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coredump: fix unexpected truncation of generated core files

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Backport from the upstream crash-gcore.

commit dbb542e10bfe1b2e21c7927bda9be1d301cfef65
Author: HATAYAMA Daisuke <d.hatayama@fujitsu.com>
Date:   Fri Jun 17 20:38:19 2022 +0900

    coredump: fix unexpected truncation of generated core files

    Core files generated by crash gcore command are sometimes unexpectedly
    truncated. Then, we can get aware of this from the following warning
    message output by gdb:

        BFD: warning: /root/./core.1.systemd is truncated: expected core file size >= 43606016, found: 43597824

    From the investigation, it turned out that this truncation is
    occurring when there is no write() operation after the area skipped by
    lseek(). Holes are generated only when there is write() operation.

    To fix this issue, use ftruncate() to allocate holes explicitly.

    Signed-off-by: HATAYAMA Daisuke <d.hatayama@fujitsu.com>

Signed-off-by: HATAYAMA Daisuke <d.hatayama@fujitsu.com>
This commit is contained in:
HATAYAMA Daisuke 2022-07-26 10:18:42 +09:00
parent 44392dfce6
commit 9f16f6a487
1 changed files with 52 additions and 0 deletions
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52
crash-gcore-1.6.3-coredump-fix-unexpected-truncation-of-generated-core.patch Normal file
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@ -0,0 +1,52 @@
From dbb542e10bfe1b2e21c7927bda9be1d301cfef65 Mon Sep 17 00:00:00 2001
From: HATAYAMA Daisuke <d.hatayama@fujitsu.com>
Date: Fri, 17 Jun 2022 20:38:19 +0900
Subject: [PATCH 7/8] coredump: fix unexpected truncation of generated core
files
Core files generated by crash gcore command are sometimes unexpectedly
truncated. Then, we can get aware of this from the following warning
message output by gdb:
BFD: warning: /root/./core.1.systemd is truncated: expected core file size >= 43606016, found: 43597824
From the investigation, it turned out that this truncation is
occurring when there is no write() operation after the area skipped by
lseek(). Holes are generated only when there is write() operation.
To fix this issue, use ftruncate() to allocate holes explicitly.
Signed-off-by: HATAYAMA Daisuke <d.hatayama@fujitsu.com>
---
src/libgcore/gcore_coredump.c | 15 +++++++++++++++
1 file changed, 15 insertions(+)
diff --git a/src/libgcore/gcore_coredump.c b/src/libgcore/gcore_coredump.c
index 424b0a4..27086d9 100644
--- a/src/libgcore/gcore_coredump.c
+++ b/src/libgcore/gcore_coredump.c
@@ -331,6 +331,21 @@ void gcore_coredump(void)
}
progressf("done.\n");
+ /*
+ * Use ftruncate() to generate holes explicitly, or core file
+ * gets truncated if there is no write() operation after the
+ * area skipped by lseek().
+ */
+ if (fflush(gcore->fp))
+ error(FATAL, "%s: fflush: %s\n",
+ gcore->corename,
+ strerror(errno));
+
+ if (ftruncate(fileno(gcore->fp), ftell(gcore->fp)) < 0)
+ error(FATAL, "%s: ftruncate: %s\n",
+ gcore->corename,
+ strerror(errno));
+
gcore->flags |= GCF_SUCCESS;
}
--
2.37.1