[DTrace-devel] [PATCH 23/47] Complete the dt_probe_lookup() implementation

[Eugene Loh]

The dt_probe_lookup() implementation provided support for lookup by id
or fully qualified probe name (no globbing) only.  This patch adds
support for globbing in the probe description, and fixes some comments
that provided inaccurate information.

Orabug: 31220519
Signed-off-by: Eugene Loh <eugene.loh at oracle.com>
Reviewed-by: Kris Van Hees <kris.van.hees at oracle.com>
---
 libdtrace/dt_probe.c | 98 +++++++++++++++++++++++++-------------------
 1 file changed, 55 insertions(+), 43 deletions(-)

diff --git a/libdtrace/dt_probe.c b/libdtrace/dt_probe.c
index e44247e6..15c4cd64 100644
--- a/libdtrace/dt_probe.c
+++ b/libdtrace/dt_probe.c
@@ -1,6 +1,6 @@
 /*
  * Oracle Linux DTrace.
- * Copyright (c) 2006, 2019, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2006, 2020, Oracle and/or its affiliates. All rights reserved.
  * Licensed under the Universal Permissive License v 1.0 as shown at
  * http://oss.oracle.com/licenses/upl.
  */
@@ -705,11 +705,30 @@ dt_probe_insert(dtrace_hdl_t *dtp, dt_provider_t *prov, const char *prv,
 	return prp;
 }
 
+static int
+dt_probe_gmatch(const dt_probe_t *prp, dtrace_probedesc_t *pdp)
+{
+#define MATCH_ONE(nam, n)						\
+	if (pdp->nam) {							\
+		if (pdp->id & (1 << n)) {				\
+			if (!dt_gmatch(prp->desc->nam, pdp->nam))	\
+				return 0;				\
+		} else if (strcmp(prp->desc->nam, pdp->nam) != 0)	\
+				return 0;				\
+	}
+
+	MATCH_ONE(prv, 3)
+	MATCH_ONE(mod, 2)
+	MATCH_ONE(fun, 1)
+	MATCH_ONE(prb, 0)
+
+	return 1;
+}
+
 /*
- * Look for a probe that matches the probe description in 'pdp', and fill in
- * the probe info referenced by 'pip' (name and argument attributes, argument
- * types, and argument count).  If no probe is found, this function will return
- * NULL (dt_errno will be set).
+ * Look for a probe that matches the probe description in 'pdp'.
+ *
+ * If no probe is found, this function will return NULL (dt_errno will be set).
  *
  * If a probe id is provided in the probe description, a direct lookup can be
  * performed in the probe array.
@@ -722,6 +741,8 @@ dt_probe_insert(dtrace_hdl_t *dtp, dt_provider_t *prov, const char *prv,
  * most restrictive (dt_byfun is usually best, then dt_byprb, then dt_bymod,
  * and finally dt_byprv).  Further matching is then done on just the probes in
  * that htab bucket.  Elements that must match exactly are compared first.
+ *
+ * More than one probe might match, but only one probe will be returned.
  */
 dt_probe_t *
 dt_probe_lookup(dtrace_hdl_t *dtp, const dtrace_probedesc_t *pdp)
@@ -763,34 +784,45 @@ dt_probe_lookup(dtrace_hdl_t *dtp, const dtrace_probedesc_t *pdp)
 		return prp;
 	}
 
-#ifdef FIXME
 	/*
 	 * If at least one element is specified as a string to match exactly,
-	 * use that to consult itr respective htab.  If all elements are
+	 * use that to consult its respective htab.  If all elements are
 	 * specified as glob patterns (or the empty string), we need to loop
 	 * through all probes and look for a match.
 	 */
-	if (!f_is_glob) {
+	if (!f_is_glob)
 		prp = dt_htab_lookup(dtp->dt_byfun, &tmpl);
-		if (!prp)
-			goto no_probe;
-	} else if (!n_is_glob) {
+	else if (!n_is_glob)
 		prp = dt_htab_lookup(dtp->dt_byprb, &tmpl);
-		if (!prp)
-			goto no_probe;
-	} else if (!m_is_glob) {
+	else if (!m_is_glob)
 		prp = dt_htab_lookup(dtp->dt_bymod, &tmpl);
-		if (!prp)
-			goto no_probe;
-	} else if (!p_is_glob) {
+	else if (!p_is_glob)
 		prp = dt_htab_lookup(dtp->dt_byprv, &tmpl);
-		if (!prp)
-			goto no_probe;
-	} else {
+	else {
+		int			i;
+		dtrace_probedesc_t	desc;
+
+		/*
+		 * To avoid checking multiple times whether an element in the
+		 * probe specification is a glob pattern, we (ab)use the
+		 * desc->id value (unused at this point) to store this
+		 * information a a bitmap.
+		 */
+		desc = *pdp;
+		desc.id = (p_is_glob << 3) | (m_is_glob << 2) |
+			  (f_is_glob << 1) | n_is_glob;
+
+		for (i = 0; i < dtp->dt_probe_id; i++) {
+			prp = dtp->dt_probes[i];
+			if (prp && dt_probe_gmatch(prp, &desc))
+				break;
+		}
+		if (i >= dtp->dt_probe_id)
+			prp = NULL;
 	}
-#endif
 
-	return NULL;
+	if (prp)
+		return prp;
 
 no_probe:
 	dt_set_errno(dtp, EDT_NOPROBE);
@@ -1031,26 +1063,6 @@ dtrace_probe_info(dtrace_hdl_t *dtp, const dtrace_probedesc_t *pdp,
 						    : -1;
 }
 
-static int
-dt_probe_gmatch(const dt_probe_t *prp, dtrace_probedesc_t *pdp)
-{
-#define MATCH_ONE(nam, n)						\
-	if (pdp->nam) {							\
-		if (pdp->id & (1 << n)) {				\
-			if (!dt_gmatch(prp->desc->nam, pdp->nam))	\
-				return 0;				\
-		} else if (strcmp(prp->desc->nam, pdp->nam) != 0)	\
-				return 0;				\
-	}
-
-	MATCH_ONE(prv, 3)
-	MATCH_ONE(mod, 2)
-	MATCH_ONE(fun, 1)
-	MATCH_ONE(prb, 0)
-
-	return 1;
-}
-
 int
 dtrace_probe_iter(dtrace_hdl_t *dtp, const dtrace_probedesc_t *pdp,
 		  dtrace_probe_f *func, void *arg)
@@ -1135,7 +1147,7 @@ dtrace_probe_iter(dtrace_hdl_t *dtp, const dtrace_probedesc_t *pdp,
 	 *
 	 * To avoid checking multiple times whether an element in the probe
 	 * specification is a glob pattern, we (ab)use the desc->id value
-	 * (used at this point) to store this information a a bitmap.
+	 * (unused at this point) to store this information a a bitmap.
 	 */
 	desc = *pdp;
 	desc.id = (p_is_glob << 3) | (m_is_glob << 2) | (f_is_glob << 1) |
-- 
2.26.0