From 09b8c1f7378278ff299046c5bfa65d5d88c09467 Mon Sep 17 00:00:00 2001
From: Christian Hergert <chergert@redhat.com>
Date: Mon, 15 May 2023 16:49:37 -0700
Subject: [PATCH] libsysprof-analyze: leave some notes on elf symbolizing

---
 src/libsysprof-analyze/meson.build            |  3 +
 .../sysprof-elf-symbolizer.c                  | 85 ++++++++++++++++++-
 2 files changed, 84 insertions(+), 4 deletions(-)

diff --git a/src/libsysprof-analyze/meson.build b/src/libsysprof-analyze/meson.build
index c0508e62..a03e26f0 100644
--- a/src/libsysprof-analyze/meson.build
+++ b/src/libsysprof-analyze/meson.build
@@ -24,6 +24,9 @@ libsysprof_analyze_public_sources = [
 ]
 
 libsysprof_analyze_private_sources = [
+  '../libsysprof/binfile.c',
+  '../libsysprof/demangle.cpp',
+  '../libsysprof/elfparser.c',
   'sysprof-address-layout.c',
   'sysprof-document-bitset-index.c',
   'sysprof-document-symbols.c',
diff --git a/src/libsysprof-analyze/sysprof-elf-symbolizer.c b/src/libsysprof-analyze/sysprof-elf-symbolizer.c
index 39d9acec..121375f3 100644
--- a/src/libsysprof-analyze/sysprof-elf-symbolizer.c
+++ b/src/libsysprof-analyze/sysprof-elf-symbolizer.c
@@ -20,6 +20,8 @@
 
 #include "config.h"
 
+#include "../libsysprof/binfile.h"
+
 #include "sysprof-elf-symbolizer.h"
 #include "sysprof-document-private.h"
 #include "sysprof-strings-private.h"
@@ -28,7 +30,8 @@
 
 struct _SysprofElfSymbolizer
 {
-  SysprofSymbolizer parent_instance;
+  SysprofSymbolizer  parent_instance;
+  GHashTable        *bin_file_cache;
 };
 
 struct _SysprofElfSymbolizerClass
@@ -45,11 +48,79 @@ sysprof_elf_symbolizer_symbolize (SysprofSymbolizer        *symbolizer,
                                   SysprofAddressContext     context,
                                   SysprofAddress            address)
 {
-  if (context != SYSPROF_ADDRESS_CONTEXT_NONE &&
-      context != SYSPROF_ADDRESS_CONTEXT_USER)
+  SysprofElfSymbolizer *self = (SysprofElfSymbolizer *)symbolizer;
+  SysprofDocumentMmap *map;
+  g_autofree char *name = NULL;
+  g_auto(GStrv) translations = NULL;
+  GMappedFile *mapped_file = NULL;
+  const char *path;
+
+  if (process_info == NULL ||
+      process_info->address_layout == NULL ||
+      process_info->mount_namespace == NULL ||
+      (context != SYSPROF_ADDRESS_CONTEXT_NONE &&
+       context != SYSPROF_ADDRESS_CONTEXT_USER))
     return NULL;
 
-  return NULL;
+  /* First find out what was mapped at that address */
+  if (!(map = sysprof_address_layout_lookup (process_info->address_layout, address)))
+    return NULL;
+
+  /* The file could be available at a number of locations in case there
+   * is an overlayfs, flatpak runtime, etc. Additionally, we may need
+   * to resolve through various debug directories. All of those also
+   * need to get translated to a location where this process can access
+   * then (which itself might be via /var/run/host/... or similar).
+   */
+  path = sysprof_document_mmap_get_file (map);
+
+  /* TODO:
+   *
+   * We need something like bin_file_t here that will let us look at
+   * all of our possible translations for the file (overlayfs, etc)
+   * and add debug directories on top of that. The debug directories
+   * can be used to follow .gnu_debuglink through debug dirs.
+   */
+
+#if 0
+  if (!(translations = sysprof_mount_namespace_translate (process_info->mount_namespace, path)))
+    goto fallback;
+
+  for (guint i = 0; translations[i]; i++)
+    {
+      /* If the file exists within our cache already, re-use that instead
+       * of re-opening a binfile.
+       */
+      if ((mapped_file = g_hash_table_lookup (self->bin_file_cache, translations[i])))
+        break;
+
+      if ((mapped_file = g_mapped_file_new (translations[i], FALSE, NULL)))
+        {
+          g_hash_table_insert (self->bin_file_cache,
+                               g_strdup (translations[i]),
+                               mapped_file);
+          break;
+        }
+    }
+
+  if (mapped_file == NULL)
+    goto fallback;
+#endif
+
+fallback:
+  /* Fallback, we failed to locate the symbol within a file we can
+   * access, so tell the user about what file contained the symbol
+   * and the offset of the ELF section mapped.
+   */
+  name = g_strdup_printf ("In file %s <+0x%"G_GINT64_MODIFIER"x>",
+                          sysprof_document_mmap_get_file (map),
+                          sysprof_document_mmap_get_file_offset (map));
+
+  return _sysprof_symbol_new (sysprof_strings_get (strings, name),
+                              NULL,
+                              NULL,
+                              sysprof_document_mmap_get_start_address (map),
+                              sysprof_document_mmap_get_end_address (map));
 }
 
 static void
@@ -57,6 +128,8 @@ sysprof_elf_symbolizer_finalize (GObject *object)
 {
   SysprofElfSymbolizer *self = (SysprofElfSymbolizer *)object;
 
+  g_clear_pointer (&self->bin_file_cache, g_hash_table_unref);
+
   G_OBJECT_CLASS (sysprof_elf_symbolizer_parent_class)->finalize (object);
 }
 
@@ -74,6 +147,10 @@ sysprof_elf_symbolizer_class_init (SysprofElfSymbolizerClass *klass)
 static void
 sysprof_elf_symbolizer_init (SysprofElfSymbolizer *self)
 {
+  self->bin_file_cache = g_hash_table_new_full (g_str_hash,
+                                                g_str_equal,
+                                                g_free,
+                                                (GDestroyNotify)bin_file_free);
 }
 
 SysprofSymbolizer *