kumquat-buildroot/support/testing/infra/emulator.py
Edgar Bonet eb3ee3078a support/testing/infra/emulator.py: prevent the commands from wrapping
Traditional VT-10x terminals (and their emulators) [0] have a "magic
margins" feature that enables the last character position to be updated
without scrolling the screen: whenever a character is printed on the
last column, the cursor stays over the character, instead of moving to
the next line.

The Busybox shell, ash, attempts to defeat this feature by printing
CR,LF right after echoing a character to the last column.[1] This
doesn't play well with emulator.py. The run() method of the Emulator
class captures the output of the emulated system and assumes the first
line it reads is the echo of the command, and all subsequent lines are
the command's output. If the line made by the command + shell prompt is
longer than 80 characters, then it is echoed as two or more lines, and
all but the first one are mistaken for the command's output.

We fix this by telling the emulated system that we are using an
ultra-wide terminal with 29999 columns. Larger values would be ignored
and replaced by the default, namely 80 columns.[2]

[0] https://vt100.net/docs/vt100-ug/chapter3.html  -  DECAWM
[1] https://git.busybox.net/busybox/tree/libbb/lineedit.c?h=1_34_0#n412
[2] https://git.busybox.net/busybox/tree/libbb/xfuncs.c?h=1_34_0#n258

Signed-off-by: Edgar Bonet <bonet@grenoble.cnrs.fr>
Reported-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
Co-authored-by: Yann E. MORIN <yann.morin.1998@free.fr>
Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>
2021-10-06 21:54:20 +02:00

129 lines
5.0 KiB
Python

import pexpect
import infra
class Emulator(object):
def __init__(self, builddir, downloaddir, logtofile, timeout_multiplier):
self.qemu = None
self.downloaddir = downloaddir
self.logfile = infra.open_log_file(builddir, "run", logtofile)
# We use elastic runners on the cloud to runs our tests. Those runners
# can take a long time to run the emulator. Use a timeout multiplier
# when running the tests to avoid sporadic failures.
self.timeout_multiplier = timeout_multiplier
# Start Qemu to boot the system
#
# arch: Qemu architecture to use
#
# kernel: path to the kernel image, or the special string
# 'builtin'. 'builtin' means a pre-built kernel image will be
# downloaded from ARTEFACTS_URL and suitable options are
# automatically passed to qemu and added to the kernel cmdline. So
# far only armv5, armv7 and i386 builtin kernels are available.
# If None, then no kernel is used, and we assume a bootable device
# will be specified.
#
# kernel_cmdline: array of kernel arguments to pass to Qemu -append option
#
# options: array of command line options to pass to Qemu
#
def boot(self, arch, kernel=None, kernel_cmdline=None, options=None):
if arch in ["armv7", "armv5"]:
qemu_arch = "arm"
else:
qemu_arch = arch
qemu_cmd = ["qemu-system-{}".format(qemu_arch),
"-serial", "stdio",
"-display", "none",
"-m", "256"]
if options:
qemu_cmd += options
if kernel_cmdline is None:
kernel_cmdline = []
if kernel:
if kernel == "builtin":
if arch in ["armv7", "armv5"]:
kernel_cmdline.append("console=ttyAMA0")
if arch == "armv7":
kernel = infra.download(self.downloaddir,
"kernel-vexpress-5.10.7")
dtb = infra.download(self.downloaddir,
"vexpress-v2p-ca9-5.10.7.dtb")
qemu_cmd += ["-dtb", dtb]
qemu_cmd += ["-M", "vexpress-a9"]
elif arch == "armv5":
kernel = infra.download(self.downloaddir,
"kernel-versatile-5.10.7")
dtb = infra.download(self.downloaddir,
"versatile-pb-5.10.7.dtb")
qemu_cmd += ["-dtb", dtb]
qemu_cmd += ["-M", "versatilepb"]
qemu_cmd += ["-device", "virtio-rng-pci"]
qemu_cmd += ["-kernel", kernel]
if kernel_cmdline:
qemu_cmd += ["-append", " ".join(kernel_cmdline)]
self.logfile.write("> starting qemu with '%s'\n" % " ".join(qemu_cmd))
self.qemu = pexpect.spawn(qemu_cmd[0], qemu_cmd[1:],
timeout=5 * self.timeout_multiplier,
encoding='utf-8',
codec_errors='replace',
env={"QEMU_AUDIO_DRV": "none"})
# We want only stdout into the log to avoid double echo
self.qemu.logfile_read = self.logfile
# Wait for the login prompt to appear, and then login as root with
# the provided password, or no password if not specified.
def login(self, password=None):
# The login prompt can take some time to appear when running multiple
# instances in parallel, so set the timeout to a large value
index = self.qemu.expect(["buildroot login:", pexpect.TIMEOUT],
timeout=60 * self.timeout_multiplier)
if index != 0:
self.logfile.write("==> System does not boot")
raise SystemError("System does not boot")
self.qemu.sendline("root")
if password:
self.qemu.expect("Password:")
self.qemu.sendline(password)
index = self.qemu.expect(["# ", pexpect.TIMEOUT])
if index != 0:
raise SystemError("Cannot login")
self.run("dmesg -n 1")
# Prevent the shell from wrapping the commands at 80 columns.
self.run("stty columns 29999")
# Run the given 'cmd' with a 'timeout' on the target
# return a tuple (output, exit_code)
def run(self, cmd, timeout=-1):
self.qemu.sendline(cmd)
if timeout != -1:
timeout *= self.timeout_multiplier
self.qemu.expect("# ", timeout=timeout)
# Remove double carriage return from qemu stdout so str.splitlines()
# works as expected.
output = self.qemu.before.replace("\r\r", "\r").splitlines()[1:]
self.qemu.sendline("echo $?")
self.qemu.expect("# ")
exit_code = self.qemu.before.splitlines()[2]
exit_code = int(exit_code)
return output, exit_code
def stop(self):
if self.qemu is None:
return
self.qemu.terminate(force=True)