add first bits of the I/O wrapper.

Signed-off-by: Gediminas Jakutis <gediminas@varciai.lt>

1 files changed, 91 insertions, 0 deletions

diff --git a/src/io.c b/src/io.c
new file mode 100644
index 0000000..74ea274
--- /dev/null
+++ b/src/io.c
@@ -0,0 +1,91 @@
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <errno.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <libgen.h>
+#include "io.h"
+
+int openstream(struct stream *in)
+{
+	struct stat st;
+	mode_t mode = S_IRUSR | S_IWUSR | S_IRGRP;
+	char *dname = NULL;
+	int ret = 0;
+
+	in->fd = -1;
+
+	if (!in->name) {
+		ret = EINVAL;
+		goto err;
+	}
+
+	if (in->out) {
+		char *tmp[2];
+
+		tmp[0] = strdup(in->name);
+		tmp[1] = dirname(tmp[0]);
+		dname = strdup(tmp[1]);
+		free(tmp[0]);
+
+		if (stat(dname, &st)) {
+			ret = errno;
+			/* TODO: error message */
+			goto err;
+		}
+
+		if(!(st.st_mode & S_IFDIR)) {
+			ret = EINVAL;
+			/* TODO: error message */
+			goto err;
+		}
+
+		if (!stat(in->name, &st)) {
+			if (!(st.st_mode & S_IFREG)) {
+				ret = EINVAL;
+				/* TODO: error message */
+				goto err;
+			}
+			mode = st.st_mode;
+		}
+	} else if (stat(in->name, &st)) {
+		ret = errno;
+		/* TODO: error message */
+		goto err;
+	} else if (!(st.st_mode & S_IFREG) || !st.st_size || (st.st_size % in->stride)) {
+		ret = EINVAL;
+		/* TODO: error message */
+		goto err;
+	} else {
+		in->n = st.st_size / in->stride;
+	}
+
+	if (in->out) {
+		in->fd = open(dname, O_TMPFILE | O_WRONLY, mode);
+		if (in->fd < 0) {
+			ret = errno;
+			/* TODO: error message */
+			goto err;
+		}
+
+		if (ftruncate(in->fd, in->stride * in->n)) {
+			ret = errno;
+			/* TODO: error message */
+			goto err;
+		}
+	} else {
+		in->fd = open(in->name, O_RDONLY | O_NOATIME);
+		if (in->fd < 0) {
+			ret = errno;
+			/* TODO: error message */
+			goto err;
+		}
+	}
+
+err:
+	free(dname);
+	return ret;
+}