diff options
Diffstat (limited to 'lib/libc/string')
| -rw-r--r-- | lib/libc/string/strlcpy.3 | 25 |
1 files changed, 23 insertions, 2 deletions
diff --git a/lib/libc/string/strlcpy.3 b/lib/libc/string/strlcpy.3 index f22c897..14cf18d 100644 --- a/lib/libc/string/strlcpy.3 +++ b/lib/libc/string/strlcpy.3 @@ -121,6 +121,27 @@ the length of .Fa src . While this may seem somewhat confusing it was done to make truncation detection simple. +.Pp +Note however, that if +.Fn strlcat +traverses +.Fa size +characters without finding a NUL, the length of the string is considered +to be +.Fa size +and the destination string will not be NUL-terminated (since there was +no space for the NUL). +This keeps +.Fn strlcat +from running off the end of a string. +In practice this should not happen (as it means that either +.Fa size +is incorrect or that +.Fa dst +is not a proper +.Dq C +string). +The check exists to prevent potential security problems in incorrect code. .Sh EXAMPLES The following code fragment illustrates the simple case: .Bd -literal -offset indent @@ -146,9 +167,9 @@ if (strlcat(pname, file, sizeof(pname)) >= sizeof(pname)) .Ed .Pp Since we know how many characters we copied the first time, we can -speed things up a bit by using a copy instead on an append: +speed things up a bit by using a copy instead of an append: .Bd -literal -offset indent -char *dir, *file, pname[MAXPATHNAMELEN]; +char *dir, *file, pname[MAXPATHLEN]; size_t n; \&... |
