plugin: use strlcpy()

Problem: strncpy() could leave a string unterminated if not
zero-initialized, and the keys for the info[2] array in main.c
not zero-initalized.

Switch strlcpy() wherever strncpy() is used.

Use sizeof() where appropriate instead of pmix "MAX" #defines,
since that removes all ambiguity about whether the #define includes
space for the NULL or not (it does not, but I have to keep checking).

src/shell/plugins/Makefile.am

@@ -46,7 +46,8 @@ pmix_la_LIBADD = \
 	$(FLUX_IDSET_LIBS) \
 	$(FLUX_HOSTLIST_LIBS) \
 	$(JANSSON_LIBS) \
-	$(top_builddir)/src/common/libccan/libccan.la
+	$(top_builddir)/src/common/libccan/libccan.la \
+	$(top_builddir)/src/common/libutil/libutil.la
 pmix_la_LDFLAGS = \
 	$(AM_LDFLAGS) \
 	$(fluxplugin_ldflags) \
@@ -58,7 +59,8 @@ TESTS = \
 
 test_ldadd = \
 	$(top_builddir)/src/common/libtap/libtap.la \
-	$(top_builddir)/src/common/libccan/libccan.la
+	$(top_builddir)/src/common/libccan/libccan.la \
+	$(top_builddir)/src/common/libutil/libutil.la
 
 test_ldflags = \
 	-no-install

src/shell/plugins/codec.c

@@ -18,6 +18,7 @@
 #include <pmix_server.h>
 
 #include "src/common/libccan/ccan/base64/base64.h"
+#include "src/common/libutil/strlcpy.h"
 
 #include "codec.h"
 
@@ -119,7 +120,7 @@ int codec_proc_decode (json_t *o, pmix_proc_t *proc)
                      "rank", &rank) < 0)
         return -1;
     proc->rank = rank;
-    strncpy (proc->nspace, nspace, PMIX_MAX_NSLEN);
+    strlcpy (proc->nspace, nspace, sizeof (proc->nspace));
     proc->nspace[PMIX_MAX_NSLEN] = '\0';
     return 0;
 }
@@ -399,7 +400,7 @@ int codec_info_decode (json_t *o, pmix_info_t *info)
         return -1;
     if (codec_value_decode (xvalue, &info->value) < 0) // allocs mem
         return -1;
-    strncpy (info->key, key, PMIX_MAX_KEYLEN);
+    strlcpy (info->key, key, sizeof (info->key));
     info->key[PMIX_MAX_KEYLEN] = '\0';
     return 0;
 }

src/shell/plugins/infovec.c

@@ -17,6 +17,8 @@
 #include <errno.h>
 #include <pmix.h>
 
+#include "src/common/libutil/strlcpy.h"
+
 #include "infovec.h"
 
 #define INFOVEC_CHUNK 8
@@ -52,7 +54,7 @@ int infovec_set_str_new (struct infovec *iv, const char *key, char *val)
     }
     if (!(info = alloc_slot (iv)))
         return -1;
-    strncpy (info->key, key, PMIX_MAX_KEYLEN);
+    strlcpy (info->key, key, sizeof (info->key));
     info->value.type = PMIX_STRING;
     info->value.data.string = val;
     return 0;
@@ -86,7 +88,7 @@ int infovec_set_u32 (struct infovec *iv, const char *key, uint32_t value)
     }
     if (!(info = alloc_slot (iv)))
         return -1;
-    strncpy (info->key, key, PMIX_MAX_KEYLEN);
+    strlcpy (info->key, key, sizeof (info->key));
     info->value.type = PMIX_UINT32;
     info->value.data.uint32 = value;
     return 0;
@@ -102,7 +104,7 @@ int infovec_set_bool (struct infovec *iv, const char *key, bool value)
     }
     if (!(info = alloc_slot (iv)))
         return -1;
-    strncpy (info->key, key, PMIX_MAX_KEYLEN);
+    strlcpy (info->key, key, sizeof (info->key));
     info->value.type = PMIX_BOOL;
     info->value.data.flag = value;
     return 0;
@@ -120,7 +122,7 @@ int infovec_set_rank (struct infovec *iv,
     }
     if (!(info = alloc_slot (iv)))
         return -1;
-    strncpy (info->key, key, PMIX_MAX_KEYLEN);
+    strlcpy (info->key, key, sizeof (info->key));
     info->value.type = PMIX_PROC_RANK;
     info->value.data.rank = value;
     return 0;

src/shell/plugins/interthread.c

@@ -17,6 +17,8 @@
 #include <jansson.h>
 #include <flux/core.h>
 
+#include "src/common/libutil/strlcpy.h"
+
 #include "interthread.h"
 
 #define MAX_HANDLERS 32
@@ -48,7 +50,7 @@ int interthread_register (struct interthread *it,
         return -1;
     }
     handler = &it->handlers[it->handler_count++];
-    strncpy (handler->topic, topic, sizeof (handler->topic) - 1);
+    strlcpy (handler->topic, topic, sizeof (handler->topic));
     handler->cb = cb;
     handler->arg = arg;
     return 0;

src/shell/plugins/main.c

@@ -19,6 +19,8 @@
 #include <pmix_server.h>
 #include <pmix.h>
 
+#include "src/common/libutil/strlcpy.h"
+
 #include "infovec.h"
 #include "maps.h"
 #include "interthread.h"
@@ -189,12 +191,12 @@ static int px_init (flux_plugin_t *p,
         return -1;
     server_callbacks.direct_modex = dmodex_server_cb;
 
-    strncpy (info[0].key, PMIX_SERVER_TMPDIR, PMIX_MAX_KEYLEN);
+    strlcpy (info[0].key, PMIX_SERVER_TMPDIR, sizeof (info[0].key));
     info[0].value.type = PMIX_STRING;
     info[0].value.data.string = (char *)px->job_tmpdir;
     info[0].flags = 0;
 
-    strncpy (info[1].key, PMIX_SERVER_RANK, PMIX_MAX_KEYLEN);
+    strlcpy (info[1].key, PMIX_SERVER_RANK, sizeof (info[1].key));
     info[1].value.type = PMIX_PROC_RANK;
     info[1].value.data.rank = px->shell_rank;
     info[1].flags = 0;