Add a module for retrieving SMBIOS information

docs/grub.texi +4 -0

+
+@itemize @bullet
+@item
+When given @option{--get-byte}, return the value of the byte

grub-core/commands/smbios.c new file +313 -0

+ *
+ *  GRUB 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.
+ *
+ *  GRUB 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 GRUB.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <grub/dl.h>
+#include <grub/env.h>
+#include <grub/extcmd.h>
+#include <grub/i18n.h>
+#include <grub/misc.h>
+#include <grub/mm.h>
+#include <grub/smbios.h>
+
+GRUB_MOD_LICENSE ("GPLv3+");
+
+
+/* Locate the SMBIOS entry point structure depending on the hardware. */
+struct grub_smbios_eps *
+grub_smbios_get_eps (void)
+{
+  static struct grub_smbios_eps *eps = NULL;
+  if (eps != NULL)
+    return eps;
+  eps = grub_machine_smbios_get_eps ();
+  return eps;
+}
+
+/* Locate the SMBIOS3 entry point structure depending on the hardware. */
+struct grub_smbios_eps3 *
+grub_smbios_get_eps3 (void)
+{
+  static struct grub_smbios_eps3 *eps = NULL;
+  if (eps != NULL)
+    return eps;
+  eps = grub_machine_smbios_get_eps3 ();
+  return eps;
+}
+
+/* Abstract useful values found in either the SMBIOS3 or SMBIOS EPS. */
+static struct {
+  grub_addr_t start;
+  grub_addr_t end;
+  grub_uint16_t structures;
+} table_desc = {0, 0, 0};
+
+
+/*
+ * These functions convert values from the various SMBIOS structure field types
+ * into a string formatted to be returned to the user.  They expect that the
+ * structure and offset were already validated.  The given buffer stores the
+ * newly formatted string if needed.  When the requested data is successfully
+ * retrieved and formatted, the pointer to the string is returned; otherwise,
+ * NULL is returned on failure.
+ */
+
+static const char *
+grub_smbios_format_byte (char *buffer, grub_size_t size,
+                         const grub_uint8_t *structure, grub_uint8_t offset)
+{
+  grub_snprintf (buffer, size, "%u", structure[offset]);
+  return (const char *)buffer;
+}
+
+static const char *
+grub_smbios_format_word (char *buffer, grub_size_t size,
+                         const grub_uint8_t *structure, grub_uint8_t offset)
+{
+  grub_uint16_t value = grub_get_unaligned16 (structure + offset);
+  grub_snprintf (buffer, size, "%u", value);
+  return (const char *)buffer;
+}
+
+static const char *
+grub_smbios_format_dword (char *buffer, grub_size_t size,
+                          const grub_uint8_t *structure, grub_uint8_t offset)
+{
+  grub_uint32_t value = grub_get_unaligned32 (structure + offset);
+  grub_snprintf (buffer, size, "%" PRIuGRUB_UINT32_T, value);
+  return (const char *)buffer;
+}
+
+static const char *
+grub_smbios_format_qword (char *buffer, grub_size_t size,
+                          const grub_uint8_t *structure, grub_uint8_t offset)
+{
+  grub_uint64_t value = grub_get_unaligned64 (structure + offset);
+  grub_snprintf (buffer, size, "%" PRIuGRUB_UINT64_T, value);
+  return (const char *)buffer;
+}
+
+/* The matching string pointer is returned directly to avoid extra copying. */
+static const char *
+grub_smbios_get_string (char *buffer __attribute__ ((unused)),
+                        grub_size_t size __attribute__ ((unused)),
+                        const grub_uint8_t *structure, grub_uint8_t offset)
+{
+  const grub_uint8_t *ptr = structure + structure[1];
+  const grub_uint8_t *table_end = (const grub_uint8_t *)table_desc.end;
+  const grub_uint8_t referenced_string_number = structure[offset];
+  grub_uint8_t i;
+
+  /* A string referenced with zero is interpreted as unset. */
+  if (referenced_string_number == 0)
+    return NULL;
+
+  /* Search the string set. */
+  for (i = 1; *ptr != 0 && ptr < table_end; i++)
+    if (i == referenced_string_number)
+      {
+        const char *str = (const char *)ptr;
+        while (*ptr++ != 0)
+          if (ptr >= table_end)
+            return NULL; /* The string isn't terminated. */
+        return str;
+      }
+    else
+      while (*ptr++ != 0 && ptr < table_end);
+
+  /* The string number is greater than the number of strings in the set. */
+  return NULL;
+}
+
+static const char *
+grub_smbios_format_uuid (char *buffer, grub_size_t size,
+                         const grub_uint8_t *structure, grub_uint8_t offset)
+{
+  const grub_uint8_t *f = structure + offset; /* little-endian fields */
+  const grub_uint8_t *g = f + 8; /* byte-by-byte fields */
+  grub_snprintf (buffer, size,
+                 "%02x%02x%02x%02x-%02x%02x-%02x%02x-"
+                 "%02x%02x-%02x%02x%02x%02x%02x%02x",
+                 f[3], f[2], f[1], f[0], f[5], f[4], f[7], f[6],
+                 g[0], g[1], g[2], g[3], g[4], g[5], g[6], g[7]);
+  return (const char *)buffer;
+}
+
+
+/* List the field formatting functions and the number of bytes they need. */
+#define MAXIMUM_FORMAT_LENGTH (sizeof ("ffffffff-ffff-ffff-ffff-ffffffffffff"))
+static const struct {
+  const char *(*format) (char *buffer, grub_size_t size,
+                         const grub_uint8_t *structure, grub_uint8_t offset);
+  grub_uint8_t field_length;
+} field_extractors[] = {
+  {grub_smbios_format_byte, 1},
+  {grub_smbios_format_word, 2},
+  {grub_smbios_format_dword, 4},
+  {grub_smbios_format_qword, 8},
+  {grub_smbios_get_string, 1},
+  {grub_smbios_format_uuid, 16}
+};
+
+/* List command options, with structure field getters ordered as above. */
+#define FIRST_GETTER_OPT (3)
+#define SETTER_OPT (FIRST_GETTER_OPT + ARRAY_SIZE(field_extractors))
+static const struct grub_arg_option options[] = {
+  {"type",       't', 0, N_("Match entries with the given type."),
+                         N_("type"), ARG_TYPE_INT},
+  {"handle",     'h', 0, N_("Match entries with the given handle."),
+                         N_("handle"), ARG_TYPE_INT},
+  {"match",      'm', 0, N_("Select a structure when several match."),
+                         N_("match"), ARG_TYPE_INT},
+  {"get-byte",   'b', 0, N_("Get the byte's value at the given offset."),
+                         N_("offset"), ARG_TYPE_INT},
+  {"get-word",   'w', 0, N_("Get two bytes' value at the given offset."),
+                         N_("offset"), ARG_TYPE_INT},
+  {"get-dword",  'd', 0, N_("Get four bytes' value at the given offset."),
+                         N_("offset"), ARG_TYPE_INT},
+  {"get-qword",  'q', 0, N_("Get eight bytes' value at the given offset."),
+                         N_("offset"), ARG_TYPE_INT},
+  {"get-string", 's', 0, N_("Get the string specified at the given offset."),
+                         N_("offset"), ARG_TYPE_INT},
+  {"get-uuid",   'u', 0, N_("Get the UUID's value at the given offset."),
+                         N_("offset"), ARG_TYPE_INT},
+  {"set",       '\0', 0, N_("Store the value in the given variable name."),
+                         N_("variable"), ARG_TYPE_STRING},
+  {0, 0, 0, 0, 0, 0}
+};
+
+
+/*
+ * Return a matching SMBIOS structure.
+ *
+ * This method can use up to three criteria for selecting a structure:
+ *   - The "type" field                  (use -1 to ignore)
+ *   - The "handle" field                (use -1 to ignore)
+ *   - Which to return if several match  (use  0 to ignore)
+ *
+ * The return value is a pointer to the first matching structure.  If no
+ * structures match the given parameters, NULL is returned.
+ */
+static const grub_uint8_t *
+grub_smbios_match_structure (const grub_int16_t type,
+                             const grub_int32_t handle,
+                             const grub_uint16_t match)
+{
+  const grub_uint8_t *ptr = (const grub_uint8_t *)table_desc.start;
+  const grub_uint8_t *table_end = (const grub_uint8_t *)table_desc.end;
+  grub_uint16_t structures = table_desc.structures;
+  grub_uint16_t structure_count = 0;
+  grub_uint16_t matches = 0;
+
+  while (ptr < table_end
+         && ptr[1] >= 4 /* Valid structures include the 4-byte header. */
+         && (structure_count++ < structures || structures == 0))
+    {
+      grub_uint16_t structure_handle = grub_get_unaligned16 (ptr + 2);
+      grub_uint8_t structure_type = ptr[0];
+
+      if ((handle < 0 || handle == structure_handle)
+          && (type < 0 || type == structure_type)
+          && (match == 0 || match == ++matches))
+        return ptr;
+
+      else
+        {
+          ptr += ptr[1];
+          while ((*ptr++ != 0 || *ptr++ != 0) && ptr < table_end);
+        }
+
+      if (structure_type == GRUB_SMBIOS_TYPE_END_OF_TABLE)
+        break;
+    }
+
+  return NULL;
+}
+
+
+static grub_err_t
+grub_cmd_smbios (grub_extcmd_context_t ctxt,
+                 int argc __attribute__ ((unused)),
+                 char **argv __attribute__ ((unused)))
+{
+  struct grub_arg_list *state = ctxt->state;
+
+  grub_int16_t type = -1;
+  grub_int32_t handle = -1;
+  grub_uint16_t match = 0;
+  grub_uint8_t offset = 0;
+
+  const grub_uint8_t *structure;
+  const char *value;
+  char buffer[MAXIMUM_FORMAT_LENGTH];
+  grub_int32_t option;
+  grub_int8_t field_type = -1;
+  grub_uint8_t i;
+
+  if (table_desc.start == 0)
+    return grub_error (GRUB_ERR_IO,
+                       N_("the SMBIOS entry point structure was not found"));
+
+  /* Read the given filtering options. */
+  if (state[0].set)
+    {
+      option = grub_strtol (state[0].arg, NULL, 0);
+      if (option < 0 || option > 255)
+        return grub_error (GRUB_ERR_BAD_ARGUMENT,
+                           N_("the type must be between 0 and 255"));
+      type = (grub_int16_t)option;
+    }
+  if (state[1].set)
+    {
+      option = grub_strtol (state[1].arg, NULL, 0);
+      if (option < 0 || option > 65535)
+        return grub_error (GRUB_ERR_BAD_ARGUMENT,
+                           N_("the handle must be between 0 and 65535"));
+      handle = (grub_int32_t)option;
+    }
+  if (state[2].set)
+    {
+      option = grub_strtol (state[2].arg, NULL, 0);
+      if (option <= 0)
+        return grub_error (GRUB_ERR_BAD_ARGUMENT,
+                           N_("the match must be a positive integer"));
+      match = (grub_uint16_t)option;
+    }
+
+  /* Determine the data type of the structure field to retrieve. */
+  for (i = 0; i < ARRAY_SIZE(field_extractors); i++)
+    if (state[FIRST_GETTER_OPT + i].set)
+      {
+        if (field_type >= 0)
+          return grub_error (GRUB_ERR_BAD_ARGUMENT,
+                             N_("only one --get option is usable at a time"));
+        field_type = i;
+      }
+
+  /* Require a choice of a structure field to return. */
+  if (field_type < 0)
+    return grub_error (GRUB_ERR_BAD_ARGUMENT,
+                       N_("one of the --get options is required"));
+
+  /* Locate a matching SMBIOS structure. */
+  structure = grub_smbios_match_structure (type, handle, match);
+  if (structure == NULL)
+    return grub_error (GRUB_ERR_IO,
+                       N_("no structure matched the given options"));
+
+  /* Ensure the requested byte offset is inside the structure. */
+  option = grub_strtol (state[FIRST_GETTER_OPT + field_type].arg, NULL, 0);
+  if (option < 0 || option >= structure[1])
+    return grub_error (GRUB_ERR_OUT_OF_RANGE,
+                       N_("the given offset is outside the structure"));