Fix code highlighting on all posts
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0171106eee
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10 changed files with 299 additions and 261 deletions
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@ -96,7 +96,7 @@ consumed by GDB nor `debuginfod` (for a good example of a distribution
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that does that, see Fedora's `debugsource` packages). Let me show you
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an example of debugging GDB itself (using `debuginfod`) on Debian:
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```
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```console
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$ HOME=/tmp DEBUGINFOD_URLS=https://debuginfod.debian.net gdb -q gdb
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Reading symbols from gdb...
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Downloading separate debug info for /tmp/gdb...
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@ -176,7 +176,7 @@ package. Notice that the last directory's name in both paths is the
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same, so in this case we can use GDB's `set substitute-path` command
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do the job for us (in this example `$PWD` is `/tmp/`):
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```
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```console
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$ HOME=/tmp DEBUGINFOD_URLS=https://debuginfod.debian.net gdb -q gdb
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Reading symbols from gdb...
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Reading symbols from /tmp/.cache/debuginfod_client/02046bac4352940d19d9164bab73b2f5cefc8c73/debuginfo...
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@ -224,7 +224,7 @@ whether she wants to use our service by default.
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If you would like to start using the service right now, all you have
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to do is set the following environment variable in your shell:
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```
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```bash
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DEBUGINFOD_URLS="https://debuginfod.debian.net"
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```
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@ -122,8 +122,9 @@ We're almost there! The last step before you boot your Fedora LiveUSB is
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to actually enable SeaBIOS. Just go inside your superuser shell (from
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the previous step) and type:
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#!bash
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```console
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> crossystem dev_boot_usb=1 dev_boot_legacy=1
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```
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And that's it!
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@ -149,8 +150,9 @@ You can solve that by passing the `mem` parameter to Linux. So, when
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GRUB complains that it was unable to load the specified image, it will
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give you a command prompt (`boot:`), and you just need to type:
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#!bash
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```console
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boot: linux mem=1980M
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```
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And that's it, things should work.
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@ -220,16 +222,18 @@ bug](https://bugzilla.redhat.com/show_bug.cgi?id=1045821#c63)), I found
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out about a few Linux flags that I could provide in boot time. To save
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you time, this is what I have now in my `/etc/default/grub` file:
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#!bash
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```console
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GRUB_CMDLINE_LINUX="tpm_tis.force=1 tpm_tis.interrupts=0 ..."
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```
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The final `...` means that you should keep whatever was there before you
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included those parameters, of course. Also, after you edit this file,
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you need to regenerate the GRUB configuration file on `/boot`. Run the
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following command as `root`:
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#!bash
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```console
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> grub2-mkconfig -o /boot/grub2/grub.cfg
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```
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Then, after I rebooted the system, I found that only adding those flags
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was still not enough. I saw a bunch of errors on `dmesg`, which showed
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@ -247,16 +251,17 @@ because the system is using the touchpad and the touchscreen to
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determine whether it should resume from suspend or not. So basically
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what you have to do is to disable those sources of events:
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#!bash
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```console
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echo TPAD > /proc/acpi/wakeup
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echo TSCR > /proc/acpi/wakeup
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```
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And voilà! Now everything should work as expected :-). You might want to
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issue those commands every time you boot the system, in order to get
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suspend to work every time, of course. To do that, you can create a
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`/etc/rc.d/rc.local`, which gets executed when the system starts:
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#!bash
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```console
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> cat /etc/rc.d/rc.local
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#!/bin/bash
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@ -269,11 +274,13 @@ suspend to work every time, of course. To do that, you can create a
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suspend_tricks
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exit 0
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```
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Don't forget to make this file executable:
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#!bash
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```console
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> chmod +x /etc/rc.d/rc.local
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```
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Conclusion
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----------
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@ -30,7 +30,7 @@ systems, you can obtain this header file by installing the package
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Here's a simple example of an application with a one-argument probe:
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#!c
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```c
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#include <sys/sdt.h>
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int
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@ -42,12 +42,14 @@ Here's a simple example of an application with a one-argument probe:
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return 0;
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}
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```
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As you can see, this is a very simple program with one probe, which
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contains one argument. You can now compile the program:
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#!bash
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```console
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$ gcc test_program.c -o test_program
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```
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Now you must be thinking: "*Wait, wait... Didn't you just forget to link
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this program against some SystemTap-specific library or something?*" And
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@ -59,7 +61,7 @@ As Tom said in [his blog post](http://tromey.com/blog/?p=687), this is
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If you want to make sure your probe was inserted in the binary, you can
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use `readelf` command:
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#!bash
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```console
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$ readelf -x .note.stapsdt ./test_program
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Hex dump of section '.note.stapsdt':
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@ -68,6 +70,7 @@ use `readelf` command:
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0x00000020 00000000 00000000 00000000 74657374 ............test
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0x00000030 5f70726f 6772616d 006d795f 70726f62 _program.my_prob
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0x00000040 65002d34 402d3428 25726270 29000000 e.-4@-4(%rbp)...
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```
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*(I will think about writing an explanation on how the probes are laid
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out on the binary, but for now you just have to care if you actually
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@ -75,9 +78,10 @@ see an output from this* `readelf` *command.)*
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You can also use SystemTap to perform this verification:
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#!bash
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```console
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$ stap -L 'process("./test_program").mark("*")'
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process("./test_program").mark("my_probe") $arg1:long
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```
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So far, so good. If you see an output like the one above, it means your
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probe is correctly inserted. You could obviously use SystemTap to
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@ -33,9 +33,10 @@ It is not the goal of this post to explain it in detail, but you might
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want to give it a try by compiling your binary with debuginfo support
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(use the `-g` flag on `GCC`), and do something like:
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#!bash
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```console
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$ stap -e 'probe process("/bin/foo").function("name") { log($$parms) }' -c /bin/foo
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$ stap -e 'probe process("/bin/foo").statement("*@file.c:443") { log($$vars) }' -c /bin/foo
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```
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And that's it. You can read SystemTap's documentation, or
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[this](http://sourceware.org/systemtap/wiki/AddingUserSpaceProbingToApps)
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@ -48,7 +49,7 @@ Well, now let's get to the interesting part. It is time to make `GDB`
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work with the `SDT` probe that we have put in our example code. Let's
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remember it:
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#!c
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```c
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#include <sys/sdt.h>
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int
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@ -60,6 +61,7 @@ remember it:
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return 0;
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}
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```
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It is a very simple example, and we will have to extend it later in
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order to show more features. But for now, it will do.
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@ -68,7 +70,7 @@ The first thing to do is to open `GDB` (with SystemTap support, of
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course!), and check to see if it can actually see probe inserted in our
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example.
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#!bash
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```console
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$ gdb ./test_program
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GNU gdb (GDB) 7.5.50.20121014-cvs
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Copyright (C) 2012 Free Software Foundation, Inc.
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@ -77,6 +79,7 @@ example.
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(gdb) info probes
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Provider Name Where Semaphore Object
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test_program my_probe 0x00000000004004ae /home/sergio/work/src/git/build/gdb/test_program
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```
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Wow, it actually works! :-)
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@ -91,9 +94,10 @@ use the `SDT` support.
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Anyway, now it is time to start using this support. The first thing I
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want to show you is how to put a breakpoint in a probe.
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#!bash
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```console
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(gdb) break -probe-stap my_probe
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Breakpoint 1 at 0x4004ae
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```
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That's all! We have chosen to extend the `break` command in order to
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support the new `-probe-stap` parameter. If you're wondering *... why
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@ -112,12 +116,13 @@ the one reported by `break`: they should be the same.
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Ok, so now, with our `breakpoint` in place, let's run the program and
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see what happens.
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#!bash
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```console
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(gdb) run
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Starting program: /home/sergio/work/src/git/build/gdb/test_program
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Breakpoint 1, main (argc=1, argv=0x7fffffffdf68) at /tmp/example-stap.c:8
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8 STAP_PROBE1 (test_program, my_probe, a);
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```
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As you can see, `GDB` stopped at the exact location of the probe.
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Therefore, you are now able to put marks (i.e., probes) in your source
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@ -135,11 +140,12 @@ inspect the probe's arguments? Yes, let's do it now!
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Just remember that, in `SDT`'s parlance, the current probe's argument is
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`a`. So let's print its value.
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#!bash
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```console
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(gdb) p $_probe_arg0
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$1 = 10
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(gdb) p a
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$2 = 10
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```
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*"Hey, captain, it seems the boat really floats!"*
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@ -59,7 +59,7 @@ Ok, so now we have to learn how to put `tracepoints` in our code, and
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how to define actions for them. But before that, let's remember our
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example program:
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#!c
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```c
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#include <sys/sdt.h>
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int
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return 0;
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}
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```
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Very simple, isn't it? Ok, to the `tracepoints` now, my friends.
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Fedora, the package name you will have to install is `gdb-gdbserver`. If
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you have it installed, you can do:
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#!bash
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```console
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$ gdbserver :3001 ./test_program
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Process ./test_program created; pid = 17793
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Listening on port 3001
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```
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The second argument passed to `gdbserver` instructs it to listen on the
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port 3001 of your loopback interface, a.k.a. `localhost`.
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@ -109,7 +110,7 @@ for new connections to arrive. Don't worry, we will connect to it soon!
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Now, go to another terminal and start `GDB` with our program:
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#!bash
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```console
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$ gdb ./test_program
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...
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(gdb) target remote :3001
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@ -117,6 +118,7 @@ Now, go to another terminal and start `GDB` with our program:
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Reading symbols from /lib64/ld-linux-x86-64.so.2...(no debugging symbols found)...done.
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Loaded symbols for /lib64/ld-linux-x86-64.so.2
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0x0000003d60401530 in _start () from /lib64/ld-linux-x86-64.so.2
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```
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The command you have to use inside `GDB` is `target remote`. It takes as
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an argument the host and the port to which you want to connect. In our
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@ -135,9 +137,10 @@ Ok, so now it is time to start our *trace experiment*!
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In your `GDB` prompt, put a `tracepoint` in the probe named `my_probe`:
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#!bash
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```console
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(gdb) trace -probe-stap my_probe
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Tracepoint 1 at 0x4005a9
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```
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As you can see, the `trace` command takes exactly the same arguments as
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the `break` command. Thus, you need to use the `-probe-stap` modified in
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@ -152,13 +155,14 @@ For this example, we will use only the `collect` keyword, which tells
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`GDB` to... hm... collect something :-). In our case, it will collect
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the probe's first argument, or `$_probe_arg0`, as you may remember.
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#!bash
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```console
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(gdb) actions
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Enter actions for tracepoint 1, one per line.
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End with a line saying just "end".
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>collect $_probe_arg0
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>end
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(gdb)
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```
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Simple as that. Finally, we have to define a `breakpoint` in the last
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instruction of our program, because it is necessary to keep it running
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@ -174,7 +178,7 @@ Ok, time to run our trace experiment. First, we must issue a `tstart` to
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tell `GDB` to start monitoring the `tracepoints`. And then, we can
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continue our program normally.
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#!bash
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```console
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(gdb) tstart
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(gdb) continue
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Continuing.
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@ -183,6 +187,7 @@ continue our program normally.
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10 return 0;
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(gdb) tstop
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(gdb)
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```
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Remember, `GDB` is **not** going to stop your program, because
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`tracepoints` are designed to not interfere with the execution of it.
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@ -193,12 +198,13 @@ Now, we will be able to examine what the `tracepoint` has collected.
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First, we will the `tfind` command to make sure the `tracepoint` has
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hit, and then we can inspect what we ordered it to collect:
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#!bash
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```console
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(gdb) tfind start
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Found trace frame 0, tracepoint 1
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8 STAP_PROBE1 (test_program, my_probe, a);
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(gdb) p $_probe_arg0
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$1 = 10
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```
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And it works! Notice that we are printing the probe argument using the
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same notation as with `breakpoints`, even though we are not exactly
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@ -47,8 +47,9 @@ to always encrypt the message to myself too.
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You basically have to edit your `$HOME/.gnupg/gpg.conf` file and put
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this setting there:
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#!bash
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```console
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hidden-encrypt-to ID
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```
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That's it. Now, whenever I send an encrypted message, GnuPG encrypts it
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for me as well, so I just need to go to my “Sent/” folder, and decrypt
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@ -66,11 +66,13 @@ the binutils guys to fix it, which meant less work for us :-).
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With a lot of help from Keith Seitz, I was able to bisect the problem
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and found that it started with the following commit:
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```
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commit f6aec96dce1ddbd8961a3aa8a2925db2021719bb
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Author: H.J. Lu <hjl.tools@gmail.com>
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Date: Tue Feb 27 11:34:20 2018 -0800
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ld: Add --enable-separate-code
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```
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This is a commit that touches the linker, which is part of binutils.
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So that means this is not GDB's problem, right?!? Hmm. No,
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@ -95,6 +97,7 @@ everything (code and data) was put together in the same memory
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region. What this means in practice is that, before, you would see
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something like this when you examined `/proc/PID/smaps`:
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```
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00400000-00401000 r-xp 00000000 fc:01 798593 /file
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Size: 4 kB
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KernelPageSize: 4 kB
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@ -117,9 +120,11 @@ something like this when you examined `/proc/PID/smaps`:
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Locked: 0 kB
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THPeligible: 0
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VmFlags: rd ex mr mw me dw sd
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```
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And now, you will see two memory regions instead, like this:
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```
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00400000-00401000 r--p 00000000 fc:01 799548 /file
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Size: 4 kB
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KernelPageSize: 4 kB
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@ -164,6 +169,7 @@ And now, you will see two memory regions instead, like this:
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Locked: 0 kB
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THPeligible: 0
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VmFlags: rd ex mr mw me dw sd
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```
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A few minor things have changed, but the most important of them is the
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fact that, before, the whole memory region **had** anonymous data in
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@ -240,9 +246,8 @@ Linux also makes these checks, by the way.
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The patch, finally
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------------------
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I
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submitted
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[the patch](https://sourceware.org/ml/gdb-patches/2019-04/msg00479.html) to
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I submitted [the
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patch](https://sourceware.org/ml/gdb-patches/2019-04/msg00479.html) to
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the mailing list, and it was approved fairly quickly (with a few minor
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nits).
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@ -253,8 +258,7 @@ interesting to come up with a solution that extended the work I did a
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few years ago. I was also able to close a few bug reports upstream,
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as well as the one reported against Fedora GDB.
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The patch has
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been
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The patch has been
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[pushed](https://sourceware.org/git/?p=binutils-gdb.git;a=commit;h=57e5e645010430b3d73f8c6a757d09f48dc8f8d5),
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and is also present at the latest version of Fedora GDB for Rawhide.
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It wasn't possible to write a self-contained testcase for this
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@ -180,10 +180,12 @@ Java 8, but unlike Keycloak, it doesn't work out of the box with
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OpenJDK 11. I had to make a small but important addition in the file
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`etc/gerrit.config`:
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|
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```ini
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[container]
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...
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javaOptions = "--add-opens=jdk.management/com.sun.management.internal=ALL-UNNAMED"
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...
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```
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After that, I was able to start gerrit. And then I started trying to
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set it up for OAuth2 authentication using Keycloak. This took a
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@ -198,6 +200,7 @@ causing a very strange error on Gerrit (as you can see, a
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`java.lang.StringIndexOutOfBoundsException`!), which didn't make
|
||||
sense. In the end, my Apache config file looks like this:
|
||||
|
||||
```apacheconf
|
||||
<VirtualHost *:80>
|
||||
ServerName gnutoolchain-gerrit.osci.io
|
||||
|
||||
|
@ -244,6 +247,7 @@ sense. In the end, my Apache config file looks like this:
|
|||
ProxyPass /r/ http://127.0.0.1:8081/ nocanon
|
||||
#ProxyPassReverse /r/ http://127.0.0.1:8081/r/
|
||||
</VirtualHost>
|
||||
```
|
||||
|
||||
I confess I was almost giving up Keycloak when I finally found
|
||||
the problem...
|
||||
|
@ -259,10 +263,12 @@ gerrit that the user was already logged in, and gerrit would
|
|||
automatically log the user in again! I was able to solve this by
|
||||
redirecting the user to Keycloak's logout page, like this:
|
||||
|
||||
```ini
|
||||
[auth]
|
||||
...
|
||||
logoutUrl = https://keycloak-url:port/auth/realms/REALM/protocol/openid-connect/logout?redirect_uri=https://gerrit-url/
|
||||
...
|
||||
```
|
||||
|
||||
After that, it was already possible to start worrying about configure
|
||||
gerrit itself. I don't know if I'll write a post about that, but let
|
||||
|
|
|
@ -156,10 +156,11 @@ here](http://sergiodj.net/~sergio/jabberd2-migration/j2to1.txt). Save
|
|||
the file as `j2to1.pl`, and run the script (don't forget to edit the
|
||||
source code in order to provide the database name/file):
|
||||
|
||||
#!bash
|
||||
```console
|
||||
$> perl j2to1.pl jabberd14-dir/
|
||||
Converting user@host...
|
||||
$>
|
||||
```
|
||||
|
||||
This will convert the database from Jabberd2 to Jabberd14, and put the
|
||||
XML file of each Jabber user in the server into `jabberd14-dir/host/`.
|
||||
|
@ -171,8 +172,9 @@ page](https://github.com/Kev/sleekmigrate) on how to set it up, you can
|
|||
run it on your Jabberd14 data directory in order to finally generate a
|
||||
XEP-0227 XML file that will be imported into Prosody.
|
||||
|
||||
#!bash
|
||||
```console
|
||||
$> ./sleekmigrate.py -j /path/to/jabberd14-dir/
|
||||
```
|
||||
|
||||
This should create a file called `227.xml` on your current directory,
|
||||
which is the exported version of the Jabberd14 data directory. As a side
|
||||
|
@ -194,15 +196,17 @@ working. I also had to build some POSIX module of Prosody in order to
|
|||
make everything work. To do that, unpack the `tar.gz` file, go to the
|
||||
Prosody source code directory, and do:
|
||||
|
||||
#!bash
|
||||
```console
|
||||
$> apt-get build-dep prosody && ./configure --ostype=debian && make
|
||||
```
|
||||
|
||||
Only after I did that I could finally run the conversion script
|
||||
successfully. The script is locate inside the `tools/` directory. To run
|
||||
it:
|
||||
|
||||
#!bash
|
||||
```console
|
||||
$> cd tools && lua ./xep227toprosody.lua /path/to/227.xml
|
||||
```
|
||||
|
||||
And yay! I **finally** had everything imported into Prosody!!!! Then it
|
||||
was just a matter of finishing the server configuration, initializing
|
||||
|
|
|
@ -42,7 +42,7 @@ little configuration.
|
|||
On the server side (i.e., VPS or dedicated server), you will create
|
||||
the first endpoint. Something like the following should do:
|
||||
|
||||
```nil
|
||||
```ini
|
||||
[Interface]
|
||||
PrivateKey = PRIVATE_KEY_HERE
|
||||
Address = 10.0.0.1/32
|
||||
|
@ -73,7 +73,7 @@ A few interesting points to note:
|
|||
|
||||
At your home, you will configure the peer:
|
||||
|
||||
```nil
|
||||
```ini
|
||||
[Interface]
|
||||
PrivateKey = PRIVATE_KEY_HERE
|
||||
Address = 10.0.0.2/32
|
||||
|
|
Loading…
Reference in a new issue