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add page

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源文雨
2022-05-01 01:19:38 +08:00
parent f4fad55ca4
commit 1463c1f606
8 changed files with 151 additions and 9 deletions
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66
src/binary.h
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@@ -1,66 +0,0 @@
#include <stdio.h>
#include <stdint.h>
#include <stdlib.h>
#ifdef __linux__
# include <endian.h>
#endif
#ifdef __FreeBSD__
# include <sys/endian.h>
#endif
#ifdef __NetBSD__
# include <sys/endian.h>
#endif
#ifdef __OpenBSD__
# include <sys/types.h>
# define be16toh(x) betoh16(x)
# define be32toh(x) betoh32(x)
# define be64toh(x) betoh64(x)
#endif
#ifdef __MAC_10_0
# define be16toh(x) ntohs(x)
# define be32toh(x) ntohl(x)
# define be64toh(x) ntohll(x)
# define htobe16(x) ntohs(x)
# define htobe32(x) htonl(x)
# define htobe64(x) htonll(x)
#endif
#ifdef _WIN64
#ifdef WORDS_BIGENDIAN
# define be16toh(x) (x)
# define be32toh(x) (x)
# define be64toh(x) (x)
# define htobe16(x) (x)
# define htobe32(x) (x)
# define htobe64(x) (x)
#else
# define be16toh(x) _byteswap_ushort(x)
# define be32toh(x) _byteswap_ulong(x)
# define be64toh(x) _byteswap_uint64(x)
# define htobe16(x) _byteswap_ushort(x)
# define htobe32(x) _byteswap_ulong(x)
# define htobe64(x) _byteswap_uint64(x)
#endif
#endif
#ifdef _WIN64
#ifdef WORDS_BIGENDIAN
#define putle16(buf, x) (*(uint16_t*)(buf) = _byteswap_ushort((uint16_t)(x)))
#define putle32(buf, x) (*(uint32_t*)(buf) = _byteswap_ulong((uint32_t)(x)))
#define putle64(buf, x) (*(uint64_t*)(buf) = _byteswap_uint64((uint64_t)(x)))
#else
#define putle16(buf, x) (*(uint16_t*)(buf) = (uint16_t)(x))
#define putle32(buf, x) (*(uint32_t*)(buf) = (uint32_t)(x))
#define putle64(buf, x) (*(uint64_t*)(buf) = (uint64_t)(x))
#endif
#else
#ifdef WORDS_BIGENDIAN
#define putle16(buf, x) (*(uint16_t*)(buf) = __builtin_bswap16((uint16_t)(x)))
#define putle32(buf, x) (*(uint32_t*)(buf) = __builtin_bswap32((uint32_t)(x)))
#define putle64(buf, x) (*(uint64_t*)(buf) = __builtin_bswap64((uint64_t)(x)))
#else
#define putle16(buf, x) (*(uint16_t*)(buf) = (uint16_t)(x))
#define putle32(buf, x) (*(uint32_t*)(buf) = (uint32_t)(x))
#define putle64(buf, x) (*(uint64_t*)(buf) = (uint64_t)(x))
#endif
#endif

38
src/page.c Normal file
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// page.c
// 管理文件中的空闲块
#define _GNU_SOURCE /* See feature_test_macros(7) */
#include <stdint.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/mman.h>
#include "../include/binary.h"
#include "../include/page.h"
uint8_t nullpage[PAGESZ];
void* alloc_page(int fd) {
uint64_t ptr, prev_ptr = 8;
void* page;
if(lseek(fd, 8, SEEK_SET) < 0) return EOF;
// 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
return page;
}
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);
}