diff options
Diffstat (limited to 'crypto/openssh/bitmap.c')
| -rw-r--r-- | crypto/openssh/bitmap.c | 212 |
1 files changed, 212 insertions, 0 deletions
diff --git a/crypto/openssh/bitmap.c b/crypto/openssh/bitmap.c new file mode 100644 index 0000000..f950322 --- /dev/null +++ b/crypto/openssh/bitmap.c @@ -0,0 +1,212 @@ +/* + * Copyright (c) 2015 Damien Miller <djm@mindrot.org> + * + * Permission to use, copy, modify, and distribute this software for any + * purpose with or without fee is hereby granted, provided that the above + * copyright notice and this permission notice appear in all copies. + * + * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES + * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF + * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR + * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES + * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN + * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF + * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. + */ + +#include "includes.h" + +#include <sys/types.h> +#include <string.h> +#include <stdlib.h> + +#include "bitmap.h" + +#define BITMAP_WTYPE u_int +#define BITMAP_MAX (1<<24) +#define BITMAP_BYTES (sizeof(BITMAP_WTYPE)) +#define BITMAP_BITS (sizeof(BITMAP_WTYPE) * 8) +#define BITMAP_WMASK ((BITMAP_WTYPE)BITMAP_BITS - 1) +struct bitmap { + BITMAP_WTYPE *d; + size_t len; /* number of words allocated */ + size_t top; /* index of top word allocated */ +}; + +struct bitmap * +bitmap_new(void) +{ + struct bitmap *ret; + + if ((ret = calloc(1, sizeof(*ret))) == NULL) + return NULL; + if ((ret->d = calloc(1, BITMAP_BYTES)) == NULL) { + free(ret); + return NULL; + } + ret->len = 1; + ret->top = 0; + return ret; +} + +void +bitmap_free(struct bitmap *b) +{ + if (b != NULL && b->d != NULL) { + explicit_bzero(b->d, b->len); + free(b->d); + } + free(b); +} + +void +bitmap_zero(struct bitmap *b) +{ + memset(b->d, 0, b->len * BITMAP_BYTES); + b->top = 0; +} + +int +bitmap_test_bit(struct bitmap *b, u_int n) +{ + if (b->top >= b->len) + return 0; /* invalid */ + if (b->len == 0 || (n / BITMAP_BITS) > b->top) + return 0; + return (b->d[n / BITMAP_BITS] >> (n & BITMAP_WMASK)) & 1; +} + +static int +reserve(struct bitmap *b, u_int n) +{ + BITMAP_WTYPE *tmp; + size_t nlen; + + if (b->top >= b->len || n > BITMAP_MAX) + return -1; /* invalid */ + nlen = (n / BITMAP_BITS) + 1; + if (b->len < nlen) { + if ((tmp = reallocarray(b->d, nlen, BITMAP_BYTES)) == NULL) + return -1; + b->d = tmp; + memset(b->d + b->len, 0, (nlen - b->len) * BITMAP_BYTES); + b->len = nlen; + } + return 0; +} + +int +bitmap_set_bit(struct bitmap *b, u_int n) +{ + int r; + size_t offset; + + if ((r = reserve(b, n)) != 0) + return r; + offset = n / BITMAP_BITS; + if (offset > b->top) + b->top = offset; + b->d[offset] |= (BITMAP_WTYPE)1 << (n & BITMAP_WMASK); + return 0; +} + +/* Resets b->top to point to the most significant bit set in b->d */ +static void +retop(struct bitmap *b) +{ + if (b->top >= b->len) + return; + while (b->top > 0 && b->d[b->top] == 0) + b->top--; +} + +void +bitmap_clear_bit(struct bitmap *b, u_int n) +{ + size_t offset; + + if (b->top >= b->len || n > BITMAP_MAX) + return; /* invalid */ + offset = n / BITMAP_BITS; + if (offset > b->top) + return; + b->d[offset] &= ~((BITMAP_WTYPE)1 << (n & BITMAP_WMASK)); + /* The top may have changed as a result of the clear */ + retop(b); +} + +size_t +bitmap_nbits(struct bitmap *b) +{ + size_t bits; + BITMAP_WTYPE w; + + retop(b); + if (b->top >= b->len) + return 0; /* invalid */ + if (b->len == 0 || (b->top == 0 && b->d[0] == 0)) + return 0; + /* Find MSB set */ + w = b->d[b->top]; + bits = (b->top + 1) * BITMAP_BITS; + while (!(w & ((BITMAP_WTYPE)1 << (BITMAP_BITS - 1)))) { + w <<= 1; + bits--; + } + return bits; +} + +size_t +bitmap_nbytes(struct bitmap *b) +{ + return (bitmap_nbits(b) + 7) / 8; +} + +int +bitmap_to_string(struct bitmap *b, void *p, size_t l) +{ + u_char *s = (u_char *)p; + size_t i, j, k, need = bitmap_nbytes(b); + + if (l < need || b->top >= b->len) + return -1; + if (l > need) + l = need; + /* Put the bytes from LSB backwards */ + for (i = k = 0; i < b->top + 1; i++) { + for (j = 0; j < BITMAP_BYTES; j++) { + if (k >= l) + break; + s[need - 1 - k++] = (b->d[i] >> (j * 8)) & 0xff; + } + } + return 0; +} + +int +bitmap_from_string(struct bitmap *b, const void *p, size_t l) +{ + int r; + size_t i, offset, shift; + u_char *s = (u_char *)p; + + if (l > BITMAP_MAX / 8) + return -1; + if ((r = reserve(b, l * 8)) != 0) + return r; + bitmap_zero(b); + if (l == 0) + return 0; + b->top = offset = ((l + (BITMAP_BYTES - 1)) / BITMAP_BYTES) - 1; + shift = ((l + (BITMAP_BYTES - 1)) % BITMAP_BYTES) * 8; + for (i = 0; i < l; i++) { + b->d[offset] |= (BITMAP_WTYPE)s[i] << shift; + if (shift == 0) { + offset--; + shift = BITMAP_BITS - 8; + } else + shift -= 8; + } + retop(b); + return 0; +} |
