libsysprof-analyze: give shape to ELF loading APIs

We need to separate a number of concerns here, such as debug-dirs within
the process namespace vs global debug-dirs (external symbols on a developer
workstation vs IoT/Laptop/VM/alternate-device).

That means we need to be able to resolve paths via the mount namespace of
the process as it was seen in the capture file.

Additionally, we need to follow .gnu_debuglink section headers so that we
can associate the version with symbols with the ELF that is loaded from
the processes SysprofAddressLayout.

src/libsysprof-analyze/sysprof-elf.c

@@ -0,0 +1,201 @@
+/* sysprof-elf.c
+ *
+ * Copyright 2023 Christian Hergert <chergert@redhat.com>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+
+#include "config.h"
+
+#include "sysprof-elf-private.h"
+
+struct _SysprofElf
+{
+  GObject parent_instance;
+  char *build_id;
+  char *debug_link;
+  SysprofElf *debug_link_elf;
+};
+
+enum {
+  PROP_0,
+  PROP_BUILD_ID,
+  PROP_DEBUG_LINK,
+  PROP_DEBUG_LINK_ELF,
+  N_PROPS
+};
+
+G_DEFINE_FINAL_TYPE (SysprofElf, sysprof_elf, G_TYPE_OBJECT)
+
+static GParamSpec *properties [N_PROPS];
+
+static void
+sysprof_elf_finalize (GObject *object)
+{
+  SysprofElf *self = (SysprofElf *)object;
+
+  g_clear_pointer (&self->build_id, g_free);
+  g_clear_pointer (&self->debug_link, g_free);
+  g_clear_object (&self->debug_link_elf);
+
+  G_OBJECT_CLASS (sysprof_elf_parent_class)->finalize (object);
+}
+
+static void
+sysprof_elf_get_property (GObject    *object,
+                          guint       prop_id,
+                          GValue     *value,
+                          GParamSpec *pspec)
+{
+  SysprofElf *self = SYSPROF_ELF (object);
+
+  switch (prop_id)
+    {
+    case PROP_BUILD_ID:
+      g_value_set_string (value, sysprof_elf_get_build_id (self));
+      break;
+
+    case PROP_DEBUG_LINK:
+      g_value_set_string (value, sysprof_elf_get_debug_link (self));
+      break;
+
+    case PROP_DEBUG_LINK_ELF:
+      g_value_set_object (value, sysprof_elf_get_debug_link_elf (self));
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
+    }
+}
+
+static void
+sysprof_elf_set_property (GObject      *object,
+                          guint         prop_id,
+                          const GValue *value,
+                          GParamSpec   *pspec)
+{
+  SysprofElf *self = SYSPROF_ELF (object);
+
+  switch (prop_id)
+    {
+    case PROP_DEBUG_LINK_ELF:
+      sysprof_elf_set_debug_link_elf (self, g_value_get_object (value));
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
+    }
+}
+
+static void
+sysprof_elf_class_init (SysprofElfClass *klass)
+{
+  GObjectClass *object_class = G_OBJECT_CLASS (klass);
+
+  object_class->finalize = sysprof_elf_finalize;
+  object_class->get_property = sysprof_elf_get_property;
+  object_class->set_property = sysprof_elf_set_property;
+
+  properties [PROP_BUILD_ID] =
+    g_param_spec_string ("build-id", NULL, NULL,
+                         NULL,
+                         (G_PARAM_READABLE | G_PARAM_STATIC_STRINGS));
+
+  properties [PROP_DEBUG_LINK] =
+    g_param_spec_string ("debug-link", NULL, NULL,
+                         NULL,
+                         (G_PARAM_READABLE | G_PARAM_STATIC_STRINGS));
+
+  properties [PROP_DEBUG_LINK_ELF] =
+    g_param_spec_object ("debug-link-elf", NULL, NULL,
+                         SYSPROF_TYPE_ELF,
+                         (G_PARAM_READWRITE | G_PARAM_EXPLICIT_NOTIFY | G_PARAM_STATIC_STRINGS));
+
+  g_object_class_install_properties (object_class, N_PROPS, properties);
+}
+
+static void
+sysprof_elf_init (SysprofElf *self)
+{
+}
+
+SysprofElf *
+sysprof_elf_new (const char  *filename,
+                 GError     **error)
+{
+  g_return_val_if_fail (filename != NULL, NULL);
+
+  return NULL;
+}
+
+const char *
+sysprof_elf_get_build_id (SysprofElf *self)
+{
+  g_return_val_if_fail (SYSPROF_IS_ELF (self), NULL);
+
+  return self->build_id;
+}
+
+const char *
+sysprof_elf_get_debug_link (SysprofElf *self)
+{
+  g_return_val_if_fail (SYSPROF_IS_ELF (self), NULL);
+
+  return self->debug_link;
+}
+
+const char *
+sysprof_elf_get_symbol_at_address (SysprofElf *self,
+                                   guint64     address,
+                                   guint64    *begin_address,
+                                   guint64    *end_address)
+{
+  g_return_val_if_fail (SYSPROF_IS_ELF (self), NULL);
+  g_return_val_if_fail (begin_address != NULL, NULL);
+  g_return_val_if_fail (end_address != NULL, NULL);
+
+  *begin_address = *end_address = 0;
+
+  return NULL;
+}
+
+/**
+ * sysprof_elf_get_debug_link_elf:
+ * @self: a #SysprofElf
+ *
+ * Gets a #SysprofElf that was resolved from the `.gnu_debuglink`
+ * ELF section header.
+ *
+ * Returns: (transfer none) (nullable): a #SysprofElf or %NULL
+ */
+SysprofElf *
+sysprof_elf_get_debug_link_elf (SysprofElf *self)
+{
+  g_return_val_if_fail (SYSPROF_IS_ELF (self), NULL);
+
+  return self->debug_link_elf;
+}
+
+void
+sysprof_elf_set_debug_link_elf (SysprofElf *self,
+                                SysprofElf *debug_link_elf)
+{
+  g_return_if_fail (SYSPROF_IS_ELF (self));
+  g_return_if_fail (!debug_link_elf || SYSPROF_IS_ELF (debug_link_elf));
+
+  if (g_set_object (&self->debug_link_elf, debug_link_elf))
+    g_object_notify_by_pspec (G_OBJECT (self), properties [PROP_DEBUG_LINK_ELF]);
+}