a625a24b8de511ad2708b30202f6f5f
author Christopher Ferris <cferris@google.com> Wed Apr 03 14:14:30 2019 -0700
committer Christopher Ferris <cferris@google.com> Thu Apr 04 09:26:28 2019 -0700
tree da3b8024c90244fbe20d28de100344d62c159bc7
parent e93ebdf9feaa52214c06cc032a64df9875d1351f

Fix off by one reading build id.

Update unit tests and add new build id displaying in offline unwinds.

Bug: 129873279

Test: All unit tests pass.
Test: Verify that debuggerd displays build id properly.
Change-Id: I97f4a204842447a20c812f535a458155b937d5e1
Merged-In: I97f4a204842447a20c812f535a458155b937d5e1
(cherry picked from commit 1760b45709df4d925c3a131db0b443b585837703)

libunwindstack/ElfInterface.cpp

diff --git a/libunwindstack/ElfInterface.cpp b/libunwindstack/ElfInterface.cpp
index e09a2ae..32c637f 100644
--- a/libunwindstack/ElfInterface.cpp
+++ b/libunwindstack/ElfInterface.cpp
@@ -285,7 +285,7 @@
         if (gnu_build_id_size_ - offset < hdr.n_descsz || hdr.n_descsz == 0) {
           return "";
         }
-        std::string build_id(hdr.n_descsz - 1, '\0');
+        std::string build_id(hdr.n_descsz, '\0');
         if (memory_->ReadFully(gnu_build_id_offset_ + offset, &build_id[0], hdr.n_descsz)) {
           return build_id;
         }

libunwindstack/tests/ElfInterfaceTest.cpp

diff --git a/libunwindstack/tests/ElfInterfaceTest.cpp b/libunwindstack/tests/ElfInterfaceTest.cpp
index d895863..cdc927a 100644
--- a/libunwindstack/tests/ElfInterfaceTest.cpp
+++ b/libunwindstack/tests/ElfInterfaceTest.cpp
@@ -1192,14 +1192,16 @@
   char note_section[128];
   Nhdr note_header = {};
   note_header.n_namesz = 4;  // "GNU"
-  note_header.n_descsz = 8; // "BUILDID"
+  note_header.n_descsz = 7;  // "BUILDID"
   note_header.n_type = NT_GNU_BUILD_ID;
   memcpy(&note_section, &note_header, sizeof(note_header));
   size_t note_offset = sizeof(note_header);
+  // The note information contains the GNU and trailing '\0'.
   memcpy(&note_section[note_offset], "GNU", sizeof("GNU"));
   note_offset += sizeof("GNU");
-  memcpy(&note_section[note_offset], "BUILDID", sizeof("BUILDID"));
-  note_offset += sizeof("BUILDID");
+  // This part of the note does not contain any trailing '\0'.
+  memcpy(&note_section[note_offset], "BUILDID", 7);
+  note_offset += 8;
 
   Shdr shdr = {};
   shdr.sh_type = SHT_NOTE;
@@ -1244,24 +1246,27 @@
   char note_section[128];
   Nhdr note_header = {};
   note_header.n_namesz = 8;  // "WRONG" aligned to 4
-  note_header.n_descsz = 8; // "BUILDID"
+  note_header.n_descsz = 7;  // "BUILDID"
   note_header.n_type = NT_GNU_BUILD_ID;
   memcpy(&note_section, &note_header, sizeof(note_header));
   size_t note_offset = sizeof(note_header);
   memcpy(&note_section[note_offset], "WRONG", sizeof("WRONG"));
   note_offset += 8;
-  memcpy(&note_section[note_offset], "BUILDID", sizeof("BUILDID"));
-  note_offset += sizeof("BUILDID");
+  // This part of the note does not contain any trailing '\0'.
+  memcpy(&note_section[note_offset], "BUILDID", 7);
+  note_offset += 8;
 
   note_header.n_namesz = 4;  // "GNU"
-  note_header.n_descsz = 8; // "BUILDID"
+  note_header.n_descsz = 7;  // "BUILDID"
   note_header.n_type = NT_GNU_BUILD_ID;
   memcpy(&note_section[note_offset], &note_header, sizeof(note_header));
   note_offset += sizeof(note_header);
+  // The note information contains the GNU and trailing '\0'.
   memcpy(&note_section[note_offset], "GNU", sizeof("GNU"));
   note_offset += sizeof("GNU");
-  memcpy(&note_section[note_offset], "BUILDID", sizeof("BUILDID"));
-  note_offset += sizeof("BUILDID");
+  // This part of the note does not contain any trailing '\0'.
+  memcpy(&note_section[note_offset], "BUILDID", 7);
+  note_offset += 8;
 
   Shdr shdr = {};
   shdr.sh_type = SHT_NOTE;
@@ -1306,14 +1311,16 @@
   char note_section[128];
   Nhdr note_header = {};
   note_header.n_namesz = 4;  // "GNU"
-  note_header.n_descsz = 8; // "BUILDID"
+  note_header.n_descsz = 7;  // "BUILDID"
   note_header.n_type = NT_GNU_BUILD_ID;
   memcpy(&note_section, &note_header, sizeof(note_header));
   size_t note_offset = sizeof(note_header);
+  // The note information contains the GNU and trailing '\0'.
   memcpy(&note_section[note_offset], "GNU", sizeof("GNU"));
   note_offset += sizeof("GNU");
-  memcpy(&note_section[note_offset], "BUILDID", sizeof("BUILDID"));
-  note_offset += sizeof("BUILDID");
+  // This part of the note does not contain any trailing '\0'.
+  memcpy(&note_section[note_offset], "BUILDID", 7);
+  note_offset += 8;
 
   Shdr shdr = {};
   shdr.sh_type = SHT_NOTE;
@@ -1358,14 +1365,16 @@
   char note_section[128];
   Nhdr note_header = {};
   note_header.n_namesz = 4;  // "GNU"
-  note_header.n_descsz = 8; // "BUILDID"
+  note_header.n_descsz = 7;  // "BUILDID"
   note_header.n_type = NT_GNU_BUILD_ID;
   memcpy(&note_section, &note_header, sizeof(note_header));
   size_t note_offset = sizeof(note_header);
+  // The note information contains the GNU and trailing '\0'.
   memcpy(&note_section[note_offset], "GNU", sizeof("GNU"));
   note_offset += sizeof("GNU");
-  memcpy(&note_section[note_offset], "BUILDID", sizeof("BUILDID"));
-  note_offset += sizeof("BUILDID");
+  // This part of the note does not contain any trailing '\0'.
+  memcpy(&note_section[note_offset], "BUILDID", 7);
+  note_offset += 8;
 
   Shdr shdr = {};
   shdr.sh_type = SHT_NOTE;
@@ -1410,14 +1419,16 @@
   char note_section[128];
   Nhdr note_header = {};
   note_header.n_namesz = 4;  // "GNU"
-  note_header.n_descsz = 8; // "BUILDID"
+  note_header.n_descsz = 7;  // "BUILDID"
   note_header.n_type = NT_GNU_BUILD_ID;
   memcpy(&note_section, &note_header, sizeof(note_header));
   size_t note_offset = sizeof(note_header);
+  // The note information contains the GNU and trailing '\0'.
   memcpy(&note_section[note_offset], "GNU", sizeof("GNU"));
   note_offset += sizeof("GNU");
-  memcpy(&note_section[note_offset], "BUILDID", sizeof("BUILDID"));
-  note_offset += sizeof("BUILDID");
+  // This part of the note does not contain any trailing '\0'.
+  memcpy(&note_section[note_offset], "BUILDID", 7);
+  note_offset += 8;
 
   Shdr shdr = {};
   shdr.sh_type = SHT_NOTE;

libunwindstack/tests/UnwindOfflineTest.cpp

diff --git a/libunwindstack/tests/UnwindOfflineTest.cpp b/libunwindstack/tests/UnwindOfflineTest.cpp
index 0867561..e3c646a 100644
--- a/libunwindstack/tests/UnwindOfflineTest.cpp
+++ b/libunwindstack/tests/UnwindOfflineTest.cpp
@@ -204,6 +204,7 @@
 TEST_F(UnwindOfflineTest, pc_straddle_arm) {
   ASSERT_NO_FATAL_FAILURE(Init("straddle_arm/", ARCH_ARM));
 
+  std::unique_ptr<Regs> regs_copy(regs_->Clone());
   Unwinder unwinder(128, maps_.get(), regs_.get(), process_memory_);
   unwinder.Unwind();
 
@@ -223,6 +224,22 @@
   EXPECT_EQ(0xe9c86730U, unwinder.frames()[2].sp);
   EXPECT_EQ(0xf3367147U, unwinder.frames()[3].pc);
   EXPECT_EQ(0xe9c86778U, unwinder.frames()[3].sp);
+
+  // Display build ids now.
+  unwinder.SetRegs(regs_copy.get());
+  unwinder.SetDisplayBuildID(true);
+  unwinder.Unwind();
+
+  frame_info = DumpFrames(unwinder);
+  ASSERT_EQ(4U, unwinder.NumFrames()) << "Unwind:\n" << frame_info;
+  EXPECT_EQ(
+      "  #00 pc 0001a9f8  libc.so (abort+64) (BuildId: 2dd0d4ba881322a0edabeed94808048c)\n"
+      "  #01 pc 00006a1b  libbase.so (android::base::DefaultAborter(char const*)+6) (BuildId: "
+      "ed43842c239cac1a618e600ea91c4cbd)\n"
+      "  #02 pc 00007441  libbase.so (android::base::LogMessage::~LogMessage()+748) (BuildId: "
+      "ed43842c239cac1a618e600ea91c4cbd)\n"
+      "  #03 pc 00015147  /does/not/exist/libhidlbase.so\n",
+      frame_info);
 }
 
 TEST_F(UnwindOfflineTest, pc_in_gnu_debugdata_arm) {