Add "mkpath()" helper function

[git.git] / path.c

diff --git a/path.c b/path.c
new file mode 100644 (file)
index 0000000..d217ef0
--- /dev/null
+++ b/path.c
@@ -0,0 +1,60 @@
+/*
+ * I'm tired of doing "vsnprintf()" etc just to open a
+ * file, so here's a "return static buffer with printf"
+ * interface for paths.
+ *
+ * It's obviously not thread-safe. Sue me. But it's quite
+ * useful for doing things like
+ *
+ *   f = open(mkpath("%s/%s.git", base, name), O_RDONLY);
+ *
+ * which is what it's designed for.
+ */
+#include "cache.h"
+
+static char pathname[PATH_MAX];
+static char bad_path[] = "/bad-path/";
+
+static char *cleanup_path(char *path)
+{
+       /* Clean it up */
+       if (!memcmp(path, "./", 2)) {
+               path += 2;
+               while (*path == '/')
+                       path++;
+       }
+       return path;
+}
+
+char *mkpath(const char *fmt, ...)
+{
+       va_list args;
+       unsigned len;
+
+       va_start(args, fmt);
+       len = vsnprintf(pathname, PATH_MAX, fmt, args);
+       va_end(args);
+       if (len >= PATH_MAX)
+               return bad_path;
+       return cleanup_path(pathname);
+}
+
+char *git_path(const char *fmt, ...)
+{
+       const char *git_dir = gitenv(GIT_DIR_ENVIRONMENT) ? : DEFAULT_GIT_DIR_ENVIRONMENT;
+       va_list args;
+       unsigned len;
+
+       len = strlen(git_dir);
+       if (len > PATH_MAX-100)
+               return bad_path;
+       memcpy(pathname, git_dir, len);
+       if (len && git_dir[len-1] != '/')
+               pathname[len++] = '/';
+       va_start(args, fmt);
+       len += vsnprintf(pathname + len, PATH_MAX - len, fmt, args);
+       va_end(args);
+       if (len >= PATH_MAX)
+               return bad_path;
+       return cleanup_path(pathname);
+}