libufdt: device tree overlay via unflattening FDT

The original version of libdtoverlay is slow in searching for
particular nodes and adding subnodes/properties due to the operations
on flattened device tree (FDT).

`libufdt` builds a real tree structure (named ufdt -- unflattned
device tree) from FDT. In the real tree, we can perform certain
operations (e.g., merge 2 subtrees, search for a node by path) in
almost optimal time complexity with acceptable additional memory usage.

With libufdt, we improve the merging of two dtb files from O(N^2) to
O(N), where N is the number of nodes in the tree.

Bug: 30800619
Test: run test scripts (see libufdt/tests/README)
Test: manually ported libufdt into a bootloader,
      checked it can merge a base dtb and a dtbo to generate a final dtb
      to boot the device
Change-Id: I6a282cc99129d5280ecbf40852723f83735fa523

1 files changed, 209 insertions, 0 deletions

diff --git a/sysdeps/libufdt_sysdeps_vendor.c b/sysdeps/libufdt_sysdeps_vendor.c
new file mode 100644
index 0000000..e21a2e1
--- /dev/null
+++ b/sysdeps/libufdt_sysdeps_vendor.c
@@ -0,0 +1,209 @@
+#include "libufdt_sysdeps.h"
+
+#include <debug.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/types.h>
+
+int dto_print(const char *fmt, ...) {
+  int err;
+
+  va_list ap;
+  va_start(ap, fmt);
+  err = _dvprintf(fmt, ap);
+  va_end(ap);
+
+  return err;
+}
+
+/* Codes from
+ * https://android.googlesource.com/platform/bionic.git/+/eclair-release/libc/stdlib/qsort.c
+ * Start
+ */
+
+/* $OpenBSD: qsort.c,v 1.10 2005/08/08 08:05:37 espie Exp $ */
+/*-
+ * Copyright (c) 1992, 1993
+ * The Regents of the University of California.  All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of the University nor the names of its contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+static __inline char *med3(char *, char *, char *,
+                           int (*)(const void *, const void *));
+static __inline void swapfunc(char *, char *, int, int);
+#define min(a, b) (a) < (b) ? a : b
+
+/*
+ * Qsort routine from Bentley & McIlroy's "Engineering a Sort Function".
+ */
+#define swapcode(TYPE, parmi, parmj, n) \
+  {                                     \
+    long i = (n) / sizeof(TYPE);        \
+    TYPE *pi = (TYPE *)(parmi);         \
+    TYPE *pj = (TYPE *)(parmj);         \
+    do {                                \
+      TYPE t = *pi;                     \
+      *pi++ = *pj;                      \
+      *pj++ = t;                        \
+    } while (--i > 0);                  \
+  }
+#define SWAPINIT(a, es)                                                  \
+  swaptype = ((char *)a - (char *)0) % sizeof(long) || es % sizeof(long) \
+                 ? 2                                                     \
+                 : es == sizeof(long) ? 0 : 1;
+
+static __inline void swapfunc(char *a, char *b, int n, int swaptype) {
+  if (swaptype <= 1) swapcode(long, a, b, n) else swapcode(char, a, b, n)
+}
+
+#define swap(a, b)               \
+  if (swaptype == 0) {           \
+    long t = *(long *)(a);       \
+    *(long *)(a) = *(long *)(b); \
+    *(long *)(b) = t;            \
+  } else                         \
+    swapfunc(a, b, es, swaptype)
+#define vecswap(a, b, n) \
+  if ((n) > 0) swapfunc(a, b, n, swaptype)
+
+static __inline char *med3(char *a, char *b, char *c,
+                           int (*cmp)(const void *, const void *)) {
+  return cmp(a, b) < 0 ? (cmp(b, c) < 0 ? b : (cmp(a, c) < 0 ? c : a))
+                       : (cmp(b, c) > 0 ? b : (cmp(a, c) < 0 ? a : c));
+}
+
+void qsort(void *aa, size_t n, size_t es,
+           int (*cmp)(const void *, const void *)) {
+  char *pa, *pb, *pc, *pd, *pl, *pm, *pn;
+  int d, r, swaptype, swap_cnt;
+  char *a = aa;
+loop:
+  SWAPINIT(a, es);
+  swap_cnt = 0;
+  if (n < 7) {
+    for (pm = (char *)a + es; pm < (char *)a + n * es; pm += es)
+      for (pl = pm; pl > (char *)a && cmp(pl - es, pl) > 0; pl -= es)
+        swap(pl, pl - es);
+    return;
+  }
+  pm = (char *)a + (n / 2) * es;
+  if (n > 7) {
+    pl = (char *)a;
+    pn = (char *)a + (n - 1) * es;
+    if (n > 40) {
+      d = (n / 8) * es;
+      pl = med3(pl, pl + d, pl + 2 * d, cmp);
+      pm = med3(pm - d, pm, pm + d, cmp);
+      pn = med3(pn - 2 * d, pn - d, pn, cmp);
+    }
+    pm = med3(pl, pm, pn, cmp);
+  }
+  swap(a, pm);
+  pa = pb = (char *)a + es;
+
+  pc = pd = (char *)a + (n - 1) * es;
+  for (;;) {
+    while (pb <= pc && (r = cmp(pb, a)) <= 0) {
+      if (r == 0) {
+        swap_cnt = 1;
+        swap(pa, pb);
+        pa += es;
+      }
+      pb += es;
+    }
+    while (pb <= pc && (r = cmp(pc, a)) >= 0) {
+      if (r == 0) {
+        swap_cnt = 1;
+        swap(pc, pd);
+        pd -= es;
+      }
+      pc -= es;
+    }
+    if (pb > pc) break;
+    swap(pb, pc);
+    swap_cnt = 1;
+    pb += es;
+    pc -= es;
+  }
+  if (swap_cnt == 0) { /* Switch to insertion sort */
+    for (pm = (char *)a + es; pm < (char *)a + n * es; pm += es)
+      for (pl = pm; pl > (char *)a && cmp(pl - es, pl) > 0; pl -= es)
+        swap(pl, pl - es);
+    return;
+  }
+  pn = (char *)a + n * es;
+  r = min(pa - (char *)a, pb - pa);
+  vecswap(a, pb - r, r);
+  r = min(pd - pc, pn - pd - (int)es);
+  vecswap(pb, pn - r, r);
+  if ((r = pb - pa) > (int)es) qsort(a, r / es, es, cmp);
+  if ((r = pd - pc) > (int)es) {
+    /* Iterate rather than recurse to save stack space */
+    a = pn - r;
+    n = r / es;
+    goto loop;
+  }
+  /* qsort(pn - r, r / es, es, cmp); */
+}
+
+/* End of the copied qsort. */
+
+void dto_qsort(void *base, size_t nmemb, size_t size,
+               int (*compar)(const void *, const void *)) {
+  qsort(base, nmemb, size, compar);
+}
+
+/* Assuming the following functions are already defined in the
+ * bootloader source with the names conforming to POSIX.
+ */
+
+void *dto_malloc(size_t size) { return malloc(size); }
+
+void dto_free(void *ptr) { free(ptr); }
+
+char *dto_strdup(const char *s) { return strdup(s); }
+
+char *dto_strchr(const char *s, int c) { return strchr(s, c); }
+
+unsigned long int dto_strtoul(const char *nptr, char **endptr, int base) {
+  return strtoul(nptr, endptr, base);
+}
+
+size_t dto_strlen(const char *s) { return strlen(s); }
+
+void *dto_memcpy(void *dest, const void *src, size_t n) {
+  return memcpy(dest, src, n);
+}
+
+int dto_strcmp(const char *s1, const char *s2) { return strcmp(s1, s2); }
+
+int dto_strncmp(const char *s1, const char *s2, size_t n) {
+  return strncmp(s1, s2, n);
+}
+
+void *dto_memchr(const void *s, int c, size_t n) { return memchr(s, c, n); }
+
+void *dto_memset(void *s, int c, size_t n) { return memset(s, c, n); }