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6447733eb2
Change-Id: I6f11d123b68fd077f558d3c21349c55c5f251019 Reviewed-on: https://gerrit-review.googlesource.com/c/git-repo/+/383715 Reviewed-by: Gavin Mak <gavinmak@google.com> Tested-by: Mike Frysinger <vapier@google.com> Commit-Queue: Mike Frysinger <vapier@google.com>
131 lines
3.5 KiB
Python
131 lines
3.5 KiB
Python
# Copyright (C) 2008 The Android Open Source Project
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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import os
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import select
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import subprocess
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import sys
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import platform_utils
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active = False
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pager_process = None
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old_stdout = None
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old_stderr = None
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def RunPager(globalConfig):
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if not os.isatty(0) or not os.isatty(1):
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return
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pager = _SelectPager(globalConfig)
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if pager == "" or pager == "cat":
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return
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if platform_utils.isWindows():
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_PipePager(pager)
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else:
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_ForkPager(pager)
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def TerminatePager():
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global pager_process, old_stdout, old_stderr
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if pager_process:
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sys.stdout.flush()
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sys.stderr.flush()
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pager_process.stdin.close()
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pager_process.wait()
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pager_process = None
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# Restore initial stdout/err in case there is more output in this
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# process after shutting down the pager process.
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sys.stdout = old_stdout
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sys.stderr = old_stderr
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def _PipePager(pager):
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global pager_process, old_stdout, old_stderr
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assert pager_process is None, "Only one active pager process at a time"
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# Create pager process, piping stdout/err into its stdin.
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try:
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pager_process = subprocess.Popen(
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[pager], stdin=subprocess.PIPE, stdout=sys.stdout, stderr=sys.stderr
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)
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except FileNotFoundError:
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sys.exit(f'fatal: cannot start pager "{pager}"')
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old_stdout = sys.stdout
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old_stderr = sys.stderr
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sys.stdout = pager_process.stdin
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sys.stderr = pager_process.stdin
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def _ForkPager(pager):
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global active
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# This process turns into the pager; a child it forks will
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# do the real processing and output back to the pager. This
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# is necessary to keep the pager in control of the tty.
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try:
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r, w = os.pipe()
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pid = os.fork()
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if not pid:
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os.dup2(w, 1)
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os.dup2(w, 2)
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os.close(r)
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os.close(w)
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active = True
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return
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os.dup2(r, 0)
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os.close(r)
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os.close(w)
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_BecomePager(pager)
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except Exception:
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print("fatal: cannot start pager '%s'" % pager, file=sys.stderr)
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sys.exit(255)
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def _SelectPager(globalConfig):
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try:
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return os.environ["GIT_PAGER"]
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except KeyError:
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pass
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pager = globalConfig.GetString("core.pager")
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if pager:
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return pager
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try:
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return os.environ["PAGER"]
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except KeyError:
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pass
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return "less"
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def _BecomePager(pager):
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# Delaying execution of the pager until we have output
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# ready works around a long-standing bug in popularly
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# available versions of 'less', a better 'more'.
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_a, _b, _c = select.select([0], [], [0])
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# This matches the behavior of git, which sets $LESS to `FRX` if it is not
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# set. See:
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# https://git-scm.com/docs/git-config#Documentation/git-config.txt-corepager
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os.environ.setdefault("LESS", "FRX")
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try:
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os.execvp(pager, [pager])
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except OSError:
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os.execv("/bin/sh", ["sh", "-c", pager])
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