git: 22310af02da3 - stable/13 - LinuxKPI: Implement strscpy

[Vladimir Kondratyev]

The branch stable/13 has been updated by wulf:

URL: https://cgit.FreeBSD.org/src/commit/?id=22310af02da3c40eae4a11b20019bcead508a0c9

commit 22310af02da3c40eae4a11b20019bcead508a0c9
Author:     Vladimir Kondratyev <wulf at FreeBSD.org>
AuthorDate: 2021-07-05 00:20:42 +0000
Commit:     Vladimir Kondratyev <wulf at FreeBSD.org>
CommitDate: 2021-07-20 22:43:52 +0000

    LinuxKPI: Implement strscpy
    
    strscpy copies the src string, or as much of it as fits, into the dst
    buffer.  The dst buffer is always NUL terminated, unless it's zero-sized.
    strscpy returns the number of characters copied (not including the
    trailing NUL) or -E2BIG if len is 0 or src was truncated.
    
    Currently drm-kmod replaces strscpy with strncpy that is not quite
    correct as strncpy does not NUL-terminate truncated strings and returns
    different values on exit.
    
    Reviewed by:    hselasky, imp, manu
    Differential revision:  https://reviews.freebsd.org/D31005
    
    (cherry picked from commit 019391bf852771070cb739900f9e20ae6c41c746)
---
 sys/compat/linuxkpi/common/include/linux/string.h | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/sys/compat/linuxkpi/common/include/linux/string.h b/sys/compat/linuxkpi/common/include/linux/string.h
index 39201e203162..659a48d93596 100644
--- a/sys/compat/linuxkpi/common/include/linux/string.h
+++ b/sys/compat/linuxkpi/common/include/linux/string.h
@@ -167,4 +167,20 @@ str_has_prefix(const char *str, const char *prefix)
 	return (strncmp(str, prefix, len) == 0 ? len : 0);
 }
 
+static inline ssize_t
+strscpy(char* dst, const char* src, size_t len)
+{
+	size_t i;
+
+	if (len <= INT_MAX) {
+		for (i = 0; i < len; i++)
+			if ('\0' == (dst[i] = src[i]))
+				return ((ssize_t)i);
+		if (i != 0)
+			dst[--i] = '\0';
+	}
+
+	return (-E2BIG);
+}
+
 #endif					/* _LINUX_STRING_H_ */