| | 1 | /* |
| | 2 | * Copyright (c) 2018 Apple Inc. All rights reserved. |
| | 3 | * |
| | 4 | * @APPLE_LICENSE_HEADER_START@ |
| | 5 | * |
| | 6 | * This file contains Original Code and/or Modifications of Original Code |
| | 7 | * as defined in and that are subject to the Apple Public Source License |
| | 8 | * Version 2.0 (the 'License'). You may not use this file except in |
| | 9 | * compliance with the License. Please obtain a copy of the License at |
| | 10 | * http://www.opensource.apple.com/apsl/ and read it before using this |
| | 11 | * file. |
| | 12 | * |
| | 13 | * The Original Code and all software distributed under the License are |
| | 14 | * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER |
| | 15 | * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES, |
| | 16 | * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY, |
| | 17 | * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT. |
| | 18 | * Please see the License for the specific language governing rights and |
| | 19 | * limitations under the License. |
| | 20 | * |
| | 21 | * @APPLE_LICENSE_HEADER_END@ |
| | 22 | */ |
| | 23 | |
| | 24 | /*! |
| | 25 | * @header |
| | 26 | * Non-standard, Darwin-specific additions for the stdio(3) family of APIs. |
| | 27 | */ |
| | 28 | #ifndef __DARWIN_STDIO_H |
| | 29 | #define __DARWIN_STDIO_H |
| | 30 | |
| | 31 | #include <os/base.h> |
| | 32 | #include <os/api.h> |
| | 33 | #include <sys/cdefs.h> |
| | 34 | |
| | 35 | __BEGIN_DECLS; |
| | 36 | |
| | 37 | /*! |
| | 38 | * @function zsnprintf_np |
| | 39 | * snprintf(3) variant which returns the numnber of bytes written less the null |
| | 40 | * terminator. |
| | 41 | * |
| | 42 | * @param buff |
| | 43 | * The buffer in which to write the string. |
| | 44 | * |
| | 45 | * @param len |
| | 46 | * The length of the buffer. |
| | 47 | * |
| | 48 | * @param fmt |
| | 49 | * The printf(3)-like format string. |
| | 50 | * |
| | 51 | * @param ... |
| | 52 | * The arguments corresponding to the format string. |
| | 53 | * |
| | 54 | * @result |
| | 55 | * The number of bytes written into the buffer, less the null terminator. This |
| | 56 | * routine is useful for successive string printing that may be lossy, as it |
| | 57 | * will simply return zero when there is no space left in the destination |
| | 58 | * buffer, i.e. enables the following pattern: |
| | 59 | * |
| | 60 | * char *cur = buff; |
| | 61 | * size_t left = sizeof(buff); |
| | 62 | * for (i = 0; i < n_strings; i++) { |
| | 63 | * size_t n_written = zsnprintf_np(buff, left, "%s", strings[i]); |
| | 64 | * cur += n_written; |
| | 65 | * left -= n_written; |
| | 66 | * } |
| | 67 | * |
| | 68 | * This loop will safely terminate without any special care since, as soon as |
| | 69 | * the buffer's space is exhausted, all further calls to zsnprintf_np() will |
| | 70 | * write nothing and return zero. |
| | 71 | */ |
| | 72 | DARWIN_API_AVAILABLE_20170407 |
| | 73 | OS_EXPORT OS_WARN_RESULT OS_NONNULL1 OS_NONNULL3 OS_FORMAT_PRINTF(3, 4) |
| | 74 | size_t |
| | 75 | zsnprintf_np(char *buff, size_t len, const char *fmt, ...); |
| | 76 | |
| | 77 | __END_DECLS; |
| | 78 | |
| | 79 | #endif // __DARWIN_STDIO_H |
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