Re: [Libguestfs] [PATCH nbdkit v2 2/6] main: Tighten up characters permitted in config keys.
On 09/08/2018 03:15 AM, Richard W.M. Jones wrote:
Previously key=value on the command line allowed the key to be
pretty
much anything that didn't contain an '=' character. Even empty
strings were permitted.
This tightens up the permitted keys so they must contain only ASCII
alphanumeric, period, underscore or dash characters, and must not be
an empty string.
Do we want to further restrict things to start with a letter or
underscore (and not a dot, digit, or dash)?
---
docs/nbdkit-plugin.pod | 18 ++++++++++--------
src/main.c | 32 +++++++++++++++++++++++++++++++-
2 files changed, 41 insertions(+), 9 deletions(-)
+static int
+is_config_key (const char *key, size_t len)
+{
+ const char allowed[] =
+ "abcdefghijklmnopqrstuvwxyz"
+ "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
+ "0123456789"
+ "._-";
+ size_t i;
+
+ if (key[0] == '\0')
+ return 0;
+
+ for (i = 0; i < len; ++i) {
+ if (strchr (allowed, key[i]) == NULL)
Why not use strspn and checking against the length, instead of rolling
an O(n^2) algorithm yourself? The libc version might have optimizations
to run faster, although the speed of this loop is probably in the noise.
--
Eric Blake, Principal Software Engineer
Red Hat, Inc. +1-919-301-3266
Virtualization: qemu.org | libvirt.org