The skip_prefix function has been very useful for
simplifying pointer arithmetic and avoiding repeated magic
numbers, but we have no equivalent for length-limited
buffers. So we're stuck with:
if (3 <= len && skip_prefix(buf, "foo", &buf))
len -= 3;
That's not that complicated, but it needs to use magic
numbers for the length of the prefix (or else write out
strlen("foo"), repeating the string). By using a helper, we
can get the string length behind the scenes (and often at
compile time for string literals).
Signed-off-by: Jeff King <peff@xxxxxxxx>
---
Obviously a helper to be used later in the series. I didn't hunt around
for other places that could make use of it, but I suspect there are
some.
git-compat-util.h | 17 +++++++++++++++++
1 file changed, 17 insertions(+)
diff --git a/git-compat-util.h b/git-compat-util.h
index 49d4029..c99cddc 100644
--- a/git-compat-util.h
+++ b/git-compat-util.h
@@ -473,6 +473,23 @@ static inline int skip_prefix(const char *str, const char *prefix,
return 0;
}
+/*
+ * Like skip_prefix, but promises never to read past "len" bytes of the input
+ * buffer, and returns the remaining number of bytes in "out" via "outlen".
+ */
+static inline int skip_prefix_mem(const char *buf, size_t len,
+ const char *prefix,
+ const char **out, size_t *outlen)
+{
+ size_t prefix_len = strlen(prefix);
+ if (prefix_len <= len && !memcmp(buf, prefix, prefix_len)) {
+ *out = buf + prefix_len;
+ *outlen = len - prefix_len;
+ return 1;
+ }
+ return 0;
+}
+
/*
* If buf ends with suffix, return 1 and subtract the length of the suffix
* from *len. Otherwise, return 0 and leave *len untouched.
--
2.9.0.209.g845fbc1
--
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