iscsiadm: fix parallel rescan handling of exit codes

The parallel rescan patches work, in so much as the rescans happen, but
if a target is specified the non-matching cases cause warning to be
printed and a non-zero exit code.

To reproduce: have more than one session to different targets, issue a
node mode rescan command to one of them (-m node -T <iqn.target> -R).

The problem is that while exit() takes an int, only the low byte is part
of the exit code and it's combined with other exit status information.
iscsiadm tries to use exit(-1) to indicate a non-match (not a fatal
error). The value retrieved with wait() after an exit(-1) is actually
65280.

Fix this by making use of the wait.h macros for checking the exit code.

3 files changed, 20 insertions, 3 deletions

diff --git a/include/iscsi_err.h b/include/iscsi_err.h
index 125f443..506bd8c 100644
--- a/include/iscsi_err.h
+++ b/include/iscsi_err.h
@@ -66,6 +66,8 @@ enum {
 	ISCSI_ERR_AGAIN			= 29,
 	/* unknown discovery type */
 	ISCSI_ERR_UNKNOWN_DISCOVERY_TYPE = 30,
+	/* child process terminated */
+	ISCSI_ERR_CHILD_TERMINATED	= 31,
 
 	/* Always last. Indicates end of error code space */
 	ISCSI_MAX_ERR_VAL,
diff --git a/usr/iscsi_err.c b/usr/iscsi_err.c
index 11e0348..1ba9e64 100644
--- a/usr/iscsi_err.c
+++ b/usr/iscsi_err.c
@@ -53,6 +53,7 @@ static char *iscsi_err_msgs[] = {
 	/* 28 */ "device or resource in use",
 	/* 29 */ "operation failed but retry may succeed",
 	/* 30 */ "unknown discovery type",
+	/* 31 */ "child process terminated",
 };
 
 char *iscsi_err_to_str(int err)
diff --git a/usr/iscsi_sysfs.c b/usr/iscsi_sysfs.c
index 3a37a48..a8fe156 100644
--- a/usr/iscsi_sysfs.c
+++ b/usr/iscsi_sysfs.c
@@ -1472,13 +1472,27 @@ int iscsi_sysfs_for_each_session(void *data, int *nr_found,
 				break;
 			}
 
-			if ((chldrc > 0) && (rc == 0)) {
+			if (!WIFEXITED(chldrc)) {
 				/*
+				 * abnormal termination (signal, exception, etc.)
+				 *
 				 * The non-parallel code path returns the first
 				 * error so this keeps the same semantics.
 				 */
-				rc = chldrc;
-			} else if (chldrc == 0) {
+				if (rc == 0)
+					rc = ISCSI_ERR_CHILD_TERMINATED;
+			} else if ((WEXITSTATUS(chldrc) != 0) &&
+			           (WEXITSTATUS(chldrc) != 255)) {
+				/*
+				 * 0 is success
+				 * 255 is a truncated return code from exit(-1)
+				 *     and means no match
+				 * anything else (this case) is an error
+				 */
+				if (rc == 0)
+					rc = WEXITSTATUS(chldrc);
+			} else if (WEXITSTATUS(chldrc) == 0) {
+				/* success */
 				(*nr_found)++;
 			}
 		}