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From: B Horn <b@horn.uk>
Date: Sat, 15 Jun 2024 02:33:08 +0100
Subject: misc: Implement grub_strlcpy()
grub_strlcpy() acts the same way as strlcpy() does on most *NIX,
returning the length of src and ensuring dest is always NUL
terminated except when size is 0.
Signed-off-by: B Horn <b@horn.uk>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
---
include/grub/misc.h | 39 +++++++++++++++++++++++++++++++++++++++
1 file changed, 39 insertions(+)
diff --git a/include/grub/misc.h b/include/grub/misc.h
index 1b35a16..1031754 100644
--- a/include/grub/misc.h
+++ b/include/grub/misc.h
@@ -64,6 +64,45 @@ grub_stpcpy (char *dest, const char *src)
return d - 1;
}
+static inline grub_size_t
+grub_strlcpy (char *dest, const char *src, grub_size_t size)
+{
+ char *d = dest;
+ grub_size_t res = 0;
+ /*
+ * We do not subtract one from size here to avoid dealing with underflowing
+ * the value, which is why to_copy is always checked to be greater than one
+ * throughout this function.
+ */
+ grub_size_t to_copy = size;
+
+ /* Copy size - 1 bytes to dest. */
+ if (to_copy > 1)
+ while ((*d++ = *src++) != '\0' && ++res && --to_copy > 1)
+ ;
+
+ /*
+ * NUL terminate if size != 0. The previous step may have copied a NUL byte
+ * if it reached the end of the string, but we know dest[size - 1] must always
+ * be a NUL byte.
+ */
+ if (size != 0)
+ dest[size - 1] = '\0';
+
+ /* If there is still space in dest, but are here, we reached the end of src. */
+ if (to_copy > 1)
+ return res;
+
+ /*
+ * If we haven't reached the end of the string, iterate through to determine
+ * the strings total length.
+ */
+ while (*src++ != '\0' && ++res)
+ ;
+
+ return res;
+}
+
/* XXX: If grub_memmove is too slow, we must implement grub_memcpy. */
static inline void *
grub_memcpy (void *dest, const void *src, grub_size_t n)
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