On 1/17/21 2:27 AM, Dov Murik wrote:
Detect whether qmp-shell's standard input is not a TTY; in such case, assume a non-interactive mode, which suppresses the welcome banner and the "(QEMU)" prompt. This allows for easier consumption of qmp-shell's output in scripts.Example usage before this change: $ printf "query-status\nquery-kvm\n" | sudo scripts/qmp/qmp-shell qmp-unix-sock Welcome to the QMP low-level shell! Connected to QEMU 5.1.50 (QEMU) {"return": {"status": "running", "singlestep": false, "running": true}} (QEMU) {"return": {"enabled": true, "present": true}} (QEMU) Example usage after this change: $ printf "query-status\nquery-kvm\n" | sudo scripts/qmp/qmp-shell qmp-unix-sock {"return": {"status": "running", "singlestep": false, "running": true}} {"return": {"enabled": true, "present": true}} Signed-off-by: Dov Murik <dovmu...@linux.vnet.ibm.com>
Hiya! I've been taking lead on modernizing a lot of our python infrastructure, including our QMP library and qmp-shell.
(Sorry, not in MAINTAINERS yet; but I am in the process of moving these scripts and tools over to ./python/qemu/qmp.)
This change makes me nervous, because qmp-shell is not traditionally a component we've thought of as needing to preserve backwards-compatible behavior. Using it as a script meant to be consumed in a headless fashion runs a bit counter to that assumption.
I'd be less nervous if the syntax of qmp-shell was something that was well thought-out and rigorously tested, but it's a hodge-podge of whatever people needed at the moment. I am *very* reluctant to cement it.
Are you trying to leverage the qmp.py library from bash? --js
--- Notes: Note that this might be considered a breaking change; if users have automated scripts which assume that qmp-shell prints 3 lines of banner, this change will break their scripts. If there are special considerations/procedures for breaking changes, please let me know.The rationale behaind the TTY check is to imitate python's behaviour: $ python3Python 3.7.5 (default, Apr 19 2020, 20:18:17) [GCC 9.2.1 20191008] on linux Type "help", "copyright", "credits" or "license" for more information. >>> print(19+23) 42 >>>$ echo 'print(19+23)' | python342 scripts/qmp/qmp-shell | 19 +++++++++++++++++-- 1 file changed, 17 insertions(+), 2 deletions(-) diff --git a/scripts/qmp/qmp-shell b/scripts/qmp/qmp-shell index b4d06096ab..9336066fa8 100755 --- a/scripts/qmp/qmp-shell +++ b/scripts/qmp/qmp-shell @@ -288,6 +288,8 @@ class QMPShell(qmp.QEMUMonitorProtocol): self.__completer_setup()def show_banner(self, msg='Welcome to the QMP low-level shell!'):+ if not self._interactive: + return print(msg) if not self._greeting: print('Connected') @@ -300,6 +302,15 @@ class QMPShell(qmp.QEMUMonitorProtocol): return "TRANS> " return "(QEMU) "+ def read_command(self, prompt):+ if self._interactive: + return input(prompt) + else: + line = sys.stdin.readline() + if not line: + raise EOFError + return line + def read_exec_command(self, prompt): """ Read and execute a command. @@ -307,7 +318,7 @@ class QMPShell(qmp.QEMUMonitorProtocol): @return True if execution was ok, return False if disconnected. """ try: - cmdline = input(prompt) + cmdline = self.read_command(prompt) except EOFError: print() return False @@ -322,6 +333,9 @@ class QMPShell(qmp.QEMUMonitorProtocol): def set_verbosity(self, verbose): self._verbose = verbose+ def set_interactive(self, interactive):+ self._interactive = interactive + class HMPShell(QMPShell): def __init__(self, address): QMPShell.__init__(self, address) @@ -449,8 +463,9 @@ def main(): except qemu.error: die('Could not connect to %s' % addr)- qemu.show_banner()qemu.set_verbosity(verbose) + qemu.set_interactive(sys.stdin.isatty()) + qemu.show_banner() while qemu.read_exec_command(qemu.get_prompt()): pass qemu.close()
