ardupilot/libraries/AP_HAL_Linux/Storage.cpp

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#include "Storage.h"
#include <assert.h>
#include <errno.h>
#include <fcntl.h>
#include <stdio.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <unistd.h>
#include <AP_HAL/AP_HAL.h>
#include <AP_Vehicle/AP_Vehicle_Type.h>
using namespace Linux;
/*
This stores 'eeprom' data on the SD card, with a 4k size, and a
in-memory buffer. This keeps the latency down.
*/
// name the storage file after the sketch so you can use the same board
// card for ArduCopter and ArduPlane
#define STORAGE_FILE SKETCHNAME ".stg"
extern const AP_HAL::HAL& hal;
static inline int is_dir(const char *path)
{
struct stat st;
if (stat(path, &st) < 0) {
return -errno;
}
return S_ISDIR(st.st_mode);
}
static int mkdir_p(const char *path, int len, mode_t mode)
{
char *start, *end;
start = strndupa(path, len);
end = start + len;
/*
* scan backwards, replacing '/' with '\0' while the component doesn't
* exist
*/
for (;;) {
int r = is_dir(start);
if (r > 0) {
end += strlen(end);
if (end == start + len) {
return 0;
}
/* end != start, since it would be caught on the first
* iteration */
*end = '/';
break;
} else if (r == 0) {
return -ENOTDIR;
}
if (end == start) {
break;
}
*end = '\0';
/* Find the next component, backwards, discarding extra '/'*/
while (end > start && *end != '/') {
end--;
}
while (end > start && *(end - 1) == '/') {
end--;
}
}
while (end < start + len) {
if (mkdir(start, mode) < 0 && errno != EEXIST) {
return -errno;
}
end += strlen(end);
*end = '/';
}
return 0;
}
int Storage::_storage_create(const char *dpath)
{
int dfd = -1;
mkdir_p(dpath, strlen(dpath), 0777);
dfd = open(dpath, O_RDONLY|O_CLOEXEC);
if (dfd == -1) {
fprintf(stderr, "Failed to open storage directory: %s (%m)\n", dpath);
return -1;
}
unlinkat(dfd, dpath, 0);
int fd = openat(dfd, STORAGE_FILE, O_RDWR|O_CREAT|O_CLOEXEC, 0666);
close(dfd);
if (fd == -1) {
fprintf(stderr, "Failed to create storage file %s/%s\n", dpath,
STORAGE_FILE);
goto fail;
}
// take up all needed space
if (ftruncate(fd, sizeof(_buffer)) == -1) {
fprintf(stderr, "Failed to set file size to %u kB (%m)\n",
unsigned(sizeof(_buffer) / 1024));
goto fail;
}
// ensure the directory is updated with the new size
fsync(fd);
fsync(dfd);
close(dfd);
return fd;
fail:
close(dfd);
return -1;
}
void Storage::init()
{
const char *dpath;
if (_initialised) {
return;
}
_dirty_mask = 0;
dpath = hal.util->get_custom_storage_directory();
if (!dpath) {
dpath = HAL_BOARD_STORAGE_DIRECTORY;
}
int fd = open(dpath, O_RDWR|O_CLOEXEC);
if (fd == -1) {
fd = _storage_create(dpath);
if (fd == -1) {
AP_HAL::panic("Cannot create storage %s (%m)", dpath);
}
}
ssize_t ret = read(fd, _buffer, sizeof(_buffer));
if (ret != sizeof(_buffer)) {
close(fd);
_storage_create(dpath);
fd = open(dpath, O_RDONLY|O_CLOEXEC);
if (fd == -1) {
AP_HAL::panic("Failed to open %s (%m)", dpath);
}
if (read(fd, _buffer, sizeof(_buffer)) != sizeof(_buffer)) {
AP_HAL::panic("Failed to read %s (%m)", dpath);
}
}
_fd = fd;
_initialised = true;
}
/*
mark some lines as dirty. Note that there is no attempt to avoid
the race condition between this code and the _timer_tick() code
below, which both update _dirty_mask. If we lose the race then the
result is that a line is written more than once, but it won't result
in a line not being written.
*/
void Storage::_mark_dirty(uint16_t loc, uint16_t length)
{
if (length == 0) {
return;
}
uint16_t end = loc + length - 1;
for (uint8_t line=loc>>LINUX_STORAGE_LINE_SHIFT;
line <= end>>LINUX_STORAGE_LINE_SHIFT;
line++) {
_dirty_mask |= 1U << line;
}
}
void Storage::read_block(void *dst, uint16_t loc, size_t n)
{
if (loc >= sizeof(_buffer)-(n-1)) {
return;
}
init();
memcpy(dst, &_buffer[loc], n);
}
void Storage::write_block(uint16_t loc, const void *src, size_t n)
{
if (loc >= sizeof(_buffer)-(n-1)) {
return;
}
if (memcmp(src, &_buffer[loc], n) != 0) {
init();
memcpy(&_buffer[loc], src, n);
_mark_dirty(loc, n);
}
}
void Storage::_timer_tick(void)
{
if (!_initialised || _dirty_mask == 0 || _fd == -1) {
return;
}
// write out the first dirty set of lines. We don't write more
// than one to keep the latency of this call to a minimum
uint8_t i, n;
for (i=0; i<LINUX_STORAGE_NUM_LINES; i++) {
if (_dirty_mask & (1<<i)) {
break;
}
}
if (i == LINUX_STORAGE_NUM_LINES) {
// this shouldn't be possible
return;
}
uint32_t write_mask = (1U<<i);
// see how many lines to write
for (n=1; (i+n) < LINUX_STORAGE_NUM_LINES &&
n < (LINUX_STORAGE_MAX_WRITE>>LINUX_STORAGE_LINE_SHIFT); n++) {
if (!(_dirty_mask & (1<<(n+i)))) {
break;
}
// mark that line clean
write_mask |= (1<<(n+i));
}
/*
write the lines. This also updates _dirty_mask. Note that
because this is a SCHED_FIFO thread it will not be preempted
by the main task except during blocking calls. This means we
don't need a semaphore around the _dirty_mask updates.
*/
if (lseek(_fd, i<<LINUX_STORAGE_LINE_SHIFT, SEEK_SET) == (i<<LINUX_STORAGE_LINE_SHIFT)) {
_dirty_mask &= ~write_mask;
if (write(_fd, &_buffer[i<<LINUX_STORAGE_LINE_SHIFT], n<<LINUX_STORAGE_LINE_SHIFT) != n<<LINUX_STORAGE_LINE_SHIFT) {
// write error - likely EINTR
_dirty_mask |= write_mask;
close(_fd);
_fd = -1;
}
if (_dirty_mask == 0) {
if (fsync(_fd) != 0) {
close(_fd);
_fd = -1;
}
}
}
}
/*
get storage size and ptr
*/
bool Storage::get_storage_ptr(void *&ptr, size_t &size)
{
if (!_initialised) {
return false;
}
ptr = _buffer;
size = sizeof(_buffer);
return true;
}