char *strappend(const char *s, const char *suffix);
char *strnappend(const char *s, const char *suffix, size_t length);
-char *replace_env(const char *format, char **env);
-char **replace_env_argv(char **argv, char **env);
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int readlinkat_malloc(int fd, const char *p, char **ret);
int readlink_malloc(const char *p, char **r);
int readlink_value(const char *p, char **ret);