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23fe1083ca
Testing of a new feature revealed that calling sysctl() to retrieve the value of the user.localbase variable passing too low a buffer size could leave the result buffer unchanged. The behavior in the normal case of a sufficiently large buffer was correct. All known callers pass a sufficiently large buffer and have thus not been affected by this issue. If a non-default value had been assigned to this variable, the result was as documented, too. Fix the function to fill the buffer with a partial result, if the passed in buffer size is too low to hold the full result. (cherry picked from commite11ad014d1) libc: add helper furnction to set sysctl() user.* variables Testing had revealed that trying to retrieve the user.localbase variable into to small a buffer would return the correct error code, but would not fill the available buffer space with a partial result. A partial result is of no use, but this is still a violation of the documented behavior, which has been fixed in the previous commit to this function. I just checked the code for "user.cs_path" and found that it had the same issue. Instead of fixing the logic for each user.* sysctl string variable individually, this commit adds a helper function set_user_str() that implements the semantics specified in the sysctl() man page. It is currently only used for "user.cs_path" and "user.localbase", but it will offer a significant simplification when further such variables will be added (as I intend to do). (cherry picked from commit9535d9f104) sysctlbyname(): restore access to user variables The optimization of sysctlbyname() in commitd05b53e0bahad the side-effect of not going through the fix-up for the user.* variables in the previously called sysctl() function. This lead to 0 or an empty strings being returned by sysctlbyname() for all user.* variables. An alternate implementation would store the user variables in the kernel during system start-up. That would allow to remove the fix-up code in the C library that is currently required to provide the actual values. This update restores the previous code path for the user.* variables and keeps the performance optimization intact for all other variables. (cherry picked from commitaf7d105379)
57 lines
2 KiB
C
57 lines
2 KiB
C
/*-
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* SPDX-License-Identifier: BSD-2-Clause
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*
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* Copyright 2019 Pawel Biernacki, Mysterious Code Ltd.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND ANY
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* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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* DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE FOR
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* ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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#include <sys/param.h>
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#include <sys/sysctl.h>
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#include <string.h>
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extern int __sysctlbyname(const char *name, size_t namelen, void *oldp,
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size_t *oldlenp, const void *newp, size_t newlen);
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int
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sysctlbyname(const char *name, void *oldp, size_t *oldlenp,
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const void *newp, size_t newlen)
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{
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size_t len;
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int oid[2];
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if (__predict_true(strncmp(name, "user.", 5) != 0)) {
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len = strlen(name);
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return (__sysctlbyname(name, len, oldp, oldlenp, newp,
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newlen));
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} else {
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len = nitems(oid);
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if (sysctlnametomib(name, oid, &len) == -1)
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return (-1);
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return (sysctl(oid, (u_int)len, oldp, oldlenp, newp,
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newlen));
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}
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}
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