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Re: [Minios-devel] [UNIKRAFT PATCH 3/8] lib/uk9p: Add 9P protocol core definitions



Hey Christian,

where did you get your 9PFS protocol specification from? I was wondering if you derived your names, constants and API function from there. Maybe you want to add a comment with the reference within one of the headers.

On 19.06.19 09:03, Cristian Banu wrote:
This patch adds the 9P protocol core definitions for the structures it
uses and the wire format required.

Signed-off-by: Cristian Banu <cristb@xxxxxxxxx>
---
  lib/uk9p/include/uk/9p_core.h | 249 ++++++++++++++++++++++++++++++++++++++++++
  1 file changed, 249 insertions(+)
  create mode 100644 lib/uk9p/include/uk/9p_core.h

diff --git a/lib/uk9p/include/uk/9p_core.h b/lib/uk9p/include/uk/9p_core.h
new file mode 100644
index 000000000000..8f2cdf6b2a66
--- /dev/null
+++ b/lib/uk9p/include/uk/9p_core.h
@@ -0,0 +1,249 @@
+/* SPDX-License-Identifier: BSD-3-Clause */
+/*
+ * Authors: Cristian Banu <cristb@xxxxxxxxx>
+ *
+ * Copyright (c) 2019, University Politehnica of Bucharest. All rights 
reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of the copyright holder nor the names of its
+ *    contributors may be used to endorse or promote products derived from
+ *    this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ * THIS HEADER MAY NOT BE EXTRACTED OR MODIFIED IN ANY WAY.
+ */
+
+#ifndef __UK_9P_CORE__
+#define __UK_9P_CORE__
+
+#include <string.h>

You should also include the integer definitions (uint32_t, etc.) here because you are using them in this file.

+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * 9P request types.
+ */
+enum uk_9p_type {
+       UK_9P_TVERSION          = 100,
+       UK_9P_RVERSION,
+       UK_9P_TAUTH             = 102,
+       UK_9P_RAUTH,
+       UK_9P_TATTACH           = 104,
+       UK_9P_RATTACH,
+       UK_9P_TERROR            = 106,
+       UK_9P_RERROR,
+       UK_9P_TFLUSH            = 108,
+       UK_9P_RFLUSH,
+       UK_9P_TWALK             = 110,
+       UK_9P_RWALK,
+       UK_9P_TOPEN             = 112,
+       UK_9P_ROPEN,
+       UK_9P_TCREATE           = 114,
+       UK_9P_RCREATE,
+       UK_9P_TREAD             = 116,
+       UK_9P_RREAD,
+       UK_9P_TWRITE            = 118,
+       UK_9P_RWRITE,
+       UK_9P_TCLUNK            = 120,
+       UK_9P_RCLUNK,
+       UK_9P_TREMOVE           = 122,
+       UK_9P_RREMOVE,
+       UK_9P_TSTAT             = 124,
+       UK_9P_RSTAT,
+       UK_9P_TWSTAT            = 126,
+       UK_9P_RWSTAT,
+};
+
+/**
+ * 9P values of a qid.type.
+ */
+enum uk_9p_qid_type {
+       UK_9P_QTDIR             = 0x80,
+       UK_9P_QTAPPEND          = 0x40,
+       UK_9P_QTEXCL            = 0x20,
+       UK_9P_QTMOUNT           = 0x20,
+       UK_9P_QTAUTH            = 0x08,
+       UK_9P_QTTMP             = 0x04,
+       UK_9P_QTSYMLINK         = 0x02,
+       UK_9P_QTLINK            = 0x01,
+       UK_9P_QTFILE            = 0x00,
+};

Are these values treated as bits, meaning that you can have multiple of them bitwise-ORed in a uk_9p_qid_type field? See my next comment, too.

+
+/**
+ * 9P permission bits.
+ */
+enum uk_9p_perm {
+       UK_9P_DMDIR             = 0x80000000,
+       UK_9P_DMAPPEND          = 0x40000000,
+       UK_9P_DMEXCL            = 0x20000000,
+       UK_9P_DMMOUNT           = 0x10000000,
+       UK_9P_DMAUTH            = 0x08000000,
+       UK_9P_DMTMP             = 0x04000000,
+       UK_9P_DMSYMLINK         = 0x02000000,
+       UK_9P_DMLINK            = 0x01000000,
+       UK_9P_DMDEVICE          = 0x00800000,
+       UK_9P_DMNAMEDPIPE       = 0x00200000,
+       UK_9P_DMSOCKET          = 0x00100000,
+       UK_9P_DMSETUID          = 0x00080000,
+       UK_9P_DMSETGID          = 0x00040000,
+       UK_9P_DMSETVTX          = 0x00010000,
+};

Usually, we defined bits and flags with macros and used enums when you hand-over just a single value.

+
+/**
+ * 9P open mode bits.
+ */
+enum uk_9p_open_mode {
+       UK_9P_OREAD             = 0x00,
+       UK_9P_OWRITE            = 0x01,
+       UK_9P_ORDWR             = 0x02,
+       UK_9P_OEXEC             = 0x03,
+       UK_9P_OTRUNC            = 0x10,
+       UK_9P_OREXEC            = 0x20,
+       UK_9P_ORCLOSE           = 0x40,
+       UK_9P_OAPPEND           = 0x80,
+       UK_9P_OEXCL             = 0x1000,
+};

Same here.

+
+/**
+ * 9P qid.
+ */
+struct uk_9p_qid {
+       uint8_t                 type;
+       uint32_t                version;
+       uint64_t                path;
+};
+
+/**
+ * 9P string.
+ */
+struct uk_9p_str {
+       uint16_t                size;
+       char                    *data;
+};
+
+/**
+ * Check if a 9P string is equal to a given null-terminated string.
+ *
+ * @param s
+ *   9P string.
+ * @param p
+ *   Null-terminated string.
+ * @return
+ *   1 if equal, 0 otherwise.
+ */
+static inline int uk_9p_str_equal(const struct uk_9p_str *s, const char *p)
+{
+       return strlen(p) == s->size && !strncmp(s->data, p, s->size);
+}
+
+/**
+ * Initialize a 9P string from a given null-terminated string.
+ *
+ * @param s
+ *   9P string.
+ * @param p
+ *   Null-terminated string.
+ */
+static inline void uk_9p_str_init(struct uk_9p_str *s, const char *p)
+{
+       if (!p) {
+               s->size = 0;
+               return;
+       }
+
+       s->size = strlen(p);
+       s->data = (char *)p;
+}
+
+/**
+ * 9P stat structure.
+ */
+struct uk_9p_stat {
+       uint16_t                size;
+       uint16_t                type;
+       uint32_t                dev;
+       struct uk_9p_qid        qid;
+       uint32_t                mode;
+       uint32_t                atime;
+       uint32_t                mtime;
+       uint64_t                length;
+       struct uk_9p_str        name;
+       struct uk_9p_str        uid;
+       struct uk_9p_str        gid;
+       struct uk_9p_str        muid;
+       struct uk_9p_str        extension;
+       uint32_t                n_uid;
+       uint32_t                n_gid;
+       uint32_t                n_muid;
+};

Out of curiosity: Does 9p has something like potential difference of endianess on the wire and the host?; I mean something similar to what you find in networking protocols. If this is the case, it may make sense to add a TODO comment that we are not supporting this currently.

+
+/**
+ * Initialize a 9P stat structure that won't modify any fields if sent with a
+ * WSTAT message, by setting all integer fields to ~0 and all string fields to
+ * empty strings.
+ *
+ * @param stat
+ *   The 9P stat structure.
+ */
+static inline void uk_9p_stat_init(struct uk_9p_stat *stat)
+{

Can you add an assertion to check that stat != NULL?

+       memset(stat, ~0, sizeof(struct uk_9p_stat));
+       stat->name.size = 0;
+       stat->uid.size = 0;
+       stat->gid.size = 0;
+       stat->muid.size = 0;
+       stat->extension.size = 0;
+}
+
+/**
+ * No tag, used by the Tversion/Rversion pair of request/reply messages.
+ */
+#define UK_9P_NOTAG                    UINT16_MAX

Remember to include the header that defines the limits.

+
+/**
+ * Maximum available tag for use.
+ * UK_9P_NOTAG (~0) is reserved by the 9P RFC for representing no tag.
+ */
+#define UK_9P_MAXTAG                   (UINT16_MAX - 1)
+
+/**
+ * Number of possible tags, including NOTAG.
+ */
+#define UK_9P_NUMTAGS                  ((uint32_t)(UINT16_MAX) + 1)
+
+/**
+ * No fid, used to mark a fid field as unused.
+ */
+#define UK_9P_NOFID                    UINT32_MAX
+
+/**
+ * No n_uname in TATTACH requests, used to mark the field as unused.
+ */
+#define UK_9P_NONUNAME                 UINT32_MAX
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* __UK_9P_CORE__ */


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