Initial support for multiple UIs

Move the device discovery code from separate udev helpers to a single
process to listen on two sockets: one SOCK_DGRAM for incoming udev
events, and one SOCK_STREAM for UIs to connect.

Initial support for client/server infrastructure, still need to wire-up
the udev messages.

Signed-off-by: Jeremy Kerr <jk@ozlabs.org>

2 files changed, 364 insertions, 0 deletions

diff --git a/lib/pb-protocol/pb-protocol.c b/lib/pb-protocol/pb-protocol.c
new file mode 100644
index 0000000..2fd76c5
--- /dev/null
+++ b/lib/pb-protocol/pb-protocol.c
@@ -0,0 +1,307 @@
+
+#include <string.h>
+#include <stdint.h>
+#include <asm/byteorder.h>
+
+#include <talloc/talloc.h>
+
+#include "pb-protocol.h"
+
+
+/* Message format:
+ *
+ * 4-byte action, determines the remaining message content
+ * 4-byte total payload len
+ *   - not including action and payload len header
+ *
+ * action = 0x1: device add message
+ *  payload:
+ *   4-byte len, id
+ *   4-byte len, name
+ *   4-byte len, description
+ *   4-byte len, icon_file
+ *
+ *   4-byte option count
+ *   for each option:
+ *    4-byte len, id
+ *    4-byte len, name
+ *    4-byte len, description
+ *    4-byte len, icon_file
+ *    4-byte len, boot_image_file
+ *    4-byte len, initrd_file
+ *    4-byte len, boot_args
+ *
+ * action = 0x2: device remove message
+ *  payload:
+ *   4-byte len, id
+ */
+
+
+/* Write a string into the buffer, starting at pos.
+ *
+ * Returns the total length used for the write, including length header.
+ */
+int pb_protocol_serialise_string(char *pos, const char *str)
+{
+	int len = 0;
+
+	if (str)
+		len = strlen(str);
+
+	*(uint32_t *)pos = __cpu_to_be32(len);
+	pos += sizeof(uint32_t);
+
+	memcpy(pos, str, len);
+
+	return len + sizeof(uint32_t);
+}
+
+/* Read a string from a buffer, allocating the new string as necessary.
+ *
+ * @param[in] ctx	The talloc context to base the allocation on
+ * @param[in,out] pos	Where to start reading
+ * @param[in,out] len	The amount of data remaining in the buffer
+ * @param[out] str	Pointer to resuling string
+ * @return		zero on success, non-zero on failure
+ */
+static int read_string(void *ctx, char **pos, int *len, char **str)
+{
+	uint32_t str_len, read_len;
+
+	if (*len < sizeof(uint32_t))
+		return -1;
+
+	str_len = __be32_to_cpu(*(uint32_t *)(*pos));
+	read_len = sizeof(uint32_t);
+
+	if (read_len + str_len > *len)
+		return -1;
+
+	if (str_len == 0)
+		*str = NULL;
+	else
+		*str = talloc_strndup(ctx, *pos + read_len, str_len);
+
+	read_len += str_len;
+
+	/* all ok, update the caller's pointers */
+	*pos += read_len;
+	*len -= read_len;
+
+	return 0;
+}
+
+char *pb_protocol_deserialise_string(void *ctx,
+		struct pb_protocol_message *message)
+{
+	char *buf, *str;
+	int len;
+
+	len = message->payload_len;
+	buf = message->payload;
+
+	if (read_string(ctx, &buf, &len, &str))
+		return NULL;
+
+	return str;
+}
+
+static int optional_strlen(const char *str)
+{
+	if (!str)
+		return 0;
+	return strlen(str);
+}
+
+int pb_protocol_device_len(struct device *dev)
+{
+	int len, i;
+
+	len =	4 + optional_strlen(dev->id) +
+		4 + optional_strlen(dev->name) +
+		4 + optional_strlen(dev->description) +
+		4 + optional_strlen(dev->icon_file) +
+		4;
+
+	for (i = 0; i < dev->n_options; i++) {
+		struct boot_option *opt = &dev->options[i];
+		len +=	4 + optional_strlen(opt->id) +
+			4 + optional_strlen(opt->name) +
+			4 + optional_strlen(opt->description) +
+			4 + optional_strlen(opt->icon_file) +
+			4 + optional_strlen(opt->boot_image_file) +
+			4 + optional_strlen(opt->initrd_file) +
+			4 + optional_strlen(opt->boot_args);
+	}
+
+	return len;
+}
+
+int pb_protocol_serialise_device(struct device *dev, char *buf, int buf_len)
+{
+	char *pos;
+	int i;
+
+	pos = buf;
+
+	/* construct payload into buffer */
+	pos += pb_protocol_serialise_string(pos, dev->id);
+	pos += pb_protocol_serialise_string(pos, dev->name);
+	pos += pb_protocol_serialise_string(pos, dev->description);
+	pos += pb_protocol_serialise_string(pos, dev->icon_file);
+
+	/* write option count */
+	*(uint32_t *)pos = __cpu_to_be32(dev->n_options);
+	pos += sizeof(uint32_t);
+
+	/* write each option */
+	for (i = 0; i < dev->n_options; i++) {
+		struct boot_option *opt = &dev->options[i];
+		pos += pb_protocol_serialise_string(pos, opt->id);
+		pos += pb_protocol_serialise_string(pos, opt->name);
+		pos += pb_protocol_serialise_string(pos, opt->description);
+		pos += pb_protocol_serialise_string(pos, opt->icon_file);
+		pos += pb_protocol_serialise_string(pos, opt->boot_image_file);
+		pos += pb_protocol_serialise_string(pos, opt->initrd_file);
+		pos += pb_protocol_serialise_string(pos, opt->boot_args);
+	}
+
+	return 0;
+}
+
+int pb_protocol_write_message(int fd, struct pb_protocol_message *message)
+{
+	int total_len, rc;
+	char *pos;
+
+	total_len = sizeof(*message) + message->payload_len;
+
+	message->payload_len = __cpu_to_be32(message->payload_len);
+	message->action = __cpu_to_be32(message->action);
+
+	for (pos = (void *)message; total_len;) {
+		rc = write(fd, pos, total_len);
+
+		if (rc <= 0)
+			break;
+
+		total_len -= rc;
+		pos += rc;
+	}
+
+	talloc_free(message);
+
+	return total_len ? -1 : 0;
+}
+
+struct pb_protocol_message *pb_protocol_create_message(void *ctx,
+		int action, int payload_len)
+{
+	struct pb_protocol_message *message;
+
+	if (payload_len > PB_PROTOCOL_MAX_PAYLOAD_SIZE)
+		return NULL;
+
+	message = talloc_size(ctx, sizeof(*message) + payload_len);
+
+	/* we convert these to big-endian in write_message() */
+	message->action = action;
+	message->payload_len = payload_len;
+
+	return message;
+
+}
+
+struct pb_protocol_message *pb_protocol_read_message(void *ctx, int fd)
+{
+	struct pb_protocol_message *message, m;
+	int rc, len;
+
+	/* use the stack for the initial 8-byte read */
+
+	rc = read(fd, &m, sizeof(m));
+	if (rc != sizeof(m))
+		return NULL;
+
+	m.payload_len = __be32_to_cpu(m.payload_len);
+	m.action = __be32_to_cpu(m.action);
+
+	if (m.payload_len > PB_PROTOCOL_MAX_PAYLOAD_SIZE)
+		return NULL;
+
+	message = talloc_size(ctx, sizeof(m) + m.payload_len);
+	memcpy(message, &m, sizeof(m));
+
+	for (len = 0; len < m.payload_len;) {
+		rc = read(fd, message->payload + len, m.payload_len - len);
+
+		if (rc <= 0) {
+			talloc_free(message);
+			return NULL;
+		}
+
+		len += rc;
+	}
+
+	return message;
+}
+
+
+struct device *pb_protocol_deserialise_device(void *ctx,
+		struct pb_protocol_message *message)
+{
+	struct device *dev;
+	char *pos;
+	int i, len;
+
+	len = message->payload_len;
+	pos = message->payload;
+
+	dev = talloc(ctx, struct device);
+
+	if (read_string(dev, &pos, &len, &dev->id))
+		goto out_err;
+
+	if (read_string(dev, &pos, &len, &dev->name))
+		goto out_err;
+
+	if (read_string(dev, &pos, &len, &dev->description))
+		goto out_err;
+
+	if (read_string(dev, &pos, &len, &dev->icon_file))
+		goto out_err;
+
+	dev->n_options = __be32_to_cpu(*(uint32_t *)pos);
+	dev->options = talloc_array(dev, struct boot_option, dev->n_options);
+	pos += sizeof(uint32_t);
+
+	for (i = 0; i < dev->n_options; i++) {
+		struct boot_option *opt = &dev->options[i];
+
+		if (read_string(opt, &pos, &len, &opt->id))
+			goto out_err;
+		if (read_string(opt, &pos, &len, &opt->name))
+			goto out_err;
+		if (read_string(opt, &pos, &len,
+					&opt->description))
+			goto out_err;
+		if (read_string(opt, &pos, &len,
+					&opt->icon_file))
+			goto out_err;
+		if (read_string(opt, &pos, &len,
+					&opt->boot_image_file))
+			goto out_err;
+		if (read_string(opt, &pos, &len,
+					&opt->initrd_file))
+			goto out_err;
+		if (read_string(opt, &pos, &len,
+					&opt->boot_args))
+			goto out_err;
+	}
+
+	return dev;
+
+out_err:
+	talloc_free(dev);
+	return NULL;
+}
diff --git a/lib/pb-protocol/pb-protocol.h b/lib/pb-protocol/pb-protocol.h
new file mode 100644
index 0000000..7b557d6
--- /dev/null
+++ b/lib/pb-protocol/pb-protocol.h
@@ -0,0 +1,57 @@
+#ifndef _PB_PROTOCOL_H
+#define _PB_PROTOCOL_H
+
+#include <stdint.h>
+
+#define PB_SOCKET_PATH "/tmp/petitboot.ui"
+
+#define PB_PROTOCOL_MAX_PAYLOAD_SIZE 4096
+
+enum pb_protocol_action {
+	PB_PROTOCOL_ACTION_ADD		= 0x1,
+	PB_PROTOCOL_ACTION_REMOVE	= 0x2,
+};
+
+struct pb_protocol_message {
+	uint32_t action;
+	uint32_t payload_len;
+	char     payload[];
+};
+
+struct device {
+	char *id;
+	char *name;
+	char *description;
+	char *icon_file;
+
+	struct boot_option {
+		char *id;
+		char *name;
+		char *description;
+		char *icon_file;
+		char *boot_image_file;
+		char *initrd_file;
+		char *boot_args;
+	} *options;
+	int n_options;
+};
+
+int pb_protocol_device_len(struct device *dev);
+
+int pb_protocol_serialise_string(char *pos, const char *str);
+char *pb_protocol_deserialise_string(void *ctx,
+		struct pb_protocol_message *message);
+
+int pb_protocol_serialise_device(struct device *dev, char *buf, int buf_len);
+
+int pb_protocol_write_message(int fd, struct pb_protocol_message *message);
+
+struct pb_protocol_message *pb_protocol_create_message(void *ctx,
+		int action, int payload_len);
+
+struct pb_protocol_message *pb_protocol_read_message(void *ctx, int fd);
+
+struct device *pb_protocol_deserialise_device(void *ctx,
+		struct pb_protocol_message *message);
+
+#endif /* _PB_PROTOCOL_H */