grub2/0276-blscfg-store-the-BLS-entries-in-a-sorted-linked-list.patch

From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Javier Martinez Canillas <javierm@redhat.com>
Date: Mon, 21 Jan 2019 17:33:13 +0100
Subject: [PATCH] blscfg: store the BLS entries in a sorted linked list

The parsed BLS entries are stored in an array, that it's sorted
using the quick sort algorithm before populating the boot menu.

This works on the assumption that all BLS entries are parsed at
the same time and that are displayed just after being retrieved.

But the support could be made more flexible, and have different
commands to load and display the entries. Keeping the BLS in a
sorted link simplify the code considerably, while not making it
much less efficient.

While being there, mark entries that have been used to populate
the boot menu so multiple calls to the blscfg command don't add
duplicated entries.

Signed-off-by: Javier Martinez Canillas <javierm@redhat.com>
---
 grub-core/Makefile.core.def    |   1 -
 grub-core/commands/blscfg.c    | 177 ++++++++++++----------------
 grub-core/commands/bls_qsort.h | 255 -----------------------------------------
 3 files changed, 71 insertions(+), 362 deletions(-)
 delete mode 100644 grub-core/commands/bls_qsort.h

diff --git a/grub-core/Makefile.core.def b/grub-core/Makefile.core.def
index 017080bd599..8a00c6177e1 100644
--- a/grub-core/Makefile.core.def
+++ b/grub-core/Makefile.core.def
@@ -796,7 +796,6 @@ module = {
 module = {
   name = blscfg;
   common = commands/blscfg.c;
-  common = commands/bls_qsort.h;
   common = commands/loadenv.h;
   enable = powerpc_ieee1275;
   enable = efi;
diff --git a/grub-core/commands/blscfg.c b/grub-core/commands/blscfg.c
index c432c6ba27a..304d73908ae 100644
--- a/grub-core/commands/blscfg.c
+++ b/grub-core/commands/blscfg.c
@@ -19,6 +19,7 @@
  *  along with GRUB.  If not, see <http://www.gnu.org/licenses/>.
  */
 
+#include <grub/list.h>
 #include <grub/types.h>
 #include <grub/misc.h>
 #include <grub/mm.h>
@@ -36,7 +37,6 @@
 
 GRUB_MOD_LICENSE ("GPLv3+");
 
-#include "bls_qsort.h"
 #include "loadenv.h"
 
 #define GRUB_BLS_CONFIG_PATH "/loader/entries/"
@@ -54,45 +54,17 @@ struct keyval
 
 struct bls_entry
 {
+  struct bls_entry *next;
+  struct bls_entry **prev;
   struct keyval **keyvals;
   int nkeyvals;
   char *filename;
+  bool visible;
 };
 
-static struct bls_entry **entries;
-static int nentries;
+static struct bls_entry *entries = NULL;
 
-static struct bls_entry *bls_new_entry(void)
-{
-  struct bls_entry **new_entries;
-  struct bls_entry *entry;
-  int new_n = nentries + 1;
-
-  new_entries = grub_realloc (entries,  new_n * sizeof (struct bls_entry *));
-  if (!new_entries)
-    {
-      grub_error (GRUB_ERR_OUT_OF_MEMORY,
-		  "couldn't find space for BLS entry list");
-      return NULL;
-    }
-
-  entries = new_entries;
-
-  entry = grub_malloc (sizeof (*entry));
-  if (!entry)
-    {
-      grub_error (GRUB_ERR_OUT_OF_MEMORY,
-		  "couldn't find space for BLS entry list");
-      return NULL;
-    }
-
-  grub_memset (entry, 0, sizeof (*entry));
-  entries[nentries] = entry;
-
-  nentries = new_n;
-
-  return entry;
-}
+#define FOR_BLS_ENTRIES(var) FOR_LIST_ELEMENTS (var, entries)
 
 static int bls_add_keyval(struct bls_entry *entry, char *key, char *val)
 {
@@ -138,24 +110,6 @@ static int bls_add_keyval(struct bls_entry *entry, char *key, char *val)
   return 0;
 }
 
-static void bls_free_entry(struct bls_entry *entry)
-{
-  int i;
-
-  for (i = 0; i < entry->nkeyvals; i++)
-    {
-      struct keyval *kv = entry->keyvals[i];
-      grub_free ((void *)kv->key);
-      grub_free (kv->val);
-      grub_free (kv);
-    }
-
-  grub_free (entry->keyvals);
-  grub_free (entry->filename);
-  grub_memset (entry, 0, sizeof (*entry));
-  grub_free (entry);
-}
-
 /* Find they value of the key named by keyname.  If there are allowed to be
  * more than one, pass a pointer to an int set to -1 the first time, and pass
  * the same pointer through each time after, and it'll return them in sorted
@@ -387,43 +341,17 @@ split_cmp(char *nvr0, char *nvr1, int has_name)
   return ret;
 }
 
-/* return 1: p0 is newer than p1 */
-/*        0: p0 and p1 are the same version */
-/*       -1: p1 is newer than p0 */
-static int bls_cmp(const void *p0, const void *p1, void *state)
+/* return 1: e0 is newer than e1 */
+/*        0: e0 and e1 are the same version */
+/*       -1: e1 is newer than e0 */
+static int bls_cmp(const struct bls_entry *e0, const struct bls_entry *e1)
 {
-  struct bls_entry * e0 = *(struct bls_entry **)p0;
-  struct bls_entry * e1 = *(struct bls_entry **)p1;
-  bool use_version = *(bool *)state;
-  char *v0, *v1;
   char *id0, *id1;
-  int l, r;
-
-  if (use_version)
-    {
-      v0 = grub_strdup(bls_get_val(e0, "version", NULL));
-      v1 = grub_strdup(bls_get_val(e1, "version", NULL));
-
-      r = split_cmp(v0, v1, 0);
-
-      grub_free(v0);
-      grub_free(v1);
-
-      if (r != 0)
-	return r;
-    }
+  int r;
 
   id0 = grub_strdup(e0->filename);
   id1 = grub_strdup(e1->filename);
 
-  l = grub_strlen(id0);
-  if (l > 5 && grub_strcmp(id0 + l - 5, ".conf"))
-    id0[l-5] = '\0';
-
-  l = grub_strlen(id1);
-  if (l > 5 && grub_strcmp(id1 + l - 5, ".conf"))
-    id1[l-5] = '\0';
-
   r = split_cmp(id0, id1, 1);
 
   grub_free(id0);
@@ -432,6 +360,53 @@ static int bls_cmp(const void *p0, const void *p1, void *state)
   return r;
 }
 
+static void list_add_tail(grub_list_t head, grub_list_t item)
+{
+  item->next = head;
+  if (head->prev)
+    (*head->prev)->next = item;
+  item->prev = head->prev;
+  head->prev = &item;
+}
+
+static int bls_add_entry(struct bls_entry *entry)
+{
+  struct bls_entry *e, *last = NULL;
+  int rc;
+
+  if (!entries) {
+    grub_dprintf ("blscfg", "Add entry with id \"%s\"\n", entry->filename);
+    entries = entry;
+    return 0;
+  }
+
+  FOR_BLS_ENTRIES(e) {
+    rc = bls_cmp(entry, e);
+
+    if (!rc)
+      return GRUB_ERR_BAD_ARGUMENT;
+
+    if (rc == 1) {
+      grub_dprintf ("blscfg", "Add entry with id \"%s\"\n", entry->filename);
+      list_add_tail (GRUB_AS_LIST (e), GRUB_AS_LIST (entry));
+      if (e == entries) {
+	entries = entry;
+	entry->prev = NULL;
+      }
+      return 0;
+    }
+    last = e;
+  }
+
+  if (last) {
+    grub_dprintf ("blscfg", "Add entry with id \"%s\"\n", entry->filename);
+    last->next = entry;
+    entry->prev = &last;
+  }
+
+  return 0;
+}
+
 struct read_entry_info {
   const char *devid;
   const char *dirname;
@@ -442,6 +417,7 @@ static int read_entry (
     const struct grub_dirhook_info *dirhook_info UNUSED,
     void *data)
 {
+  int rc = 0;
   grub_size_t n;
   char *p;
   grub_file_t f = NULL;
@@ -471,7 +447,7 @@ static int read_entry (
   if (sz == GRUB_FILE_SIZE_UNKNOWN || sz > 1024*1024)
     goto finish;
 
-  entry = bls_new_entry();
+  entry = grub_zalloc (sizeof (*entry));
   if (!entry)
     goto finish;
 
@@ -485,7 +461,6 @@ static int read_entry (
     {
       char *buf;
       char *separator;
-      int rc;
 
       buf = grub_file_getline (f);
       if (!buf)
@@ -519,6 +494,9 @@ static int read_entry (
 	break;
     }
 
+    if (!rc)
+      bls_add_entry(entry);
+
 finish:
   grub_free (p);
 
@@ -779,10 +757,10 @@ struct find_entry_info {
 static int find_entry (struct find_entry_info *info)
 {
   struct read_entry_info read_entry_info;
+  struct bls_entry *entry = NULL;
   grub_fs_t blsdir_fs = NULL;
   grub_device_t blsdir_dev = NULL;
   const char *blsdir = NULL;
-  bool use_version = true;
   int fallback = 0;
   int r = 0;
 
@@ -810,7 +788,7 @@ read_fallback:
 	} while (e);
   }
 
-  if (!nentries && !fallback) {
+  if (!entries && !fallback) {
     read_entry_info.dirname = "/boot" GRUB_BLS_CONFIG_PATH;
     grub_dprintf ("blscfg", "Entries weren't found in %s, fallback to %s\n",
 		  blsdir, read_entry_info.dirname);
@@ -818,27 +796,14 @@ read_fallback:
     goto read_fallback;
   }
 
-  grub_dprintf ("blscfg", "Sorting %d entries\n", nentries);
+  grub_dprintf ("blscfg", "%s Creating entries from bls\n", __func__);
+  FOR_BLS_ENTRIES(entry) {
+    if (entry->visible)
+      continue;
 
-  for (r = 0; r < nentries && use_version; r++) {
-    if (!bls_get_val(entries[r], "version", NULL))
-      use_version = false;
+    create_entry(entry);
+    entry->visible = true;
   }
-
-  bls_qsort(&entries[0], nentries, sizeof (struct bls_entry *), bls_cmp, &use_version);
-
-  grub_dprintf ("blscfg", "%s Creating %d entries from bls\n", __func__, nentries);
-  for (r = nentries - 1; r >= 0; r--)
-      create_entry(entries[r]);
-
-  for (r = 0; r < nentries; r++)
-      bls_free_entry (entries[r]);
-
-  nentries = 0;
-
-  grub_free (entries);
-  entries = NULL;
-
   return 0;
 }
 
diff --git a/grub-core/commands/bls_qsort.h b/grub-core/commands/bls_qsort.h
deleted file mode 100644
index 572765fa3f2..00000000000
--- a/grub-core/commands/bls_qsort.h
+++ /dev/null
@@ -1,255 +0,0 @@
-/* quicksort
- * This file from the GNU C Library.
- * Copyright (C) 1991-2016 Free Software Foundation, Inc.
- * Written by Douglas C. Schmidt (schmidt@ics.uci.edu).
- *
- *  GRUB  --  GRand Unified Bootloader
- *
- *  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/>.
- */
-
-/* If you consider tuning this algorithm, you should consult first:
-   Engineering a sort function; Jon Bentley and M. Douglas McIlroy;
-   Software - Practice and Experience; Vol. 23 (11), 1249-1265, 1993.  */
-
-#include <grub/types.h>
-#include <grub/misc.h>
-#include <grub/mm.h>
-
-#define CHAR_BIT 8
-
-/* Byte-wise swap two items of size SIZE. */
-#define SWAP(a, b, size)						      \
-  do									      \
-    {									      \
-      grub_size_t __size = (size);						      \
-      char *__a = (a), *__b = (b);					      \
-      do								      \
-	{								      \
-	  char __tmp = *__a;						      \
-	  *__a++ = *__b;						      \
-	  *__b++ = __tmp;						      \
-	} while (--__size > 0);						      \
-    } while (0)
-
-/* Discontinue quicksort algorithm when partition gets below this size.
-   This particular magic number was chosen to work best on a Sun 4/260. */
-#define MAX_THRESH 4
-
-/* Stack node declarations used to store unfulfilled partition obligations. */
-typedef struct
-  {
-    char *lo;
-    char *hi;
-  } stack_node;
-
-/* The next 4 #defines implement a very fast in-line stack abstraction. */
-/* The stack needs log (total_elements) entries (we could even subtract
-   log(MAX_THRESH)).  Since total_elements has type grub_size_t, we get as
-   upper bound for log (total_elements):
-   bits per byte (CHAR_BIT) * sizeof(grub_size_t).  */
-#define STACK_SIZE	(CHAR_BIT * sizeof(grub_size_t))
-#define PUSH(low, high)	((void) ((top->lo = (low)), (top->hi = (high)), ++top))
-#define	POP(low, high)	((void) (--top, (low = top->lo), (high = top->hi)))
-#define	STACK_NOT_EMPTY	(stack < top)
-
-typedef int (*grub_compar_d_fn_t) (const void *p0, const void *p1, void *state);
-
-/* Order size using quicksort.  This implementation incorporates
-   four optimizations discussed in Sedgewick:
-
-   1. Non-recursive, using an explicit stack of pointer that store the
-      next array partition to sort.  To save time, this maximum amount
-      of space required to store an array of SIZE_MAX is allocated on the
-      stack.  Assuming a 32-bit (64 bit) integer for grub_size_t, this needs
-      only 32 * sizeof(stack_node) == 256 bytes (for 64 bit: 1024 bytes).
-      Pretty cheap, actually.
-
-   2. Chose the pivot element using a median-of-three decision tree.
-      This reduces the probability of selecting a bad pivot value and
-      eliminates certain extraneous comparisons.
-
-   3. Only quicksorts TOTAL_ELEMS / MAX_THRESH partitions, leaving
-      insertion sort to order the MAX_THRESH items within each partition.
-      This is a big win, since insertion sort is faster for small, mostly
-      sorted array segments.
-
-   4. The larger of the two sub-partitions is always pushed onto the
-      stack first, with the algorithm then concentrating on the
-      smaller partition.  This *guarantees* no more than log (total_elems)
-      stack size is needed (actually O(1) in this case)!  */
-
-static inline void UNUSED
-bls_qsort (void *const pbase, grub_size_t total_elems, grub_size_t size,
-	    grub_compar_d_fn_t cmp, void *arg)
-{
-  char *base_ptr = (char *) pbase;
-
-  const grub_size_t max_thresh = MAX_THRESH * size;
-
-  if (total_elems == 0)
-    /* Avoid lossage with unsigned arithmetic below.  */
-    return;
-
-  if (total_elems > MAX_THRESH)
-    {
-      char *lo = base_ptr;
-      char *hi = &lo[size * (total_elems - 1)];
-      stack_node stack[STACK_SIZE];
-      stack_node *top = stack;
-
-      PUSH (NULL, NULL);
-
-      while (STACK_NOT_EMPTY)
-        {
-          char *left_ptr;
-          char *right_ptr;
-
-	  /* Select median value from among LO, MID, and HI. Rearrange
-	     LO and HI so the three values are sorted. This lowers the
-	     probability of picking a pathological pivot value and
-	     skips a comparison for both the LEFT_PTR and RIGHT_PTR in
-	     the while loops. */
-
-	  char *mid = lo + size * ((hi - lo) / size >> 1);
-
-	  if ((*cmp) ((void *) mid, (void *) lo, arg) < 0)
-	    SWAP (mid, lo, size);
-	  if ((*cmp) ((void *) hi, (void *) mid, arg) < 0)
-	    SWAP (mid, hi, size);
-	  else
-	    goto jump_over;
-	  if ((*cmp) ((void *) mid, (void *) lo, arg) < 0)
-	    SWAP (mid, lo, size);
-	jump_over:;
-
-	  left_ptr  = lo + size;
-	  right_ptr = hi - size;
-
-	  /* Here's the famous ``collapse the walls'' section of quicksort.
-	     Gotta like those tight inner loops!  They are the main reason
-	     that this algorithm runs much faster than others. */
-	  do
-	    {
-	      while ((*cmp) ((void *) left_ptr, (void *) mid, arg) < 0)
-		left_ptr += size;
-
-	      while ((*cmp) ((void *) mid, (void *) right_ptr, arg) < 0)
-		right_ptr -= size;
-
-	      if (left_ptr < right_ptr)
-		{
-		  SWAP (left_ptr, right_ptr, size);
-		  if (mid == left_ptr)
-		    mid = right_ptr;
-		  else if (mid == right_ptr)
-		    mid = left_ptr;
-		  left_ptr += size;
-		  right_ptr -= size;
-		}
-	      else if (left_ptr == right_ptr)
-		{
-		  left_ptr += size;
-		  right_ptr -= size;
-		  break;
-		}
-	    }
-	  while (left_ptr <= right_ptr);
-
-          /* Set up pointers for next iteration.  First determine whether
-             left and right partitions are below the threshold size.  If so,
-             ignore one or both.  Otherwise, push the larger partition's
-             bounds on the stack and continue sorting the smaller one. */
-
-          if ((grub_size_t) (right_ptr - lo) <= max_thresh)
-            {
-              if ((grub_size_t) (hi - left_ptr) <= max_thresh)
-		/* Ignore both small partitions. */
-                POP (lo, hi);
-              else
-		/* Ignore small left partition. */
-                lo = left_ptr;
-            }
-          else if ((grub_size_t) (hi - left_ptr) <= max_thresh)
-	    /* Ignore small right partition. */
-            hi = right_ptr;
-          else if ((right_ptr - lo) > (hi - left_ptr))
-            {
-	      /* Push larger left partition indices. */
-              PUSH (lo, right_ptr);
-              lo = left_ptr;
-            }
-          else
-            {
-	      /* Push larger right partition indices. */
-              PUSH (left_ptr, hi);
-              hi = right_ptr;
-            }
-        }
-    }
-
-  /* Once the BASE_PTR array is partially sorted by quicksort the rest
-     is completely sorted using insertion sort, since this is efficient
-     for partitions below MAX_THRESH size. BASE_PTR points to the beginning
-     of the array to sort, and END_PTR points at the very last element in
-     the array (*not* one beyond it!). */
-
-#define min(x, y) ((x) < (y) ? (x) : (y))
-
-  {
-    char *const end_ptr = &base_ptr[size * (total_elems - 1)];
-    char *tmp_ptr = base_ptr;
-    char *thresh = min(end_ptr, base_ptr + max_thresh);
-    char *run_ptr;
-
-    /* Find smallest element in first threshold and place it at the
-       array's beginning.  This is the smallest array element,
-       and the operation speeds up insertion sort's inner loop. */
-
-    for (run_ptr = tmp_ptr + size; run_ptr <= thresh; run_ptr += size)
-      if ((*cmp) ((void *) run_ptr, (void *) tmp_ptr, arg) < 0)
-        tmp_ptr = run_ptr;
-
-    if (tmp_ptr != base_ptr)
-      SWAP (tmp_ptr, base_ptr, size);
-
-    /* Insertion sort, running from left-hand-side up to right-hand-side.  */
-
-    run_ptr = base_ptr + size;
-    while ((run_ptr += size) <= end_ptr)
-      {
-	tmp_ptr = run_ptr - size;
-	while ((*cmp) ((void *) run_ptr, (void *) tmp_ptr, arg) < 0)
-	  tmp_ptr -= size;
-
-	tmp_ptr += size;
-        if (tmp_ptr != run_ptr)
-          {
-            char *trav;
-
-	    trav = run_ptr + size;
-	    while (--trav >= run_ptr)
-              {
-                char c = *trav;
-                char *hi, *lo;
-
-                for (hi = lo = trav; (lo -= size) >= tmp_ptr; hi = lo)
-                  *hi = *lo;
-                *hi = c;
-              }
-          }
-      }
-  }
-}
-