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From dbb542e10bfe1b2e21c7927bda9be1d301cfef65 Mon Sep 17 00:00:00 2001
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From: HATAYAMA Daisuke <d.hatayama@fujitsu.com>
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Date: Fri, 17 Jun 2022 20:38:19 +0900
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Subject: [PATCH 4/5] coredump: fix unexpected truncation of generated core
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files
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Core files generated by crash gcore command are sometimes unexpectedly
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truncated. Then, we can get aware of this from the following warning
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message output by gdb:
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BFD: warning: /root/./core.1.systemd is truncated: expected core file size >= 43606016, found: 43597824
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From the investigation, it turned out that this truncation is
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occurring when there is no write() operation after the area skipped by
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lseek(). Holes are generated only when there is write() operation.
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To fix this issue, use ftruncate() to allocate holes explicitly.
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Signed-off-by: HATAYAMA Daisuke <d.hatayama@fujitsu.com>
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Signed-off-by: Lianbo Jiang <lijiang@redhat.com>
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---
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src/libgcore/gcore_coredump.c | 15 +++++++++++++++
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1 file changed, 15 insertions(+)
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diff --git a/src/libgcore/gcore_coredump.c b/src/libgcore/gcore_coredump.c
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index 424b0a40a42b..27086d91468b 100644
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--- a/src/libgcore/gcore_coredump.c
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+++ b/src/libgcore/gcore_coredump.c
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@@ -331,6 +331,21 @@ void gcore_coredump(void)
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}
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progressf("done.\n");
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+ /*
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+ * Use ftruncate() to generate holes explicitly, or core file
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+ * gets truncated if there is no write() operation after the
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+ * area skipped by lseek().
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+ */
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+ if (fflush(gcore->fp))
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+ error(FATAL, "%s: fflush: %s\n",
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+ gcore->corename,
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+ strerror(errno));
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+
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+ if (ftruncate(fileno(gcore->fp), ftell(gcore->fp)) < 0)
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+ error(FATAL, "%s: ftruncate: %s\n",
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+ gcore->corename,
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+ strerror(errno));
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+
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gcore->flags |= GCF_SUCCESS;
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}
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--
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2.37.1
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