[PATCH v2 04/18] fsck.overlay: add path package and split helper

["zhangyi (F)" <yi.zhang@huawei.com>]

Add path helpers to handle redundant or missing '/' when package and
split path.

Signed-off-by: zhangyi (F) <yi.zhang@huawei.com>
---
 lib.c | 36 ++++++++++++++++++++++++++++++++++++
 lib.h |  3 +++
 2 files changed, 39 insertions(+)

diff --git a/lib.c b/lib.c
index 7607517..ecc5d27 100644
--- a/lib.c
+++ b/lib.c
@@ -126,6 +126,42 @@ int remove_xattr(const char *pathname, const char *xattrname)
 	return ret;
 }
 
+char *path_pack(char *out, int len, const char *base, const char *append)
+{
+	int baselen = strlen(base);
+
+	if (base[baselen-1] == '/' && append[0] == '/')
+		snprintf(out, len, "%s%s", base, append+1);
+	else if (base[baselen-1] != '/' && append[0] != '/')
+		snprintf(out, len, "%s/%s", base, append);
+	else
+		snprintf(out, len, "%s%s", base, append);
+
+	return out;
+}
+
+char *path_truncate(char *out, int len, const char *path, const char *filename)
+{
+	int filelen = strlen(filename);
+	int pathlen = strlen(path);
+	int cplen;
+
+	cplen = (filename[0] == '/') ? pathlen-filelen : pathlen-filelen-1;
+	cplen = cplen < len ? cplen : len-1;
+
+	memcpy(out, path, cplen);
+	out[cplen] = '\0';
+
+	return out;
+}
+
+const char *path_pick(const char *path, int baselen)
+{
+	const char *p = path + baselen;
+
+	return (*p == '/') ? p+1 : p;
+}
+
 static inline int __check_entry(struct scan_ctx *sctx,
 				  int (*do_check)(struct scan_ctx *))
 {
diff --git a/lib.h b/lib.h
index 2956235..618791c 100644
--- a/lib.h
+++ b/lib.h
@@ -73,5 +73,8 @@ ssize_t get_xattr(const char *pathname, const char *xattrname,
 int set_xattr(const char *pathname, const char *xattrname,
 	      void *value, size_t size);
 int remove_xattr(const char *pathname, const char *xattrname);
+char *path_pack(char *out, int len, const char *base, const char *append);
+char *path_truncate(char *out, int len, const char *path, const char *filename);
+const char *path_pick(const char *path, int baselen);
 
 #endif /* OVL_LIB_H */
-- 
2.9.5