Fix offsets when shared lib split across maps.

The linker was modified so that a shared library has a read-only
map, then a read-execute map to represent the whole shared library.
When backtraces are created, then the offsets are set incorrectly
for backtraces. For example, all backtraces wind up with an offset now,
and a shared library loaded out of an apk shows the wrong offset.

Changes:
- Fix the FormatFrame function which was putting the offset before the
  map name.
- Refactor the Maps and MapInfo classes to keep track of the previous map
  instead of all maps. This was the only map that was ever needed.
- Modify the unwind_for_offline tool to capture both the read-only and
  read-execute map when using the read-only segment option.

Bug: 120981155

Test: Updated unit tests pass.
Test: Unwinds on device don't show the offsets everywhere any more.
Change-Id: I75b3727221be9c20316dfdcd7a1c6d242d7ce948
diff --git a/libunwindstack/tests/UnwindOfflineTest.cpp b/libunwindstack/tests/UnwindOfflineTest.cpp
index dc015b4..aab9ec2 100644
--- a/libunwindstack/tests/UnwindOfflineTest.cpp
+++ b/libunwindstack/tests/UnwindOfflineTest.cpp
@@ -298,7 +298,7 @@
   EXPECT_EQ(
       "  #00 pc 00068fb8  libarttestd.so (_ZN3artL13CauseSegfaultEv+72)\n"
       "  #01 pc 00067f00  libarttestd.so (Java_Main_unwindInProcess+10032)\n"
-      "  #02 pc 000021a8 (offset 0x2000)  137-cfi.odex (boolean Main.unwindInProcess(boolean, int, "
+      "  #02 pc 000021a8  137-cfi.odex (offset 0x2000) (boolean Main.unwindInProcess(boolean, int, "
       "boolean)+136)\n"
       "  #03 pc 0000fe80  anonymous:ee74c000 (boolean Main.bar(boolean)+64)\n"
       "  #04 pc 006ad4d2  libartd.so (art_quick_invoke_stub+338)\n"
@@ -591,7 +591,7 @@
   ASSERT_EQ(76U, unwinder.NumFrames()) << "Unwind:\n" << frame_info;
   EXPECT_EQ(
       "  #00 pc 00018a5e  libarttestd.so (Java_Main_unwindInProcess+866)\n"
-      "  #01 pc 0000212d (offset 0x2000)  137-cfi.odex (boolean Main.unwindInProcess(boolean, int, "
+      "  #01 pc 0000212d  137-cfi.odex (offset 0x2000) (boolean Main.unwindInProcess(boolean, int, "
       "boolean)+92)\n"
       "  #02 pc 00011cb1  anonymous:e2796000 (boolean Main.bar(boolean)+72)\n"
       "  #03 pc 00462175  libartd.so (art_quick_invoke_stub_internal+68)\n"
@@ -1135,29 +1135,29 @@
   std::string frame_info(DumpFrames(unwinder));
   ASSERT_EQ(19U, unwinder.NumFrames()) << "Unwind:\n" << frame_info;
   EXPECT_EQ(
-      "  #00 pc 0032bfa0 (offset 0x42000)  libunwindstack_test (SignalInnerFunction+40)\n"
-      "  #01 pc 0032bfeb (offset 0x42000)  libunwindstack_test (SignalMiddleFunction+2)\n"
-      "  #02 pc 0032bff3 (offset 0x42000)  libunwindstack_test (SignalOuterFunction+2)\n"
-      "  #03 pc 0032fed3 (offset 0x42000)  libunwindstack_test "
+      "  #00 pc 0032bfa0  libunwindstack_test (SignalInnerFunction+40)\n"
+      "  #01 pc 0032bfeb  libunwindstack_test (SignalMiddleFunction+2)\n"
+      "  #02 pc 0032bff3  libunwindstack_test (SignalOuterFunction+2)\n"
+      "  #03 pc 0032fed3  libunwindstack_test "
       "(_ZN11unwindstackL19SignalCallerHandlerEiP7siginfoPv+26)\n"
-      "  #04 pc 00026528 (offset 0x25000)  libc.so\n"
+      "  #04 pc 00026528  libc.so\n"
       "  #05 pc 00000000  <unknown>\n"
-      "  #06 pc 0032c2d9 (offset 0x42000)  libunwindstack_test (InnerFunction+736)\n"
-      "  #07 pc 0032cc4f (offset 0x42000)  libunwindstack_test (MiddleFunction+42)\n"
-      "  #08 pc 0032cc81 (offset 0x42000)  libunwindstack_test (OuterFunction+42)\n"
-      "  #09 pc 0032e547 (offset 0x42000)  libunwindstack_test "
+      "  #06 pc 0032c2d9  libunwindstack_test (InnerFunction+736)\n"
+      "  #07 pc 0032cc4f  libunwindstack_test (MiddleFunction+42)\n"
+      "  #08 pc 0032cc81  libunwindstack_test (OuterFunction+42)\n"
+      "  #09 pc 0032e547  libunwindstack_test "
       "(_ZN11unwindstackL19RemoteThroughSignalEij+270)\n"
-      "  #10 pc 0032ed99 (offset 0x42000)  libunwindstack_test "
+      "  #10 pc 0032ed99  libunwindstack_test "
       "(_ZN11unwindstack55UnwindTest_remote_through_signal_with_invalid_func_Test8TestBodyEv+16)\n"
-      "  #11 pc 00354453 (offset 0x42000)  libunwindstack_test (_ZN7testing4Test3RunEv+154)\n"
-      "  #12 pc 00354de7 (offset 0x42000)  libunwindstack_test (_ZN7testing8TestInfo3RunEv+194)\n"
-      "  #13 pc 00355105 (offset 0x42000)  libunwindstack_test (_ZN7testing8TestCase3RunEv+180)\n"
-      "  #14 pc 0035a215 (offset 0x42000)  libunwindstack_test "
+      "  #11 pc 00354453  libunwindstack_test (_ZN7testing4Test3RunEv+154)\n"
+      "  #12 pc 00354de7  libunwindstack_test (_ZN7testing8TestInfo3RunEv+194)\n"
+      "  #13 pc 00355105  libunwindstack_test (_ZN7testing8TestCase3RunEv+180)\n"
+      "  #14 pc 0035a215  libunwindstack_test "
       "(_ZN7testing8internal12UnitTestImpl11RunAllTestsEv+664)\n"
-      "  #15 pc 00359f4f (offset 0x42000)  libunwindstack_test (_ZN7testing8UnitTest3RunEv+110)\n"
-      "  #16 pc 0034d3db (offset 0x42000)  libunwindstack_test (main+38)\n"
-      "  #17 pc 00092c0d (offset 0x25000)  libc.so (__libc_init+48)\n"
-      "  #18 pc 0004202f (offset 0x42000)  libunwindstack_test (_start_main+38)\n",
+      "  #15 pc 00359f4f  libunwindstack_test (_ZN7testing8UnitTest3RunEv+110)\n"
+      "  #16 pc 0034d3db  libunwindstack_test (main+38)\n"
+      "  #17 pc 00092c0d  libc.so (__libc_init+48)\n"
+      "  #18 pc 0004202f  libunwindstack_test (_start_main+38)\n",
       frame_info);
 
   EXPECT_EQ(0x2e55fa0U, unwinder.frames()[0].pc);
@@ -1248,14 +1248,14 @@
   std::string frame_info(DumpFrames(unwinder));
   ASSERT_EQ(7U, unwinder.NumFrames()) << "Unwind:\n" << frame_info;
   EXPECT_EQ(
-      "  #00 pc 000000000014ccbc (offset 0x39000)  linker64 (__dl_syscall+28)\n"
-      "  #01 pc 000000000005426c (offset 0x39000)  linker64 "
+      "  #00 pc 000000000014ccbc  linker64 (__dl_syscall+28)\n"
+      "  #01 pc 000000000005426c  linker64 "
       "(__dl__ZL24debuggerd_signal_handleriP7siginfoPv+1128)\n"
       "  #02 pc 00000000000008bc  vdso.so\n"
-      "  #03 pc 00000000000846f4 (offset 0x40000)  libc.so (abort+172)\n"
-      "  #04 pc 0000000000084ad4 (offset 0x40000)  libc.so (__assert2+36)\n"
-      "  #05 pc 000000000003d5b4 (offset 0x40000)  ANGLEPrebuilt.apk (ANGLEGetUtilityAPI+56)\n"
-      "  #06 pc 000000000007fe68 (offset 0x40000)  libc.so (__libc_init)\n",
+      "  #03 pc 00000000000846f4  libc.so (abort+172)\n"
+      "  #04 pc 0000000000084ad4  libc.so (__assert2+36)\n"
+      "  #05 pc 000000000003d5b4  ANGLEPrebuilt.apk (offset 0x4000) (ANGLEGetUtilityAPI+56)\n"
+      "  #06 pc 000000000007fe68  libc.so (__libc_init)\n",
       frame_info);
 
   EXPECT_EQ(0x7e82c4fcbcULL, unwinder.frames()[0].pc);
@@ -1287,14 +1287,14 @@
   std::string frame_info(DumpFrames(unwinder));
   ASSERT_EQ(7U, unwinder.NumFrames()) << "Unwind:\n" << frame_info;
   EXPECT_EQ(
-      "  #00 pc 000000000014ccbc (offset 0x39000)  linker64 (__dl_syscall+28)\n"
-      "  #01 pc 000000000005426c (offset 0x39000)  linker64 "
+      "  #00 pc 000000000014ccbc  linker64 (__dl_syscall+28)\n"
+      "  #01 pc 000000000005426c  linker64 "
       "(__dl__ZL24debuggerd_signal_handleriP7siginfoPv+1128)\n"
       "  #02 pc 00000000000008bc  vdso.so\n"
-      "  #03 pc 00000000000846f4 (offset 0x40000)  libc.so (abort+172)\n"
-      "  #04 pc 0000000000084ad4 (offset 0x40000)  libc.so (__assert2+36)\n"
-      "  #05 pc 000000000003d5b4 (offset 0x2211000)  ANGLEPrebuilt.apk\n"
-      "  #06 pc 000000000007fe68 (offset 0x40000)  libc.so (__libc_init)\n",
+      "  #03 pc 00000000000846f4  libc.so (abort+172)\n"
+      "  #04 pc 0000000000084ad4  libc.so (__assert2+36)\n"
+      "  #05 pc 000000000003d5b4  ANGLEPrebuilt.apk (offset 0x21d5000)\n"
+      "  #06 pc 000000000007fe68  libc.so (__libc_init)\n",
       frame_info);
 
   EXPECT_EQ(0x7e82c4fcbcULL, unwinder.frames()[0].pc);