lib/kasprintf.c

   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);