From: Ruediger Meier <ruediger.meier@ga-group.nl>
Date: Fri, 31 Mar 2017 15:16:07 +0000 (+0200)
Subject: ipcs: make shmall overflow a bit less worse
X-Git-Tag: v2.30-rc1~142^2
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=61e29ab44fc97bcf86c216ac66e3163739170198;p=thirdparty%2Futil-linux.git

ipcs: make shmall overflow a bit less worse

Still no large integer support but on overflow we print now
the largest possible value, maybe even the largest one which
makes sense at all.

So on x86_64 systems we'll see now:
$ echo "4503599627370496" > /proc/sys/kernel/shmall
$ ipcs -m -l | grep "max total"
max total shared memory (kbytes) = 18014398509481980

rather than this:
$ ipcs -m -l | grep "max total"
max total shared memory (kbytes) = 0

Signed-off-by: Ruediger Meier <ruediger.meier@ga-group.nl>
---

diff --git a/sys-utils/ipcs.c b/sys-utils/ipcs.c
index 4f3d23d907..3c4e5df0ea 100644
--- a/sys-utils/ipcs.c
+++ b/sys-utils/ipcs.c
@@ -198,6 +198,7 @@ static void do_shm (char format, int unit)
 	case LIMITS:
 	{
 		struct ipc_limits lim;
+		uint64_t tmp, pgsz = getpagesize();
 
 		if (ipc_shm_get_limits(&lim)) {
 			printf (_("unable to fetch shared memory limits\n"));
@@ -207,9 +208,14 @@ static void do_shm (char format, int unit)
 		printf (_("max number of segments = %ju\n"), lim.shmmni);
 		ipc_print_size(unit == IPC_UNIT_DEFAULT ? IPC_UNIT_KB : unit,
 			       _("max seg size"), lim.shmmax, "\n", 0);
+
+		tmp = (uint64_t) lim.shmall * pgsz;
+		/* overflow handling, at least we don't print ridiculous small values */
+		if (lim.shmall != 0 && tmp / lim.shmall != pgsz) {
+			tmp = UINT64_MAX - (UINT64_MAX % pgsz);
+		}
 		ipc_print_size(unit == IPC_UNIT_DEFAULT ? IPC_UNIT_KB : unit,
-			       _("max total shared memory"),
-			       (uint64_t) lim.shmall * getpagesize(), "\n", 0);
+			       _("max total shared memory"), tmp, "\n", 0);
 		ipc_print_size(unit == IPC_UNIT_DEFAULT ? IPC_UNIT_BYTES : unit,
 			       _("min seg size"), lim.shmmin, "\n", 0);
 		return;
diff --git a/tests/ts/ipcs/functions.sh b/tests/ts/ipcs/functions.sh
index a9cf2286d7..586ce42f65 100644
--- a/tests/ts/ipcs/functions.sh
+++ b/tests/ts/ipcs/functions.sh
@@ -78,6 +78,12 @@ function ipcs_limits_check {
 		#echo "IPCS-CMD:   ${IPCS_CMD[$i]}"
 		#echo
 
+		# overflow is handled differently because we don't have large
+		# int math, see https://github.com/karelzak/util-linux/issues/51
+		if [ $(bc <<<"$a >= 2^64/1024") -eq 1 ]; then
+			a=$(bc <<<"(2^64 - $PAGE_SIZE)/1024")
+		fi
+
 		if [ x"$a" == x"$b" ]; then
 			echo " OK"
 		else
diff --git a/tests/ts/ipcs/limits2 b/tests/ts/ipcs/limits2
index 4e96ce6803..62a4f5bcb2 100755
--- a/tests/ts/ipcs/limits2
+++ b/tests/ts/ipcs/limits2
@@ -27,12 +27,6 @@ ts_check_prog "bc"
 
 . $TS_SELF/functions.sh
 
-# TODO https://github.com/karelzak/util-linux/issues/51
-SHMALL=$(</proc/sys/kernel/shmall)
-if [ $(bc <<<"(2^64 / $PAGE_SIZE) <= $SHMALL") -eq 1 ]; then
-	TS_KNOWN_FAIL="yes"
-fi
-
 ts_log "check for difference between kernel and IPC"
 ipcs_limits_check >> $TS_OUTPUT