1 /* vsprintf with automatic memory allocation in C locale. 2 Copyright (C) 2002-2004, 2007-2021 Free Software Foundation, Inc. 3 4 This program is free software; you can redistribute it and/or modify 5 it under the terms of the GNU General Public License as published by 6 the Free Software Foundation; either version 3, or (at your option) 7 any later version. 8 9 This program is distributed in the hope that it will be useful, 10 but WITHOUT ANY WARRANTY; without even the implied warranty of 11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 12 GNU General Public License for more details. 13 14 You should have received a copy of the GNU General Public License along 15 with this program; if not, see <https://www.gnu.org/licenses/>. */ 16 17 #ifndef _C_VASNPRINTF_H 18 #define _C_VASNPRINTF_H 19 20 /* Get va_list. */ 21 #include <stdarg.h> 22 23 /* Get size_t. */ 24 #include <stddef.h> 25 26 /* Get _GL_ATTRIBUTE_SPEC_PRINTF_STANDARD. */ 27 #include <stdio.h> 28 29 #ifdef __cplusplus 30 extern "C" { 31 #endif 32 33 /* Write formatted output to a string dynamically allocated with malloc(). 34 You can pass a preallocated buffer for the result in RESULTBUF and its 35 size in *LENGTHP; otherwise you pass RESULTBUF = NULL. 36 If successful, return the address of the string (this may be = RESULTBUF 37 if no dynamic memory allocation was necessary) and set *LENGTHP to the 38 number of resulting bytes, excluding the trailing NUL. Upon error, set 39 errno and return NULL. 40 41 When dynamic memory allocation occurs, the preallocated buffer is left 42 alone (with possibly modified contents). This makes it possible to use 43 a statically allocated or stack-allocated buffer, like this: 44 45 char buf[100]; 46 size_t len = sizeof (buf); 47 char *output = vasnprintf (buf, &len, format, args); 48 if (output == NULL) 49 ... error handling ...; 50 else 51 { 52 ... use the output string ...; 53 if (output != buf) 54 free (output); 55 } 56 57 Formatting takes place in the C locale, that is, the decimal point used in 58 floating-point formatting directives is always '.'. 59 */ 60 extern char *c_vasnprintf (char *restrict resultbuf, size_t *lengthp, 61 const char *format, va_list args) 62 _GL_ATTRIBUTE_FORMAT ((_GL_ATTRIBUTE_SPEC_PRINTF_STANDARD, 3, 0)); 63 64 #ifdef __cplusplus 65 } 66 #endif 67 68 #endif /* _C_VASNPRINTF_H */