projects / apple / libc.git / blame
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|---|---|---|
| 70ad1dc8 A |
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 |