I’m working on a proof-of-concept:
However, when I run zig build, I get stuff like:
error: ld.lld: undefined symbol: sd_bus_open_user
note: referenced by main.c:56
note: /scratch4/yoe/mgr/zig-cache/o/65e9521a0e743fd7e872cb98008a5618/main.o:(main)
error: ld.lld: undefined symbol: sd_bus_add_object_vtable
note: referenced by main.c:63
note: /scratch4/yoe/mgr/zig-cache/o/65e9521a0e743fd7e872cb98008a5618/main.o:(main)
error: ld.lld: undefined symbol: sd_bus_request_name
note: referenced by main.c:75
note: /scratch4/yoe/mgr/zig-cache/o/65e9521a0e743fd7e872cb98008a5618/main.o:(main)
error: ld.lld: undefined symbol: sd_bus_process
note: referenced by main.c:83
note: /scratch4/yoe/mgr/zig-cache/o/65e9521a0e743fd7e872cb98008a5618/main.o:(main)
error: ld.lld: undefined symbol: sd_bus_wait
...
Appreciate any pointers or examples I can following.
Hey @cbrake , welcome!
I had an issue like this recently and I forgot to link the system library to my executable.
Here’s an example:
// If you are compiling multiple objects that have the same
// library dependencies, make a helper function to attach them in one go.
fn linkLibraries(b: *std.Build, obj: *std.Build.Step.Compile) void {
// Link a static library (archive file)
obj.addObjectFile(b.path("src/lib/mp_kernels.a"));
// Enable searching for libraries prefixed with "lib",
// such as "libcudart.so" or "libfoo.so"
obj.addLibraryPath(b.path("deps/cuda/lib64"));
// Perform a search for libraries in specified paths.
// Note that the "lib" prefix has been omitted, such as in "cudart",
// which actually has the name "libcudart.so"
obj.linkSystemLibrary("cudart");
obj.linkSystemLibrary("nvrtc");
obj.linkSystemLibrary("cuda");
// Link system libc
obj.linkLibC();
}
From: Build system tricks
Here is my build file:
const std = @import("std");
pub fn build(b: *std.Build) void {
const target = b.standardTargetOptions(.{});
const exe = b.addExecutable(.{
.name = "mgr",
.target = target,
});
exe.addCSourceFile(.{
.file = b.path("main.c"),
.flags = &[_][]const u8{},
});
exe.linkLibC();
exe.linkSystemLibrary("systemd");
b.installArtifact(exe);
}
I am attempting to link the systemd lib, but perhaps I’m not doing it right.
The following lib exists:
[cbrake@ceres ~]$ ls -l /usr/lib/libsystemd.so
lrwxrwxrwx 1 root root 15 Jun 18 14:57 /usr/lib/libsystemd.so -> libsystemd.so.0
It seems the symbols exist in the lib:
[cbrake@ceres ~]$ readelf -Ws /usr/lib/libsystemd.so | grep sd_bus_open_user
435: 0000000000040e80 568 FUNC GLOBAL DEFAULT 13 sd_bus_open_user_with_description@@LIBSYSTEMD_239
481: 00000000000410c0 12 FUNC GLOBAL DEFAULT 13 sd_bus_open_user@@LIBSYSTEMD_221
661: 0000000000041570 355 FUNC GLOBAL DEFAULT 13 sd_bus_open_user_machine@@LIBSYSTEMD_248
Maybe try zig build --verbose-cc --verbose-link to see what commands are being run.
[cbrake@ceres mgr]$ zig build --verbose-cc --verbose-link
install
└─ install mgr
└─ zig build-exe mgr Debug native 11 errors
error: ld.lld: undefined symbol: sd_bus_open_user
note: referenced by main.c:56
note: /scratch4/yoe/mgr/zig-cache/o/65e9521a0e743fd7e872cb98008a5618/main.o:(main)
error: ld.lld: undefined symbol: sd_bus_add_object_vtable
note: referenced by main.c:63
note: /scratch4/yoe/mgr/zig-cache/o/65e9521a0e743fd7e872cb98008a5618/main.o:(main)
error: ld.lld: undefined symbol: sd_bus_request_name
note: referenced by main.c:75
note: /scratch4/yoe/mgr/zig-cache/o/65e9521a0e743fd7e872cb98008a5618/main.o:(main)
error: ld.lld: undefined symbol: sd_bus_process
note: referenced by main.c:83
note: /scratch4/yoe/mgr/zig-cache/o/65e9521a0e743fd7e872cb98008a5618/main.o:(main)
error: ld.lld: undefined symbol: sd_bus_wait
note: referenced by main.c:92
note: /scratch4/yoe/mgr/zig-cache/o/65e9521a0e743fd7e872cb98008a5618/main.o:(main)
error: ld.lld: undefined symbol: sd_bus_slot_unref
note: referenced by main.c:100
note: /scratch4/yoe/mgr/zig-cache/o/65e9521a0e743fd7e872cb98008a5618/main.o:(main)
error: ld.lld: undefined symbol: sd_bus_unref
note: referenced by main.c:101
note: /scratch4/yoe/mgr/zig-cache/o/65e9521a0e743fd7e872cb98008a5618/main.o:(main)
error: ld.lld: undefined symbol: sd_bus_message_read
note: referenced by main.c:12
note: /scratch4/yoe/mgr/zig-cache/o/65e9521a0e743fd7e872cb98008a5618/main.o:(method_multiply)
note: referenced by main.c:27
note: /scratch4/yoe/mgr/zig-cache/o/65e9521a0e743fd7e872cb98008a5618/main.o:(method_divide)
error: ld.lld: undefined symbol: sd_bus_reply_method_return
note: referenced by main.c:19
note: /scratch4/yoe/mgr/zig-cache/o/65e9521a0e743fd7e872cb98008a5618/main.o:(method_multiply)
note: referenced by main.c:39
note: /scratch4/yoe/mgr/zig-cache/o/65e9521a0e743fd7e872cb98008a5618/main.o:(method_divide)
error: ld.lld: undefined symbol: sd_bus_error_set_const
note: referenced by main.c:35
note: /scratch4/yoe/mgr/zig-cache/o/65e9521a0e743fd7e872cb98008a5618/main.o:(method_divide)
error: ld.lld: undefined symbol: sd_bus_object_vtable_format
note: referenced by main.c
note: /scratch4/yoe/mgr/zig-cache/o/65e9521a0e743fd7e872cb98008a5618/main.o:(calculator_vtable)
error: ld.lld --error-limit=0 --entry _start -z stack-size=16777216 --image-base=16777216 --eh-frame-hdr -znow -m elf_x86_64 -o /scratch4/yoe/mgr/zig-cache/o/19de657a1d80d1e0a3e01b2464e4ade7/mgr /usr/lib/gcc/x86_64-pc-linux-gnu/14.1.1/../../../../lib/crt1.o /usr/lib/gcc/x86_64-pc-linux-gnu/14.1.1/../../../../lib/crti.o -L /usr/lib/gcc/x86_64-pc-linux-gnu/14.1.1/../../../../lib -dynamic-linker /lib64/ld-linux-x86-64.so.2 /scratch4/yoe/mgr/zig-cache/o/65e9521a0e743fd7e872cb98008a5618/main.o --as-needed -lm -lpthread -lc -ldl -lrt -lutil /home/cbrake/.cache/zig/o/08cdbdaa2a4d4d98dabc24567ac5e8d5/libcompiler_rt.a /usr/lib/gcc/x86_64-pc-linux-gnu/14.1.1/../../../../lib/crtn.o
error: the following command failed with 11 compilation errors:
/usr/bin/zig build-exe /scratch4/yoe/mgr/main.c -ODebug -Mroot -lc --verbose-link --verbose-cc --cache-dir /scratch4/yoe/mgr/zig-cache --global-cache-dir /home/cbrake/.cache/zig --name mgr --listen=-
Build Summary: 0/3 steps succeeded; 1 failed (disable with --summary none)
install transitive failure
└─ install mgr transitive failure
└─ zig build-exe mgr Debug native 11 errors
error: the following build command failed with exit code 1:
/scratch4/yoe/mgr/zig-cache/o/ff0a4416b81815c5ee4cba068fa93522/build /usr/bin/zig /scratch4/yoe/mgr /scratch4/yoe/mgr/zig-cache /home/cbrake/.cache/zig --seed 0x5078cc4e -Z5f9d7a959d19f7bd --verbose-cc --verbose-link
[cbrake@ceres mgr]$
I don’t see systemd referenced above – odd …
1 Like
cbrake
July 10, 2024, 3:34pm
8
Someone on Discord told me what the problem was:
exe.linkSystemLibrary(“libsystemd”) will do. The name here follows pkg-config.
This change fixes it:
diff --git a/build.zig b/build.zig
index dbb1c4b..0ca4616 100644
--- a/build.zig
+++ b/build.zig
@@ -13,6 +13,6 @@ pub fn build(b: *std.Build) void {
});
exe.linkLibC();
- exe.linkSystemLibrary("systemd");
+ exe.linkSystemLibrary("libsystemd");
b.installArtifact(exe);
}
2 Likes