/*
   * 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.perf", base, name), O_RDONLY);
   *
   * which is what it's designed for.
   */
  #include "cache.h"
  
  static char bad_path[] = "/bad-path/";
  /*
   * Two hacks:
   */
  
  static const char *get_perf_dir(void)
  {
  	return ".";
  }
  
  /*
   * If libc has strlcpy() then that version will override this
   * implementation:
   */
  size_t __weak strlcpy(char *dest, const char *src, size_t size)
  {
  	size_t ret = strlen(src);
  
  	if (size) {
  		size_t len = (ret >= size) ? size - 1 : ret;
  
  		memcpy(dest, src, len);
  		dest[len] = '\0';
  	}
  
  	return ret;
  }
  
  static char *get_pathname(void)
  {
  	static char pathname_array[4][PATH_MAX];
  	static int idx;
  
  	return pathname_array[3 & ++idx];
  }
  
  static char *cleanup_path(char *path)
  {
  	/* Clean it up */
  	if (!memcmp(path, "./", 2)) {
  		path += 2;
  		while (*path == '/')
  			path++;
  	}
  	return path;
  }
  
  static char *perf_vsnpath(char *buf, size_t n, const char *fmt, va_list args)
  {
  	const char *perf_dir = get_perf_dir();
  	size_t len;
  
  	len = strlen(perf_dir);
  	if (n < len + 1)
  		goto bad;
  	memcpy(buf, perf_dir, len);
  	if (len && !is_dir_sep(perf_dir[len-1]))
  		buf[len++] = '/';
  	len += vsnprintf(buf + len, n - len, fmt, args);
  	if (len >= n)
  		goto bad;
  	return cleanup_path(buf);
  bad:
  	strlcpy(buf, bad_path, n);
  	return buf;
  }
  
  char *perf_pathdup(const char *fmt, ...)
  {
  	char path[PATH_MAX];
  	va_list args;
  	va_start(args, fmt);
  	(void)perf_vsnpath(path, sizeof(path), fmt, args);
  	va_end(args);
  	return xstrdup(path);
  }
  
  char *mkpath(const char *fmt, ...)
  {
  	va_list args;
  	unsigned len;
  	char *pathname = get_pathname();
  
  	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 *perf_path(const char *fmt, ...)
  {
  	const char *perf_dir = get_perf_dir();
  	char *pathname = get_pathname();
  	va_list args;
  	unsigned len;
  
  	len = strlen(perf_dir);
  	if (len > PATH_MAX-100)
  		return bad_path;
  	memcpy(pathname, perf_dir, len);
  	if (len && perf_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);
  }
  
  /* strip arbitrary amount of directory separators at end of path */
  static inline int chomp_trailing_dir_sep(const char *path, int len)
  {
  	while (len && is_dir_sep(path[len - 1]))
  		len--;
  	return len;
  }
  
  /*
   * If path ends with suffix (complete path components), returns the
   * part before suffix (sans trailing directory separators).
   * Otherwise returns NULL.
   */
  char *strip_path_suffix(const char *path, const char *suffix)
  {
  	int path_len = strlen(path), suffix_len = strlen(suffix);
  
  	while (suffix_len) {
  		if (!path_len)
  			return NULL;
  
  		if (is_dir_sep(path[path_len - 1])) {
  			if (!is_dir_sep(suffix[suffix_len - 1]))
  				return NULL;
  			path_len = chomp_trailing_dir_sep(path, path_len);
  			suffix_len = chomp_trailing_dir_sep(suffix, suffix_len);
  		}
  		else if (path[--path_len] != suffix[--suffix_len])
  			return NULL;
  	}
  
  	if (path_len && !is_dir_sep(path[path_len - 1]))
  		return NULL;
  	return strndup(path, chomp_trailing_dir_sep(path, path_len));
  }