1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * linux/lib/kasprintf.c 4 * 5 * Copyright (C) 1991, 1992 Linus Torvalds 6 */ 7 8 #include <stdarg.h> 9 #include <linux/export.h> 10 #include <linux/slab.h> 11 #include <linux/types.h> 12 #include <linux/string.h> 13 14 /* Simplified asprintf. */ 15 char *kvasprintf(gfp_t gfp, const char *fmt, va_list ap) 16 { 17 unsigned int first, second; 18 char *p; 19 va_list aq; 20 21 va_copy(aq, ap); 22 first = vsnprintf(NULL, 0, fmt, aq); 23 va_end(aq); 24 25 p = kmalloc_track_caller(first+1, gfp); 26 if (!p) 27 return NULL; 28 29 second = vsnprintf(p, first+1, fmt, ap); 30 WARN(first != second, "different return values (%u and %u) from vsnprintf(\"%s\", ...)", 31 first, second, fmt); 32 33 return p; 34 } 35 EXPORT_SYMBOL(kvasprintf); 36 37 /* 38 * If fmt contains no % (or is exactly %s), use kstrdup_const. If fmt 39 * (or the sole vararg) points to rodata, we will then save a memory 40 * allocation and string copy. In any case, the return value should be 41 * freed using kfree_const(). 42 */ 43 const char *kvasprintf_const(gfp_t gfp, const char *fmt, va_list ap) 44 { 45 if (!strchr(fmt, '%')) 46 return kstrdup_const(fmt, gfp); 47 if (!strcmp(fmt, "%s")) 48 return kstrdup_const(va_arg(ap, const char*), gfp); 49 return kvasprintf(gfp, fmt, ap); 50 } 51 EXPORT_SYMBOL(kvasprintf_const); 52 53 char *kasprintf(gfp_t gfp, const char *fmt, ...) 54 { 55 va_list ap; 56 char *p; 57 58 va_start(ap, fmt); 59 p = kvasprintf(gfp, fmt, ap); 60 va_end(ap); 61 62 return p; 63 } 64 EXPORT_SYMBOL(kasprintf); 65