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git://sourceware.org/git/libabigail.git
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Plug leak of debug info handles
On recent elfutils where the libdw's function dwarf_getalt exists, we don't need to try and find the alternate debug info file ourselves by using the function dwfl_standard_find_debuginfo. Furthermore, when we use that function on those recent elfutils versions, we leak the elf resources allocated in the debug info resources; we also leak the file descriptor to access the alternate debug info sections. More generally, we also leak debug info handles used to access debug info when using get_soname_of_elf_file and get_type_of_elf_file. This patch plugs those leaks. In the first case, if the function dwarf_getalt exists, the patch just uses it to get the alternate debug info. Otherwise, the patch uses the dwfl_standard_find_debuginfo function like we used to, but then it tries hard to free the file descriptor and debuginfo memory of the alternate debug info. * configure.ac: Check the presence of dwarf_getalt in libdw. If it's present, define the preprocessor macro LIBDW_HAS_DWARF_GETALT. Update the autoconf configuration summary. * src/abg-dwarf-reader.cc: Add config.h. (find_alt_debug_info_location): Factorize this out of ... (find_alt_debug_info): ... this function. Use dwarf_getalt if present, otherwise, keep using dwfl_standard_find_debuginfo. In the later case, return the file descriptor opened to access the alternate debug info, by parameter, so that the caller can fclose it. (read_context::alt_fd_): New data member. (read_context::read_context): Initialize the new alt_fd_ data member. (read_context::load_debug_info): Store the file descriptor used to access the alternate debug info into the new alt_fd_ data member. (read_context::~read_context): New desctructor. (get_soname_of_elf_file, get_type_of_elf_file): Free the elf handle. (read_context::load_debug_info): Be paranoid in making sure we never override alt_dwarf_. * tests/data/test-alt-dwarf-file/test0-report.txt: Adjust. Signed-off-by: Dodji Seketeli <dodji@redhat.com>
This commit is contained in:
Dodji Seketeli
parent
00f79732fb
commit
ce5e4889b1
11
configure.ac
11
configure.ac
@ -124,11 +124,14 @@ AC_CHECK_HEADER([libelf.h],
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DW_LIBS=
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AC_CHECK_LIB(dw, dwfl_begin, [DW_LIBS=-ldw])
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AC_CHECK_LIB(dw, dwarf_getalt,
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[FOUND_DWARF_GETALT_IN_LIBDW=yes],
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[FOUND_DWARF_GETALT_IN_LIBDW=no])
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AC_CHECK_HEADER(elfutils/libdwfl.h,
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[],
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[AC_MSG_ERROR([could not find elfutils/libdwfl.h installed])])
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if test x$ELF_LIBS = x; then
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AC_MSG_ERROR([could not find elfutils elf library installed])
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fi
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@ -137,6 +140,11 @@ if test x$DW_LIBS = x; then
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AC_MSG_ERROR([could not find elfutils dwarf library installed])
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fi
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if test x$FOUND_DWARF_GETALT_IN_LIBDW=xyes; then
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AC_DEFINE([LIBDW_HAS_DWARF_GETALT], 1,
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[Defined if libdw has the function dwarf_getalt])
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fi
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AC_SUBST(DW_LIBS)
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AC_SUBST([ELF_LIBS])
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@ -477,6 +485,7 @@ AC_MSG_NOTICE([
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OPTIONAL FEATURES:
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Enable zip archives : ${ENABLE_ZIP_ARCHIVE}
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Use a C++-11 compiler : ${ENABLE_CXX11}
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libdw has the dwarf_getalt function : ${FOUND_DWARF_GETALT_IN_LIBDW}
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Enable rpm support in abipkgdiff : ${ENABLE_RPM}
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Enable deb support in abipkgdiff : ${ENABLE_DEB}
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Enable GNU tar archive support in abipkgdiff : ${ENABLE_TAR}
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@ -26,6 +26,7 @@
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/// de-serialize an instance of @ref abigail::corpus from a file in
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/// elf format, containing dwarf information.
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#include "config.h"
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <fcntl.h>
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@ -839,30 +840,27 @@ get_binary_load_address(Elf *elf_handle,
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return false;
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}
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/// Return the alternate debug info associated to a given main debug
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/// info file.
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/// Find the file name of the alternate debug info file, as well as
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/// its build ID.
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///
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/// @param elf_module the elf module to consider.
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///
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/// @param alt_file_name output parameter. This is set to the file
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/// path of the alternate debug info file associated to @p elf_module.
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/// This is set iff the function returns a non-null result.
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/// @param out parameter. Is set to the file name of the alternate
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/// debug info file, iff this function returns true.
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///
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/// Note that the alternate debug info file is a DWARF extension as of
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/// DWARF 4 ans is decribed at
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/// http://www.dwarfstd.org/ShowIssue.php?issue=120604.1.
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/// @param out parameter. Is set to the build ID of the alternate
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/// debug info file.
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///
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/// @return the alternate debuginfo, or null
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///
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static Dwarf*
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find_alt_debug_info(Dwfl_Module *elf_module,
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string& alt_file_name)
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/// @return true iff the location of the alternate debug info file was
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/// found.
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static bool
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find_alt_debug_info_location(Dwfl_Module *elf_module,
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string &alt_file_name,
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string &build_id)
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{
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if (elf_module == 0)
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return 0;
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GElf_Addr bias = 0;
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Elf *elf = dwarf_getelf(dwfl_module_getdwarf(elf_module, &bias));
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Dwarf *dwarf = dwfl_module_getdwarf(elf_module, &bias);
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Elf *elf = dwarf_getelf(dwarf);
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GElf_Ehdr ehmem, *elf_header;
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elf_header = gelf_getehdr(elf, &ehmem);
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@ -879,8 +877,8 @@ find_alt_debug_info(Dwfl_Module *elf_module,
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header->sh_name);
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char *alt_name = 0;
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char *build_id = 0;
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size_t build_id_len = 0;
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char *buildid = 0;
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size_t buildid_len = 0;
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if (section_name != 0
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&& strcmp(section_name, ".gnu_debugaltlink") == 0)
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{
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@ -890,39 +888,91 @@ find_alt_debug_info(Dwfl_Module *elf_module,
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alt_name = (char*) data->d_buf;
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char *end_of_alt_name =
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(char *) memchr(alt_name, '\0', data->d_size);
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build_id_len = data->d_size - (end_of_alt_name - alt_name + 1);
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if (build_id_len == 0)
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return 0;
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build_id = end_of_alt_name + 1;
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buildid_len = data->d_size - (end_of_alt_name - alt_name + 1);
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if (buildid_len == 0)
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return false;
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buildid = end_of_alt_name + 1;
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}
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}
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else
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continue;
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if (build_id == 0 || alt_name == 0)
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return 0;
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if (buildid == 0 || alt_name == 0)
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return false;
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const char *file_name = 0;
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void **user_data = 0;
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Dwarf_Addr low_addr = 0;
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char *alt_file = 0;
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file_name = dwfl_module_info(elf_module, &user_data,
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&low_addr, 0, 0, 0, 0, 0);
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int alt_fd = dwfl_standard_find_debuginfo(elf_module, user_data,
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file_name, low_addr,
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alt_name, file_name,
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0, &alt_file);
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Dwarf *result = dwarf_begin(alt_fd, DWARF_C_READ);
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if (alt_file)
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alt_file_name = alt_file;
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return result;
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build_id = buildid;
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alt_file_name = alt_name;
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return true;
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}
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return 0;
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return false;
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}
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/// Return the alternate debug info associated to a given main debug
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/// info file.
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///
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/// @param elf_module the elf module to consider.
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///
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/// @param alt_file_name output parameter. This is set to the file
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/// path of the alternate debug info file associated to @p elf_module.
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/// This is set iff the function returns a non-null result.
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///
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/// @param alt_fd the file descriptor used to access the alternate
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/// debug info. If this parameter is set by the function, then the
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/// caller needs to fclose it, otherwise the file descriptor is going
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/// to be leaked. Note however that on recent versions of elfutils
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/// where libdw.h contains the function dwarf_getalt(), this parameter
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/// is set to 0, so it doesn't need to be fclosed.
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///
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/// Note that the alternate debug info file is a DWARF extension as of
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/// DWARF 4 ans is decribed at
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/// http://www.dwarfstd.org/ShowIssue.php?issue=120604.1.
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///
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/// @return the alternate debuginfo, or null. If @p alt_fd is
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/// non-zero, then the caller of this function needs to call
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/// dwarf_end() on the returned alternate debuginfo pointer,
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/// otherwise, it's going to be leaked.
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static Dwarf*
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find_alt_debug_info(Dwfl_Module *elf_module,
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string& alt_file_name,
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int& alt_fd)
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{
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if (elf_module == 0)
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return 0;
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Dwarf* result = 0;
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string build_id;
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find_alt_debug_info_location(elf_module, alt_file_name, build_id);
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#ifdef LIBDW_HAS_DWARF_GETALT
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// We are on recent versions of elfutils where the function
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// dwarf_getalt exists, so let's use it.
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Dwarf_Addr bias = 0;
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Dwarf* dwarf = dwfl_module_getdwarf(elf_module, &bias);
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result = dwarf_getalt(dwarf);
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alt_fd = 0;
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#else
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// We are on an old version of elfutils where the function
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// dwarf_getalt doesn't exist yet, so let's open code its
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// functionality
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char *alt_name = 0;
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const char *file_name = 0;
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void **user_data = 0;
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Dwarf_Addr low_addr = 0;
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char *alt_file = 0;
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file_name = dwfl_module_info(elf_module, &user_data,
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&low_addr, 0, 0, 0, 0, 0);
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alt_fd = dwfl_standard_find_debuginfo(elf_module, user_data,
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file_name, low_addr,
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alt_name, file_name,
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0, &alt_file);
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result = dwarf_begin(alt_fd, DWARF_C_READ);
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#endif
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return result;
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}
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/// Compare a symbol name against another name, possibly demangling
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@ -1999,7 +2049,12 @@ class read_context
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Dwarf* dwarf_;
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// The alternate debug info. Alternate debug info sections are a
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// DWARF extension as of DWARF4 and are described at
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// http://www.dwarfstd.org/ShowIssue.php?issue=120604.1.
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// http://www.dwarfstd.org/ShowIssue.php?issue=120604.1. Below are
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// the file desctor used to access the alternate debug info
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// sections, and the representation of the DWARF debug info. Both
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// need to be freed after we are done using them, with fclose and
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// dwarf_end.
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int alt_fd_;
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Dwarf* alt_dwarf_;
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string alt_debug_info_path_;
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// The address range of the offline elf file we are looking at.
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@ -2086,6 +2141,7 @@ public:
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dwarf_version_(),
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handle_(),
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dwarf_(),
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alt_fd_(),
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alt_dwarf_(),
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elf_module_(),
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elf_handle_(),
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@ -2106,6 +2162,17 @@ public:
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memset(&offline_callbacks_, 0, sizeof(offline_callbacks_));
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}
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/// Detructor of the @ref read_context type.
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~read_context()
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{
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if (alt_fd_)
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{
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close(alt_fd_);
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if (alt_dwarf_)
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dwarf_end(alt_dwarf_);
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}
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}
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/// Clear the data that is relevant only for the current translation
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/// unit being read. The rest of the data is relevant for the
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/// entire ABI corpus.
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@ -2283,9 +2350,11 @@ public:
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dwfl_report_end(dwfl_handle().get(), 0, 0);
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Dwarf_Addr bias = 0;
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dwarf_ = dwfl_module_getdwarf(elf_module_, &bias);
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alt_dwarf_ = find_alt_debug_info(elf_module_, alt_debug_info_path_);
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if (!alt_dwarf_)
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alt_dwarf_ = find_alt_debug_info(elf_module_,
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alt_debug_info_path_,
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alt_fd_);
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return dwarf_;
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}
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@ -9772,6 +9841,7 @@ get_soname_of_elf_file(const string& path, string &soname)
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}
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}
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elf_end(elf);
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close(fd);
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return true;
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@ -9797,6 +9867,7 @@ get_type_of_elf_file(const string& path, elf_type& type)
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elf_version (EV_CURRENT);
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Elf *elf = elf_begin (fd, ELF_C_READ_MMAP, NULL);
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type = elf_file_type(elf);
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elf_end(elf);
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close(fd);
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return true;
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@ -1 +1 @@
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found the alternate debug info file '7088580c513b439c9ed95fe6a8b29496495f26.debug'
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found the alternate debug info file 'test0-common-dwz.debug'
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