From fbb3854aeab0142e4b65b1fc64c87b0854411ab3 Mon Sep 17 00:00:00 2001
From: Benjamin Drung <benjamin.drung@canonical.com>
Date: Wed, 19 Apr 2023 13:18:48 +0200
Subject: [PATCH] apport: Write coredump at beginning and quit

To reproduce bug #2015857 write the coredump at the beginning and quit.
Allow slowing down the writing to trigger the bug.

Bug: https://launchpad.net/bugs/2015857
Signed-off-by: Benjamin Drung <benjamin.drung@canonical.com>
---
 data/apport | 57 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 57 insertions(+)

diff --git a/data/apport b/data/apport
index 89b73c742..08237f6e7 100755
--- a/data/apport
+++ b/data/apport
@@ -37,6 +37,7 @@ import subprocess
 import sys
 import time
 import traceback
+import typing
 
 import apport.fileutils
 import apport.report
@@ -727,6 +728,50 @@ def parse_arguments(args: list[str]):
     return options
 
 
+def write_coredump_to_file(
+    coredump_path: str, coredump_fd: int, slowdown: float
+) -> None:
+    """Write coredump to given file."""
+    assert isinstance(crash_uid, int)
+    logger = logging.getLogger()
+    coredump_file = os.open(
+        coredump_path,
+        os.O_WRONLY | os.O_CREAT | os.O_EXCL,
+        mode=0o400,
+        dir_fd=cwd,
+    )
+
+    written = 0
+    while True:
+        block = os.read(coredump_fd, 1048576)
+        size = len(block)
+        if size == 0:
+            break
+        written += size
+        if os.write(coredump_file, block) != size:
+            logger.error("aborting core dump writing, could not write")
+            os.close(coredump_file)
+            os.unlink(coredump_path, dir_fd=cwd)
+            return
+        time.sleep(slowdown)
+
+    # Make sure the user can read it
+    os.fchown(coredump_file, crash_uid, -1)
+    os.close(coredump_file)
+    logger.warning(
+        "Wrote %s bytes of core to %s", f"{written:,}", coredump_path
+    )
+
+
+def get_core_path(
+    options: argparse.Namespace, timestamp: typing.Optional[int] = None
+) -> str:
+    """Get the path to the core file."""
+    return apport.fileutils.get_core_path(
+        options.pid, options.executable_path, crash_uid, timestamp
+    )[1]
+
+
 def main(args: list[str]) -> int:
     init_error_log()
     logging.basicConfig(format=LOG_FORMAT)
@@ -744,6 +789,18 @@ def main(args: list[str]) -> int:
         start_apport()
         return 0
 
+    get_pid_info(options.pid)
+    logging.getLogger(__name__).error(
+        "called for pid %s, signal %s, core limit %s, dump mode %s",
+        options.pid,
+        options.signal_number,
+        options.core_ulimit,
+        options.dump_mode,
+    )
+    write_coredump_to_file(get_core_path(options), sys.stdin.fileno(), 0.001)
+    # pylint: disable=unreachable
+    return 0
+
     # Check if we received a valid global PID (kernel >= 3.12). If we do,
     # then compare it with the local PID. If they don't match, it's an
     # indication that the crash originated from another PID namespace.
-- 
2.37.2