ardupilot/libraries/AP_Common/ExpandingString.cpp

103 lines
2.4 KiB
C++

/*
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
/*
expanding string for easy construction of text buffers
*/
#include "ExpandingString.h"
extern const AP_HAL::HAL& hal;
#define EXPAND_INCREMENT 512
/*
expand the string buffer
*/
bool ExpandingString::expand(uint32_t min_extra_space_needed)
{
// expand a reasonable amount
uint32_t newsize = (5*buflen/4) + EXPAND_INCREMENT;
if (newsize - used < min_extra_space_needed) {
newsize = used + min_extra_space_needed;
}
// add one to ensure we are always null terminated
void *newbuf = hal.util->std_realloc(buf, newsize+1);
if (newbuf == nullptr) {
allocation_failed = true;
return false;
}
buflen = newsize;
buf = (char *)newbuf;
return true;
}
/*
print into the buffer, expanding if needed
*/
void ExpandingString::printf(const char *format, ...)
{
if (allocation_failed) {
return;
}
if (buflen == used && !expand(0)) {
return;
}
int n;
/*
print into the buffer, expanding the buffer if needed
*/
while (true) {
va_list arg;
va_start(arg, format);
n = hal.util->vsnprintf(&buf[used], buflen-used, format, arg);
va_end(arg);
if (n < 0) {
return;
}
if (uint32_t(n) < buflen - used) {
break;
}
if (!expand(n+1)) {
return;
}
}
used += n;
}
/*
print into the buffer, expanding if needed
*/
void ExpandingString::append(const char *s, uint32_t len)
{
if (allocation_failed) {
return;
}
if (buflen - used < len && !expand(len)) {
return;
}
memcpy(&buf[used], s, len);
used += len;
}
ExpandingString::~ExpandingString()
{
free(buf);
}