63f1a982b9
Fixups to work with gcc 8 Experimental https boot support on UEFI XFS fixes for sparse inode support Resolves: rhbz#1575797 Signed-off-by: Peter Jones <pjones@redhat.com>
326 lines
10 KiB
Diff
326 lines
10 KiB
Diff
From a2cd100d71711b950beaf60ea7ddca4c77a70d59 Mon Sep 17 00:00:00 2001
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From: Peter Jones <pjones@redhat.com>
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Date: Fri, 9 Dec 2016 15:39:47 -0500
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Subject: [PATCH 199/250] Add quicksort implementation
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This will be used to sort the boot menu entries that are read from
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the BootLoaderSpec config files.
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---
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grub-core/kern/qsort.c | 279 +++++++++++++++++++++++++++++++++++++++++++++++++
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include/grub/misc.h | 15 +++
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2 files changed, 294 insertions(+)
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create mode 100644 grub-core/kern/qsort.c
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diff --git a/grub-core/kern/qsort.c b/grub-core/kern/qsort.c
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new file mode 100644
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index 00000000000..7f3fc9ffdae
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--- /dev/null
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+++ b/grub-core/kern/qsort.c
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@@ -0,0 +1,279 @@
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+/* quicksort
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+ * This file from the GNU C Library.
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+ * Copyright (C) 1991-2016 Free Software Foundation, Inc.
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+ * Written by Douglas C. Schmidt (schmidt@ics.uci.edu).
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+ *
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+ * GRUB -- GRand Unified Bootloader
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+ *
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+ * GRUB is free software: you can redistribute it and/or modify
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+ * it under the terms of the GNU General Public License as published by
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+ * the Free Software Foundation, either version 3 of the License, or
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+ * (at your option) any later version.
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+ *
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+ * GRUB is distributed in the hope that it will be useful,
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+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
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+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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+ * GNU General Public License for more details.
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+ *
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+ * You should have received a copy of the GNU General Public License
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+ * along with GRUB. If not, see <http://www.gnu.org/licenses/>.
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+ */
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+
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+/* If you consider tuning this algorithm, you should consult first:
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+ Engineering a sort function; Jon Bentley and M. Douglas McIlroy;
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+ Software - Practice and Experience; Vol. 23 (11), 1249-1265, 1993. */
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+
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+#include <grub/types.h>
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+#include <grub/misc.h>
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+#include <grub/mm.h>
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+
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+#define CHAR_BIT 8
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+
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+/* Byte-wise swap two items of size SIZE. */
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+#define SWAP(a, b, size) \
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+ do \
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+ { \
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+ grub_size_t __size = (size); \
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+ char *__a = (a), *__b = (b); \
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+ do \
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+ { \
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+ char __tmp = *__a; \
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+ *__a++ = *__b; \
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+ *__b++ = __tmp; \
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+ } while (--__size > 0); \
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+ } while (0)
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+
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+/* Discontinue quicksort algorithm when partition gets below this size.
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+ This particular magic number was chosen to work best on a Sun 4/260. */
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+#define MAX_THRESH 4
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+
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+/* Stack node declarations used to store unfulfilled partition obligations. */
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+typedef struct
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+ {
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+ char *lo;
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+ char *hi;
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+ } stack_node;
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+
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+/* The next 4 #defines implement a very fast in-line stack abstraction. */
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+/* The stack needs log (total_elements) entries (we could even subtract
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+ log(MAX_THRESH)). Since total_elements has type grub_size_t, we get as
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+ upper bound for log (total_elements):
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+ bits per byte (CHAR_BIT) * sizeof(grub_size_t). */
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+#define STACK_SIZE (CHAR_BIT * sizeof(grub_size_t))
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+#define PUSH(low, high) ((void) ((top->lo = (low)), (top->hi = (high)), ++top))
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+#define POP(low, high) ((void) (--top, (low = top->lo), (high = top->hi)))
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+#define STACK_NOT_EMPTY (stack < top)
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+
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+
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+/* Order size using quicksort. This implementation incorporates
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+ four optimizations discussed in Sedgewick:
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+
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+ 1. Non-recursive, using an explicit stack of pointer that store the
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+ next array partition to sort. To save time, this maximum amount
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+ of space required to store an array of SIZE_MAX is allocated on the
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+ stack. Assuming a 32-bit (64 bit) integer for grub_size_t, this needs
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+ only 32 * sizeof(stack_node) == 256 bytes (for 64 bit: 1024 bytes).
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+ Pretty cheap, actually.
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+
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+ 2. Chose the pivot element using a median-of-three decision tree.
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+ This reduces the probability of selecting a bad pivot value and
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+ eliminates certain extraneous comparisons.
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+
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+ 3. Only quicksorts TOTAL_ELEMS / MAX_THRESH partitions, leaving
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+ insertion sort to order the MAX_THRESH items within each partition.
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+ This is a big win, since insertion sort is faster for small, mostly
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+ sorted array segments.
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+
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+ 4. The larger of the two sub-partitions is always pushed onto the
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+ stack first, with the algorithm then concentrating on the
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+ smaller partition. This *guarantees* no more than log (total_elems)
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+ stack size is needed (actually O(1) in this case)! */
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+
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+void
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+grub_qsort (void *const pbase, grub_size_t total_elems, grub_size_t size,
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+ grub_compar_d_fn_t cmp, void *arg)
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+{
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+ char *base_ptr = (char *) pbase;
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+
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+ const grub_size_t max_thresh = MAX_THRESH * size;
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+
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+ if (total_elems == 0)
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+ /* Avoid lossage with unsigned arithmetic below. */
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+ return;
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+
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+ if (total_elems > MAX_THRESH)
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+ {
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+ char *lo = base_ptr;
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+ char *hi = &lo[size * (total_elems - 1)];
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+ stack_node stack[STACK_SIZE];
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+ stack_node *top = stack;
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+
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+ PUSH (NULL, NULL);
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+
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+ while (STACK_NOT_EMPTY)
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+ {
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+ char *left_ptr;
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+ char *right_ptr;
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+
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+ /* Select median value from among LO, MID, and HI. Rearrange
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+ LO and HI so the three values are sorted. This lowers the
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+ probability of picking a pathological pivot value and
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+ skips a comparison for both the LEFT_PTR and RIGHT_PTR in
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+ the while loops. */
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+
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+ char *mid = lo + size * ((hi - lo) / size >> 1);
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+
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+ if ((*cmp) ((void *) mid, (void *) lo, arg) < 0)
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+ SWAP (mid, lo, size);
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+ if ((*cmp) ((void *) hi, (void *) mid, arg) < 0)
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+ SWAP (mid, hi, size);
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+ else
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+ goto jump_over;
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+ if ((*cmp) ((void *) mid, (void *) lo, arg) < 0)
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+ SWAP (mid, lo, size);
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+ jump_over:;
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+
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+ left_ptr = lo + size;
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+ right_ptr = hi - size;
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+
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+ /* Here's the famous ``collapse the walls'' section of quicksort.
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+ Gotta like those tight inner loops! They are the main reason
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+ that this algorithm runs much faster than others. */
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+ do
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+ {
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+ while ((*cmp) ((void *) left_ptr, (void *) mid, arg) < 0)
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+ left_ptr += size;
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+
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+ while ((*cmp) ((void *) mid, (void *) right_ptr, arg) < 0)
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+ right_ptr -= size;
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+
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+ if (left_ptr < right_ptr)
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+ {
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+ SWAP (left_ptr, right_ptr, size);
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+ if (mid == left_ptr)
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+ mid = right_ptr;
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+ else if (mid == right_ptr)
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+ mid = left_ptr;
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+ left_ptr += size;
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+ right_ptr -= size;
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+ }
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+ else if (left_ptr == right_ptr)
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+ {
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+ left_ptr += size;
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+ right_ptr -= size;
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+ break;
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+ }
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+ }
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+ while (left_ptr <= right_ptr);
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+
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+ /* Set up pointers for next iteration. First determine whether
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+ left and right partitions are below the threshold size. If so,
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+ ignore one or both. Otherwise, push the larger partition's
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+ bounds on the stack and continue sorting the smaller one. */
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+
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+ if ((grub_size_t) (right_ptr - lo) <= max_thresh)
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+ {
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+ if ((grub_size_t) (hi - left_ptr) <= max_thresh)
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+ /* Ignore both small partitions. */
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+ POP (lo, hi);
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+ else
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+ /* Ignore small left partition. */
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+ lo = left_ptr;
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+ }
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+ else if ((grub_size_t) (hi - left_ptr) <= max_thresh)
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+ /* Ignore small right partition. */
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+ hi = right_ptr;
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+ else if ((right_ptr - lo) > (hi - left_ptr))
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+ {
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+ /* Push larger left partition indices. */
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+ PUSH (lo, right_ptr);
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+ lo = left_ptr;
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+ }
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+ else
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+ {
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+ /* Push larger right partition indices. */
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+ PUSH (left_ptr, hi);
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+ hi = right_ptr;
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+ }
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+ }
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+ }
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+
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+ /* Once the BASE_PTR array is partially sorted by quicksort the rest
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+ is completely sorted using insertion sort, since this is efficient
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+ for partitions below MAX_THRESH size. BASE_PTR points to the beginning
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+ of the array to sort, and END_PTR points at the very last element in
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+ the array (*not* one beyond it!). */
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+
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+#define min(x, y) ((x) < (y) ? (x) : (y))
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+
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+ {
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+ char *const end_ptr = &base_ptr[size * (total_elems - 1)];
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+ char *tmp_ptr = base_ptr;
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+ char *thresh = min(end_ptr, base_ptr + max_thresh);
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+ char *run_ptr;
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+
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+ /* Find smallest element in first threshold and place it at the
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+ array's beginning. This is the smallest array element,
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+ and the operation speeds up insertion sort's inner loop. */
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+
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+ for (run_ptr = tmp_ptr + size; run_ptr <= thresh; run_ptr += size)
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+ if ((*cmp) ((void *) run_ptr, (void *) tmp_ptr, arg) < 0)
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+ tmp_ptr = run_ptr;
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+
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+ if (tmp_ptr != base_ptr)
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+ SWAP (tmp_ptr, base_ptr, size);
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+
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+ /* Insertion sort, running from left-hand-side up to right-hand-side. */
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+
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+ run_ptr = base_ptr + size;
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+ while ((run_ptr += size) <= end_ptr)
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+ {
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+ tmp_ptr = run_ptr - size;
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+ while ((*cmp) ((void *) run_ptr, (void *) tmp_ptr, arg) < 0)
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+ tmp_ptr -= size;
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+
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+ tmp_ptr += size;
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+ if (tmp_ptr != run_ptr)
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+ {
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+ char *trav;
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+
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+ trav = run_ptr + size;
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+ while (--trav >= run_ptr)
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+ {
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+ char c = *trav;
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+ char *hi, *lo;
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+
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+ for (hi = lo = trav; (lo -= size) >= tmp_ptr; hi = lo)
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+ *hi = *lo;
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+ *hi = c;
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+ }
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+ }
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+ }
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+ }
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+}
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+
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+void *
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+grub_bsearch (const void *key, const void *base, grub_size_t nmemb, grub_size_t size,
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+ grub_compar_d_fn_t compar, void *state)
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+{
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+ grub_size_t l, u, idx;
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+ const void *p;
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+ int comparison;
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+
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+ l = 0;
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+ u = nmemb;
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+ while (l < u)
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+ {
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+ idx = (l + u) / 2;
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+ p = (void *) (((const char *) base) + (idx * size));
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+ comparison = (*compar) (key, p, state);
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+ if (comparison < 0)
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+ u = idx;
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+ else if (comparison > 0)
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+ l = idx + 1;
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+ else
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+ return (void *) p;
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+ }
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+
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+ return NULL;
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+}
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diff --git a/include/grub/misc.h b/include/grub/misc.h
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index 4737da1eaa9..3d55bafd64e 100644
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--- a/include/grub/misc.h
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+++ b/include/grub/misc.h
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@@ -506,4 +506,19 @@ void EXPORT_FUNC(grub_real_boot_time) (const char *file,
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#define grub_max(a, b) (((a) > (b)) ? (a) : (b))
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#define grub_min(a, b) (((a) < (b)) ? (a) : (b))
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+typedef int (*grub_compar_d_fn_t) (const void *p0, const void *p1, void *state);
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+
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+void *EXPORT_FUNC(grub_bsearch) (const void *key,
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+ const void *base,
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+ grub_size_t nmemb,
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+ grub_size_t size,
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+ grub_compar_d_fn_t compar,
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+ void *state);
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+
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+void EXPORT_FUNC(grub_qsort) (void *const pbase,
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+ grub_size_t total_elems,
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+ grub_size_t size,
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+ grub_compar_d_fn_t cmp,
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+ void *state);
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+
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#endif /* ! GRUB_MISC_HEADER */
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--
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2.14.3
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