CODEWITHSUNDEEP
clinuxdebugginggdblibc
spraff
spraff

Reputation: 33425

gdb/ddd can't find raise.c when debugging assert(), it is looking in my home directory

I use gdb (ddd) to debug my C/C++ projects.

Whenever an assert fails, I can debug the program as normal and backtrace to the assert which failed, but first I get an annoying popup

enter image description here

I assume raise.c defines assert, but ddd is looking within my home directory instead of /usr/... or something like that.

I may or may not have the debugging packages installed (I'm on Ubuntu), but the main question is: why is gdb looking within $HOME for this source?

Upvotes: 3

Views: 5558

Answers (1)

Mark Plotnick
Mark Plotnick

Reputation: 10271

Since the glibc debuginfo package libc6-dbg is installed on your system, gdb will look in /usr/lib/debug/lib/x86_64-linux-gnu/libc-2.23.so to map instruction addresses into source file names and line numbers.

The section of that file that contains the info for __GI_raise has the following attributes that indicate where the source code might be found (on Ubuntu 16.04):

<0><688bd>: Abbrev Number: 1 (DW_TAG_compile_unit)
    <688c3>   DW_AT_name        : (indirect string, offset: 0x9137): ../sysdeps/unix/sysv/linux/raise.c
    <688c7>   DW_AT_comp_dir    : (indirect string, offset: 0x9010): /build/glibc-Cl5G7W/glibc-2.23/signal

Ubuntu doesn't ship source code in the base distribution, so your system doesn't have any glibc source in /build/glibc-Cl5G7W/glibc-2.23, so gdb looks (unsuccessfully) for raise.c in a few other directories according to its rules Specifying Source Directories and eventually gives up, with the error message

54  ../sysdeps/unix/sysv/linux/raise.c: No such file or directory.

Then, ddd calls SourceView::full_path("../sysdeps/unix/sysv/linux/raise.c") to canonicalize the pathname, taking your working directory into account, and displays the error dialog box in your question.

See GDB complaining about missing raise.c for how to install glibc source on Ubuntu.

Upvotes: 3

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