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 <linux/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
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