| 1 | /* Copyright (C) 2008-2022 Free Software Foundation, Inc. |
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| 2 | This file is part of the GNU C Library. |
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| 3 | |
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| 4 | The GNU C Library is free software; you can redistribute it and/or |
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| 5 | modify it under the terms of the GNU Lesser General Public |
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| 6 | License as published by the Free Software Foundation; either |
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| 7 | version 2.1 of the License, or (at your option) any later version. |
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| 8 | |
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| 9 | The GNU C Library is distributed in the hope that it will be useful, |
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| 10 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
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| 11 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
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| 12 | Lesser General Public License for more details. |
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| 13 | |
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| 14 | You should have received a copy of the GNU Lesser General Public |
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| 15 | License along with the GNU C Library; if not, see |
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| 16 | <https://www.gnu.org/licenses/>. */ |
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| 17 | |
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| 18 | #include <errno.h> |
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| 19 | #include <sys/times.h> |
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| 20 | #include <sysdep.h> |
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| 21 | |
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| 22 | |
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| 23 | clock_t |
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| 24 | __times (struct tms *buf) |
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| 25 | { |
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| 26 | clock_t ret = INTERNAL_SYSCALL_CALL (times, buf); |
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| 27 | if (INTERNAL_SYSCALL_ERROR_P (ret) |
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| 28 | && __glibc_unlikely (INTERNAL_SYSCALL_ERRNO (ret) == EFAULT) |
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| 29 | && buf) |
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| 30 | { |
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| 31 | /* This might be an error or not. For architectures which have no |
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| 32 | separate return value and error indicators we cannot |
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| 33 | distinguish a return value of e.g. (clock_t) -14 from -EFAULT. |
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| 34 | Therefore the only course of action is to dereference the user |
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| 35 | -supplied structure on a return of (clock_t) -14. This will crash |
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| 36 | applications which pass in an invalid non-NULL BUF pointer. |
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| 37 | Note that Linux allows BUF to be NULL in which case we skip this. */ |
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| 38 | #define touch(v) \ |
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| 39 | do { \ |
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| 40 | clock_t temp = v; \ |
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| 41 | asm volatile ("" : "+r" (temp)); \ |
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| 42 | v = temp; \ |
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| 43 | } while (0) |
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| 44 | touch (buf->tms_utime); |
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| 45 | touch (buf->tms_stime); |
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| 46 | touch (buf->tms_cutime); |
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| 47 | touch (buf->tms_cstime); |
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| 48 | |
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| 49 | /* If we come here the memory is valid and the kernel did not |
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| 50 | return an EFAULT error, but rather e.g. (clock_t) -14. |
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| 51 | Return the value given by the kernel. */ |
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| 52 | } |
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| 53 | |
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| 54 | /* On Linux this function never fails except with EFAULT. |
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| 55 | POSIX says that returning a value (clock_t) -1 indicates an error, |
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| 56 | but on Linux this is simply one of the valid clock values after |
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| 57 | clock_t wraps. Therefore when we would return (clock_t) -1, we |
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| 58 | instead return (clock_t) 0, and loose a tick of accuracy (having |
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| 59 | returned 0 for two consecutive calls even though the clock |
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| 60 | advanced). */ |
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| 61 | if (ret == (clock_t) -1) |
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| 62 | return (clock_t) 0; |
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| 63 | |
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| 64 | return ret; |
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| 65 | } |
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| 66 | weak_alias (__times, times) |
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| 67 | |
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