Defect Report #049

Submission Date: 10 Jan 93
Submittor: Project Editor (P.J. Plauger)
Source: David Metsky
Question 1
It has been suggested that, at least in the "C" locale, the transformed string output from strxfrm will not contain more characters than the original string. I believe that this suggestion is overly restrictive, and that the standard does not impose such a restriction on implementations. I am requesting a clarification from the appropriate standards committee(s). I hope that you will agree with the following resolution:

The C Standard does not impose a requirement upon the length of the transformed string output from strxfrm. (The returned value does indicate the necessary length.)

Here are some citations from the C Standard:
Subclause 7.4.1.1 The setlocale function:

LC_COLLATE affects the behavior of the strcoll and strxfrm functions... A value of "C" for locale specifies the minimal environment for C translation... At program startup, the equivalent of

setlocale(LC_ALL, "C");

is executed.

Subclause 7.11.4.3 The strcoll function:

The strcoll function compares the string pointed to by s1 to the string pointed to by s2, both interpreted as appropriate to the LC_COLLATE category of the current locale.

Subclause 7.11.4.5 The strxfrm function:

The transformation is such that if the strcmp function is applied to two transformed strings, it returns a value greater than, equal to, or less than zero, corresponding to the result of the strcoll function applied to the same two original strings... The strxfrm function returns the length of the transformed string (not including the terminating null character). If the value returned is n or more, the contents of the array pointed to by s1 are indeterminate.

I haven't located any requirement that the "C" locale behavior of strcoll must be identical to strcmp. Even if there were such a requirement, I haven't located any requirement that the transformed string must not be longer than the original string.
Response
We support your resolution:
The C Standard does not impose a requirement upon the length of the transformed string output from strxfrm, other than a limitation on the size of objects. (The returned value does indicate the necessary length.)
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