Nils O. Selåsdal
105 lines
2.3 KiB
C
105 lines
2.3 KiB
C
#include <stdio.h>
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#include <string.h>
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#include <unistd.h>
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#include <errno.h>
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <fcntl.h>
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#include "ucore/restart_counter.h"
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static UCRCResult uc_restart_counter_lock(int fd)
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{
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int rc = lockf(fd, F_TLOCK, 0);
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if (rc == -1 && (errno == EACCES || errno == EAGAIN)) {
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return UC_RC_ERR_FILE_LOCKED;
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} else if (rc == -1) {
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return UC_RC_ERR_UNSPECIFIED;
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}
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return UC_RC_OK;
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}
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UCRCResult uc_restart_counter_init(
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struct UCRestartCounter *counter,
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const char *filename,
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unsigned int flags)
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{
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int fd;
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UCRCResult rc = UC_RC_OK;
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char buf[64];
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ssize_t n;
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counter->counter = 0;
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counter->fd = -1;
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fd = open(filename, O_CREAT|O_RDWR, 0644);
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if (fd == -1) {
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return UC_RC_ERR_FILE_ACCESS_ERROR;
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}
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if (flags & UC_RC_FL_LOCK_FILE) {
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rc = uc_restart_counter_lock(fd);
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if (rc != UC_RC_OK) {
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close(fd);
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return rc;
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}
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counter->fd = fd;
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}
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buf[0] = 0;
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n = read(fd, buf, sizeof buf - 1);
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if (n > 0) {
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buf[n] = 0;
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if (sscanf(buf, "%u", &counter->counter) == 1) {
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counter->counter++;
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rc = UC_RC_OK;
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} else {
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rc = UC_RC_ERR_FILE_CONTENT_ERROR;
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}
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if (lseek(fd, 0, SEEK_SET) != 0 ||
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ftruncate(fd,0) != 0) {
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rc = UC_RC_ERR_UNSPECIFIED;
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goto done;
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}
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} else if (n < 0) {
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rc = UC_RC_ERR_FILE_ACCESS_ERROR;
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} //if n is 0, we act as we created the file for the 1. time
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snprintf(buf, sizeof buf, "%u\n", counter->counter);
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n = strlen(buf);
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if (write(fd, buf, n) != n) {
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rc = UC_RC_ERR_UNSPECIFIED;
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}
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fsync(fd);
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done:
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if ((flags & UC_RC_FL_LOCK_FILE) == 0) {
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close(fd);
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}
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return rc;
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}
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UCRCResult uc_restart_counter_close(struct UCRestartCounter *counter)
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{
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if (counter->fd < 0) {
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return UC_RC_ERR_NOT_OPENED;
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}
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close(counter->fd); //also releases the lock
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counter->fd = -1;
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return UC_RC_OK;
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}
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unsigned int uc_restart_counter_get(const struct UCRestartCounter *counter)
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{
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return counter->counter;
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}
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