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Merged
danielocfb merged 1 commit into from
Dec 17, 2025
Merged

Simplify stream tests #1292

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3 changes: 2 additions & 1 deletion .github/workflows/test.yml
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Original file line number Diff line number Diff line change
Expand Up @@ -14,7 +14,8 @@ jobs:
uses: libbpf/github-actions/.github/workflows/build-linux.yml@bd7fc70260c9ab81801001fcd86ba94070b34e5d
secrets: inherit
with:
rev: v6.18
# TODO: Use v6.19 tag once available.
rev: ea0714d61dea6e00b853a0116d0afe2b2fe70ef3
config: 'var/config'

test:
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61 changes: 3 additions & 58 deletions libbpf-rs/tests/bin/src/stream.bpf.c
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Original file line number Diff line number Diff line change
Expand Up @@ -4,69 +4,14 @@
#include "vmlinux.h"
#include <bpf/bpf_helpers.h>

/* Definition of can_loop taken from bpf_experimental.h. */
#ifdef __BPF_FEATURE_MAY_GOTO
#define can_loop \
({ \
__label__ l_break, l_continue; \
bool ret = true; \
asm volatile goto("may_goto %l[l_break]" :: ::l_break); \
goto l_continue; \
l_break: \
ret = false; \
l_continue:; \
ret; \
})
#else
#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
#define can_loop \
({ \
__label__ l_break, l_continue; \
bool ret = true; \
asm volatile goto("1:.byte 0xe5; \
.byte 0; \
.long ((%l[l_break] - 1b - 8) / 8) & 0xffff; \
.short 0" :: ::l_break); \
goto l_continue; \
l_break: \
ret = false; \
l_continue:; \
ret; \
})
#else
#define can_loop \
({ \
__label__ l_break, l_continue; \
bool ret = true; \
asm volatile goto("1:.byte 0xe5; \
.byte 0; \
.long (((%l[l_break] - 1b - 8) / 8) & 0xffff) << 16; \
.short 0" :: ::l_break); \
goto l_continue; \
l_break: \
ret = false; \
l_continue:; \
ret; \
})
#endif
#endif

volatile u64 i;

/*
* Trigger a may_goto timeout to emit a streams error. As of 6.19 the only way
* to trigger streams output is by causing an error condition in the program.
* One of these is a loop timeout: The may_goto macro allows for loops that
* cannot be verified by embedding a timer that is guaranteed to expire in the
* condition, simplifying verification. When the timer expires, the kernel
* writes an error message to the stderr stream of the BPF program. This is the
* case below.
* Trigger writing of some messages to stdout & stderr streams.
*/
SEC("syscall")
int trigger_streams(void *ctx)
{
while (i == 0 && can_loop)
;
bpf_stream_printk(1, "stdout");
bpf_stream_printk(2, "stderr");
return 0;
}

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21 changes: 4 additions & 17 deletions libbpf-rs/tests/test_streams.rs
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Expand Up @@ -25,16 +25,9 @@ fn test_stream_stdout_read() {
let mut stdout = prog.stdout();
let mut buf = [0u8; 1024];

// The read itself should succeed and return 0 bytes
let result = stdout.read(&mut buf);
assert!(
result.is_ok(),
"Failed to read from stdout stream: {:?}",
result.err()
);

let len = result.unwrap();
assert!(len == 0, "Found {len} characters in stdout stream");
let cnt = result.unwrap();
assert_eq!(&buf[..cnt], b"stdout");
}

#[tag(root)]
Expand All @@ -50,13 +43,7 @@ fn test_stream_stderr_read() {
let mut stderr = prog.stderr();
let mut buf = [0u8; 1024];

// The read should successfully read a non-zero amount of bytes
let result = stderr.read(&mut buf);
assert!(
result.is_ok(),
"Failed to read from stderr stream: {:?}",
result.err()
);

assert!(result.unwrap() != 0, "No output from stderr stream");
let cnt = result.unwrap();
assert_eq!(&buf[..cnt], b"stderr");
}