• Thomas Haller's avatar
    shared: add nm_strerror_native() to replace strerror() and g_strerror() · e1ca3bf7
    Thomas Haller authored
    We have various options for strerror(), with ups and downsides:
    
    - strerror()
    
        - returns pointer that is overwritten on next call. It's convenient
          to use, but dangerous.
    
        - not thread-safe.
    
        - not guaranteed to be UTF-8.
    
    - strerror_r()
    
        - takes input buffer and is less convenient to use. At least, we
          are in control of when the buffer gets overwritten.
    
        - there is a Posix/XSI and a glibc variant, making it sligthly
          inconvenient to used. This could be solved by a wrapper we implement.
    
        - thread-safe.
    
        - not guaranteed to be UTF-8.
    
    - g_strerror()
    
        - convenient and safe to use. Also the buffer is never released for the
          remainder of the program.
    
        - passing untrusted error numbers to g_strerror() can result in a
          denial of service, as the internal buffer grows until out-of-memory.
    
        - thread-safe.
    
        - guaranteed to be UTF-8 (depending on locale).
    
    Add our own wrapper nm_strerror_native(). It is:
    
        - convenient to use (returning a buffer that does not require
          management).
    
        - slightly dangerous as the buffer gets overwritten on the next call
          (like strerror()).
    
        - thread-safe.
    
        - guaranteed to be UTF-8 (depending on locale).
    
        - doesn't keep an unlimited cache of strings, unlike g_strerror().
    
    You can't have it all. g_strerror() is leaking all generated error messages.
    I think that is unacceptable, because it would mean we need to
    keep track where our error numbers come from (and trust libraries we
    use to only set a restricted set of known error numbers).
    e1ca3bf7
nm-errno.c 6.21 KB