[LTP] [PATCH v2] waitid10: Set the core dump file location to temporary directory

[Hui Min Mina Chou]

When testing via NFS mount LTP folder on the board, with the NFS server
configured using 'anonuid' and 'anongid' options to set specific
uid/gid, waitid10 fails. This is due to a uid mismatch during core dump
file creation, leading to an aborted dump, resulting in the child
process receiving the signal CLD_KILLED instead of CLD_DUMPED.

  # ./waitid10
  tst_buffers.c:56: TINFO: Test is using guarded buffers
  tst_test.c:1732: TINFO: LTP version: 20240129
  tst_test.c:1616: TINFO: Timeout per run is 0h 05m 00s
  waitid10.c:64: TINFO: Raising RLIMIT_CORE rlim_cur=0 -> 0
  [  296.482665] mnt_uid= 1036, curr_uid= 0
  [  296.483041] Core dump to core aborted: cannot preserve file owner
  waitid10.c:36: TPASS: waitid(P_ALL, 0, infop, WEXITED) passed
  waitid10.c:37: TPASS: infop->si_pid == pidchild (149)
  waitid10.c:38: TPASS: infop->si_status == SIGFPE (8)
  waitid10.c:39: TPASS: infop->si_signo == SIGCHLD (17)
  waitid10.c:42: TFAIL: infop->si_code (2) != CLD_DUMPED (3)

Therefore, referring to madvise08, during testing, set the core dump file
to the temporary directory instead of the current working directory. After
testing, restore the contents of /proc/sys/kernel/core_pattern and clear
all test temporary file.

  # ./waitid10
  tst_buffers.c:56: TINFO: Test is using guarded buffers
  tst_test.c:1709: TINFO: LTP version: 20240129-45-g69537563d16a
  tst_test.c:1593: TINFO: Timeout per run is 0h 05m 00s
  waitid10.c:60: TINFO: Temporary core pattern is '/tmp/LTP_waiSzyEv2/core'
  waitid10.c:73: TINFO: Raising RLIMIT_CORE rlim_cur=0 -> 0
  [68549.534126] mnt_uid= 0, curr_uid= 0
  waitid10.c:38: TPASS: waitid(P_ALL, 0, infop, WEXITED) passed
  waitid10.c:39: TPASS: infop->si_pid == pidchild (163)
  waitid10.c:40: TPASS: infop->si_status == SIGFPE (8)
  waitid10.c:41: TPASS: infop->si_signo == SIGCHLD (17)
  waitid10.c:44: TPASS: infop->si_code == CLD_DUMPED (3)

Signed-off-by: Hui Min Mina Chou <minachou@andestech.com>
---
 testcases/kernel/syscalls/waitid/waitid10.c | 16 +++++++++++++++-
 1 file changed, 15 insertions(+), 1 deletion(-)

diff --git a/testcases/kernel/syscalls/waitid/waitid10.c b/testcases/kernel/syscalls/waitid/waitid10.c
index e55e88c2325e..3e48f52d0ea8 100644
--- a/testcases/kernel/syscalls/waitid/waitid10.c
+++ b/testcases/kernel/syscalls/waitid/waitid10.c
@@ -16,6 +16,8 @@
 #include <sys/prctl.h>
 #include "tst_test.h"
 
+#define CORE_PATTERN "/proc/sys/kernel/core_pattern"
+
 static siginfo_t *infop;
 static int core_dumps = 1;
 
@@ -48,9 +50,16 @@ static void setup(void)
 {
 	struct rlimit rlim;
 	char c;
+	char cwd[1024];
+	char tmpcpattern[1048];
 
 	SAFE_GETRLIMIT(RLIMIT_CORE, &rlim);
-	SAFE_FILE_SCANF("/proc/sys/kernel/core_pattern", "%c", &c);
+
+	SAFE_GETCWD(cwd, sizeof(cwd));
+	snprintf(tmpcpattern, sizeof(tmpcpattern), "%s/core", cwd);
+	tst_res(TINFO, "Temporary core pattern is '%s'", tmpcpattern);
+	SAFE_FILE_PRINTF(CORE_PATTERN, "%s", tmpcpattern);
+	SAFE_FILE_SCANF(CORE_PATTERN, "%c", &c);
 
 	if (rlim.rlim_cur)
 		return;
@@ -76,4 +85,9 @@ static struct tst_test test = {
 		{&infop, .size = sizeof(*infop)},
 		{},
 	},
+	.needs_tmpdir = 1,
+	.save_restore = (const struct tst_path_val[]) {
+		{CORE_PATTERN, NULL, TST_SR_TCONF},
+		{}
+	},
 };
-- 
2.34.1