[PATCH] Guard against inserting the same provider twice

[eugene.loh@oracle.com]

From: Eugene Loh <eugene.loh@oracle.com>

Add a safety net to dt_provider_create(), to check if a specified
provider has already been inserted.

This also requires a corresponding change in dt_provider_lookup(), so
that it will work even if no providers have yet been inserted.

Signed-off-by: Eugene Loh <eugene.loh@oracle.com>
---
 libdtrace/dt_provider.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/libdtrace/dt_provider.c b/libdtrace/dt_provider.c
index 848fdc132..9d75225fa 100644
--- a/libdtrace/dt_provider.c
+++ b/libdtrace/dt_provider.c
@@ -114,6 +114,8 @@ dt_provider_lookup(dtrace_hdl_t *dtp, const char *name)
 		return NULL;
 
 	strcpy(tmpl.desc.dtvd_name, name);
+	if (dtp->dt_provs == NULL)
+		return NULL;
 	return dt_htab_lookup(dtp->dt_provs, &tmpl);
 }
 
@@ -124,6 +126,10 @@ dt_provider_create(dtrace_hdl_t *dtp, const char *name,
 {
 	dt_provider_t *pvp;
 
+	pvp = dt_provider_lookup(dtp, name);
+	if (pvp)
+		return pvp;
+
 	if ((pvp = dt_zalloc(dtp, sizeof(dt_provider_t))) == NULL)
 		goto nomem;
 
-- 
2.47.3