libproc: Match prefixes when looking up mapped object by name.

When looking up an object by name, allow prefix matches if no direct match
is found. This allows one to, for example, match libc entry probes with:

 # dtrace -n 'pid$target:libc.so::entry' -c ./foo

instead of requiring "libc.so.7" or a glob.

Also remove proc_obj2map() as it currently just duplicates the
functionality of proc_name2map(). It's supposed to take a Solaris
link-map ID as a paramter, but support for this isn't implemented and
isn't required to support DTrace's pid provider.

cddl/lib/libdtrace/libproc_compat.h

@@ -44,7 +44,7 @@
 #define	Pdelbkpt proc_bkptdel
 #define	Pgrab_error strerror
 #define	Plmid(p, a, l) (-1)
-#define	Plmid_to_map(p, l, o) proc_obj2map((p), (o))
+#define	Plmid_to_map(p, l, o) proc_name2map(p, o)
 #define	Plookup_by_addr proc_addr2sym
 #define	Pname_to_ctf(p, obj) (ctf_file_t *)proc_name2ctf(p, obj)
 #define	Pname_to_map proc_name2map

lib/libproc/libproc.h

@@ -128,7 +128,6 @@ __BEGIN_DECLS
 prmap_t *proc_addr2map(struct proc_handle *, uintptr_t);
 prmap_t *proc_name2map(struct proc_handle *, const char *);
 char	*proc_objname(struct proc_handle *, uintptr_t, char *, size_t);
-prmap_t *proc_obj2map(struct proc_handle *, const char *);
 int	proc_iter_objs(struct proc_handle *, proc_map_f *, void *);
 int	proc_iter_symbyaddr(struct proc_handle *, const char *, int,
 	    int, proc_sym_f *, void *);

lib/libproc/proc_sym.c

@@ -274,31 +274,6 @@ proc_objname(struct proc_handle *p, uintptr_t addr, char *objname,
 	return (NULL);
 }
 
-/*
- * Currently just returns the first mapping of the named object, effectively
- * what Plmid_to_map(p, PR_LMID_EVERY, objname) does in illumos libproc.
- */
-prmap_t *
-proc_obj2map(struct proc_handle *p, const char *objname)
-{
-	char path[PATH_MAX], *base;
-	prmap_t *map;
-	size_t i;
-
-	map = NULL;
-	for (i = 0; i < p->nmappings; i++) {
-		strlcpy(path, p->mappings[i].map.pr_mapname, sizeof(path));
-		base = basename(path);
-		if (strcmp(base, objname) == 0) {
-			map = &p->mappings[i].map;
-			break;
-		}
-	}
-	if (map == NULL && strcmp(objname, "a.out") == 0 && p->exec_map != NULL)
-		map = p->exec_map;
-	return (map);
-}
-
 int
 proc_iter_objs(struct proc_handle *p, proc_map_f *func, void *cd)
 {
@@ -468,9 +443,10 @@ _proc_name2map(struct proc_handle *p, const char *name)
 {
 	char path[MAXPATHLEN], *base;
 	struct map_info *mapping;
-	size_t i;
+	size_t i, len;
 
-	mapping = NULL;
+	if ((len = strlen(name)) == 0)
+		return (NULL);
 	if (p->nmappings == 0)
 		if (proc_rdagent(p) == NULL)
 			return (NULL);
@@ -479,13 +455,18 @@ _proc_name2map(struct proc_handle *p, const char *name)
 		(void)strlcpy(path, mapping->map.pr_mapname, sizeof(path));
 		base = basename(path);
 		if (strcmp(base, name) == 0)
-			break;
+			return (mapping);
 	}
-	if (i == p->nmappings)
-		mapping = NULL;
-	if (mapping == NULL && strcmp(name, "a.out") == 0)
-		mapping = _proc_addr2map(p, p->exec_map->pr_vaddr);
-	return (mapping);
+	/* If we didn't find a match, try matching prefixes of the basename. */
+	for (i = 0; i < p->nmappings; i++) {
+		strlcpy(path, p->mappings[i].map.pr_mapname, sizeof(path));
+		base = basename(path);
+		if (strncmp(base, name, len) == 0)
+			return (&p->mappings[i]);
+	}
+	if (strcmp(name, "a.out") == 0)
+		return (_proc_addr2map(p, p->exec_map->pr_vaddr));
+	return (NULL);
 }
 
 prmap_t *

lib/libproc/tests/proc_test.c

@@ -1,5 +1,5 @@
 /*-
- * Copyright (c) 2014, 2015 Mark Johnston <markj@FreeBSD.org>
+ * Copyright (c) 2014-2016 Mark Johnston <markj@FreeBSD.org>
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -152,38 +152,6 @@ verify_bkpt(struct proc_handle *phdl, GElf_Sym *sym, const char *symname,
 	    "expected map name '%s' doesn't match '%s'", mapname, mapbname);
 }
 
-ATF_TC(map_alias_obj2map);
-ATF_TC_HEAD(map_alias_obj2map, tc)
-{
-	atf_tc_set_md_var(tc, "descr",
-	    "Callers are supposed to be able to use \"a.out\" as an alias for "
-	    "the program executable. Make sure that proc_obj2map() handles "
-	    "this properly.");
-}
-ATF_TC_BODY(map_alias_obj2map, tc)
-{
-	struct proc_handle *phdl;
-	prmap_t *map1, *map2;
-
-	phdl = start_prog(tc, false);
-
-	/* Initialize the rtld_db handle. */
-	(void)proc_rdagent(phdl);
-
-	/* Ensure that "target_prog" and "a.out" return the same map. */
-	map1 = proc_obj2map(phdl, target_prog_file);
-	ATF_REQUIRE_MSG(map1 != NULL, "failed to look up map for '%s'",
-	    target_prog_file);
-	map2 = proc_obj2map(phdl, aout_object);
-	ATF_REQUIRE_MSG(map2 != NULL, "failed to look up map for '%s'",
-	    aout_object);
-	ATF_CHECK_EQ(strcmp(map1->pr_mapname, map2->pr_mapname), 0);
-
-	ATF_CHECK_EQ_MSG(proc_continue(phdl), 0, "failed to resume execution");
-
-	proc_free(phdl);
-}
-
 ATF_TC(map_alias_name2map);
 ATF_TC_HEAD(map_alias_name2map, tc)
 {
@@ -216,6 +184,35 @@ ATF_TC_BODY(map_alias_name2map, tc)
 	proc_free(phdl);
 }
 
+ATF_TC(map_prefix_name2map);
+ATF_TC_HEAD(map_prefix_name2map, tc)
+{
+	atf_tc_set_md_var(tc, "descr",
+	    "Verify that proc_name2map() returns prefix matches of the "
+	    "basename of loaded objects if no full matches are found.");
+}
+ATF_TC_BODY(map_prefix_name2map, tc)
+{
+	struct proc_handle *phdl;
+	prmap_t *map1, *map2;
+
+	phdl = start_prog(tc, false);
+
+	/* Initialize the rtld_db handle. */
+	(void)proc_rdagent(phdl);
+
+	/* Make sure that "ld-elf" and "ld-elf.so" return the same map. */
+	map1 = proc_name2map(phdl, "ld-elf");
+	ATF_REQUIRE_MSG(map1 != NULL, "failed to look up map for 'ld-elf'");
+	map2 = proc_name2map(phdl, "ld-elf.so");
+	ATF_REQUIRE_MSG(map2 != NULL, "failed to look up map for 'ld-elf.so'");
+	ATF_CHECK_EQ(strcmp(map1->pr_mapname, map2->pr_mapname), 0);
+
+	ATF_CHECK_EQ_MSG(proc_continue(phdl), 0, "failed to resume execution");
+
+	proc_free(phdl);
+}
+
 ATF_TC(map_alias_name2sym);
 ATF_TC_HEAD(map_alias_name2sym, tc)
 {
@@ -315,7 +312,7 @@ ATF_TC_BODY(symbol_lookup_fail, tc)
 	/* Initialize the rtld_db handle. */
 	(void)proc_rdagent(phdl);
 
-	map = proc_obj2map(phdl, target_prog_file);
+	map = proc_name2map(phdl, target_prog_file);
 	ATF_REQUIRE_MSG(map != NULL, "failed to look up map for '%s'",
 	    target_prog_file);
 
@@ -376,8 +373,8 @@ ATF_TC_BODY(signal_forward, tc)
 ATF_TP_ADD_TCS(tp)
 {
 
-	ATF_TP_ADD_TC(tp, map_alias_obj2map);
 	ATF_TP_ADD_TC(tp, map_alias_name2map);
+	ATF_TP_ADD_TC(tp, map_prefix_name2map);
 	ATF_TP_ADD_TC(tp, map_alias_name2sym);
 	ATF_TP_ADD_TC(tp, symbol_lookup);
 	ATF_TP_ADD_TC(tp, symbol_lookup_fail);