A Swift wrapper for libavahi-client.
This exists mainly to demonstrate a bug in LLDB.
Assuming that you have Swift installed this should work:
sudo apt-get install libavahi-client-devswift buildswift test
Make sure to run with LLDB_SWIFT_DUMP_DIAGS=1 enabled. Start the debugger and set a breakpoint. Note the error to find Clibavahiclient.
$ LLDB_SWIFT_DUMP_DIAGS=1 lldb ./.build/x86_64-unknown-linux/debug/AvahiClientPackageTests.xctest
(lldb) target create "./.build/x86_64-unknown-linux/debug/AvahiClientPackageTests.xctest"
Current executable set to './.build/x86_64-unknown-linux/debug/AvahiClientPackageTests.xctest' (x86_64).
(lldb) breakpoint set -f AvahiClientTests.swift -l 12
<unknown>:0: error: missing required module 'Clibavahiclient'
Breakpoint 1: where = AvahiClientPackageTests.xctest`AvahiClientTests.AvahiClientTests.testNewAvahiClient() -> () + 135 at AvahiClientTests.swift:12, address = 0x0000000000004a07
You can see that lldb is telling the truth. It does not know about Clibavahiclient:
(lldb) target modules list
[ 0] E21ECC95-0000-0000-0000-000000000000 ./.build/x86_64-unknown-linux/debug/AvahiClientPackageTests.xctest
Try to run and print anyway:
(lldb) r
Process 10360 launched: './.build/x86_64-unknown-linux/debug/AvahiClientPackageTests.xctest' (x86_64)
Test Suite 'All tests' started at 2019-02-03 03:39:22.738
Test Suite 'debug.xctest' started at 2019-02-03 03:39:22.738
Test Suite 'AvahiClientTests' started at 2019-02-03 03:39:22.738
Test Case 'AvahiClientTests.testNewAvahiClient' started at 2019-02-03 03:39:22.738
Process 10360 stopped
* thread #1, name = 'AvahiClientPack', stop reason = breakpoint 1.1
frame #0: 0x0000555555558a07 AvahiClientPackageTests.xctest`AvahiClientTests.testNewAvahiClient(self=<unavailable>) at AvahiClientTests.swift:12
9 func testNewAvahiClient() {
10 do {
11 let c = try AvahiClient()
-> 12 print(c)
13 } catch {
14 XCTFail("\(error)")
15 }
Target 0: (AvahiClientPackageTests.xctest) stopped.
(lldb) print c
<unknown>:0: error: missing required module 'Clibavahiclient'
error: in auto-import:
failed to get module 'AvahiClientTests' from AST context:
error: missing required module 'Clibavahiclient'
If we go poking around, we do see some stuff under .build/ with Clibavahiclient in the name:
$ find . -name Clibavahiclient*
./.build/checkouts/Clibavahiclient.git--4733535768090925471
./.build/x86_64-unknown-linux/debug/ModuleCache/33J8DIMD7H8ZB/Clibavahiclient-2J8WBHG3Q43SC.pcm
./.build/repositories/Clibavahiclient.git--4733535768090925471
Clibavahiclient-2J8WBHG3Q43SC.pcm sounds promising, let's try a readelf:
ELF Header:
Magic: 7f 45 4c 46 02 01 01 00 00 00 00 00 00 00 00 00
Class: ELF64
Data: 2's complement, little endian
Version: 1 (current)
OS/ABI: UNIX - System V
ABI Version: 0
Type: REL (Relocatable file)
Machine: Advanced Micro Devices X86-64
Version: 0x1
Entry point address: 0x0
Start of program headers: 0 (bytes into file)
Start of section headers: 151568 (bytes into file)
Flags: 0x0
Size of this header: 64 (bytes)
Size of program headers: 0 (bytes)
Number of program headers: 0
Size of section headers: 64 (bytes)
Number of section headers: 18
Section header string table index: 1
Section Headers:
[Nr] Name Type Address Offset
Size EntSize Flags Link Info Align
[ 0] NULL 0000000000000000 00000000
0000000000000000 0000000000000000 0 0 0
[ 1] .strtab STRTAB 0000000000000000 00024f38
00000000000000d5 0000000000000000 0 0 1
[ 2] .text PROGBITS 0000000000000000 00000040
0000000000000000 0000000000000000 AX 0 0 4
[ 3] __clangast PROGBITS 0000000000000000 00000040
0000000000021120 0000000000000000 A 0 0 8
[ 4] .debug_str PROGBITS 0000000000000000 00021160
0000000000001250 0000000000000001 MS 0 0 1
[ 5] .debug_abbrev PROGBITS 0000000000000000 000223b0
0000000000000126 0000000000000000 0 0 1
[ 6] .debug_info PROGBITS 0000000000000000 000224d6
0000000000000ba5 0000000000000000 0 0 1
[ 7] .rela.debug_info RELA 0000000000000000 00023480
0000000000001a58 0000000000000018 17 6 8
[ 8] .debug_ranges PROGBITS 0000000000000000 0002307b
0000000000000000 0000000000000000 0 0 1
[ 9] .debug_macinfo PROGBITS 0000000000000000 0002307b
0000000000000001 0000000000000000 0 0 1
[10] .debug_pubnames PROGBITS 0000000000000000 0002307c
00000000000000ab 0000000000000000 0 0 1
[11] .rela.debug_pubna RELA 0000000000000000 00024ed8
0000000000000030 0000000000000018 17 10 8
[12] .debug_pubtypes PROGBITS 0000000000000000 00023127
0000000000000081 0000000000000000 0 0 1
[13] .rela.debug_pubty RELA 0000000000000000 00024f08
0000000000000030 0000000000000018 17 12 8
[14] .comment PROGBITS 0000000000000000 000231a8
00000000000000b4 0000000000000001 MS 0 0 1
[15] .note.GNU-stack PROGBITS 0000000000000000 0002325c
0000000000000000 0000000000000000 0 0 1
[16] .debug_line PROGBITS 0000000000000000 0002325c
000000000000017b 0000000000000000 0 0 1
[17] .symtab SYMTAB 0000000000000000 000233d8
00000000000000a8 0000000000000018 1 7 8
...
You can read the whole readelf dump here, but it does look like an ELF binary with some debug information in it.
Let's try an llvm-dwarfdump:
./.build/x86_64-unknown-linux/debug/ModuleCache/33J8DIMD7H8ZB/Clibavahiclient-2J8WBHG3Q43SC.pcm: file format ELF64-x86-64
.debug_abbrev contents:
Abbrev table for offset: 0x00000000
[1] DW_TAG_compile_unit DW_CHILDREN_yes
DW_AT_producer DW_FORM_strp
DW_AT_language DW_FORM_data2
DW_AT_name DW_FORM_strp
DW_AT_stmt_list DW_FORM_sec_offset
DW_AT_comp_dir DW_FORM_strp
DW_AT_GNU_pubnames DW_FORM_flag_present
DW_AT_GNU_dwo_id DW_FORM_data8
...
.debug_info contents:
0x00000000: Compile Unit: length = 0x00000b77 version = 0x0004 abbr_offset = 0x0000 addr_size = 0x08 (next unit at 0x00000b7b)
0x0000000b: DW_TAG_compile_unit
DW_AT_producer ("clang version 6.0.0 (git@github.com:apple/swift-clang.git 78aa734eee0a481cb13743f74a4b66a340e207fa) (git@github.com:apple/swift-llvm.git 4ba03d9389a3a5a6afccb2d6b202b7b6fa745f77)")
DW_AT_language (DW_LANG_C99)
DW_AT_name ("Clibavahiclient")
DW_AT_stmt_list (0x00000000)
DW_AT_comp_dir ("/work/AvahiClient")
DW_AT_GNU_pubnames (true)
DW_AT_GNU_dwo_id (0x73912bbb5b3343f8)
0x00000026: DW_TAG_module
DW_AT_name ("Clibavahiclient")
DW_AT_LLVM_config_macros ("\"-D__swift__=40150\"")
DW_AT_LLVM_include_path ("/work/AvahiClient/.build/checkouts/Clibavahiclient.git--4733535768090925471")
DW_AT_LLVM_isysroot ("/")
...
You can read the whole llvm-dwarfdump dump here, but it looks suspiciously like it has the debug sysmbols we need?
Also, dwarfdump:
.debug_info
COMPILE_UNIT<header overall offset = 0x00000000>:
< 0><0x0000000b> DW_TAG_compile_unit
DW_AT_producer clang version 6.0.0 (git@github.com:apple/swift-clang.git 78aa734eee0a481cb13743f74a4b66a340e207fa) (git@github.com:apple/swift-llvm.git 4ba03d9389a3a5a6afccb2d6b202b7b6fa745f77)
DW_AT_language DW_LANG_C99
DW_AT_name Clibavahiclient
DW_AT_stmt_list 0x00000000
DW_AT_comp_dir /work/AvahiClient
DW_AT_GNU_pubnames yes(1)
DW_AT_GNU_dwo_id 0xf843335bbb2b9173
LOCAL_SYMBOLS:
< 1><0x00000026> DW_TAG_module
DW_AT_name Clibavahiclient
<Unknown AT value 0x3e01> "-D__swift__=40150"
<Unknown AT value 0x3e00> /work/AvahiClient/.build/checkouts/Clibavahiclient.git--4733535768090925471
<Unknown AT value 0x3e02> /
You can read the whole dwarfdump dump here
I haven't figured out how to get them imported into lldb.