Save and restore write pointer reported by driver

src/camogm.c

@@ -1872,9 +1872,9 @@ int main(int argc, char *argv[])
 	const char usage[] =   "This program allows recording of the video/images acquired by Elphel camera to the storage media.\n" \
 			     "It is designed to run in the background and accept commands through a named pipe or a socket.\n\n" \
 			     "Usage:\n\n" \
-			     "%s -n <named_pipe_name> -p <port_number>\n\n"	\
+			     "%s -n <named_pipe_name> -p <port_number> [-s state_file_name]\n\n"	\
 			     "i.e.:\n\n" \
-			     "%s -n /var/state/camogm_cmd -p 1234\n\n" \
+			     "%s -n /var/state/camogm_cmd -p 1234 -s /mnt/sda1/write_pos\n\n" \
 			     "When the program is running you may send commands by writing strings to the command file\n" \
 			     "(/var/state/camogm_cmd in the example above) or to the socket. The complete list of available commands is available\n" \
 			     "on Elphel Wiki (http://wiki.elphel.com/index.php?title=Camogm), here is the example of usage\n" \
@@ -1890,13 +1890,15 @@ int main(int argc, char *argv[])
 	int ret;
 	int opt;
 	uint16_t port_num = 0;
+	size_t str_len;
 	char pipe_name_str[ELPHEL_PATH_MAX] = {0};
+	char state_name_str[ELPHEL_PATH_MAX] = {0};
 
 	if ((argc < 5) || (argv[1][1] == '-')) {
 		printf(usage, argv[0], argv[0]);
 		return EXIT_SUCCESS;
 	}
-	while ((opt = getopt(argc, argv, "n:p:h")) != -1) {
+	while ((opt = getopt(argc, argv, "n:p:s:h")) != -1) {
 		switch (opt) {
 		case 'n':
 			strncpy(pipe_name_str, (const char *)optarg, ELPHEL_PATH_MAX - 1);
@@ -1907,6 +1909,9 @@ int main(int argc, char *argv[])
 		case 'h':
 			printf(usage, argv[0], argv[0]);
 			return EXIT_SUCCESS;
+		case 's':
+			strncpy(state_name_str, (const char *)optarg, ELPHEL_PATH_MAX - 1);
+			break;
 		}
 	}
 
@@ -1926,6 +1931,10 @@ int main(int argc, char *argv[])
 		return EXIT_FAILURE;
 	}
 	sstate.rawdev.thread_state = STATE_RUNNING;
+	str_len = strlen(state_name_str);
+	if (str_len > 0) {
+		strncpy(&sstate.rawdev.state_path, state_name_str, str_len + 1);
+	}
 
 	ret = listener_loop(&sstate);
 

src/camogm.h

@@ -128,6 +128,7 @@ typedef struct {
 	volatile int thread_state;
 	unsigned char *disk_mmap;
 	int sysfs_fd;
+	char state_path[ELPHEL_PATH_MAX];
 } rawdev_buffer;
 
 /**

src/camogm_jpeg.c

@@ -31,6 +31,134 @@
 #include <elphel/ahci_cmd.h>
 
 #include "camogm_jpeg.h"
+#include "camogm_read.h"
+
+/** State file record format. It includes device path in /dev, starting, current and ending LBAs */
+#define STATE_FILE_FORMAT         "%s\t%llu\t%llu\t%llu\n"
+
+/** Get starting and endign LBAs of the partition specified as raw device buffer */
+static int get_disk_range(struct range *range)
+{
+	FILE *f;
+
+	// get raw device buffer starting postion on disk
+	f = fopen(SYSFS_AHCI_LBA_START, "r");
+	if (f == NULL) {
+		return -1;
+	}
+	fscanf(f, "%llu\n", &range->from);
+	fclose(f);
+
+	// get raw device buffer ending postion on disk
+	f = fopen(SYSFS_AHCI_LBA_END, "r");
+	if (f == NULL) {
+		return -1;
+	}
+	fscanf(f, "%llu\n", &range->to);
+	fclose(f);
+
+	return 0;
+}
+
+/** Get write pointer from a file. This functions check not only the name of a partition, but
+ * its geometry as well */
+static int find_state(FILE *f, uint64_t *pos, const rawdev_buffer *rawdev)
+{
+	size_t len;
+	uint64_t start_pos, curr_pos, end_pos;
+	struct range range;
+	char buff[ELPHEL_PATH_MAX];
+	char dev_name[ELPHEL_PATH_MAX];
+
+	if (f == NULL || pos == NULL)
+		return -1;
+	if (get_disk_range(&range) != 0) {
+		return -1;
+	}
+
+	// skip first line containing file header
+	fgets(buff, ELPHEL_PATH_MAX, f);
+	while (fgets(buff, ELPHEL_PATH_MAX, f) != NULL) {
+		sscanf(buff, STATE_FILE_FORMAT, dev_name, &start_pos, &curr_pos, &end_pos);
+		len = strlen(dev_name);
+		if (strncmp(rawdev->rawdev_path, dev_name, len) == 0 &&
+				range.from == start_pos &&
+				range.to == end_pos) {
+			*pos = curr_pos;
+			break;
+		}
+	}
+
+	return 0;
+}
+
+/** Read state from file and restore disk write pointer */
+static int open_state_file(const rawdev_buffer *rawdev)
+{
+	int fd, len;
+	FILE *f;
+	int ret = 0;
+	uint64_t curr_pos;
+	char buff[SMALL_BUFF_LEN] = {0};
+
+	if (strlen(rawdev->state_path) == 0) {
+		return ret;
+	}
+
+	f = fopen(rawdev->state_path, "r");
+	if (f != NULL) {
+		if (find_state(f, &curr_pos, rawdev) != -1) {
+			fd = open(SYSFS_AHCI_LBA_CURRENT, O_WRONLY);
+			if (fd >= 0) {
+				len = snprintf(buff, SMALL_BUFF_LEN, "%llu", curr_pos);
+				write(fd, buff, len + 1);
+				close(fd);
+			} else {
+				ret = -1;
+			}
+		}
+		fclose(f);
+	} else {
+		ret = -1;
+	}
+
+	return ret;
+}
+
+/** Save current position of the disk write pointer */
+static int save_state_file(const rawdev_buffer *rawdev)
+{
+	int ret = 0;
+	FILE *f;
+	struct range range;
+	uint64_t curr_pos;
+
+	if (strlen(rawdev->state_path) == 0) {
+		return ret;
+	}
+	if (get_disk_range(&range) != 0) {
+		return -1;
+	}
+
+	// get raw device buffer current postion on disk, this position indicates where recording has stopped
+	f = fopen(SYSFS_AHCI_LBA_CURRENT, "r");
+	if (f == NULL) {
+		return -1;
+	}
+	fscanf(f, "%llu\n", &curr_pos);
+	fclose(f);
+
+	// save pointers to a regular file
+	f = fopen(rawdev->state_path, "w");
+	if (f == NULL) {
+		return -1;
+	}
+	fprintf(f, "Device\t\tStart LBA\tCurrent LBA\tEnd LBA\n");
+	fprintf(f, STATE_FILE_FORMAT, rawdev->rawdev_path, range.from, curr_pos, range.to);
+	fclose(f);
+
+	return ret;
+}
 
 int camogm_init_jpeg(camogm_state *state)
 {
@@ -82,15 +210,17 @@ int camogm_start_jpeg(camogm_state *state)
 			}
 		}
 	} else {
-		if (state->rawdev_op) {
+		if (open_state_file(&state->rawdev) != 0) {
+			D0(fprintf(debug_file, "Could not set write pointer via sysfs, recording will start from the beginning of partition: "
+					"%s\n", state->rawdev.rawdev_path));
+		}
 		state->rawdev.sysfs_fd = open(SYSFS_AHCI_WRITE, O_WRONLY);
-			fprintf(debug_file, "Open sysfs file: %s\n", SYSFS_AHCI_WRITE);
+		D6(fprintf(debug_file, "Open sysfs file: %s\n", SYSFS_AHCI_WRITE));
 		if (state->rawdev.sysfs_fd < 0) {
 			D0(fprintf(debug_file, "Error opening sysfs file: %s\n", SYSFS_AHCI_WRITE));
 			return -CAMOGM_FRAME_FILE_ERR;
 		}
 	}
-	}
 
 	return 0;
 }
@@ -171,10 +301,12 @@ int camogm_end_jpeg(camogm_state *state)
 		if (write(state->rawdev.sysfs_fd, &fdata, sizeof(struct frame_data)) < 0) {
 			D0(fprintf(debug_file, "Error sending 'finish' command to driver\n"));
 		}
-		D0(fprintf(debug_file, "Closing sysfs file %s\n", SYSFS_AHCI_WRITE));
+		D6(fprintf(debug_file, "Closing sysfs file %s\n", SYSFS_AHCI_WRITE));
 		ret = close(state->rawdev.sysfs_fd);
 		if (ret == -1)
 			D0(fprintf(debug_file, "Error: %s\n", strerror(errno)));
+
+		save_state_file(&state->rawdev);
 	}
 	return ret;
 }