[PATCH] Make xstrndup common

This also improves the implementation to match how strndup is
specified (by GNU): if the length given is longer than the string,
only the string's length is allocated and copied, but the string need
not be null-terminated if it is at least as long as the given length.

Signed-off-by: Daniel Barkalow <redacted>
---
Haven't got the rest of my series updated for comments, but I'd like to 
get this change, which is logically unrelated aside from being a 
dependancy, in now.

 commit.c          |    8 --------
 git-compat-util.h |   12 ++++++++++++
 2 files changed, 12 insertions(+), 8 deletions(-)

diff --git a/commit.c b/commit.c
index f1ba972..aa7059c 100644
--- a/commit.c
+++ b/commit.c

@@ -718,14 +718,6 @@ static char *logmsg_reencode(const struct commit *commit,
 	return out;
 }
 
-static char *xstrndup(const char *text, int len)
-{
-	char *result = xmalloc(len + 1);
-	memcpy(result, text, len);
-	result[len] = '\0';
-	return result;
-}
-
 static void fill_person(struct interp *table, const char *msg, int len)
 {
 	int start, end, tz = 0;

diff --git a/git-compat-util.h b/git-compat-util.h
index 2c84016..0dcd4e2 100644
--- a/git-compat-util.h
+++ b/git-compat-util.h

@@ -197,6 +197,18 @@ static inline void *xmalloc(size_t size)
 	return ret;
 }
 
+static inline char *xstrndup(const char *str, int len)
+{
+	char *ret;
+	int i;
+	for (i = 0; i < len && str[i]; i++)
+		;
+	ret = xmalloc(i + 1);
+	strncpy(ret, str, i);
+	ret[i] = '\0';
+	return ret;
+}
+
 static inline void *xrealloc(void *ptr, size_t size)
 {
 	void *ret = realloc(ptr, size);

-- 
1.5.1.2.255.g6ead4-dirty

On 5/3/07, Daniel Barkalow [off-list ref] wrote:

+static inline char *xstrndup(const char *str, int len)
+{
+       char *ret;
+       int i;
+       for (i = 0; i < len && str[i]; i++)
+               ;
+       ret = xmalloc(i + 1);
+       strncpy(ret, str, i);
+       ret[i] = '\0';
+       return ret;
+}

I'd suggest using platform-optimized memchr:

static inline char *xstrndup(const char *s, int len)
{
    char *p = memchr(s, 0, len);
    int n = p ? p - s: len;
    p = xmalloc(n + 1);
    memcpy(p, s, n);
    p[n] = '\0';
    return p;
}