diff options
Diffstat (limited to 'lib/kasprintf.c')
| -rw-r--r-- | lib/kasprintf.c | 29 |
1 files changed, 24 insertions, 5 deletions
diff --git a/lib/kasprintf.c b/lib/kasprintf.c index 32f12150fc4f..cd2f5974ed98 100644 --- a/lib/kasprintf.c +++ b/lib/kasprintf.c @@ -1,10 +1,11 @@ +// SPDX-License-Identifier: GPL-2.0 /* * linux/lib/kasprintf.c * * Copyright (C) 1991, 1992 Linus Torvalds */ -#include <stdarg.h> +#include <linux/stdarg.h> #include <linux/export.h> #include <linux/slab.h> #include <linux/types.h> @@ -13,24 +14,42 @@ /* Simplified asprintf. */ char *kvasprintf(gfp_t gfp, const char *fmt, va_list ap) { - unsigned int len; + unsigned int first, second; char *p; va_list aq; va_copy(aq, ap); - len = vsnprintf(NULL, 0, fmt, aq); + first = vsnprintf(NULL, 0, fmt, aq); va_end(aq); - p = kmalloc_track_caller(len+1, gfp); + p = kmalloc_track_caller(first+1, gfp); if (!p) return NULL; - vsnprintf(p, len+1, fmt, ap); + second = vsnprintf(p, first+1, fmt, ap); + WARN(first != second, "different return values (%u and %u) from vsnprintf(\"%s\", ...)", + first, second, fmt); return p; } EXPORT_SYMBOL(kvasprintf); +/* + * If fmt contains no % (or is exactly %s), use kstrdup_const. If fmt + * (or the sole vararg) points to rodata, we will then save a memory + * allocation and string copy. In any case, the return value should be + * freed using kfree_const(). + */ +const char *kvasprintf_const(gfp_t gfp, const char *fmt, va_list ap) +{ + if (!strchr(fmt, '%')) + return kstrdup_const(fmt, gfp); + if (!strcmp(fmt, "%s")) + return kstrdup_const(va_arg(ap, const char*), gfp); + return kvasprintf(gfp, fmt, ap); +} +EXPORT_SYMBOL(kvasprintf_const); + char *kasprintf(gfp_t gfp, const char *fmt, ...) { va_list ap; |