mm/util.c

   1 #include <linux/slab.h>
   2 #include <linux/string.h>
   3 #include <linux/module.h>
   4 #include <linux/err.h>
   5 #include <asm/uaccess.h>
   6
   7 /**
   8  * __kzalloc - allocate memory. The memory is set to zero.
   9  * @size: how many bytes of memory are required.
  10  * @flags: the type of memory to allocate.
  11  */
  12 void *__kzalloc(size_t size, gfp_t flags)
  13 {
  14         void *ret = kmalloc_track_caller(size, flags);
  15         if (ret)
  16                 memset(ret, 0, size);
  17         return ret;
  18 }
  19 EXPORT_SYMBOL(__kzalloc);
  20
  21 /*
  22  * kstrdup - allocate space for and copy an existing string
  23  *
  24  * @s: the string to duplicate
  25  * @gfp: the GFP mask used in the kmalloc() call when allocating memory
  26  */
  27 char *kstrdup(const char *s, gfp_t gfp)
  28 {
  29         size_t len;
  30         char *buf;
  31
  32         if (!s)
  33                 return NULL;
  34
  35         len = strlen(s) + 1;
  36         buf = kmalloc_track_caller(len, gfp);
  37         if (buf)
  38                 memcpy(buf, s, len);
  39         return buf;
  40 }
  41 EXPORT_SYMBOL(kstrdup);
  42
  43 /**
  44  * kmemdup - duplicate region of memory
  45  *
  46  * @src: memory region to duplicate
  47  * @len: memory region length
  48  * @gfp: GFP mask to use
  49  */
  50 void *kmemdup(const void *src, size_t len, gfp_t gfp)
  51 {
  52         void *p;
  53
  54         p = kmalloc_track_caller(len, gfp);
  55         if (p)
  56                 memcpy(p, src, len);
  57         return p;
  58 }
  59 EXPORT_SYMBOL(kmemdup);
  60
  61 /*
  62  * strndup_user - duplicate an existing string from user space
  63  *
  64  * @s: The string to duplicate
  65  * @n: Maximum number of bytes to copy, including the trailing NUL.
  66  */
  67 char *strndup_user(const char __user *s, long n)
  68 {
  69         char *p;
  70         long length;
  71
  72         length = strnlen_user(s, n);
  73
  74         if (!length)
  75                 return ERR_PTR(-EFAULT);
  76
  77         if (length > n)
  78                 return ERR_PTR(-EINVAL);
  79
  80         p = kmalloc(length, GFP_KERNEL);
  81
  82         if (!p)
  83                 return ERR_PTR(-ENOMEM);
  84
  85         if (copy_from_user(p, s, length)) {
  86                 kfree(p);
  87                 return ERR_PTR(-EFAULT);
  88         }
  89
  90         p[length - 1] = '\0';
  91
  92         return p;
  93 }
  94 EXPORT_SYMBOL(strndup_user);