On 04/09/2011 10:29 AM, Andrew Dunbar wrote: You could try writing your own.  Off the top of my head (untested): char *vasprintf (const char *format, va_list ap) {        int len; char *buf;        len = vsnprintf(NULL, 0, format, ap);  /* get needed size */        if (len < 0) return NULL;        buf = malloc(len + 1);  /* reserve 1 byte for trailing \0 */        if (!len) return NULL;        if (vsnprintf(buf, len + 1, format, ap) == len) return buf;        free(buf);  /* something went wrong in second vsnprintf() */        return NULL; } I think the vsnprintf(NULL, 0, ...) trick should work, although I haven't tried it.  If it complains about the NULL, just use some valid dummy pointer instead.  You could probably trade some memory for speed in some cases by guessing and allocating some reasonable initial size for the buffer before the first vsnprintf() call and extending it only if the first guess wasn't long enough.

-- Ilmari Karonen _______________________________________________ Toolserver-l mailing list (Toolserver-l(a)lists.wikimedia.org) https://lists.wikimedia.org/mailman/listinfo/toolserver-l Posting guidelines for this list: https://wiki.toolserver.org/view/Mailing_list_etiquette

-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Andrew Dunbar: *printf() is not part of the compiler, but the C library (libc); GNU glibc (used on Linux) provides it, while Solaris doesn't.  There's been some discussion about it, but there are several incompatible asprintf() interfaces around and it's not clear which one should be implemented. Someone else already provided a version using snprintf, but you could also use g_vasprintf() from glib, or the version from gettext's libintl.h (which means you need to include <libintl.h> and link against - -lasprintf, both of which live in /opt/ts/gettext).  I personally find the snprintf solution the best and this is what I use in my own code.

       - river. _______________________________________________ Toolserver-l mailing list (Toolserver-l(a)lists.wikimedia.org) https://lists.wikimedia.org/mailman/listinfo/toolserver-l Posting guidelines for this list: https://wiki.toolserver.org/view/Mailing_list_etiquette

-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Andrew Dunbar: That's true, but no current Unix implementation should do that, since the return value of snprintf() is standardised in the current POSIX standard (IEEE 1003.1-2004) and in the C99 standard (ISO/IEC 9899:1999). The following code should handle Windows and both old and new Unix, although it's completely untested and comes with no warranty: /* Compile with "-D_XOPEN_SOURCE=600 -std=c99" */ int my_vasprintf(char **res, char const *fmt, va_list args) { int      sz, r; #ifdef _WIN32        sz = _vscprintf(fmt, args); #else        sz = snprintf(NULL, 0, fmt, args); #endif #if defined(_WIN32) || (defined(__STDC__) && __STDC__ >= 199901L) \                || (defined(_XOPEN_VERSION) && (_XOPEN_VERSION >= 600))        if (sz < 0)                return sz;        if (sz >= 0) { #else        if (sz >= 1) { #endif                if ((*res = malloc(sz + 1)) == NULL)                        return -1;                if ((sz = sprintf(*res, fmt, args)) < 0) {                        free(*res);                        *res = NULL;                }                return sz;        } #define MAXLN 65535        *res = NULL;        for (sz = 128; sz <= MAXLN; sz *= 2) {                if ((*res = realloc(*res, sz)) == NULL)                        return -1;                r = vsnprintf(*res, sz, fmt, args);                if (r > 0 && r < sz)                        return r;        }        errno = ENOMEM;        if (*res) {                free(*res);                *res = NULL;        }        return -1; } Obviously, this will be slower than the modern implementation, and you may want to tune the initial buffer size for the expected string length.

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