zio-dump: a user-space utility to read ZIO control and data

The tools shows how to use control and data, and can work with any
ZIO input channel.

Signed-off-by: Alessandro Rubini <rubini@gnudd.com>
Signed-off by: Federico Vaga <federico.vaga@gmail.com>

zio-dump.c

+/*
+ * Trivial utility that reports data from ZIO input channels
+ */
+#include <stdio.h>
+#include <stdint.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <string.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+
+#include <linux/zio.h>
+#include <linux/zio-buffer.h>
+
+#define FD_C 0
+#define FD_D 1
+#define ZIO_CONTROL_SIZE	512
+#define ZIO_NAME_LEN 32
+
+unsigned char buf[1024*1024];
+
+int main(int argc, char **argv)
+{
+	FILE *f;
+	char *outfname;
+	int fd[2];
+	int i, j;
+
+	if (argc !=3) {
+		fprintf(stderr, "%s: use \"%s <ctrl-file> <data-file>\"\n",
+			argv[0], argv[0]);
+		exit(1);
+	}
+
+	for (i = 0; i < 2; i++) {
+		fd[i] = open(argv[i + 1], O_RDONLY);
+		if (fd[i] < 0) {
+			fprintf(stderr, "%s: %s: %s\n", argv[0], argv[i + 1],
+				strerror(errno));
+			exit(1);
+		}
+	}
+	/* the data channel is non-blocking */
+	fcntl(fd[FD_D], F_SETFL, fcntl(fd[FD_D], F_GETFL) | O_NONBLOCK);
+
+	/* always log data we read to some filename */
+	outfname = getenv("ZIO_DUMP_TO");
+	if (!outfname)
+		outfname = "/dev/null";
+	f = fopen(outfname, "w");
+	if (!f) {
+		fprintf(stderr, "%s: %s: %s\n", argv[0], outfname,
+			strerror(errno));
+		exit(1);
+	}
+	/* ensure proper strace information and output to pipes */
+	setlinebuf(stdout);
+	setbuf(f, NULL);
+
+	/* now read control and data, forever */
+	while (1) {
+		struct zio_control ctrl;
+
+		/* This is a blocking read to the control file */
+		i = read(fd[FD_C], &ctrl, sizeof(ctrl));
+		switch(i) {
+		case -1:
+			fprintf(stderr, "%s: %s: read(): %s\n",
+				argv[0], argv[1 + FD_C], strerror(errno));
+			exit(1);
+		case 0:
+			fprintf(stderr, "%s: %s: unexpected EOF\n",
+				argv[0], argv[1 + FD_C]);
+			exit(1);
+		default:
+			fprintf(stderr, "%s: ctrl: read %i bytes (exp %i)\n",
+				argv[0], i, sizeof(ctrl));
+			/* continue anyways */
+		case sizeof(ctrl):
+			break; /* ok */
+		}
+		printf("Ctrl: version %i.%i, trigger %.16s, dev %.16s, "
+		       "cset %i, chan %i\n",
+		       ctrl.major_version, ctrl.minor_version,
+		       ctrl.triggername, ctrl.devname, ctrl.cset_i,
+		       ctrl.chan_i);
+		printf("Ctrl: seq %i, n %i, size %i, bits %i, "
+		       "flags %08x (%s)\n",
+		       ctrl.seq_num,
+		       ctrl.nsamples,
+		       ctrl.ssize,
+		       ctrl.sbits,
+		       ctrl.flags,
+		       ctrl.flags & ZIO_CONTROL_LITTLE_ENDIAN
+		       ? "little-endian" :
+		       ctrl.flags & ZIO_CONTROL_BIG_ENDIAN
+		       ? "big-endian" : "unknown-endian");
+		printf("Ctrl: stamp %lli.%09lli (%lli)\n",
+		       (long long)ctrl.tstamp.secs,
+		       (long long)ctrl.tstamp.ticks,
+		       (long long)ctrl.tstamp.bins);
+		/* FIXME: some control information is missing */
+
+		i = read(fd[FD_D], buf, sizeof(buf));
+		if (i < 0) {
+			fprintf(stderr, "%s: %s: read(): %s\n",
+				argv[0], argv[1 + FD_D], strerror(errno));
+			continue; /* next ctrl, let's see... */
+		}
+		if (!i) {
+			fprintf(stderr, "%s: %s: unexpected EOF\n",
+				argv[0], argv[1 + FD_D]);
+			continue;
+		}
+		if (i != ctrl.nsamples * ctrl.ssize) {
+			if (i == sizeof(buf)) {
+				fprintf(stderr, "%s: buffer too small\n",
+					argv[0]);
+				/* FIXME: empty the data channel */
+			} else {
+				fprintf(stderr, "%s: ctrl: read %i bytes "
+					"(exp %i)\n", argv[0], i,
+					ctrl.nsamples * ctrl.ssize);
+			}
+			/* continue anyways */
+		}
+		fwrite(buf, 1, i, f);
+
+		/* report data to stdout */
+		for (j = 0; j < i; j++) {
+			if (!(j & 0xf))
+				printf("Data:");
+			printf(" %02x", buf[j]);
+			if ((j & 0xf) == 0xf || j == i - 1)
+			putchar('\n');
+		}
+	putchar('\n');
+	}
+}