[DTrace-devel] [PATCH 17/20] speculations, bpf: check for nonexistent CTF before using it

[Nick Alcock]

This turns coredumps into a not-all-that-much-more-helpful "no such file
or directory" error (but turning DT_DEBUG on at least tells you which
file is missing, i.e. some ctfa file)

Signed-off-by: Nick Alcock <nick.alcock at oracle.com>
---
 libdtrace/dt_cc.c | 15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)

diff --git a/libdtrace/dt_cc.c b/libdtrace/dt_cc.c
index c6c31fc92712..9a61134057a0 100644
--- a/libdtrace/dt_cc.c
+++ b/libdtrace/dt_cc.c
@@ -2378,10 +2378,14 @@ dt_link_construct(dtrace_hdl_t *dtp, const dt_probe_t *prp, dtrace_difo_t *dp,
 			case DT_CONST_TASK_REAL_PARENT:
 			case DT_CONST_TASK_COMM: {
 				ctf_file_t *cfp = dtp->dt_shared_ctf;
-				ctf_id_t type = ctf_lookup_by_name(cfp, "struct task_struct");
+				ctf_id_t type;
 				ctf_membinfo_t ctm;
 				int rc = 0;
 
+				if (!cfp)
+					return dt_set_errno(dtp, EDT_NOCTF);
+
+				type = ctf_lookup_by_name(cfp, "struct task_struct");
 				if (type == CTF_ERR)
 					goto err_ctf;
 
@@ -2406,10 +2410,14 @@ dt_link_construct(dtrace_hdl_t *dtp, const dt_probe_t *prp, dtrace_difo_t *dp,
 			}
 			case DT_CONST_MUTEX_OWNER: {
 				ctf_file_t *cfp = dtp->dt_shared_ctf;
-				ctf_id_t type = ctf_lookup_by_name(cfp, "struct mutex");
+				ctf_id_t type;
 				ctf_membinfo_t ctm;
 				ctf_id_t rc = CTF_ERR;
 
+				if (!cfp)
+					return dt_set_errno(dtp, EDT_NOCTF);
+
+				type = ctf_lookup_by_name(cfp, "struct mutex");
 				if (type == CTF_ERR)
 					goto err_ctf;
 
@@ -2436,6 +2444,9 @@ dt_link_construct(dtrace_hdl_t *dtp, const dt_probe_t *prp, dtrace_difo_t *dp,
 				ctf_id_t rc = CTF_ERR;
 				uint64_t total_offset;
 
+				if (!cfp)
+					return dt_set_errno(dtp, EDT_NOCTF);
+
 				type = ctf_lookup_by_name(cfp, "rwlock_t");
 				if (type == CTF_ERR)
 					goto err_ctf;
-- 
2.36.1.263.g194b774378.dirty