LXR linux/lib/kasprintf.c

   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. */
  15char *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}
  35EXPORT_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 */
  43const 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}
  51EXPORT_SYMBOL(kvasprintf_const);
  52
  53char *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}
  64EXPORT_SYMBOL(kasprintf);
  65