xref: /linux/lib/kasprintf.c (revision e5c86679d5e864947a52fb31e45a425dea3e7fa9)
1 /*
2  *  linux/lib/kasprintf.c
3  *
4  *  Copyright (C) 1991, 1992  Linus Torvalds
5  */
6 
7 #include <stdarg.h>
8 #include <linux/export.h>
9 #include <linux/slab.h>
10 #include <linux/types.h>
11 #include <linux/string.h>
12 
13 /* Simplified asprintf. */
14 char *kvasprintf(gfp_t gfp, const char *fmt, va_list ap)
15 {
16 	unsigned int first, second;
17 	char *p;
18 	va_list aq;
19 
20 	va_copy(aq, ap);
21 	first = vsnprintf(NULL, 0, fmt, aq);
22 	va_end(aq);
23 
24 	p = kmalloc_track_caller(first+1, gfp);
25 	if (!p)
26 		return NULL;
27 
28 	second = vsnprintf(p, first+1, fmt, ap);
29 	WARN(first != second, "different return values (%u and %u) from vsnprintf(\"%s\", ...)",
30 	     first, second, fmt);
31 
32 	return p;
33 }
34 EXPORT_SYMBOL(kvasprintf);
35 
36 /*
37  * If fmt contains no % (or is exactly %s), use kstrdup_const. If fmt
38  * (or the sole vararg) points to rodata, we will then save a memory
39  * allocation and string copy. In any case, the return value should be
40  * freed using kfree_const().
41  */
42 const char *kvasprintf_const(gfp_t gfp, const char *fmt, va_list ap)
43 {
44 	if (!strchr(fmt, '%'))
45 		return kstrdup_const(fmt, gfp);
46 	if (!strcmp(fmt, "%s"))
47 		return kstrdup_const(va_arg(ap, const char*), gfp);
48 	return kvasprintf(gfp, fmt, ap);
49 }
50 EXPORT_SYMBOL(kvasprintf_const);
51 
52 char *kasprintf(gfp_t gfp, const char *fmt, ...)
53 {
54 	va_list ap;
55 	char *p;
56 
57 	va_start(ap, fmt);
58 	p = kvasprintf(gfp, fmt, ap);
59 	va_end(ap);
60 
61 	return p;
62 }
63 EXPORT_SYMBOL(kasprintf);
64