mm/util.c

   1 #include <linux/mm.h>
   2 #include <linux/slab.h>
   3 #include <linux/string.h>
   4 #include <linux/module.h>
   5 #include <linux/err.h>
   6 #include <asm/uaccess.h>
   7
   8 /**
   9  * kstrdup - allocate space for and copy an existing string
  10  * @s: the string to duplicate
  11  * @gfp: the GFP mask used in the kmalloc() call when allocating memory
  12  */
  13 char *kstrdup(const char *s, gfp_t gfp)
  14 {
  15         size_t len;
  16         char *buf;
  17
  18         if (!s)
  19                 return NULL;
  20
  21         len = strlen(s) + 1;
  22         buf = kmalloc_track_caller(len, gfp);
  23         if (buf)
  24                 memcpy(buf, s, len);
  25         return buf;
  26 }
  27 EXPORT_SYMBOL(kstrdup);
  28
  29 /**
  30  * kstrndup - allocate space for and copy an existing string
  31  * @s: the string to duplicate
  32  * @max: read at most @max chars from @s
  33  * @gfp: the GFP mask used in the kmalloc() call when allocating memory
  34  */
  35 char *kstrndup(const char *s, size_t max, gfp_t gfp)
  36 {
  37         size_t len;
  38         char *buf;
  39
  40         if (!s)
  41                 return NULL;
  42
  43         len = strnlen(s, max);
  44         buf = kmalloc_track_caller(len+1, gfp);
  45         if (buf) {
  46                 memcpy(buf, s, len);
  47                 buf[len] = '\0';
  48         }
  49         return buf;
  50 }
  51 EXPORT_SYMBOL(kstrndup);
  52
  53 /**
  54  * kmemdup - duplicate region of memory
  55  *
  56  * @src: memory region to duplicate
  57  * @len: memory region length
  58  * @gfp: GFP mask to use
  59  */
  60 void *kmemdup(const void *src, size_t len, gfp_t gfp)
  61 {
  62         void *p;
  63
  64         p = kmalloc_track_caller(len, gfp);
  65         if (p)
  66                 memcpy(p, src, len);
  67         return p;
  68 }
  69 EXPORT_SYMBOL(kmemdup);
  70
  71 /**
  72  * krealloc - reallocate memory. The contents will remain unchanged.
  73  * @p: object to reallocate memory for.
  74  * @new_size: how many bytes of memory are required.
  75  * @flags: the type of memory to allocate.
  76  *
  77  * The contents of the object pointed to are preserved up to the
  78  * lesser of the new and old sizes.  If @p is %NULL, krealloc()
  79  * behaves exactly like kmalloc().  If @size is 0 and @p is not a
  80  * %NULL pointer, the object pointed to is freed.
  81  */
  82 void *krealloc(const void *p, size_t new_size, gfp_t flags)
  83 {
  84         void *ret;
  85         size_t ks = 0;
  86
  87         if (unlikely(!new_size)) {
  88                 kfree(p);
  89                 return ZERO_SIZE_PTR;
  90         }
  91
  92         if (p)
  93                 ks = ksize(p);
  94
  95         if (ks >= new_size)
  96                 return (void *)p;
  97
  98         ret = kmalloc_track_caller(new_size, flags);
  99         if (ret && p) {
 100                 memcpy(ret, p, ks);
 101                 kfree(p);
 102         }
 103         return ret;
 104 }
 105 EXPORT_SYMBOL(krealloc);
 106
 107 /*
 108  * strndup_user - duplicate an existing string from user space
 109  * @s: The string to duplicate
 110  * @n: Maximum number of bytes to copy, including the trailing NUL.
 111  */
 112 char *strndup_user(const char __user *s, long n)
 113 {
 114         char *p;
 115         long length;
 116
 117         length = strnlen_user(s, n);
 118
 119         if (!length)
 120                 return ERR_PTR(-EFAULT);
 121
 122         if (length > n)
 123                 return ERR_PTR(-EINVAL);
 124
 125         p = kmalloc(length, GFP_KERNEL);
 126
 127         if (!p)
 128                 return ERR_PTR(-ENOMEM);
 129
 130         if (copy_from_user(p, s, length)) {
 131                 kfree(p);
 132                 return ERR_PTR(-EFAULT);
 133         }
 134
 135         p[length - 1] = '\0';
 136
 137         return p;
 138 }
 139 EXPORT_SYMBOL(strndup_user);
 140
 141 #ifndef HAVE_ARCH_PICK_MMAP_LAYOUT
 142 void arch_pick_mmap_layout(struct mm_struct *mm)
 143 {
 144         mm->mmap_base = TASK_UNMAPPED_BASE;
 145         mm->get_unmapped_area = arch_get_unmapped_area;
 146         mm->unmap_area = arch_unmap_area;
 147 }
 148 #endif