[PATCH V2] fabrics: fix return value of hostnqn_read_file()

[Chaitanya Kulkarni]

From: Chaitanya Kulkarni <kch at nvidia.com>

Current code returns the value of strdup and callers of
hostnqn_read_file() check for the NULL value in order to determine the
success or failure. The value return by the strdup will never be NULL
unless strdup() results in an error that is making function return
success all the time resulting in blktests failures.

Check the string value to NULL before we return the pointer.

Signed-off-by: Chaitanya Kulkarni <kch at nvidia.com>
---
# ./check nvme/012
nvme/012 (run mkfs and data verification fio job on NVMeOF block device-backed ns) [failed]
    runtime  0.866s  ...  0.868s
    --- tests/nvme/012.out	2021-08-29 01:09:20.287901783 -0700
    +++ /mnt/data/blktests/results/nodev/nvme/012.out.bad	2021-09-09 10:22:36.837204035 -0700
    @@ -1,5 +1,24 @@
     Running nvme/012
    -91fdba0d-f87b-4c25-b80f-db7be1418b9e
    -uuid.91fdba0d-f87b-4c25-b80f-db7be1418b9e
    -NQN:blktests-subsystem-1 disconnected 1 controller(s)
    +Failed to write to /dev/nvme-fabrics: Invalid argument
    +cat: '/sys/class/nvme/nvme*/subsysnqn': No such file or directory
    +cat: /sys/block/n1/uuid: No such file or directory
    ...
    (Run 'diff -u tests/nvme/012.out /mnt/data/blktests/results/nodev/nvme/012.out.bad' to see the entire diff)
root at dev blktests (master) # dmesg  -c 
[168877.017464] run blktests nvme/012 at 2021-09-09 10:22:35
[168877.045656] loop2: detected capacity change from 0 to 2097152
[168877.058783] nvmet: adding nsid 1 to subsystem blktests-subsystem-1
[168877.063406] nvme_fabrics: unknown parameter or missing value 'hostnqn=' in ctrl creation request
[168877.099819] loop3: detected capacity change from 0 to 265176
[168877.108359] XFS (loop3): Mounting V5 Filesystem
[168877.110346] XFS (loop3): Ending clean mount
[168877.110678] xfs filesystem being mounted at /mnt/blktests supports timestamps until 2038 (0x7fffffff)
[168877.840376] XFS (loop3): Unmounting Filesystem
root at dev blktests (master) # cdnvmecli 
root at dev nvme-cli ((HEAD detached at v1.15)) # git am 0001-fabrics-fix-return-value-of-hostnqn_read_file.patch
Applying: fabrics: fix return value of hostnqn_read_file()
root at dev nvme-cli ((HEAD detached from v1.15)) # makej install 
NVME_VERSION = 1.15.1.gd23e.dirty
    CC fabrics.o
make -C Documentation install-no-build
install -d /usr/share/bash-completion/completions
install -d /usr/share/zsh/site-functions
install -d /etc/nvme
install -d /usr/lib/systemd/system
install -d /etc/udev/rules.d
install -m 644 -T ./completions/bash-nvme-completion.sh /usr/share/bash-completion/completions/nvme
install -m 644 -T ./completions/_nvme /usr/share/zsh/site-functions/_nvme
touch /etc/nvme/hostnqn
install -m 644 ./nvmf-autoconnect/systemd/* /usr/lib/systemd/system
install -m 644 ./nvmf-autoconnect/udev-rules/* /etc/udev/rules.d
install -d /usr/lib/dracut/dracut.conf.d
touch /etc/nvme/hostid
if [ ! -f /etc/nvme/discovery.conf ]; then \
	install -m 644 -T ./etc/discovery.conf.in /etc/nvme/discovery.conf; \
fi
install -m 644 70-nvmf-autoconnect.conf /usr/lib/dracut/dracut.conf.d
if [ ! -s /etc/nvme/hostnqn ]; then \
	echo `/usr/sbin/nvme gen-hostnqn` > /etc/nvme/hostnqn; \
fi
if [ ! -s /etc/nvme/hostid ]; then \
	uuidgen > /etc/nvme/hostid; \
fi
make[1]: Entering directory '/mnt/data/nvme-cli/Documentation'
install -d -m 755 /usr/local/share/man/man1
install -m 644 nvme-admin-passthru.1 nvme-ana-log.1 nvme-attach-ns.1 nvme-capacity-mgmt.1 nvme-changed-ns-list-log.1 nvme-compare.1 nvme-connect-all.1 nvme-connect.1 nvme-copy.1 nvme-create-ns.1 nvme-delete-ns.1 nvme-dera-stat.1 nvme-detach-ns.1 nvme-device-self-test.1 nvme-dir-receive.1 nvme-dir-send.1 nvme-disconnect-all.1 nvme-disconnect.1 nvme-discover.1 nvme-dsm.1 nvme-effects-log.1 nvme-endurance-event-agg-log.1 nvme-endurance-log.1 nvme-error-log.1 nvme-flush.1 nvme-format.1 nvme-fw-commit.1 nvme-fw-download.1 nvme-fw-log.1 nvme-gen-hostnqn.1 nvme-get-feature.1 nvme-get-lba-status.1 nvme-get-log.1 nvme-get-ns-id.1 nvme-get-property.1 nvme-help.1 nvme-huawei-id-ctrl.1 nvme-huawei-list.1 nvme-id-ctrl.1 nvme-id-domain.1 nvme-id-iocs.1 nvme-id-ns.1 nvme-id-nvmset.1 nvme-intel-id-ctrl.1 nvme-intel-internal-log.1 nvme-intel-lat-stats.1 nvme-intel-market-name.1 nvme-intel-smart-log-add.1 nvme-intel-temp-stats.1 nvme-io-passthru.1 nvme-lba-status-log.1 nvme-list-ctrl.1 nvme-list-ns.1 nvme-list-subsys.1 nvme-list.1 nvme-lnvm-create.1 nvme-lnvm-diag-bbtbl.1 nvme-lnvm-diag-set-bbtbl.1 nvme-lnvm-factory.1 nvme-lnvm-id-ns.1 nvme-lnvm-info.1 nvme-lnvm-init.1 nvme-lnvm-list.1 nvme-lnvm-remove.1 nvme-micron-clear-pcie-errors.1 nvme-micron-internal-log.1 nvme-micron-nand-stats.1 nvme-micron-pcie-stats.1 nvme-micron-selective-download.1 nvme-micron-smart-add-log.1 nvme-micron-temperature-stats.1 nvme-netapp-ontapdevices.1 nvme-netapp-smdevices.1 nvme-ns-descs.1 nvme-ns-rescan.1 nvme-nvm-id-ctrl.1 nvme-persistent-event-log.1 nvme-predictable-lat-log.1 nvme-pred-lat-event-agg-log.1 nvme-primary-ctrl-caps.1 nvme-read.1 nvme-reset.1 nvme-resv-acquire.1 nvme-resv-notif-log.1 nvme-resv-register.1 nvme-resv-release.1 nvme-resv-report.1 nvme-rpmb.1 nvme-sanitize-log.1 nvme-sanitize.1 nvme-security-recv.1 nvme-security-send.1 nvme-self-test-log.1 nvme-set-feature.1 nvme-set-property.1 nvme-show-hostnqn.1 nvme-show-regs.1 nvme-smart-log.1 nvme-subsystem-reset.1 nvme-telemetry-log.1 nvme-toshiba-clear-pcie-correctable-errors.1 nvme-toshiba-vs-internal-log.1 nvme-toshiba-vs-smart-add-log.1 nvme-transcend-badblock.1 nvme-transcend-healthvalue.1 nvme-verify.1 nvme-virtium-save-smart-to-vtview-log.1 nvme-virtium-show-identify.1 nvme-wdc-capabilities.1 nvme-wdc-cap-diag.1 nvme-wdc-clear-assert-dump.1 nvme-wdc-clear-fw-activate-history.1 nvme-wdc-clear-pcie-correctable-errors.1 nvme-wdc-cloud-SSD-plugin-version.1 nvme-wdc-drive-essentials.1 nvme-wdc-drive-log.1 nvme-wdc-drive-resize.1 nvme-wdc-enc-get-log.1 nvme-wdc-get-crash-dump.1 nvme-wdc-get-drive-status.1 nvme-wdc-get-pfail-dump.1 nvme-wdc-id-ctrl.1 nvme-wdc-log-page-directory.1 nvme-wdc-namespace-resize.1 nvme-wdc-purge-monitor.1 nvme-wdc-purge.1 nvme-wdc-vs-drive-info.1 nvme-wdc-vs-error-reason-identifier.1 nvme-wdc-vs-fw-activate-history.1 nvme-wdc-vs-internal-log.1 nvme-wdc-vs-nand-stats.1 nvme-wdc-vs-smart-add-log.1 nvme-wdc-vs-telemetry-controller-option.1 nvme-wdc-vs-temperature-stats.1 nvme-write.1 nvme-write-uncor.1 nvme-write-zeroes.1 nvme-zns-changed-zone-list.1 nvme-zns-close-zone.1 nvme-zns-finish-zone.1 nvme-zns-id-ctrl.1 nvme-zns-id-ns.1 nvme-zns-offline-zone.1 nvme-zns-open-zone.1 nvme-zns-report-zones.1 nvme-zns-reset-zone.1 nvme-zns-set-zone-desc.1 nvme-zns-zone-append.1 nvme-zns-zone-mgmt-recv.1 nvme-zns-zone-mgmt-send.1 nvme.1 /usr/local/share/man/man1
make[1]: Leaving directory '/mnt/data/nvme-cli/Documentation'
    CC nvme
rm -f /usr/local/sbin/nvme
install -d /usr/sbin
install -m 755 nvme /usr/sbin
root at dev nvme-cli ((HEAD detached from v1.15)) # cdblktests 
root at dev blktests (master) # ./check nvme/012
nvme/012 (run mkfs and data verification fio job on NVMeOF block device-backed ns) [passed]

---
 fabrics.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/fabrics.c b/fabrics.c
index 39bee97..446a71d 100644
--- a/fabrics.c
+++ b/fabrics.c
@@ -852,9 +852,12 @@ static char *hostnqn_read_file(void)
 		goto out;
 
 	ret = strndup(hostnqn, strcspn(hostnqn, "\n"));
-
 out:
 	fclose(f);
+	if (ret && strcmp(ret, "") == 0) {
+		free(ret);
+		ret = NULL;
+	}
 	return ret;
 }
 
-- 
2.29.0