void str_vprintfa(string_t *str, const char *fmt, va_list args)
{
#define SNPRINTF_INITIAL_EXTRA_SIZE 128
va_list args2;
char *tmp;
unsigned int init_size;
size_t pos = str->used;
int ret, ret2;
VA_COPY(args2, args);
/* the format string is modified only if %m exists in it. it happens
only in error conditions, so don't try to t_push() here since it'll
just slow down the normal code path. */
fmt = printf_format_fix_get_len(fmt, &init_size);
init_size += SNPRINTF_INITIAL_EXTRA_SIZE;
/* @UNSAFE */
if (pos+init_size > buffer_get_size(str) &&
pos < buffer_get_size(str)) {
/* avoid growing buffer larger if possible. this is also
required if buffer isn't dynamically growing. */
init_size = buffer_get_size(str)-pos;
}
tmp = buffer_get_space_unsafe(str, pos, init_size);
ret = vsnprintf(tmp, init_size, fmt, args);
i_assert(ret >= 0);
if ((unsigned int)ret >= init_size) {
/* didn't fit with the first guess. now we know the size,
so try again. */
tmp = buffer_get_space_unsafe(str, pos, ret + 1);
ret2 = vsnprintf(tmp, ret + 1, fmt, args2);
i_assert(ret2 == ret);
}
/* drop the unused data, including terminating NUL */
buffer_set_used_size(str, pos + ret);
}
char *t_noalloc_strdup_vprintf(const char *format, va_list args,
unsigned int *size_r)
{
#define SNPRINTF_INITIAL_EXTRA_SIZE 256
va_list args2;
char *tmp;
unsigned int init_size;
int ret;
#ifdef DEBUG
int old_errno = errno;
#endif
VA_COPY(args2, args);
/* the format string is modified only if %m exists in it. it happens
only in error conditions, so don't try to t_push() here since it'll
just slow down the normal code path. */
format = printf_format_fix_get_len(format, &init_size);
init_size += SNPRINTF_INITIAL_EXTRA_SIZE;
tmp = t_buffer_get(init_size);
ret = vsnprintf(tmp, init_size, format, args);
i_assert(ret >= 0);
*size_r = ret + 1;
if ((unsigned int)ret >= init_size) {
/* didn't fit with the first guess. now we know the size,
so try again. */
tmp = t_buffer_get(*size_r);
ret = vsnprintf(tmp, *size_r, format, args2);
i_assert((unsigned int)ret == *size_r-1);
}
#ifdef DEBUG
/* we rely on errno not changing. it shouldn't. */
i_assert(errno == old_errno);
#endif
va_end(args2);
return tmp;
}
