libsysprof-analyze: check if ELF matches inode/build-id

We still want to load it into the cache as it could get used by other
symbols/mmap regions, but don't return the ELF if it won't match an inode
or build-id check. Rely on other fallbacks to create fallback symbols
for those use cases.

src/libsysprof-analyze/sysprof-elf-loader-private.h

@@ -43,6 +43,7 @@ SysprofElf         *sysprof_elf_loader_load                    (SysprofElfLoader
                                                                 SysprofMountNamespace  *mount_namespace,
                                                                 const char             *file,
                                                                 const char             *build_id,
+                                                                guint64                 file_inode,
                                                                 GError                **error);
 
 

src/libsysprof-analyze/sysprof-elf-loader.c

@@ -270,6 +270,7 @@ sysprof_elf_loader_annotate (SysprofElfLoader      *self,
   g_autofree char *directory_name = NULL;
   g_autofree char *debug_path = NULL;
   g_autofree char *container_path = NULL;
+  const char *build_id;
 
   g_assert (SYSPROF_IS_ELF_LOADER (self));
   g_assert (SYSPROF_IS_MOUNT_NAMESPACE (mount_namespace));
@@ -278,8 +279,9 @@ sysprof_elf_loader_annotate (SysprofElfLoader      *self,
 
   directory_name = g_path_get_dirname (orig_file);
   debug_path = g_build_filename ("/usr/lib/debug", directory_name, debug_link, NULL);
+  build_id = sysprof_elf_get_build_id (elf);
 
-  if ((debug_link_elf = sysprof_elf_loader_load (self, mount_namespace, debug_path, NULL, NULL)))
+  if ((debug_link_elf = sysprof_elf_loader_load (self, mount_namespace, debug_path, build_id, 0, NULL)))
     sysprof_elf_set_debug_link_elf (elf, get_deepest_debuglink (debug_link_elf));
 }
 
@@ -290,6 +292,8 @@ sysprof_elf_loader_annotate (SysprofElfLoader      *self,
  * @file: the path of the file to load within the mount namespace
  * @build_id: (nullable): an optional build-id that can be used to resolve
  *   the file alternatively to the file path
+ * @file_inode: expected inode for @file
+ * @error: a location for a #GError, or %NULL
  *
  * Attempts to load a #SysprofElf for @file (or optionally by @build_id).
  *
@@ -305,6 +309,7 @@ sysprof_elf_loader_load (SysprofElfLoader       *self,
                          SysprofMountNamespace  *mount_namespace,
                          const char             *file,
                          const char             *build_id,
+                         guint64                 file_inode,
                          GError                **error)
 {
   g_auto(GStrv) paths = NULL;
@@ -355,8 +360,20 @@ sysprof_elf_loader_load (SysprofElfLoader       *self,
                            g_strdup (path),
                            elf ? g_object_ref (elf) : NULL);
 
-      if (elf && (debug_link = sysprof_elf_get_debug_link (elf)))
-        sysprof_elf_loader_annotate (self, mount_namespace, file, elf, debug_link);
+      if (elf != NULL)
+        {
+          if ((debug_link = sysprof_elf_get_debug_link (elf)))
+            sysprof_elf_loader_annotate (self, mount_namespace, file, elf, debug_link);
+
+          /* If we loaded the ELF, but it doesn't match what this request is looking
+           * for in terms of inode/build-id, then we need to bail and not return it.
+           * We can, however, leave it in the cache incase another process/sample
+           * will need the ELF.
+           */
+          if (!sysprof_elf_matches (elf, file_inode, build_id))
+            g_clear_object (&elf);
+        }
+
 
       return g_steal_pointer (&elf);
     }

src/libsysprof-analyze/sysprof-elf-private.h

@@ -31,6 +31,9 @@ G_DECLARE_FINAL_TYPE (SysprofElf, sysprof_elf, SYSPROF, ELF, GObject)
 SysprofElf *sysprof_elf_new                   (const char   *filename,
                                                GMappedFile  *mapped_file,
                                                GError      **error);
+gboolean    sysprof_elf_matches               (SysprofElf   *self,
+                                               guint64       file_inode,
+                                               const char   *build_id);
 const char *sysprof_elf_get_file              (SysprofElf   *self);
 const char *sysprof_elf_get_build_id          (SysprofElf   *self);
 const char *sysprof_elf_get_debug_link        (SysprofElf   *self);

src/libsysprof-analyze/sysprof-elf.c

@@ -31,6 +31,7 @@ struct _SysprofElf
   char *file;
   SysprofElf *debug_link_elf;
   ElfParser *parser;
+  guint64 file_inode;
 };
 
 enum {
@@ -259,3 +260,25 @@ sysprof_elf_set_debug_link_elf (SysprofElf *self,
   if (g_set_object (&self->debug_link_elf, debug_link_elf))
     g_object_notify_by_pspec (G_OBJECT (self), properties [PROP_DEBUG_LINK_ELF]);
 }
+
+gboolean
+sysprof_elf_matches (SysprofElf *self,
+                     guint64     file_inode,
+                     const char *build_id)
+{
+  g_return_val_if_fail (SYSPROF_IS_ELF (self), FALSE);
+
+  if (build_id != NULL)
+    {
+      const char *elf_build_id = elf_parser_get_build_id (self->parser);
+
+      /* Not matching build-id, you definitely don't want this ELF */
+      if (elf_build_id != NULL && !g_str_equal (build_id, elf_build_id))
+        return FALSE;
+    }
+
+  if (file_inode && self->file_inode && file_inode != self->file_inode)
+    return FALSE;
+
+  return TRUE;
+}

src/libsysprof-analyze/tests/test-elf-loader.c

@@ -69,7 +69,8 @@ main (int   argc,
           g_autoptr(SysprofDocumentMmap) memory_map = g_list_model_get_item (memory_maps, j);
           const char *file = sysprof_document_mmap_get_file (memory_map);
           const char *build_id = sysprof_document_mmap_get_build_id (memory_map);
-          g_autoptr(SysprofElf) elf = sysprof_elf_loader_load (elf_loader, info->mount_namespace, file, build_id, &error);
+          guint64 file_inode = sysprof_document_mmap_get_file_inode (memory_map);
+          g_autoptr(SysprofElf) elf = sysprof_elf_loader_load (elf_loader, info->mount_namespace, file, build_id, file_inode, &error);
 
           if (elf == NULL)
             g_print ("%u: %s [unresolved]\n", info->pid, file);