tree 1d11346325da9855b8874f11c317f7588755b669
parent 5d08381e9038f4d2fe279b2ee259a6409fb9f2be
author Fletcher Woodruff <fletcherw@chromium.org> 1548353333 -0700
committer chrome-bot <chrome-bot@chromium.org> 1551228565 -0800

debugd: Have log_tool read file logs directly

log_tool aggregates logs from many different sources. The logs are specified
as the output of running a shell command. However, often this shell command is
just running cat on some file. There is no need to start another process just
to read a file from disk.

This change adds two different log types to log_tool: file logs, and command
logs. Command logs are the same as before; the output of a shell command. File
logs instead just specify a path, and that path is read directly from C++. The
process effective uid and effective gid are set before the reads so that file
permissions are respected.

Additionally, this change splits a couple of log entries that were the combined
output of two files into two different log entries.

Performance testing over 5 trials showed a .6 second improvement in response
time for log_tool when calling GetAllLogs.

TEST=load chrome://system
BUG=chromium:657156
BUG=chromium:925969

Change-Id: Iaf5b8cdbd216d4e1c55b2f6155095192aa18ccbe
Reviewed-on: https://chromium-review.googlesource.com/1479152
Commit-Ready: Fletcher Woodruff <fletcherw@chromium.org>
Tested-by: Fletcher Woodruff <fletcherw@chromium.org>
Reviewed-by: Mike Frysinger <vapier@chromium.org>