MFC r264467:

Take into account when zpool history block grows exceeding 128KB in zpool(8)
and zdb(8) by growing the buffer on demand with a cap of 1GB (specified in
spa_history_create_obj()).

PR:		bin/186574
Submitted by:	Andrew Childs <lorne cons org nz> (with changes)

2 files changed, 54 insertions, 7 deletions

diff --git a/cddl/contrib/opensolaris/cmd/zdb/zdb.c b/cddl/contrib/opensolaris/cmd/zdb/zdb.c
index 932687a..b9dc923 100644
--- a/cddl/contrib/opensolaris/cmd/zdb/zdb.c
+++ b/cddl/contrib/opensolaris/cmd/zdb/zdb.c
@@ -929,11 +929,16 @@ dump_dtl(vdev_t *vd, int indent)
 		dump_dtl(vd->vdev_child[c], indent + 4);
 }
 
+/* from spa_history.c: spa_history_create_obj() */
+#define	HIS_BUF_LEN_DEF	(128 << 10)
+#define	HIS_BUF_LEN_MAX	(1 << 30)
+
 static void
 dump_history(spa_t *spa)
 {
 	nvlist_t **events = NULL;
-	char buf[SPA_MAXBLOCKSIZE];
+	char *buf = NULL;
+	uint64_t bufsize = HIS_BUF_LEN_DEF;
 	uint64_t resid, len, off = 0;
 	uint_t num = 0;
 	int error;
@@ -942,8 +947,11 @@ dump_history(spa_t *spa)
 	char tbuf[30];
 	char internalstr[MAXPATHLEN];
 
+	if ((buf = malloc(bufsize)) == NULL)
+		(void) fprintf(stderr, "Unable to read history: "
+		    "out of memory\n");
 	do {
-		len = sizeof (buf);
+		len = bufsize;
 
 		if ((error = spa_history_get(spa, &off, &len, buf)) != 0) {
 			(void) fprintf(stderr, "Unable to read history: "
@@ -953,9 +961,26 @@ dump_history(spa_t *spa)
 
 		if (zpool_history_unpack(buf, len, &resid, &events, &num) != 0)
 			break;
-
 		off -= resid;
+
+		/*
+		 * If the history block is too big, double the buffer
+		 * size and try again.
+		 */
+		if (resid == len) {
+			free(buf);
+			buf = NULL;
+
+			bufsize <<= 1;
+			if ((bufsize >= HIS_BUF_LEN_MAX) ||
+			    ((buf = malloc(bufsize)) == NULL)) {
+				(void) fprintf(stderr, "Unable to read history: "
+				    "out of memory\n");
+				return;
+			}
+		}
 	} while (len != 0);
+	free(buf);
 
 	(void) printf("\nHistory:\n");
 	for (int i = 0; i < num; i++) {
diff --git a/cddl/contrib/opensolaris/lib/libzfs/common/libzfs_pool.c b/cddl/contrib/opensolaris/lib/libzfs/common/libzfs_pool.c
index e691df1..8dd24a7 100644
--- a/cddl/contrib/opensolaris/lib/libzfs/common/libzfs_pool.c
+++ b/cddl/contrib/opensolaris/lib/libzfs/common/libzfs_pool.c
@@ -3744,7 +3744,9 @@ zpool_history_unpack(char *buf, uint64_t bytes_read, uint64_t *leftover,
 	return (0);
 }
 
-#define	HIS_BUF_LEN	(128*1024)
+/* from spa_history.c: spa_history_create_obj() */
+#define	HIS_BUF_LEN_DEF	(128 << 10)
+#define	HIS_BUF_LEN_MAX	(1 << 30)
 
 /*
  * Retrieve the command history of a pool.
@@ -3752,21 +3754,24 @@ zpool_history_unpack(char *buf, uint64_t bytes_read, uint64_t *leftover,
 int
 zpool_get_history(zpool_handle_t *zhp, nvlist_t **nvhisp)
 {
-	char buf[HIS_BUF_LEN];
+	char *buf = NULL;
+	uint64_t bufsize = HIS_BUF_LEN_DEF;
 	uint64_t off = 0;
 	nvlist_t **records = NULL;
 	uint_t numrecords = 0;
 	int err, i;
 
+	if ((buf = malloc(bufsize)) == NULL)
+		return (ENOMEM);
 	do {
-		uint64_t bytes_read = sizeof (buf);
+		uint64_t bytes_read = bufsize;
 		uint64_t leftover;
 
 		if ((err = get_history(zhp, buf, &off, &bytes_read)) != 0)
 			break;
 
 		/* if nothing else was read in, we're at EOF, just return */
-		if (!bytes_read)
+		if (bytes_read == 0)
 			break;
 
 		if ((err = zpool_history_unpack(buf, bytes_read,
@@ -3774,8 +3779,25 @@ zpool_get_history(zpool_handle_t *zhp, nvlist_t **nvhisp)
 			break;
 		off -= leftover;
 
+		/*
+		 * If the history block is too big, double the buffer
+		 * size and try again.
+		 */
+		if (leftover == bytes_read) {
+			free(buf);
+			buf = NULL;
+
+			bufsize <<= 1;
+			if ((bufsize >= HIS_BUF_LEN_MAX) ||
+			    ((buf = malloc(bufsize)) == NULL)) {
+				err = ENOMEM;
+				break;
+			}
+		}
+
 		/* CONSTCOND */
 	} while (1);
+	free(buf);
 
 	if (!err) {
 		verify(nvlist_alloc(nvhisp, NV_UNIQUE_NAME, 0) == 0);