From: Minep <zelong56@gmail.com>
Date: Fri, 21 Oct 2022 21:52:08 +0000 (+0100)
Subject: laying out the iso9660 structure definitions
X-Git-Url: https://scm.lunaixsky.com/lunaix-os.git/commitdiff_plain/e416a48f7adc0931edfad8139671ebd8c1f089c6?ds=sidebyside

laying out the iso9660 structure definitions
fix: switch the order of hash mangling, as it gives higher empirical collision rarity.
refactor: own primitive type shadowing, will be good for future portability.
---

diff --git a/lunaix-os/includes/lunaix/fs/iso9660.h b/lunaix-os/includes/lunaix/fs/iso9660.h
new file mode 100644
index 0000000..edccadc
--- /dev/null
+++ b/lunaix-os/includes/lunaix/fs/iso9660.h
@@ -0,0 +1,176 @@
+/**
+ * @file iso9660.h
+ * @author Lunaixsky (zelong56@gmail.com)
+ * @brief ISO9660 File system header file. (Reference: ECMA-119, 4th ed.)
+ * @version 0.1
+ * @date 2022-10-03
+ *
+ * @copyright Copyright (c) 2022
+ *
+ */
+
+#ifndef __LUNAIX_ISO9660_H
+#define __LUNAIX_ISO9660_H
+
+#include <lunaix/types.h>
+
+// Volume Types
+#define ISO_VOLBOOT 0   // Boot Record
+#define ISO_VOLPRIM 1   // Primary
+#define ISO_VOLSUPP 2   // Supplementary
+#define ISO_VOLPART 3   // Partition
+#define ISO_VOLTERM 255 // Volume descriptor set terminator
+
+#define ISO_FHIDDEN 0x1   // a hidden file
+#define ISO_FDIR 0x2      // a directory file
+#define ISO_FASSOC 0x4    // a associated file
+#define ISO_FRECORD 0x8   // file store in iso record fashion
+#define ISO_FPROTECT 0x10 // file being protected by access control
+#define ISO_FEXTENTS 0x80 // the extent by this record is a file partial
+
+// NOTES:
+// Each Descriptor sized 1 logical block (2048 bytes in common cases)
+// ISO9660 store number in both-byte order. That is, for a d-bits number, it
+//   will result in 2d bits of storage. The lower d-bits are little-endian and
+//   upper d-bits are big-endian.
+
+struct iso_vol
+{
+    u8_t type;
+    u8_t std_id[5]; // CD001
+    u8_t version;
+} PACKED;
+
+struct iso_vol_boot
+{
+    struct iso_vol header;
+    u8_t sys_id[32];
+    u8_t boot_id[32];
+    u8_t reserved; // align to data line width
+} PACKED;
+
+struct iso_datetime
+{
+    u8_t year[4];
+    u8_t month[2];
+    u8_t day[2];
+    u8_t hour[2];
+    u8_t min[2];
+    u8_t sec[2];
+    u8_t ms[2];
+    u8_t gmt;
+} PACKED;
+
+// (8.4) Describe a primary volume space
+struct iso_vol_primary
+{
+    struct iso_vol header;
+    u8_t reserved_1;
+    u8_t sys_id[32];
+    u8_t vol_id[32];
+    u8_t reserved_2;
+    u32_t sz_lo; // (8.4.8) only lower portion is valid.
+    u32_t sz_hi;
+    u8_t reserved_2;
+    u32_t set_size;
+    u32_t seq_num;
+    u32_t lb_size;
+    u32_t path_tbl_sz_lo; // lower partition - LE.
+    u32_t path_tbl_sz_hi;
+    u32_t lpath_tbl_ptr; // Type L Path table location (LBA)
+    u32_t reserved_3[3]; // use type M if big endian machine.
+    u8_t root_record[34];
+    u8_t set_id[128];
+    u8_t publisher_id[128];
+    u8_t preparer_id[128];
+    u8_t app_id[128];
+    u8_t copyright_id[128];
+    u8_t asbtract_id[128];
+    u8_t bib_id[128];
+    struct iso_datetime ctime;   // creation
+    struct iso_datetime mtime;   // modification
+    struct iso_datetime ex_time; // expiration
+    struct iso_datetime ef_time; // effective
+    u8_t fstruct_ver;            // file structure version, don't care!
+} PACKED;                        // size 1124
+
+// Layout for Supplementary Vol. is almost identical to primary vol.
+// We ignore it for now. (see section 8.5, table 6)
+
+// (8.6) Describe a volume partition within a volume space
+struct iso_partition
+{
+    struct iso_vol header;
+    u8_t reserved;
+    u8_t sys_id[32];
+    u8_t part_id[32];
+    u32_t part_addr_lo; // (8.6.7) only lower portion is valid.
+    u32_t part_addr_hi;
+    u32_t part_sz_lo; // (8.6.8) only lower portion is valid.
+    u32_t part_sz_hi;
+} PACKED;
+
+// (6.10.4) MDU with variable record
+struct iso_var_mdu
+{
+    u8_t len;
+    u8_t content[0];
+} PACKED;
+
+// (9.1) Directory Record [Embedded into Variable MDU]
+struct iso_drecord
+{
+    u8_t xattr_len;
+    u32_t extent_lo; // location of extent, lower 32 bits is valid.
+    u32_t extent_hi;
+    u32_t data_sz_lo; // size of extent, lower 32 bits is valid.
+    u32_t data_sz_hi;
+    struct
+    {
+        u8_t year;
+        u8_t month;
+        u8_t hour;
+        u8_t min;
+        u8_t sec;
+        u8_t gmt;
+    } PACKED mktime; // Time the record is made, see 9.1.5
+    u8_t flags;
+    u8_t fu_sz;  // size of file unit (FU)
+    u8_t gap_sz; // size of gap if FU is interleaved.
+    u32_t vol_seq;
+    struct iso_var_mdu name;
+} PACKED;
+
+// (9.4) Path Table Record. [Embedded into Variable MDU]
+struct iso_precord
+{
+    u8_t xattr_len;
+    u32_t extent_addr;
+    u8_t parent; // indexed into path table
+    u8_t id[0];  // length = iso_var_mdu::len
+} PACKED;
+
+struct iso_xattr
+{
+    u32_t owner;
+    u32_t group;
+    u16_t perm;
+    struct iso_datetime ctime;
+    struct iso_datetime mtime;
+    struct iso_datetime ex_time;
+    struct iso_datetime ef_time;
+    u8_t record_fmt;
+    u8_t record_attr;
+    u8_t record_len;
+    u32_t sys_id;
+    u8_t reserved1[64];
+    u8_t version;
+    u8_t len_esc;
+    u8_t reserved2[64];
+    u32_t payload_sz;
+    u8_t payload[0];
+    // There is also a escape sequence after payload,
+    // It however marked as optional, hence we ignore it.
+} PACKED;
+
+#endif /* __LUNAIX_ISO9660_H */
diff --git a/lunaix-os/includes/lunaix/types.h b/lunaix-os/includes/lunaix/types.h
index fbe7e1e..1251b70 100644
--- a/lunaix-os/includes/lunaix/types.h
+++ b/lunaix-os/includes/lunaix/types.h
@@ -19,8 +19,19 @@
     ((wstatus & PEXITTERM) && ((char)WEXITSTATUS(wstatus) >= 0))
 
 #define WIFSIGNALED(wstatus) ((wstatus & PEXITSIG))
+
+#define PACKED __attribute__((packed))
+
 // TODO: WTERMSIG
 
+// TODO: replace the integer type with these. To make thing more portable.
+
+typedef unsigned char u8_t;
+typedef unsigned short u16_t;
+typedef unsigned int u32_t;
+typedef unsigned long long u64_t;
+typedef unsigned long ptr_t;
+
 typedef int32_t pid_t;
 typedef int64_t lba_t;
 
diff --git a/lunaix-os/kernel/fs/vfs.c b/lunaix-os/kernel/fs/vfs.c
index df374cd..d0fbb1c 100644
--- a/lunaix-os/kernel/fs/vfs.c
+++ b/lunaix-os/kernel/fs/vfs.c
@@ -112,10 +112,10 @@ inline struct hbucket*
 __dcache_hash(struct v_dnode* parent, uint32_t* hash)
 {
     uint32_t _hash = *hash;
-    // 与parent的指针值做加法，来减小碰撞的可能性。
-    _hash += (uint32_t)parent;
     // 确保低位更加随机
     _hash = _hash ^ (_hash >> VFS_HASHBITS);
+    // 与parent的指针值做加法，来减小碰撞的可能性。
+    _hash += (uint32_t)parent;
     *hash = _hash;
     return &dnode_cache[_hash & VFS_HASH_MASK];
 }