Problems with compiling version 9.4 on Fedora 27

bgstack15 8 Jan 2018, 00:04

I have been struggling with compiling FreeFileSync 9.4 from source. I started on this version before 9.6 came out, and didn't want to change mid-stream. I'll try 9.6 eventually, though, don't worry.

I can compile the application and execute it. Most of the time, it segfaults and dumps the core (haven't found where yet). I finally learned enough about gdb to get some output.

**

Gtk:ERROR:gtkicontheme.c:4024:proxy_pixbuf_destroy: assertion failed: (icon_info->proxy_pixbuf != NULL)



Thread 8 "Icon Buffer Wor" received signal SIGABRT, Aborted.

[Switching to Thread 0x7fffcf163700 (LWP 10133)]

0x00007ffff227169b in raise () from /lib64/libc.so.6

Missing separate debuginfos, use: dnf debuginfo-install <TRUNCATED...>

Another execution of the same binary produced this output in strace, but this looks like a different message.

futex(0x2b495c8, FUTEX_WAKE_PRIVATE, 2147483647) = 1

openat(AT_FDCWD, "/usr/share/icons/Numix/24/mimetypes/application-vnd.openxmlformats-officedocument.wordprocessingml.document.svg", O_RDONLY) = 10

fstat(10, {st_mode=S_IFREG|0644, st_size=1045, ...}) = 0

read(10, "<svg xmlns=\"http:/www.w3.org/20"..., 65536) = 1045

read(10, "", 65536)                     = 0

close(10)                               = 0

futex(0x2b495cc, FUTEX_WAKE_PRIVATE, 2147483647) = 1

futex(0x7fae2f0ab218, FUTEX_WAKE_PRIVATE, 1) = 0

getpeername(2, 0x7ffd794a85f0, [128])   = -1 ENOTSOCK (Socket operation on non-socket)

futex(0x7fae2ee57e88, FUTEX_WAKE_PRIVATE, 2147483647) = 0

ioctl(2, TCGETS, {B38400 opost isig icanon echo ...}) = 0

getpid()                                = 8750

write(2, "\n(FreeFileSync:8750): GLib-GObje"..., 116

(FreeFileSync:8750): GLib-GObject-CRITICAL **: g_object_unref: assertion 'object->ref_count > 0' failed

) = 116

futex(0x2b495c8, FUTEX_WAKE_PRIVATE, 2147483647) = ?

+++ killed by SIGSEGV (core dumped) +++

Segmentation fault (core dumped)

I will keep investigating this issue on my own, but if anyone can help me figure out how to get the application to maybe use a generic icon or otherwise side-step this proxy_pixbuf NULL issue, that would be fantastic! I know nothing about C++ yet so am learning everything as I go.

Attached is my patch so far from the 9.4 base code. I should mention I use gtk3 as do others on this forum. I
Web references available in my next post (no links, to minimize spam according to the notice)

bgstack15 17 Jan 2018, 02:03

I observed that the file I mentioned in the strace output, when it segfaulted, is a symlink. I wonder if that is the cause of the problem.

I am now compiling FreeFileSync 9.7, released a few days ago. I am still compiling on gcc 7.2.1.2.fc27.x86_64 against gtk3.

Somehow, when I package the utility up in an rpm, the built file includes the debug info. I'm still trying to figure out the flags passed to gcc (maybe -g or -Og or something like that [cf. https://www.ostechnix.com/compile-run-c-c-programs-linux/]).

I was able to get a full backtrace from gdb, when debugging that packaged up binary:

#0  0x00007ffff4cef480 in proxy_pixbuf_destroy () at /lib64/libgtk-3.so.0

#1  0x00007ffff3a38f44 in gdk_pixbuf_finalize () at /lib64/libgdk_pixbuf-2.0.so.0

#2  0x00007ffff3458689 in g_object_unref () at /lib64/libgobject-2.0.so.0

#3  0x000055555577bb3a in (anonymous namespace)::<lambda()>::operator() (__closure=<synthetic pointer>) at lib/icon_loader.cpp:87

#4  0x000055555577bb3a in zen::runScopeGuardDestructor<(anonymous namespace)::imageHolderFromGicon(GIcon*, int)::<lambda()> > (fun=<synthetic pointer>...)

    at ../../zen/scope_guard.h:58

#5  0x000055555577bb3a in zen::ScopeGuard<(zen::ScopeGuardRunMode)0, (anonymous namespace)::imageHolderFromGicon(GIcon*, int)::<lambda()> >::~ScopeGuard (this=<synthetic pointer>, __in_chrg=<optimized out>) at ../../zen/scope_guard.h:96

#6  0x000055555577bb3a in (anonymous namespace)::imageHolderFromGicon(GIcon*, int) (gicon=gicon@entry=0x555556128120, pixelSize=pixelSize@entry=24) at lib/icon_loader.cpp:87

#7  0x000055555577bd75 in zen::genericFileIcon(int) (pixelSize=24) at lib/icon_loader.cpp:122

#8  0x0000555555776407 in zen::IconBuffer::genericFileIcon(zen::IconBuffer::IconSize) (sz=sz@entry=zen::IconBuffer::SIZE_SMALL) at lib/icon_buffer.cpp:412

#9  0x0000555555709ea7 in MainDialog::MainDialog(zen::Zbase<char, zen::DefaultStoragePolicy> const&, xmlAccess::XmlGuiConfig const&, std::vector<zen::Zbase<char, zen::DefaultStoragePolicy>, std::allocator<zen::Zbase<char, zen::DefaultStoragePolicy> > > const&, xmlAccess::XmlGlobalSettings const&, bool) (this=0x555555e02e00, globalConfigFilePath=..., guiCfg=..., referenceFiles=std::vector of length 1, capacity 1 = {...}, globalSettings=..., startComparison=<optimized out>) at ui/main_dlg.cpp:564

#10 0x000055555570c906 in MainDialog::create(zen::Zbase<char, zen::DefaultStoragePolicy> const&, xmlAccess::XmlGlobalSettings const*, xmlAccess::XmlGuiConfig const&, std::vector<zen::Zbase<char, zen::DefaultStoragePolicy>, std::allocator<zen::Zbase<char, zen::DefaultStoragePolicy> > > const&, bool) (globalConfigFilePath=..., globalSettings=globalSettings@entry=0x7fffffffd030, guiCfg=..., referenceFiles=std::vector of length 1, capacity 1 = {...}, startComparison=startComparison@entry=false) at ui/main_dlg.cpp:387

#11 0x000055555570cf6c in MainDialog::create(zen::Zbase<char, zen::DefaultStoragePolicy> const&) (globalConfigFilePath=...) at ui/main_dlg.cpp:364

#12 0x00005555555ed2b9 in runGuiMode(zen::Zbase<char, zen::DefaultStoragePolicy> const&) (globalConfigFilePath=...) at application.cpp:461

#13 0x00005555555ed2b9 in Application::launch(std::vector<zen::Zbase<char, zen::DefaultStoragePolicy>, std::allocator<zen::Zbase<char, zen::DefaultStoragePolicy> > > const&) (this=0x555555b20470, commandArgs=std::vector of length 0, capacity 0) at application.cpp:365

#14 0x00005555555ee598 in Application::onEnterEventLoop(wxEvent&) (this=0x555555b20470, event=...) at application.cpp:100

#15 0x00007ffff5e3471a in wxEvtHandler::ProcessEventIfMatchesId(wxEventTableEntryBase const&, wxEvtHandler*, wxEvent&) () at /lib64/libwx_baseu-3.0.so.0

#16 0x00007ffff5e34b2a in wxEvtHandler::SearchDynamicEventTable(wxEvent&) () at /lib64/libwx_baseu-3.0.so.0

#17 0x00007ffff5e34bbf in wxEvtHandler::TryHereOnly(wxEvent&) () at /lib64/libwx_baseu-3.0.so.0

#18 0x00007ffff5e34c73 in wxEvtHandler::ProcessEventLocally(wxEvent&) () at /lib64/libwx_baseu-3.0.so.0

#19 0x00007ffff5e34cd5 in wxEvtHandler::ProcessEvent(wxEvent&) () at /lib64/libwx_baseu-3.0.so.0

#20 0x00007ffff5e35e02 in wxEvtHandler::ProcessPendingEvents() () at /lib64/libwx_baseu-3.0.so.0

#21 0x00007ffff5cbc7b7 in wxAppConsoleBase::ProcessPendingEvents() () at /lib64/libwx_baseu-3.0.so.0

#22 0x00007ffff67812dd in wxApp::DoIdle() () at /lib64/libwx_gtk3u_core-3.0.so.0

#23 0x00007ffff6781403 in wxapp_idle_callback () at /lib64/libwx_gtk3u_core-3.0.so.0

#24 0x00007ffff3177597 in g_idle_dispatch () at /lib64/libglib-2.0.so.0

#25 0x00007ffff317abb7 in g_main_context_dispatch () at /lib64/libglib-2.0.so.0

#26 0x00007ffff317af60 in g_main_context_iterate.isra () at /lib64/libglib-2.0.so.0

#27 0x00007ffff317b272 in g_main_loop_run () at /lib64/libglib-2.0.so.0

#28 0x00007ffff4d25ca5 in gtk_main () at /lib64/libgtk-3.so.0

#29 0x00007ffff679f8a5 in wxGUIEventLoop::DoRun() () at /lib64/libwx_gtk3u_core-3.0.so.0

#30 0x00007ffff5cf5ea3 in wxEventLoopBase::Run() () at /lib64/libwx_baseu-3.0.so.0

#31 0x00007ffff5cbdea6 in wxAppConsoleBase::MainLoop() () at /lib64/libwx_baseu-3.0.so.0

#32 0x00005555555ead2b in Application::OnRun() (this=0x555555b20470) at application.cpp:110

#33 0x00007ffff5d463e7 in wxEntry(int&, wchar_t**) () at /lib64/libwx_baseu-3.0.so.0

#34 0x00005555555ce5b8 in main(int, char**) (argc=<optimized out>, argv=<optimized out>) at application.cpp:32

So I pulled up file lib/icon_loader.cpp:87 from the FreeFileSync tree.

ImageHolder imageHolderFromGicon(GIcon* gicon, int pixelSize)

{

    if (gicon)

        if (GtkIconTheme* defaultTheme = ::gtk_icon_theme_get_default()) //not owned!

            if (GtkIconInfo* iconInfo = ::gtk_icon_theme_lookup_by_gicon(defaultTheme, gicon, pixelSize, GTK_ICON_LOOKUP_USE_BUILTIN)) //this may fail if icon is not installed on system

            {

                ZEN_ON_SCOPE_EXIT(::gtk_icon_info_free(iconInfo));

                if (GdkPixbuf* pixBuf = ::gtk_icon_info_load_icon(iconInfo, nullptr))

                {

                    ZEN_ON_SCOPE_EXIT(::g_object_unref(pixBuf)); //superseedes "::gdk_pixbuf_unref"!

                    return copyToImageHolder(pixBuf);

                }

            }

    return ImageHolder();

}

Line 87 is the one with the misspelled "superseedes" comment. Can you guys help me step through this backtrace and see if there's something we can modify or add a try-catch block around?