Exit code 141 with local agent when logs exceed certain size

[fauust]

Component

server, agent, web-ui

Describe the bug

Pipeline steps will systematically fail with exit code 141 if the log size is over something between 2063600 and 2079000 bytes.

Here is how to test it.

The following pipeline will work:

pipeline:
  logs exec:
    image: bash
    commands:
      - bash -c "for i in {1..134}; do base64 /dev/urandom | head -n 200; done"

The following pipeline will not work (exit code 141):

pipeline:
  logs exec:
    image: bash
    commands:
      - bash -c "for i in {1..135}; do base64 /dev/urandom | head -n 200; done"

2063600 - 2079000 bytes range is given by:

for i in {1..134}; do base64 /dev/urandom | head -n 200; done >limit.log
stat --format="%s" limit.log
2063600
for i in {1..135}; do base64 /dev/urandom | head -n 200; done >limit.log
stat --format="%s" limit.log
2079000

This problem does not appear with docker agent, for instance, the following pipeline works without pb:

pipeline:
  generate log:
    image: debian:11-slim
    commands:
      - bash -c "for i in {1..400}; do base64 /dev/urandom | head -n 200; done"

But then, the log file seems to be trunkated to 2000000 bytes and it's impossible to download the full log from the web interface.

System Info

Server:

❯ docker images | grep woodpecker-server
woodpeckerci/woodpecker-server   next                abdf33e30acc   35 hours ago   24.1MB

Local agent:
Run from commit 08a9915, with go run ./cmd/agent --log-level debug

Docker agent:

❯ docker images | grep woodpecker-agent
woodpeckerci/woodpecker-agent    next                374ee61b7354   35 hours ago   13.3MB

Additional context

No response

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[6543]

at the moment we use os Pipe but we should move to a buffer instead ... we do need it anyway as soon as we start using commands as list

[6543]

https://github.com/woodpecker-ci/woodpecker/pull/1397/files#diff-a04c642ebae3a1409872e78fbebc32223305acdfb5ec9a67edf544176b000d82R43