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 4f3d23d90762afcc0cd1560d8c92b6133a260ba7..3c4e5df0ead33f73f0dced8d6265e54b8a6ec86c 100644 (file)
--- 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 a9cf2286d78a935ee2f81678463128e7ecfa630e..586ce42f6543a0a0b3764e7036d96bdba394a122 100644 (file)
--- 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 4e96ce68031d90586f430a10577183134b97fa29..62a4f5bcb27d21e542d7957129a2b21340ae00cb 100755 (executable)
--- 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