mirror of https://gerrit.osmocom.org/asn1c
296 lines
7.4 KiB
C
296 lines
7.4 KiB
C
/*
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* Copyright (c) 2005-2017 Lev Walkin <vlm@lionet.info>. All rights reserved.
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* Redistribution and modifications are permitted subject to BSD license.
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*/
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#include <asn_system.h>
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#include <asn_internal.h>
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#include <per_support.h>
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/*
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* X.691-201508 #10.9 General rules for encoding a length determinant.
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* Get the optionally constrained length "n" from the stream.
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*/
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ssize_t
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uper_get_length(asn_per_data_t *pd, int ebits, size_t lower_bound,
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int *repeat) {
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ssize_t value;
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*repeat = 0;
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/* #11.9.4.1 Encoding if constrained (according to effective bits) */
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if(ebits >= 0 && ebits <= 16) {
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value = per_get_few_bits(pd, ebits);
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if(value >= 0) value += lower_bound;
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return value;
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}
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value = per_get_few_bits(pd, 8);
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if((value & 0x80) == 0) { /* #11.9.3.6 */
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return (value & 0x7F);
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} else if((value & 0x40) == 0) { /* #11.9.3.7 */
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/* bit 8 ... set to 1 and bit 7 ... set to zero */
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value = ((value & 0x3f) << 8) | per_get_few_bits(pd, 8);
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return value; /* potential -1 from per_get_few_bits passes through. */
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} else if(value < 0) {
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ASN_DEBUG("END of stream reached for PER");
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return -1;
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}
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value &= 0x3f; /* this is "m" from X.691, #11.9.3.8 */
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if(value < 1 || value > 4) {
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return -1; /* Prohibited by #11.9.3.8 */
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}
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*repeat = 1;
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return (16384 * value);
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}
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/*
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* Get the normally small length "n".
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* This procedure used to decode length of extensions bit-maps
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* for SET and SEQUENCE types.
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*/
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ssize_t
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uper_get_nslength(asn_per_data_t *pd) {
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ssize_t length;
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ASN_DEBUG("Getting normally small length");
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if(per_get_few_bits(pd, 1) == 0) {
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length = per_get_few_bits(pd, 6) + 1;
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if(length <= 0) return -1;
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ASN_DEBUG("l=%d", (int)length);
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return length;
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} else {
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int repeat;
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length = uper_get_length(pd, -1, 0, &repeat);
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if(length >= 0 && !repeat) return length;
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return -1; /* Error, or do not support >16K extensions */
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}
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}
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/*
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* Get the normally small non-negative whole number.
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* X.691, #10.6
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*/
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ssize_t
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uper_get_nsnnwn(asn_per_data_t *pd) {
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ssize_t value;
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value = per_get_few_bits(pd, 7);
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if(value & 64) { /* implicit (value < 0) */
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value &= 63;
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value <<= 2;
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value |= per_get_few_bits(pd, 2);
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if(value & 128) /* implicit (value < 0) */
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return -1;
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if(value == 0)
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return 0;
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if(value >= 3)
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return -1;
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value = per_get_few_bits(pd, 8 * value);
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return value;
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}
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return value;
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}
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/*
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* X.691-11/2008, #11.6
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* Encoding of a normally small non-negative whole number
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*/
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int
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uper_put_nsnnwn(asn_per_outp_t *po, int n) {
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int bytes;
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if(n <= 63) {
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if(n < 0) return -1;
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return per_put_few_bits(po, n, 7);
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}
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if(n < 256)
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bytes = 1;
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else if(n < 65536)
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bytes = 2;
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else if(n < 256 * 65536)
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bytes = 3;
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else
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return -1; /* This is not a "normally small" value */
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if(per_put_few_bits(po, bytes, 8))
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return -1;
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return per_put_few_bits(po, n, 8 * bytes);
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}
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/* X.691-2008/11, #11.5.6 -> #11.3 */
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int uper_get_constrained_whole_number(asn_per_data_t *pd, unsigned long *out_value, int nbits) {
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unsigned long lhalf; /* Lower half of the number*/
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long half;
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if(nbits <= 31) {
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half = per_get_few_bits(pd, nbits);
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if(half < 0) return -1;
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*out_value = half;
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return 0;
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}
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if((size_t)nbits > 8 * sizeof(*out_value))
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return -1; /* RANGE */
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half = per_get_few_bits(pd, 31);
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if(half < 0) return -1;
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if(uper_get_constrained_whole_number(pd, &lhalf, nbits - 31))
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return -1;
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*out_value = ((unsigned long)half << (nbits - 31)) | lhalf;
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return 0;
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}
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/* X.691-2008/11, #11.5.6 -> #11.3 */
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int
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uper_put_constrained_whole_number_u(asn_per_outp_t *po, unsigned long v,
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int nbits) {
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if(nbits <= 31) {
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return per_put_few_bits(po, v, nbits);
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} else {
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/* Put higher portion first, followed by lower 31-bit */
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if(uper_put_constrained_whole_number_u(po, v >> 31, nbits - 31))
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return -1;
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return per_put_few_bits(po, v, 31);
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}
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}
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/*
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* X.691 (08/2015) #11.9 "General rules for encoding a length determinant"
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* Put the length "n" (or part of it) into the stream.
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*/
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ssize_t
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uper_put_length(asn_per_outp_t *po, size_t length, int *need_eom) {
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int dummy = 0;
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if(!need_eom) need_eom = &dummy;
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if(length <= 127) { /* #11.9.3.6 */
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*need_eom = 0;
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return per_put_few_bits(po, length, 8)
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? -1 : (ssize_t)length;
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} else if(length < 16384) { /* #10.9.3.7 */
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*need_eom = 0;
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return per_put_few_bits(po, length|0x8000, 16)
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? -1 : (ssize_t)length;
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}
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*need_eom = 0 == (length & 16383);
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length >>= 14;
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if(length > 4) {
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*need_eom = 0;
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length = 4;
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}
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return per_put_few_bits(po, 0xC0 | length, 8)
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? -1 : (ssize_t)(length << 14);
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}
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/*
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* Put the normally small length "n" into the stream.
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* This procedure used to encode length of extensions bit-maps
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* for SET and SEQUENCE types.
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*/
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int
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uper_put_nslength(asn_per_outp_t *po, size_t length) {
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if(length <= 64) {
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/* #11.9.3.4 */
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if(length == 0) return -1;
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return per_put_few_bits(po, length - 1, 7) ? -1 : 0;
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} else {
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int need_eom = 0;
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if(uper_put_length(po, length, &need_eom) != (ssize_t)length
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|| need_eom) {
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/* This might happen in case of >16K extensions */
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return -1;
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}
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}
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return 0;
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}
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static int
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per__long_range(long lb, long ub, unsigned long *range_r) {
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unsigned long bounds_range;
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if((ub < 0) == (lb < 0)) {
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bounds_range = ub - lb;
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} else if(lb < 0) {
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assert(ub >= 0);
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bounds_range = 1 + ((unsigned long)ub + (unsigned long)-(lb + 1));
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} else {
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assert(!"Unreachable");
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return -1;
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}
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*range_r = bounds_range;
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return 0;
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}
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int
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per_long_range_rebase(long v, long lb, long ub, unsigned long *output) {
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unsigned long range;
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assert(lb <= ub);
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if(v < lb || v > ub || per__long_range(lb, ub, &range) < 0) {
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/* Range error. */
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return -1;
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}
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/*
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* Fundamentally what we're doing is returning (v-lb).
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* However, this triggers undefined behavior when the word width
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* of signed (v) is the same as the size of unsigned (*output).
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* In practice, it triggers the UndefinedSanitizer. Therefore we shall
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* compute the ranges accurately to avoid C's undefined behavior.
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*/
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if((v < 0) == (lb < 0)) {
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*output = v-lb;
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return 0;
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} else if(v < 0) {
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unsigned long rebased = 1 + (unsigned long)-(v+1) + (unsigned long)lb;
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assert(rebased <= range); /* By construction */
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*output = rebased;
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return 0;
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} else if(lb < 0) {
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unsigned long rebased = 1 + (unsigned long)-(lb+1) + (unsigned long)v;
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assert(rebased <= range); /* By construction */
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*output = rebased;
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return 0;
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} else {
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assert(!"Unreachable");
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return -1;
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}
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}
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int
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per_long_range_unrebase(unsigned long inp, long lb, long ub, long *outp) {
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unsigned long range;
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if(per__long_range(lb, ub, &range) != 0) {
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return -1;
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}
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if(inp > range) {
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/*
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* We can encode something in the given number of bits that technically
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* exceeds the range. This is an avenue for security errors,
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* so we don't allow that.
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*/
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return -1;
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}
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if(inp <= LONG_MAX) {
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*outp = (long)inp + lb;
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} else {
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*outp = (lb + LONG_MAX + 1) + (long)((inp - LONG_MAX) - 1);
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}
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return 0;
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}
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