From dbb542e10bfe1b2e21c7927bda9be1d301cfef65 Mon Sep 17 00:00:00 2001 From: HATAYAMA Daisuke Date: Fri, 17 Jun 2022 20:38:19 +0900 Subject: [PATCH 4/5] 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 Signed-off-by: Lianbo Jiang --- 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 424b0a40a42b..27086d91468b 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