finish page & file

2026-06-07 01:30:35 +08:00 · 2022-05-01 17:42:11 +08:00
parent 1463c1f606
commit eda10fba91
8 changed files with 546 additions and 35 deletions
--- a/src/file.c
+++ b/src/file.c
@@ -0,0 +1,49 @@
+#include <stdint.h>
+#include <unistd.h>
+#include <sys/mman.h>
+
+#include "../include/binary.h"
+#include "../include/page.h"
+#include "../include/file.h"
+
+uint8_t header[PAGESZ] = {'F', 'U', 'M', 'I', 'D', 'B', 1, 0};
+
+int init_file_header_page(int fd) {
+    lseek(fd, 0, SEEK_SET);
+    return write(fd, header, PAGESZ) != PAGESZ;
+}
+
+uint16_t get_db_version(int fd) {
+    uint16_t v;
+    if(lseek(fd, 6, SEEK_SET) < 0) return EOF;
+    readle16(fd, v);
+    return v;
+}
+
+int set_first_unused_block(int fd, uint64_t ptr) {
+    uint8_t buf[8];
+    if(lseek(fd, 8, SEEK_SET) < 0) return EOF;
+    putle64(buf, ptr);
+    return write(fd, buf, 8) != 8;
+}
+
+uint64_t get_first_unused_block(int fd) {
+    uint64_t ptr;
+    if(lseek(fd, 8, SEEK_SET) < 0) return EOF;
+    readle64(fd, ptr);
+    return ptr;
+}
+
+int set_first_table(int fd, uint64_t ptr) {
+    uint8_t buf[8];
+    if(lseek(fd, 16, SEEK_SET) < 0) return EOF;
+    putle64(buf, ptr);
+    return write(fd, buf, 8) != 8;
+}
+
+uint64_t get_first_table(int fd) {
+    uint64_t ptr;
+    if(lseek(fd, 16, SEEK_SET) < 0) return EOF;
+    readle64(fd, ptr);
+    return ptr;
+}
--- a/src/page.c
+++ b/src/page.c
@@ -1,12 +1,11 @@
 // page.c
 // 管理文件中的空闲块

-#define _GNU_SOURCE /* See feature_test_macros(7) */
-
 #include <stdint.h>
+#include <stdlib.h>
 #include <unistd.h>
 #include <fcntl.h>
-#include <sys/mman.h>
+#include <errno.h>

 #include "../include/binary.h"
 #include "../include/page.h"
@@ -14,25 +13,239 @@
 uint8_t nullpage[PAGESZ];

 void* alloc_page(int fd) {
-    uint64_t ptr, prev_ptr = 8;
+    uint64_t ptr = 8, prev_ptr = 0, prev_prev_ptr = 0;
    void* page;
-    if(lseek(fd, 8, SEEK_SET) < 0) return EOF;
+    uint8_t buf[8];
    // 对于 page，只关心位于第一页 8~15 字节的 ptr of unused blk
-    readle64(fd, ptr);
    while(ptr) {
        if(!(ptr%PAGESZ)) { // 找到符合要求的页
-            page = mmap(NULL, PAGESZ, PROT_READ|PROT_WRITE, MAP_PRIVATE, fd, ptr);
-            if(page < 0) return page;
-            if(lseek(fd, prev_ptr, SEEK_SET) < 0) return EOF;
-            write(fd, page, 8); // 从空闲块链表移除本块
+            if(lseek(fd, ptr, SEEK_SET) < 0) return NULL;
+            if(read(fd, buf, 8) != 8) return NULL;
+            page = malloc(PAGESZ+8);
+            if(page == NULL) return NULL;
+            putle64(page, ptr);
+            page += 8;
+            if(lseek(fd, prev_ptr, SEEK_SET) < 0) return NULL;
+            if(write(fd, buf, 8) != 8) return NULL; // 从空闲块链表移除本块
            return page;
        }
+        if(prev_prev_ptr && ptr < prev_ptr) { // 不符合顺序，进行一次调整
+            lseek(fd, prev_prev_ptr, SEEK_SET);
+            putle64(buf, ptr);
+            if(write(fd, buf, 8) != 8) return NULL;   // 1->next = 3
+            if(lseek(fd, ptr, SEEK_SET) < 0) return NULL;
+            prev_prev_ptr = ptr;                            // new1 = 3
+            readle64(fd, ptr);                              // ptr(new3) = 3->next
+            lseek(fd, -8, SEEK_SET);
+            putle64(buf, prev_ptr);                         // new2 = 2
+            if(write(fd, buf, 8) != 8) return NULL;   // 3->next = 2
+            lseek(fd, prev_ptr, SEEK_SET);
+            putle64(buf, ptr);
+            if(write(fd, buf, 8) != 8) return NULL;   // 2->next = ptr
+            continue;
+        }
+        prev_prev_ptr = prev_ptr;
+        prev_ptr = ptr;
+        if(lseek(fd, ptr, SEEK_SET) < 0) return NULL;
+        readle64(fd, ptr);
+    }
+    ptr = lseek(fd, 0, SEEK_END);
+    if(ptr < 0) return NULL;
+    if(ptr%PAGESZ) { // 文件没有页对齐
+        errno = ESPIPE;
+        return NULL;
+    }
+    if(write(fd, nullpage, PAGESZ) != PAGESZ) return NULL;
+    page = malloc(PAGESZ+8);
+    if(page == NULL) return NULL;
+    putle64(page, ptr);
+    return page+8;
+}
+
+int sync_page(int fd, void* page) {
+    uint64_t ptr = le64(page-8);
+    if(lseek(fd, ptr, SEEK_SET) < 0) return EOF;
+    return write(fd, page, PAGESZ) != PAGESZ;
+}
+
+int unmount_page(int fd, void* page) {
+    int r = sync_page(fd, page);
+    free(page-8);
+    return r;
+}
+
+int free_page(int fd, void* page) {
+    uint64_t ptr = 8, prev_ptr = 0, prev_prev_ptr = 0, page_ptr = le64(page-8);
+    uint8_t buf[8];
+    while(ptr && ptr < page_ptr) {
+        if(prev_ptr == ptr) return EOF;
+        if(prev_prev_ptr && ptr < prev_ptr) { // 不符合顺序，进行一次调整
+            lseek(fd, prev_prev_ptr, SEEK_SET);
+            putle64(buf, ptr);
+            if(write(fd, buf, 8) != 8) return EOF; // 1->next = 3
+            if(lseek(fd, ptr, SEEK_SET) < 0) return EOF;
+            prev_prev_ptr = ptr;                   // new1 = 3
+            readle64(fd, ptr);                     // ptr(new3) = 3->next
+            lseek(fd, -8, SEEK_SET);
+            putle64(buf, prev_ptr);                // new2 = 2
+            if(write(fd, buf, 8) != 8) return EOF; // 3->next = 2
+            lseek(fd, prev_ptr, SEEK_SET);
+            putle64(buf, ptr);
+            if(write(fd, buf, 8) != 8) return EOF; // 2->next = ptr
+            continue;
+        }
+        prev_prev_ptr = prev_ptr;
        prev_ptr = ptr;
        if(lseek(fd, ptr, SEEK_SET) < 0) return EOF;
        readle64(fd, ptr);
    }
-    ptr = lseek(fd, 0, SEEK_END);
-    if(ptr < 0 || !(ptr%PAGESZ)) return EOF;
-    if(write(fd, nullpage, PAGESZ) != PAGESZ) return EOF;
-    return mmap(NULL, PAGESZ, PROT_READ|PROT_WRITE, MAP_PRIVATE, fd, ptr);
+    putle64(page, ptr);
+    putle16(page+8, PAGESZ);
+    putle64(buf, page_ptr);
+    lseek(fd, prev_ptr, SEEK_SET);
+    if(write(fd, buf, 8) != 8) return EOF; // 将本页附加到链表
+    sync_page(fd, page);
+    free(page-8);
+    return 0;
+}
+
+void* alloc_block(int fd, uint16_t size) {
+    uint64_t ptr = 8, prev_ptr = 0, prev_prev_ptr = 0;
+    void* blk;
+    uint8_t buf[8];
+    uint16_t blksz;
+
+    if(size > PAGESZ) return NULL;
+    // 对于 page，只关心位于第一页 8~15 字节的 ptr of unused blk
+    while(ptr) {
+        if(lseek(fd, ptr, SEEK_SET) < 0) return NULL;
+        if(read(fd, buf, 8) != 8) return NULL;
+        readle16(fd, blksz);
+        if(blksz >= size) { // 找到符合要求的块
+            blk = malloc(size+10);
+            if(blk == NULL) return NULL;
+            if(blksz - size > 10) { // 分裂块
+                lseek(fd, ptr+size, SEEK_SET);
+                write(fd, buf, 8);
+                blksz -= size;
+                putle16(buf, blksz);
+                write(fd, buf, 2);
+                putle64(buf, ptr+size);
+            }
+            putle64(blk, ptr);
+            putle16(blk+8, size);
+            blk += 10;
+            if(lseek(fd, prev_ptr, SEEK_SET) < 0) return NULL;
+            if(write(fd, buf, 8) != 8) return NULL; // 从空闲块链表移除本块
+            return blk;
+        }
+        if(prev_prev_ptr && ptr < prev_ptr) { // 不符合顺序，进行一次调整
+            lseek(fd, prev_prev_ptr, SEEK_SET);
+            putle64(buf, ptr);
+            if(write(fd, buf, 8) != 8) return NULL;   // 1->next = 3
+            if(lseek(fd, ptr, SEEK_SET) < 0) return NULL;
+            prev_prev_ptr = ptr;                            // new1 = 3
+            readle64(fd, ptr);                              // ptr(new3) = 3->next
+            lseek(fd, -8, SEEK_SET);
+            putle64(buf, prev_ptr);                         // new2 = 2
+            if(write(fd, buf, 8) != 8) return NULL;   // 3->next = 2
+            lseek(fd, prev_ptr, SEEK_SET);
+            putle64(buf, ptr);
+            if(write(fd, buf, 8) != 8) return NULL;   // 2->next = ptr
+            continue;
+        }
+        prev_prev_ptr = prev_ptr;
+        prev_ptr = ptr;
+        if(lseek(fd, ptr, SEEK_SET) < 0) return NULL;
+        readle64(fd, ptr);
+    }
+    ptr = lseek(fd, 0, SEEK_END);
+    if(ptr < 0) return NULL;
+    if(ptr%PAGESZ) { // 文件没有页对齐
+        errno = ESPIPE;
+        return NULL;
+    }
+    if(write(fd, nullpage, PAGESZ) != PAGESZ) return NULL;
+    if(PAGESZ-size > 10) { // 回收冗余
+        if(lseek(fd, prev_ptr, SEEK_SET) < 0) return NULL;
+        putle64(buf, ptr+size);
+        if(write(fd, buf, 8) != 8) return NULL;
+        if(lseek(fd, ptr+size+8, SEEK_SET) < 0) return NULL;
+        putle16(buf, PAGESZ - size);
+        if(write(fd, buf, 2) != 2) return NULL;
+    }
+    blk = malloc(size+10);
+    if(blk == NULL) return NULL;
+    putle64(blk, ptr);
+    putle16(blk+8, size);
+    return blk+10;
+}
+
+int sync_block(int fd, void* blk) {
+    uint64_t off = le64(blk-10);
+    uint16_t size = le16(blk-2);
+    if(size > PAGESZ) {
+        errno = EFBIG;
+        return EOF;
+    }
+    if(lseek(fd, off, SEEK_SET) < 0) return EOF;
+    return write(fd, blk, size) != size;
+}
+
+int unmount_block(int fd, void* blk) {
+    int r = sync_block(fd, blk);
+    free(blk-10);
+    return r;
+}
+
+int free_block(int fd, void* blk) {
+    uint64_t ptr = 8, prev_ptr = 0, prev_prev_ptr = 0, off = le64(blk-10);
+    uint8_t buf[8];
+    uint16_t size = le16(blk-2), sz;
+    while(ptr && ptr < off) {
+        if(prev_ptr == ptr) return EOF;
+        if(prev_prev_ptr && ptr < prev_ptr) { // 不符合顺序，进行一次调整
+            lseek(fd, prev_prev_ptr, SEEK_SET);
+            putle64(buf, ptr);
+            if(write(fd, buf, 8) != 8) return EOF; // 1->next = 3
+            if(lseek(fd, ptr, SEEK_SET) < 0) return EOF;
+            prev_prev_ptr = ptr;                   // new1 = 3
+            readle64(fd, ptr);                     // ptr(new3) = 3->next
+            lseek(fd, -8, SEEK_SET);
+            putle64(buf, prev_ptr);                // new2 = 2
+            if(write(fd, buf, 8) != 8) return EOF; // 3->next = 2
+            lseek(fd, prev_ptr, SEEK_SET);
+            putle64(buf, ptr);
+            if(write(fd, buf, 8) != 8) return EOF; // 2->next = ptr
+            continue;
+        }
+        prev_prev_ptr = prev_ptr;
+        prev_ptr = ptr;
+        if(lseek(fd, ptr, SEEK_SET) < 0) return EOF;
+        readle64(fd, ptr);
+    }
+    putle64(blk, ptr);
+    putle16(blk+8, size);
+    putle64(buf, off);
+    lseek(fd, prev_ptr, SEEK_SET);
+    if(write(fd, buf, 8) != 8) return EOF; // 将本页附加到链表
+    readle16(fd, sz);
+    if(prev_ptr+sz == off && prev_ptr%PAGESZ < off%PAGESZ) { // 可以和前一块合并
+        lseek(fd, prev_ptr, SEEK_SET);
+        write(fd, blk, 8);
+        putle16(buf, size+sz);
+        write(fd, buf, 2);
+        free(blk-10);
+        return 0;
+    }
+    if(off+size == ptr && off%PAGESZ < ptr%PAGESZ) { // 可以和后一块合并
+        if(lseek(fd, ptr, SEEK_SET) < 0) return EOF;
+        readle64(fd, prev_ptr);
+        readle16(fd, sz);
+        putle64(blk, prev_ptr);
+        putle16(blk, size+sz);
+    }
+    sync_block(fd, blk);
+    free(blk-10);
+    return 0;
 }