libdrgn: embed type and object finders in drgn_debug_info

This is preparation for embedding drgn_debug_info in drgn_program and initializing it earlier. Signed-off-by: Omar Sandoval <[email protected]>
osandov · Sep 29, 2023 · f248054 · f248054
1 parent 085b0bc
commit f248054
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Showing 8 changed files with 67 additions and 44 deletions.
diff --git a/libdrgn/debug_info.c b/libdrgn/debug_info.c
@@ -2105,6 +2105,11 @@ struct drgn_error *drgn_debug_info_create(struct drgn_program *prog,
 		free(dbinfo);
 		return drgn_error_libdwfl();
 	}
+	drgn_program_add_type_finder_impl(prog, &dbinfo->type_finder,
+					  drgn_debug_info_find_type, dbinfo);
+	drgn_program_add_object_finder_impl(prog, &dbinfo->object_finder,
+					    drgn_debug_info_find_object,
+					    dbinfo);
 	drgn_module_table_init(&dbinfo->modules);
 	c_string_set_init(&dbinfo->module_names);
 	drgn_dwarf_info_init(dbinfo);

diff --git a/libdrgn/debug_info.h b/libdrgn/debug_info.h
@@ -20,8 +20,10 @@
 #include "drgn.h"
 #include "dwarf_info.h"
 #include "hash_table.h"
+#include "object_index.h"
 #include "orc_info.h"
 #include "string_builder.h"
+#include "type.h"
 #include "vector.h"
 
 struct drgn_elf_file;
@@ -133,6 +135,9 @@ struct drgn_debug_info {
 	/** Program owning this cache. */
 	struct drgn_program *prog;
 
+	struct drgn_type_finder type_finder;
+	struct drgn_object_finder object_finder;
+
 	/** DWARF frontend library handle. */
 	Dwfl *dwfl;
 	/** Modules keyed by build ID and address range. */

diff --git a/libdrgn/object_index.c b/libdrgn/object_index.c
@@ -13,40 +13,35 @@ void drgn_object_index_init(struct drgn_object_index *oindex)
 
 void drgn_object_index_deinit(struct drgn_object_index *oindex)
 {
-	struct drgn_object_finder *finder;
-
-	finder = oindex->finders;
+	struct drgn_object_finder *finder = oindex->finders;
 	while (finder) {
 		struct drgn_object_finder *next = finder->next;
-
-		free(finder);
+		if (finder->free)
+			free(finder);
 		finder = next;
 	}
 }
 
 struct drgn_error *
 drgn_object_index_add_finder(struct drgn_object_index *oindex,
+			     struct drgn_object_finder *finder,
 			     drgn_object_find_fn fn, void *arg)
 {
-	struct drgn_object_finder *finder;
-
-	finder = malloc(sizeof(*finder));
-	if (!finder)
-		return &drgn_enomem;
+	if (finder) {
+		finder->free = false;
+	} else {
+		finder = malloc(sizeof(*finder));
+		if (!finder)
+			return &drgn_enomem;
+		finder->free = true;
+	}
 	finder->fn = fn;
 	finder->arg = arg;
 	finder->next = oindex->finders;
 	oindex->finders = finder;
 	return NULL;
 }
 
-void drgn_object_index_remove_finder(struct drgn_object_index *oindex)
-{
-	struct drgn_object_finder *finder = oindex->finders->next;
-	free(oindex->finders);
-	oindex->finders = finder;
-}
-
 struct drgn_error *drgn_object_index_find(struct drgn_object_index *oindex,
 					  const char *name,
 					  const char *filename,

diff --git a/libdrgn/object_index.h b/libdrgn/object_index.h
@@ -35,6 +35,8 @@ struct drgn_object_finder {
 	void *arg;
 	/** Next callback to try. */
 	struct drgn_object_finder *next;
+	/** Whether this structure needs to be freed. */
+	bool free;
 };
 
 /**
@@ -56,14 +58,11 @@ void drgn_object_index_init(struct drgn_object_index *oindex);
 /** Deinitialize a @ref drgn_object_index. */
 void drgn_object_index_deinit(struct drgn_object_index *oindex);
 
-/** @sa drgn_program_add_object_finder() */
 struct drgn_error *
 drgn_object_index_add_finder(struct drgn_object_index *oindex,
+			     struct drgn_object_finder *finder,
 			     drgn_object_find_fn fn, void *arg);
 
-/** Remove the most recently added object finding callback. */
-void drgn_object_index_remove_finder(struct drgn_object_index *oindex);
-
 /**
  * Find an object in a @ref drgn_object_index.
  *

diff --git a/libdrgn/program.c b/libdrgn/program.c
@@ -189,11 +189,19 @@ drgn_program_add_memory_segment(struct drgn_program *prog, uint64_t address,
 					      physical);
 }
 
+struct drgn_error *
+drgn_program_add_object_finder_impl(struct drgn_program *prog,
+				    struct drgn_object_finder *finder,
+				    drgn_object_find_fn fn, void *arg)
+{
+	return drgn_object_index_add_finder(&prog->oindex, finder, fn, arg);
+}
+
 LIBDRGN_PUBLIC struct drgn_error *
 drgn_program_add_object_finder(struct drgn_program *prog,
 			       drgn_object_find_fn fn, void *arg)
 {
-	return drgn_object_index_add_finder(&prog->oindex, fn, arg);
+	return drgn_program_add_object_finder_impl(prog, NULL, fn, arg);
 }
 
 static struct drgn_error *
@@ -731,21 +739,6 @@ drgn_program_load_debug_info(struct drgn_program *prog, const char **paths,
 		err = drgn_debug_info_create(prog, &dbinfo);
 		if (err)
 			return err;
-		err = drgn_program_add_object_finder(prog,
-						     drgn_debug_info_find_object,
-						     dbinfo);
-		if (err) {
-			drgn_debug_info_destroy(dbinfo);
-			return err;
-		}
-		err = drgn_program_add_type_finder(prog,
-						   drgn_debug_info_find_type,
-						   dbinfo);
-		if (err) {
-			drgn_object_index_remove_finder(&prog->oindex);
-			drgn_debug_info_destroy(dbinfo);
-			return err;
-		}
 		prog->dbinfo = dbinfo;
 	}
 

diff --git a/libdrgn/program.h b/libdrgn/program.h
@@ -244,6 +244,11 @@ struct drgn_error *drgn_program_init_kernel(struct drgn_program *prog);
  */
 struct drgn_error *drgn_program_init_pid(struct drgn_program *prog, pid_t pid);
 
+struct drgn_error *
+drgn_program_add_object_finder_impl(struct drgn_program *prog,
+				    struct drgn_object_finder *finder,
+				    drgn_object_find_fn fn, void *arg);
+
 static inline struct drgn_error *
 drgn_program_is_little_endian(struct drgn_program *prog, bool *ret)
 {

diff --git a/libdrgn/type.c b/libdrgn/type.c
@@ -1307,25 +1307,39 @@ void drgn_program_deinit_types(struct drgn_program *prog)
 	struct drgn_type_finder *finder = prog->type_finders;
 	while (finder) {
 		struct drgn_type_finder *next = finder->next;
-		free(finder);
+		if (finder->free)
+			free(finder);
 		finder = next;
 	}
 }
 
-LIBDRGN_PUBLIC struct drgn_error *
-drgn_program_add_type_finder(struct drgn_program *prog, drgn_type_find_fn fn,
-			     void *arg)
+struct drgn_error *
+drgn_program_add_type_finder_impl(struct drgn_program *prog,
+				  struct drgn_type_finder *finder,
+				  drgn_type_find_fn fn, void *arg)
 {
-	struct drgn_type_finder *finder = malloc(sizeof(*finder));
-	if (!finder)
-		return &drgn_enomem;
+	if (finder) {
+		finder->free = false;
+	} else {
+		finder = malloc(sizeof(*finder));
+		if (!finder)
+			return &drgn_enomem;
+		finder->free = true;
+	}
 	finder->fn = fn;
 	finder->arg = arg;
 	finder->next = prog->type_finders;
 	prog->type_finders = finder;
 	return NULL;
 }
 
+LIBDRGN_PUBLIC struct drgn_error *
+drgn_program_add_type_finder(struct drgn_program *prog, drgn_type_find_fn fn,
+			     void *arg)
+{
+	return drgn_program_add_type_finder_impl(prog, NULL, fn, arg);
+}
+
 struct drgn_error *drgn_program_find_type_impl(struct drgn_program *prog,
 					       uint64_t kinds, const char *name,
 					       size_t name_len,

diff --git a/libdrgn/type.h b/libdrgn/type.h
@@ -56,8 +56,15 @@ struct drgn_type_finder {
 	void *arg;
 	/** Next callback to try. */
 	struct drgn_type_finder *next;
+	/** Whether this structure needs to be freed. */
+	bool free;
 };
 
+struct drgn_error *
+drgn_program_add_type_finder_impl(struct drgn_program *prog,
+				  struct drgn_type_finder *finder,
+				  drgn_type_find_fn fn, void *arg);
+
 DEFINE_HASH_SET_TYPE(drgn_dedupe_type_set, struct drgn_type *);
 
 /** <tt>(type, member name)</tt> pair. */