libdw: Parse DWARF package file index sections

The .debug_cu_index and .debug_tu_index sections in DWARF package files
are basically hash tables mapping a unit's 8 byte signature to an offset
and size in each section used by that unit [1].  Add support for parsing
and doing lookups in the index sections.

We look up a unit in the index when we intern it and cache its hash
table row in Dwarf_CU.  Then, a new function, dwarf_cu_dwp_section_info,
can be used to look up the section offsets and sizes for a unit.  This
will mostly be used internally in libdw, but it will also be needed in
static inline functions shared with eu-readelf.  Additionally, making it
public it makes dwp support much easier for external tools that do their
own low-level parsing of DWARF information, like drgn [2].

1: https://gcc.gnu.org/wiki/DebugFissionDWP#Format_of_the_CU_and_TU_Index_Sections
2: https://github.com/osandov/drgn

	* libdw/dwarf.h: Add DW_SECT_TYPES.
	* libdw/libdwP.h (Dwarf): Add cu_index and tu_index.
	(Dwarf_CU): Add dwp_row.
	(Dwarf_Package_Index): New type.
	(__libdw_dwp_find_unit): New declaration.
	(dwarf_cu_dwp_section_info): New INTDECL.
	Add DWARF_E_UNKNOWN_SECTION.
	* libdw/Makefile.am (libdw_a_SOURCES): Add
	dwarf_cu_dwp_section_info.c.
	* libdw/dwarf_end.c (dwarf_end): Free dwarf->cu_index and
	dwarf->tu_index.
	* libdw/dwarf_error.c (errmsgs): Add DWARF_E_UNKNOWN_SECTION.
	* libdw/libdw.h (dwarf_cu_dwp_section_info): New declaration.
	* libdw/libdw.map (ELFUTILS_0.190): Add
	dwarf_cu_dwp_section_info.
	* libdw/libdw_findcu.c (__libdw_intern_next_unit): Call
	__libdw_dwp_find_unit, and use it to adjust abbrev_offset and
	assign newp->dwp_row.
	* libdw/dwarf_cu_dwp_section_info.c: New file.
	* tests/Makefile.am (check_PROGRAMS): Add cu-dwp-section-info.
	(TESTS): Add run-cu-dwp-section-info.sh
	(EXTRA_DIST): Add run-cu-dwp-section-info.sh and new test files.
	(cu_dwp_section_info_LDADD): New variable.
	* tests/cu-dwp-section-info.c: New test.
	* tests/run-cu-dwp-section-info.sh: New test.
	* tests/testfile-dwp-4-strict.bz2: New test file.
	* tests/testfile-dwp-4-strict.dwp.bz2: New test file.
	* tests/testfile-dwp-4.bz2: New test file.
	* tests/testfile-dwp-4.dwp.bz2: New test file.
	* tests/testfile-dwp-5.bz2: New test file.
	* tests/testfile-dwp-5.dwp.bz2: New test file.
	* tests/testfile-dwp.source: New file.

Signed-off-by: Omar Sandoval <[email protected]>

11 files changed, 352 insertions, 2 deletions

diff --git a/tests/.gitignore b/tests/.gitignore
index d00a883e..d38f0f9e 100644
--- a/tests/.gitignore
+++ b/tests/.gitignore
@@ -28,6 +28,7 @@
 /backtrace-dwarf
 /buildid
 /core-dump-backtrace.lock
+/cu-dwp-section-info
 /debugaltlink
 /debuginfod_build_id_find
 /debuglink
diff --git a/tests/Makefile.am b/tests/Makefile.am
index b075e3c3..d7c53144 100644
--- a/tests/Makefile.am
+++ b/tests/Makefile.am
@@ -63,6 +63,7 @@ check_PROGRAMS = arextract arsymtest newfile saridx scnnames sectiondump \
 		  getphdrnum leb128 read_unaligned \
 		  msg_tst system-elf-libelf-test system-elf-gelf-test \
 		  nvidia_extended_linemap_libdw elf-print-reloc-syms \
+		  cu-dwp-section-info \
 		  $(asm_TESTS)
 
 asm_TESTS = asm-tst1 asm-tst2 asm-tst3 asm-tst4 asm-tst5 \
@@ -212,7 +213,7 @@ TESTS = run-arextract.sh run-arsymtest.sh run-ar.sh newfile test-nlist \
 	$(asm_TESTS) run-disasm-bpf.sh run-low_high_pc-dw-form-indirect.sh \
 	run-nvidia-extended-linemap-libdw.sh run-nvidia-extended-linemap-readelf.sh \
 	run-readelf-dw-form-indirect.sh run-strip-largealign.sh \
-	run-readelf-Dd.sh run-dwfl-core-noncontig.sh
+	run-readelf-Dd.sh run-dwfl-core-noncontig.sh run-cu-dwp-section-info.sh
 
 if !BIARCH
 export ELFUTILS_DISABLE_BIARCH = 1
@@ -635,7 +636,11 @@ EXTRA_DIST = run-arextract.sh run-arsymtest.sh run-ar.sh \
 	     run-funcretval++11.sh \
 	     test-ar-duplicates.a.bz2 \
 	     run-dwfl-core-noncontig.sh testcore-noncontig.bz2 \
-	     testfile-dwarf5-line-clang.bz2
+	     testfile-dwarf5-line-clang.bz2 \
+	     testfile-dwp-4.bz2 testfile-dwp-4.dwp.bz2 \
+	     testfile-dwp-4-strict.bz2 testfile-dwp-4-strict.dwp.bz2 \
+	     testfile-dwp-5.bz2 testfile-dwp-5.dwp.bz2 testfile-dwp.source \
+	     run-cu-dwp-section-info.sh
 
 
 if USE_VALGRIND
@@ -812,6 +817,7 @@ leb128_LDADD = $(libelf) $(libdw)
 read_unaligned_LDADD = $(libelf) $(libdw)
 nvidia_extended_linemap_libdw_LDADD = $(libelf) $(libdw)
 elf_print_reloc_syms_LDADD = $(libelf)
+cu_dwp_section_info_LDADD = $(libdw)
 
 # We want to test the libelf headers against the system elf.h header.
 # Don't include any -I CPPFLAGS. Except when we install our own elf.h.
diff --git a/tests/cu-dwp-section-info.c b/tests/cu-dwp-section-info.c
new file mode 100644
index 00000000..f1756979
--- /dev/null
+++ b/tests/cu-dwp-section-info.c
@@ -0,0 +1,73 @@
+/* Test program for dwarf_cu_dwp_section_info
+   Copyright (c) 2023 Meta Platforms, Inc. and affiliates.
+   This file is part of elfutils.
+
+   This file is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   elfutils is distributed in the hope that it will be useful, but
+   WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+#ifdef HAVE_CONFIG_H
+# include <config.h>
+#endif
+#include <stdio.h>
+#include <inttypes.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <unistd.h>
+
+#include <dwarf.h>
+#include ELFUTILS_HEADER(dw)
+
+int
+main (int argc, char *argv[])
+{
+  for (int i = 1; i < argc; i++)
+    {
+      printf ("file: %s\n", argv[i]);
+      int fd = open (argv[i], O_RDONLY);
+      Dwarf *dbg = dwarf_begin (fd, DWARF_C_READ);
+      if (dbg == NULL)
+	{
+	  printf ("%s not usable: %s\n", argv[i], dwarf_errmsg (-1));
+	  return -1;
+	}
+
+      Dwarf_CU *cu = NULL;
+      while (dwarf_get_units (dbg, cu, &cu, NULL, NULL, NULL, NULL) == 0)
+	{
+#define SECTION_INFO(section) do {					\
+	    printf (#section ": ");					\
+	    Dwarf_Off offset, size;					\
+	    if (dwarf_cu_dwp_section_info (cu, DW_SECT_##section,	\
+					   &offset, &size) == 0)	\
+	      printf ("0x%" PRIx64 " 0x%" PRIx64 "\n", offset, size);	\
+	    else							\
+	      printf ("%s\n", dwarf_errmsg (-1));			\
+	  } while (0)
+	  SECTION_INFO (INFO);
+	  SECTION_INFO (TYPES);
+	  SECTION_INFO (ABBREV);
+	  SECTION_INFO (LINE);
+	  SECTION_INFO (LOCLISTS);
+	  SECTION_INFO (STR_OFFSETS);
+	  SECTION_INFO (MACRO);
+	  SECTION_INFO (RNGLISTS);
+	  printf ("\n");
+	}
+
+      dwarf_end (dbg);
+      close (fd);
+    }
+
+  return 0;
+}
diff --git a/tests/run-cu-dwp-section-info.sh b/tests/run-cu-dwp-section-info.sh
new file mode 100755
index 00000000..202319c6
--- /dev/null
+++ b/tests/run-cu-dwp-section-info.sh
@@ -0,0 +1,168 @@
+#! /bin/sh
+# Copyright (c) 2023 Meta Platforms, Inc. and affiliates.
+# This file is part of elfutils.
+#
+# This file is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# elfutils is distributed in the hope that it will be useful, but
+# WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+. $srcdir/test-subr.sh
+
+# See testfile-dwp.source.
+testfiles testfile-dwp-5.dwp testfile-dwp-4.dwp testfile-dwp-4-strict.dwp
+
+testrun_compare ${abs_builddir}/cu-dwp-section-info testfile-dwp-5.dwp << EOF
+file: testfile-dwp-5.dwp
+INFO: 0x0 0x70
+TYPES: 0x0 0x0
+ABBREV: 0x0 0x160
+LINE: 0x0 0x7f
+LOCLISTS: 0x0 0xdb
+STR_OFFSETS: 0x0 0x75c
+MACRO: 0x0 0x6c6
+RNGLISTS: 0x0 0x22
+
+INFO: 0x70 0x108
+TYPES: 0x0 0x0
+ABBREV: 0x0 0x160
+LINE: 0x0 0x7f
+LOCLISTS: 0x0 0xdb
+STR_OFFSETS: 0x0 0x75c
+MACRO: 0x0 0x6c6
+RNGLISTS: 0x0 0x22
+
+INFO: 0x178 0x6e
+TYPES: 0x0 0x0
+ABBREV: 0x160 0xca
+LINE: 0x7f 0x7f
+LOCLISTS: 0x0 0x0
+STR_OFFSETS: 0x75c 0x758
+MACRO: 0x6c6 0x6c5
+RNGLISTS: 0x0 0x0
+
+INFO: 0x1e6 0x78
+TYPES: 0x0 0x0
+ABBREV: 0x160 0xca
+LINE: 0x7f 0x7f
+LOCLISTS: 0x0 0x0
+STR_OFFSETS: 0x75c 0x758
+MACRO: 0x6c6 0x6c5
+RNGLISTS: 0x0 0x0
+
+INFO: 0x25e 0x193
+TYPES: 0x0 0x0
+ABBREV: 0x22a 0x18a
+LINE: 0xfe 0x81
+LOCLISTS: 0xdb 0xc9
+STR_OFFSETS: 0xeb4 0x77c
+MACRO: 0xd8b 0x6c6
+RNGLISTS: 0x22 0x43
+
+EOF
+
+testrun_compare ${abs_builddir}/cu-dwp-section-info testfile-dwp-4.dwp << EOF
+file: testfile-dwp-4.dwp
+INFO: 0x0 0x11e
+TYPES: 0x0 0x0
+ABBREV: 0x0 0x172
+LINE: 0x0 0x52
+LOCLISTS: 0x0 0x11b
+STR_OFFSETS: 0x0 0x754
+MACRO: 0x0 0x6c7
+RNGLISTS: 0x0 0x0
+
+INFO: 0x11e 0x76
+TYPES: 0x0 0x0
+ABBREV: 0x172 0xd7
+LINE: 0x52 0x52
+LOCLISTS: 0x0 0x0
+STR_OFFSETS: 0x754 0x750
+MACRO: 0x6c7 0x6c6
+RNGLISTS: 0x0 0x0
+
+INFO: 0x194 0x1c5
+TYPES: 0x0 0x0
+ABBREV: 0x249 0x19e
+LINE: 0xa4 0x53
+LOCLISTS: 0x11b 0xf1
+STR_OFFSETS: 0xea4 0x774
+MACRO: 0xd8d 0x6c7
+RNGLISTS: 0x0 0x0
+
+INFO: 0x0 0x0
+TYPES: 0x0 0x6f
+ABBREV: 0x0 0x172
+LINE: 0x0 0x52
+LOCLISTS: 0x0 0x11b
+STR_OFFSETS: 0x0 0x754
+MACRO: 0x0 0x6c7
+RNGLISTS: 0x0 0x0
+
+INFO: 0x0 0x0
+TYPES: 0x6f 0x6d
+ABBREV: 0x172 0xd7
+LINE: 0x52 0x52
+LOCLISTS: 0x0 0x0
+STR_OFFSETS: 0x754 0x750
+MACRO: 0x6c7 0x6c6
+RNGLISTS: 0x0 0x0
+
+EOF
+
+testrun_compare ${abs_builddir}/cu-dwp-section-info testfile-dwp-4-strict.dwp << EOF
+file: testfile-dwp-4-strict.dwp
+INFO: 0x0 0x105
+TYPES: 0x0 0x0
+ABBREV: 0x0 0x15f
+LINE: 0x0 0x52
+LOCLISTS: 0x0 0xe2
+STR_OFFSETS: 0x0 0x24
+MACRO: 0x0 0x38e4
+RNGLISTS: 0x0 0x0
+
+INFO: 0x105 0x72
+TYPES: 0x0 0x0
+ABBREV: 0x15f 0xd3
+LINE: 0x52 0x52
+LOCLISTS: 0x0 0x0
+STR_OFFSETS: 0x24 0x20
+MACRO: 0x38e4 0x38db
+RNGLISTS: 0x0 0x0
+
+INFO: 0x177 0x17b
+TYPES: 0x0 0x0
+ABBREV: 0x232 0x157
+LINE: 0xa4 0x53
+LOCLISTS: 0xe2 0xb1
+STR_OFFSETS: 0x44 0x44
+MACRO: 0x71bf 0x38f5
+RNGLISTS: 0x0 0x0
+
+INFO: 0x0 0x0
+TYPES: 0x0 0x6e
+ABBREV: 0x0 0x15f
+LINE: 0x0 0x52
+LOCLISTS: 0x0 0xe2
+STR_OFFSETS: 0x0 0x24
+MACRO: 0x0 0x38e4
+RNGLISTS: 0x0 0x0
+
+INFO: 0x0 0x0
+TYPES: 0x6e 0x6b
+ABBREV: 0x15f 0xd3
+LINE: 0x52 0x52
+LOCLISTS: 0x0 0x0
+STR_OFFSETS: 0x24 0x20
+MACRO: 0x38e4 0x38db
+RNGLISTS: 0x0 0x0
+
+EOF
diff --git a/tests/testfile-dwp-4-strict.bz2 b/tests/testfile-dwp-4-strict.bz2
new file mode 100755
index 00000000..4f419c07
--- /dev/null
+++ b/tests/testfile-dwp-4-strict.bz2
diff --git a/tests/testfile-dwp-4-strict.dwp.bz2 b/tests/testfile-dwp-4-strict.dwp.bz2
new file mode 100644
index 00000000..8cc1bbe2
--- /dev/null
+++ b/tests/testfile-dwp-4-strict.dwp.bz2
diff --git a/tests/testfile-dwp-4.bz2 b/tests/testfile-dwp-4.bz2
new file mode 100755
index 00000000..ece5817b
--- /dev/null
+++ b/tests/testfile-dwp-4.bz2
diff --git a/tests/testfile-dwp-4.dwp.bz2 b/tests/testfile-dwp-4.dwp.bz2
new file mode 100644
index 00000000..1a63b42d
--- /dev/null
+++ b/tests/testfile-dwp-4.dwp.bz2
diff --git a/tests/testfile-dwp-5.bz2 b/tests/testfile-dwp-5.bz2
new file mode 100755
index 00000000..2c768eac
--- /dev/null
+++ b/tests/testfile-dwp-5.bz2
diff --git a/tests/testfile-dwp-5.dwp.bz2 b/tests/testfile-dwp-5.dwp.bz2
new file mode 100644
index 00000000..ba28e501
--- /dev/null
+++ b/tests/testfile-dwp-5.dwp.bz2
diff --git a/tests/testfile-dwp.source b/tests/testfile-dwp.source
new file mode 100644
index 00000000..b0b0a97c
--- /dev/null
+++ b/tests/testfile-dwp.source
@@ -0,0 +1,102 @@
+# Nonsensical program used to generate example DWARF package files with type
+# units, location lists, range lists, and macros.
+
+# = foobar.h =
+
+struct Foo
+{
+  int a, b;
+  int foo ();
+};
+
+struct Bar
+{
+  long a, b;
+  long bar ();
+};
+
+#define FROB(x) ((x) ^ 0x2a2a2a2a)
+#define FRY(x) ((x) * 0x100000001b3)
+
+inline long
+fibonacci (unsigned int n)
+{
+  if (n == 0)
+    return 0;
+  else
+    {
+      long a = 0;
+      long b = 1;
+      for (unsigned int i = 2; i < n; i++)
+	{
+	  long tmp = a + b;
+	  a = b;
+	  b = tmp;
+	}
+      return b;
+    }
+}
+
+# = foo.cc =
+
+#include "foobar.h"
+
+#define ZERO() (1 - 1)
+
+int
+x_x (int x)
+{
+  for (int i = x; i > ZERO(); i--)
+    x *= x;
+  return x;
+}
+
+int
+Foo::foo ()
+{
+  int x = a;
+  if (a > b)
+    x -= b;
+  return FROB (x_x (x));
+}
+
+# = bar.cc =
+
+#include "foobar.h"
+
+#define ONE 1
+
+long
+Bar::bar ()
+{
+  if (a == b)
+    return ONE;
+  else
+    return a > b ? b : a;
+}
+
+# = main.cc =
+
+#include "foobar.h"
+
+#define MAIN_ARGS int argc, char **argv
+
+int
+main(MAIN_ARGS)
+{
+  struct Foo myfoo { argc, FROB (argc) };
+  struct Bar mybar { fibonacci (argc), FRY (argc) };
+  return myfoo.foo() + mybar.bar();
+}
+
+# Built with GCC at commit 80048aa13a6b ("debug/111409 - don't generate COMDAT
+# macro sections for split DWARF").
+$ g++ -gdwarf-5 -gsplit-dwarf -fdebug-types-section -g3 -O2 foo.cc bar.cc main.cc -o testfile-dwp-5
+# GNU dwp as of binutils 2.41 only supports DWARF 4.
+$ llvm-dwp -e testfile-dwp-5 -o testfile-dwp-5.dwp
+
+$ g++ -gdwarf-4 -gsplit-dwarf -fdebug-types-section -g3 -O2 foo.cc bar.cc main.cc -o testfile-dwp-4
+$ dwp -e testfile-dwp-4
+
+$ g++ -gdwarf-4 -gstrict-dwarf -gsplit-dwarf -fdebug-types-section -g3 -O2 foo.cc bar.cc main.cc -o testfile-dwp-4-strict
+$ dwp -e testfile-dwp-4-strict