Re: [Qemu-devel] [PATCH 1/8] cutils: unsigned int parsing functions

[Eric Blake <eblake@redhat.com>]

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On 01/16/2013 08:24 AM, Eduardo Habkost wrote:
> There are lots of duplicate parsing code using strto*() in QEMU, and
> most of that code is broken in one way or another. Even the visitors
> code have duplicate integer parsing code[1]. This introduces functions
> to help parsing unsigned int values: parse_uint() and parse_uint_full().
> 
> Parsing functions for signed ints and floats will be submitted later.
> 
> parse_uint_full() has all the checks made by opts_type_uint64() at
> opts-visitor.c:
> 
>  - Check for NULL (returns -EINVAL)
>  - Check for negative numbers (returns -ERANGE)
>  - Check for empty string (returns -EINVAL)
>  - Check for overflow or other errno values set by strtoll() (returns
>    -errno)
>  - Check for end of string (reject invalid characters after number)
>    (returns -EINVAL)
> 
> parse_uint() does everything above except checking for the end of the
> string, so callers can continue parsing the remainder of string after
> the number.
> 
> Unit tests included.
> 
> [1] string-input-visitor.c:parse_int() could use the same parsing code
>     used by opts-visitor.c:opts_type_int(), instead of duplicating that
>     logic.
> 
> Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
> ---
> Cc: Laszlo Ersek <lersek@redhat.com>
> Cc: Eric Blake <eblake@redhat.com>
> ---

> +++ b/tests/test-cutils.c

> + *
> + * Permission is hereby granted, free of charge, to any person obtaining a copy

Interesting that you chose a BSD license instead of GPL, but doesn't
affect my review.

Your test case lacks test of octal or hexadecimal input strings; is that
worth adding?

> +++ b/util/cutils.c
> @@ -270,6 +270,82 @@ int64_t strtosz(const char *nptr, char **end)
>      return strtosz_suffix(nptr, end, STRTOSZ_DEFSUFFIX_MB);
>  }
>  
> +/* Try to parse an unsigned integer
> + *
> + * Error checks done by the function:
> + * - NULL pointer will return -EINVAL.
> + * - Empty strings will return -EINVAL.
> + * - Overflow errors or other errno values  set by strtoull() will
> + *   return -errno (-ERANGE in case of overflow).
> + * - Differently from strtoull(), values starting with a minus sign are
> + *   rejected (returning -ERANGE).

Interesting that you chose to reject negative numbers, even though
strtoull() is required to accept them.  But you documented it and tested
for it, so I can live with it.

> +    errno = 0;
> +    val = strtoull(s, &endp, 0);
> +    if (errno) {
> +        r =  -errno;

Why two spaces?

Reviewed-by: Eric Blake <eblake@redhat.com>

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org


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