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From: Markus Armbruster <armbru@redhat.com>
Subject: Re: [Qemu-devel] [PATCH 1/4] Introduce strtosz() library function to
	convert a string to a byte count.
References: <1286954450-30860-1-git-send-email-Jes.Sorensen@redhat.com>
	<1286954450-30860-2-git-send-email-Jes.Sorensen@redhat.com>
Date: Wed, 13 Oct 2010 10:19:12 +0200
In-Reply-To: <1286954450-30860-2-git-send-email-Jes.Sorensen@redhat.com> (Jes
	Sorensen's message of "Wed, 13 Oct 2010 09:20:47 +0200")
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To: Jes.Sorensen@redhat.com
Cc: pbonzini@redhat.com, qemu-devel@nongnu.org

Jes.Sorensen@redhat.com writes:

> From: Jes Sorensen <Jes.Sorensen@redhat.com>
>
> strtosz() returns -1 on error. It now supports human unit formats in
> eg. 1.0G, with better error handling.
>
> The following suffixes are supported:
> B/b = bytes
> K/k = KB
> M/m = MB
> G/g = GB
> T/t = TB
>
> This patch changes -numa and -m input to use strtosz().
>
> Signed-off-by: Jes Sorensen <Jes.Sorensen@redhat.com>
> ---
>  cutils.c      |   79 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++
>  qemu-common.h |    1 +
>  vl.c          |   31 +++++++---------------
>  3 files changed, 90 insertions(+), 21 deletions(-)
>
> diff --git a/cutils.c b/cutils.c
> index 5883737..44a862a 100644
> --- a/cutils.c
> +++ b/cutils.c
> @@ -23,6 +23,7 @@
>   */
>  #include "qemu-common.h"
>  #include "host-utils.h"
> +#include <math.h>
>  
>  void pstrcpy(char *buf, int buf_size, const char *str)
>  {
> @@ -283,3 +284,81 @@ int fcntl_setfl(int fd, int flag)
>  }
>  #endif
>  
> +/*
> + * Convert string to bytes, allowing either B/b for bytes, K/k for KB,
> + * M/m for MB, G/g for GB or T/t for TB. Default without any postfix
> + * is MB. End pointer will be returned in *end, if not NULL.
> + * Return -1 on error.
> + */
> +ssize_t strtosz(const char *nptr, char **end)
> +{
> +    ssize_t retval = -1;
> +    char *endptr, c;
> +    int mul_required = 0;
> +    double val, mul, integral, fraction;
> +
> +    errno = 0;
> +    val = strtod(nptr, &endptr);
> +    if (isnan(val) || endptr == nptr || errno != 0 || val < 0 ||
> +        val >= HUGE_VAL) {
> +        goto fail;
> +    }
> +    integral = modf(val, &fraction);
> +    if (integral != 0) {
> +        mul_required = 1;
> +    }
> +    /*
> +     * Any whitespace character is fine for terminating the number,
> +     * in addition we accept ',' to handle strings where the size is
> +     * part of a multi token argument. Otherwise check that the suffix
> +     * is just one character.
> +     */
> +    c = *endptr++;
> +    if (isspace(c) || c == '\0' || c == ',') {
> +        c = 0;
> +    } else if (!isspace(*endptr) && *endptr != 0) {
> +        goto fail;
> +    }
> +    switch (c) {
> +    case 'B':
> +    case 'b':
> +        mul = 1;
> +        if (mul_required) {
> +            goto fail;
> +        }
> +        break;
> +    case 'K':
> +    case 'k':
> +        mul = 1 << 10;
> +        break;
> +    case 0:
> +        if (mul_required) {
> +            goto fail;
> +        }
> +    case 'M':
> +    case 'm':
> +        mul = 1ULL << 20;
> +        break;
> +    case 'G':
> +    case 'g':
> +        mul = 1ULL << 30;
> +        break;
> +    case 'T':
> +    case 't':
> +        mul = 1ULL << 40;
> +        break;
> +    default:
> +        goto fail;
> +    }
> +    if (val * mul >= ~(size_t)0) {
> +        goto fail;
> +    }
> +    retval = (val * mul);

Redundant parenthesis.  Not worth a respin.

> +
> +    if (end) {
> +        *end = endptr;
> +    }

Unlike strtol() & friends, we assign to *end only on success.

> +
> +fail:
> +    return retval;
> +}
[...]

*Not* worth a respin.