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implemented from scratch, an optimized variant of strcpy_s. Note that the intel fork also has it, with the same API. This adds a src termination check, when src is static.
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| Original file line number | Diff line number | Diff line change |
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| /*------------------------------------------------------------------ | ||
| * stpcpy_s.c | ||
| * | ||
| * November 2020, Reini Urban | ||
| * | ||
| * Copyright (c) 2020 by Reini Urban | ||
| * All rights reserved. | ||
| * | ||
| * Permission is hereby granted, free of charge, to any person | ||
| * obtaining a copy of this software and associated documentation | ||
| * files (the "Software"), to deal in the Software without | ||
| * restriction, including without limitation the rights to use, | ||
| * copy, modify, merge, publish, distribute, sublicense, and/or | ||
| * sell copies of the Software, and to permit persons to whom the | ||
| * Software is furnished to do so, subject to the following | ||
| * conditions: | ||
| * | ||
| * The above copyright notice and this permission notice shall be | ||
| * included in all copies or substantial portions of the Software. | ||
| * | ||
| * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, | ||
| * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES | ||
| * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND | ||
| * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT | ||
| * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, | ||
| * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING | ||
| * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR | ||
| * OTHER DEALINGS IN THE SOFTWARE. | ||
| *------------------------------------------------------------------ | ||
| */ | ||
|
|
||
| #ifdef FOR_DOXYGEN | ||
| #include "safe_str_lib.h" | ||
| #else | ||
| #include "safeclib_private.h" | ||
| #endif | ||
|
|
||
| /* TODO not via the naive byte copy, but aligned long word copy | ||
| via the (((X) - 0x0101010101010101) & ~(X) & 0x8080808080808080) | ||
| trick */ | ||
|
|
||
| /** | ||
| * @def stpcpy_s(dest,dmax,src,errp) | ||
| * @brief | ||
| * The stpcpy_s function copies the string pointed to by src | ||
| * (including the terminating null character) into the array | ||
| * pointed to by dest. The strings my not overlap. | ||
| * With SAFECLIB_STR_NULL_SLACK defined all elements following the | ||
| * terminating null character (if any) written by stpcpy_s in the | ||
| * array of dmax characters pointed to by dest are nulled when | ||
| * stpcpy_s returns. | ||
| * With modern compilers and constant arguments most errors | ||
| * will be caught at compile-time. | ||
| * | ||
| * @remark SPECIFIED IN | ||
| * * Since glibc 2.10: _POSIX_C_SOURCE >= 200809L | ||
| * * Before glibc 2.10: _GNU_SOURCE | ||
| * | ||
| * @param[out] dest pointer to string that will be replaced by src. | ||
| * @param[in] dmax restricted maximum length of dest | ||
| * @param[in] src pointer to the string that will be copied to dest | ||
| * @param[out] err EOK when successful operation, the characters in src were | ||
| * copied into dest and the result is null terminated. | ||
| * ESNULLP when dest or src is a NULL pointer | ||
| * ESZEROL when dmax = 0 | ||
| * ESLEMAX when dmax > RSIZE_MAX_STR | ||
| * EOVERFLOW when dmax > size of dest (optionally, when the compiler | ||
| * knows the object_size statically) | ||
| * ESLEWRNG when dmax != size of dest and --enable-error-dmax | ||
| * ESUNTERM when src is unterminated | ||
| * ESOVRLP when strings overlap | ||
| * ESNOSPC when dest < src | ||
| * | ||
| * @pre Neither dest, src nor err nor shall be a null pointer. | ||
| * @pre dmax shall be size of dest | ||
| * @pre dmax shall not be greater than RSIZE_MAX_STR or size of dest. | ||
| * @pre dmax shall not equal zero. | ||
| * @pre dmax shall be greater than strnlen_s(src, dmax). | ||
| * @pre Copying shall not take place between objects that overlap. | ||
| * | ||
| * @note C11 uses RSIZE_MAX, not RSIZE_MAX_STR. | ||
| * | ||
| * @return stpcpy_s() returns a pointer to the end of the string dest (that is, | ||
| * the address of the terminating null byte) rather than the beginning. | ||
| * @return If there is a runtime-constraint violation, and if dest | ||
| * and dmax are valid, then stpcpy_s nulls dest. | ||
| * | ||
| * @see | ||
| * stpncpy_s(), strcpy_s(), strncpy_s() | ||
| * | ||
| */ | ||
| #ifdef FOR_DOXYGEN | ||
| char *stpcpy_s(char *restrict dest, rsize_t dmax, const char *restrict src, | ||
| errno_t *restrict err) | ||
| #else | ||
| EXPORT char *_stpcpy_s_chk(char *restrict dest, rsize_t dmax, | ||
| const char *restrict src, errno_t *restrict err, | ||
| const size_t destbos, const size_t srcbos) | ||
| #endif | ||
| { | ||
| rsize_t orig_dmax = dmax; | ||
| char* orig_dest = dest; | ||
| const char *overlap_bumper; | ||
| size_t slen; | ||
|
|
||
| if (unlikely(err == NULL)) { | ||
| invoke_safe_str_constraint_handler("stpcpy_s: err is null", | ||
| (void *)dest, ESNULLP); | ||
| return NULL; | ||
| } | ||
| if (unlikely(dest == NULL)) { | ||
| invoke_safe_str_constraint_handler("stpcpy_s: dest is null", | ||
| (void *)dest, ESNULLP); | ||
| *err = RCNEGATE(ESNULLP); | ||
| return NULL; | ||
| } | ||
| if (unlikely(dmax == 0)) { | ||
| invoke_safe_str_constraint_handler("stpcpy_s: dmax is 0", (void *)dest, | ||
| ESNULLP); | ||
| *err = RCNEGATE(ESZEROL); | ||
| return NULL; | ||
| } | ||
| if (destbos == BOS_UNKNOWN) { | ||
| if (unlikely(dmax > RSIZE_MAX_STR)) { | ||
| invoke_safe_str_constraint_handler("stpcpy_s: dmax exceeds max", | ||
| (void *)dest, ESLEMAX); | ||
| *err = RCNEGATE(ESLEMAX); | ||
| return NULL; | ||
| } | ||
| BND_CHK_PTR_BOUNDS(dest, dmax); | ||
| } else { | ||
| if (unlikely(dmax > destbos)) { | ||
| if (dmax > RSIZE_MAX_STR) { | ||
| handle_error(dest, destbos, "stpcpy_s: dmax exceeds max", | ||
| ESLEMAX); | ||
| *err = RCNEGATE(ESLEMAX); | ||
| return NULL; | ||
| } else { | ||
| *err = handle_str_bos_overload("stpcpy_s: dmax exceeds dest", | ||
| (char *)dest, destbos); | ||
| return NULL; | ||
| } | ||
| } | ||
| } | ||
| if (unlikely(src == NULL)) { | ||
| handle_error(dest, _BOS_KNOWN(dest) ? BOS(dest) : dmax, | ||
| "strpcpy_s: src is null", ESNULLP); | ||
| *err = RCNEGATE(ESNULLP); | ||
| return NULL; | ||
| } | ||
| slen = 0; | ||
|
|
||
| if (unlikely(dest == src)) { | ||
| /* walk to the terminating null character */ | ||
| while (dmax > 0) { | ||
| if (*dest == '\0') { | ||
| goto eok; | ||
| } | ||
| dmax--; | ||
| dest++; | ||
| } | ||
| goto enospc; | ||
| } | ||
|
|
||
| if (dest < src) { | ||
| overlap_bumper = src; | ||
|
|
||
| while (dmax > 0) { | ||
| if (unlikely(dest == overlap_bumper)) { | ||
| handle_error(orig_dest, orig_dmax, | ||
| "stpcpy_s: " | ||
| "overlapping objects", | ||
| ESOVRLP); | ||
| *err = RCNEGATE(ESOVRLP); | ||
| return NULL; | ||
| } | ||
|
|
||
| *dest = *src; | ||
| if (*dest == '\0') | ||
| goto eok; | ||
| dmax--; | ||
| slen++; | ||
| dest++; | ||
| src++; | ||
| /* sentinel srcbos -1 = ULONG_MAX */ | ||
| if (unlikely(slen >= srcbos)) { | ||
| invoke_safe_str_constraint_handler("stpcpy_s: src unterminated", | ||
| (void *)src, ESUNTERM); | ||
| *err = RCNEGATE(ESUNTERM); | ||
| return NULL; | ||
| } | ||
| } | ||
| } else { | ||
| overlap_bumper = dest; | ||
|
|
||
| while (dmax > 0) { | ||
| if (unlikely(src == overlap_bumper)) { | ||
| handle_error(orig_dest, orig_dmax, | ||
| "stpcpy_s: " | ||
| "overlapping objects", | ||
| ESOVRLP); | ||
| *err = RCNEGATE(ESOVRLP); | ||
| return NULL; | ||
| } | ||
|
|
||
| *dest = *src; | ||
| if (*dest == '\0') { | ||
| eok: | ||
| #ifdef SAFECLIB_STR_NULL_SLACK | ||
| /* null slack to clear any data */ | ||
| if (dmax > 0x20) | ||
| memset(dest, 0, dmax); | ||
| else { | ||
| while (dmax) { | ||
| *dest = '\0'; | ||
| dmax--; | ||
| dest++; | ||
| } | ||
| } | ||
| #endif | ||
| *err = RCNEGATE(EOK); | ||
| return dest; | ||
| } | ||
|
|
||
| dmax--; | ||
| slen++; | ||
| dest++; | ||
| src++; | ||
| if (unlikely(slen >= srcbos)) { | ||
| invoke_safe_str_constraint_handler("stpcpy_s: src unterminated", | ||
| (void *)src, ESUNTERM); | ||
| *err = RCNEGATE(ESUNTERM); | ||
| return NULL; | ||
| } | ||
| } | ||
| } | ||
|
|
||
| enospc: | ||
| /* | ||
| * the entire src must have been copied, if not reset dest | ||
| * to null the string. (only with SAFECLIB_STR_NULL_SLACK) | ||
| */ | ||
| handle_error(orig_dest, orig_dmax, | ||
| "stpcpy_s: not enough space for src", | ||
| ESNOSPC); | ||
| *err = RCNEGATE(ESNOSPC); | ||
| return NULL; | ||
| } | ||
| #ifdef __KERNEL__ | ||
| EXPORT_SYMBOL(_stpcpy_s_chk); | ||
| #endif /* __KERNEL__ */ | ||
|
|
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