redis并未使用C语言提供的传统字符串表示，而是使用了自定义的简单字符串（SDS），本文所有的源码解析均基于6.0.8版本，大家可以直接到github上下载。sds数据结构相关实现源码位于sds.h 及sds.c两个文件中。
- SDS结构定义
在3.2版本前，redis只提供了一种SDS结构，3.2版本后，sds.h中的源码改成了这个样子，，，
/* Note: sdshdr5 is never used, we just access the flags byte directly.
* However is here to document the layout of type 5 SDS strings. */
struct __attribute__ ((__packed__)) sdshdr5 {
unsigned char flags; /* 3 lsb of type, and 5 msb of string length */
char buf[];
};
struct __attribute__ ((__packed__)) sdshdr8 {
uint8_t len; /* used */
uint8_t alloc; /* excluding the header and null terminator */
unsigned char flags; /* 3 lsb of type, 5 unused bits */
char buf[];
};
struct __attribute__ ((__packed__)) sdshdr16 {
uint16_t len; /* used */
uint16_t alloc; /* excluding the header and null terminator */
unsigned char flags; /* 3 lsb of type, 5 unused bits */
char buf[];
};
struct __attribute__ ((__packed__)) sdshdr32 {
uint32_t len; /* used */
uint32_t alloc; /* excluding the header and null terminator */
unsigned char flags; /* 3 lsb of type, 5 unused bits */
char buf[];
};
struct __attribute__ ((__packed__)) sdshdr64 {
uint64_t len; /* used */
uint64_t alloc; /* excluding the header and null terminator */
unsigned char flags; /* 3 lsb of type, 5 unused bits */
char buf[];
};
根据存储内容的不同redis会从上面不同的数据结构中选择最合适的一个最为数据结构。除了sdshdr5，其他struct里均定义了len、alloc、flags以及buf数组。其中：
- len记录当前字节数组的长度（不包括\0），使得获取字符串长度的时间复杂度由O(N)变为了O(1)
- alloc记录了当前字节数组总共分配的内存大小（不包括\0）
- flags记录了当前字节数组的属性、用来标识到底是sdshdr8还是sdshdr16等
- buf保存了字符串真正的值以及末尾的一个\0
- 在c语言体系中，结构体理论上各个成员在内存中是连续存储的，但是为了提高寻址效率，c语言默认开启内存对齐，讲每个成员尽量放在一个步长内存储，避免跨步长存储，
__attribute__ ((__packed__))取消了c语言的内存对齐，这样会节省一些内存。
sds.h带注释:
#ifndef __SDS_H
#define __SDS_H
#define SDS_MAX_PREALLOC (1024*1024)
extern const char *SDS_NOINIT;
#include
#include
#include
// char*的别名
typedef char *sds;
// sds有五种，后边的数字对应于字符串的最大长度,例如sdshdr8对应于1<<8=256
// __attribute__ ((__packed__))解除c语言的自动对齐，采用紧凑编码
struct __attribute__ ((__packed__)) sdshdr5 {
unsigned char flags; /* 3 lsb of type, and 5 msb of string length */
char buf[];
};
struct __attribute__ ((__packed__)) sdshdr8 {
uint8_t len; //不算\0的长度
uint8_t alloc; //记录字节数组总共分配的内存大小，不包括\0
unsigned char flags; //记录当前字节数组的属性，用来标记是sdshdr8还是dsdhdr16等* 3 lsb of type, 5 unused bits */
char buf[]; //char[]数组，用来存储字符串要保存的内容加上一个空字符'\0',加入'\0’之后方便直接复用c语言函数库的某些函数
};
struct __attribute__ ((__packed__)) sdshdr16 {
uint16_t len; /* used */
uint16_t alloc; /* excluding the header and null terminator */
unsigned char flags; /* 3 lsb of type, 5 unused bits */
char buf[];
};
struct __attribute__ ((__packed__)) sdshdr32 {
uint32_t len; /* used */
uint32_t alloc; /* excluding the header and null terminator */
unsigned char flags; /* 3 lsb of type, 5 unused bits */
char buf[];
};
struct __attribute__ ((__packed__)) sdshdr64 {
uint64_t len; /* used */
uint64_t alloc; /* excluding the header and null terminator */
unsigned char flags; /* 3 lsb of type, 5 unused bits */
char buf[];
};
// flags值的定义
#define SDS_TYPE_5 0
#define SDS_TYPE_8 1
#define SDS_TYPE_16 2
#define SDS_TYPE_32 3
#define SDS_TYPE_64 4
#define SDS_TYPE_MASK 7
#define SDS_TYPE_BITS 3
// 通过buf获取结构体指针sh
#define SDS_HDR_VAR(T,s) struct sdshdr##T *sh = (void*)((s)-(sizeof(struct sdshdr##T)));
/*返回sds内容的地址*/
#define SDS_HDR(T,s) ((struct sdshdr##T *)((s)-(sizeof(struct sdshdr##T))))
#define SDS_TYPE_5_LEN(f) ((f)>>SDS_TYPE_BITS)
//返回通过结构体的len属性值，即字符串长度
static inline size_t sdslen(const sds s) {
/*struct内容是紧凑的，所以当我们取到字符串的内容(struct中的buf[])时，指针后退1位就是它的类型*/
unsigned char flags = s[-1];
switch(flags&SDS_TYPE_MASK) {
case SDS_TYPE_5:
return SDS_TYPE_5_LEN(flags);
case SDS_TYPE_8:
return SDS_HDR(8,s)->len;
case SDS_TYPE_16:
return SDS_HDR(16,s)->len;
case SDS_TYPE_32:
return SDS_HDR(32,s)->len;
case SDS_TYPE_64:
return SDS_HDR(64,s)->len;
}
return 0;
}
// 返回sds目前可用的空间字节数
static inline size_t sdsavail(const sds s) {
unsigned char flags = s[-1];
switch(flags&SDS_TYPE_MASK) {
case SDS_TYPE_5: {
return 0;
}
case SDS_TYPE_8: {
SDS_HDR_VAR(8,s);
return sh->alloc - sh->len;
}
case SDS_TYPE_16: {
SDS_HDR_VAR(16,s);
return sh->alloc - sh->len;
}
case SDS_TYPE_32: {
SDS_HDR_VAR(32,s);
return sh->alloc - sh->len;
}
case SDS_TYPE_64: {
SDS_HDR_VAR(64,s);
return sh->alloc - sh->len;
}
}
return 0;
}
// 设置目前存储数据的字节长度
static inline void sdssetlen(sds s, size_t newlen) {
unsigned char flags = s[-1];
switch(flags&SDS_TYPE_MASK) {
case SDS_TYPE_5:
{
unsigned char *fp = ((unsigned char*)s)-1;
*fp = SDS_TYPE_5 | (newlen << SDS_TYPE_BITS);
}
break;
case SDS_TYPE_8:
SDS_HDR(8,s)->len = newlen;
break;
case SDS_TYPE_16:
SDS_HDR(16,s)->len = newlen;
break;
case SDS_TYPE_32:
SDS_HDR(32,s)->len = newlen;
break;
case SDS_TYPE_64:
SDS_HDR(64,s)->len = newlen;
break;
}
}
/*sds存储的字符串长度 + inc*/
static inline void sdsinclen(sds s, size_t inc) {
unsigned char flags = s[-1];
switch(flags&SDS_TYPE_MASK) {
case SDS_TYPE_5:
{
unsigned char *fp = ((unsigned char*)s)-1;
unsigned char newlen = SDS_TYPE_5_LEN(flags)+inc;
*fp = SDS_TYPE_5 | (newlen << SDS_TYPE_BITS);
}
break;
case SDS_TYPE_8:
SDS_HDR(8,s)->len += inc;
break;
case SDS_TYPE_16:
SDS_HDR(16,s)->len += inc;
break;
case SDS_TYPE_32:
SDS_HDR(32,s)->len += inc;
break;
case SDS_TYPE_64:
SDS_HDR(64,s)->len += inc;
break;
}
}
/* sdsalloc() = sdsavail() + sdslen() 获取结构体alloc */
static inline size_t sdsalloc(const sds s) {
unsigned char flags = s[-1];
switch(flags&SDS_TYPE_MASK) {
case SDS_TYPE_5:
return SDS_TYPE_5_LEN(flags);
case SDS_TYPE_8:
return SDS_HDR(8,s)->alloc;
case SDS_TYPE_16:
return SDS_HDR(16,s)->alloc;
case SDS_TYPE_32:
return SDS_HDR(32,s)->alloc;
case SDS_TYPE_64:
return SDS_HDR(64,s)->alloc;
}
return 0;
}
/* 设置字节数组总大小 */
static inline void sdssetalloc(sds s, size_t newlen) {
unsigned char flags = s[-1];
switch(flags&SDS_TYPE_MASK) {
case SDS_TYPE_5:
/* Nothing to do, this type has no total allocation info. */
break;
case SDS_TYPE_8:
SDS_HDR(8,s)->alloc = newlen;
break;
case SDS_TYPE_16:
SDS_HDR(16,s)->alloc = newlen;
break;
case SDS_TYPE_32:
SDS_HDR(32,s)->alloc = newlen;
break;
case SDS_TYPE_64:
SDS_HDR(64,s)->alloc = newlen;
break;
}
}
sds sdsnewlen(const void *init, size_t initlen);
sds sdsnew(const char *init);
sds sdsempty(void);
sds sdsdup(const sds s);
void sdsfree(sds s);
sds sdsgrowzero(sds s, size_t len);
sds sdscatlen(sds s, const void *t, size_t len);
sds sdscat(sds s, const char *t);
sds sdscatsds(sds s, const sds t);
sds sdscpylen(sds s, const char *t, size_t len);
sds sdscpy(sds s, const char *t);
sds sdscatvprintf(sds s, const char *fmt, va_list ap);
#ifdef __GNUC__
sds sdscatprintf(sds s, const char *fmt, ...)
__attribute__((format(printf, 2, 3)));
#else
sds sdscatprintf(sds s, const char *fmt, ...);
#endif
sds sdscatfmt(sds s, char const *fmt, ...);
sds sdstrim(sds s, const char *cset);
void sdsrange(sds s, ssize_t start, ssize_t end);
void sdsupdatelen(sds s);
void sdsclear(sds s);
int sdscmp(const sds s1, const sds s2);
sds *sdssplitlen(const char *s, ssize_t len, const char *sep, int seplen, int *count);
void sdsfreesplitres(sds *tokens, int count);
void sdstolower(sds s);
void sdstoupper(sds s);
sds sdsfromlonglong(long long value);
sds sdscatrepr(sds s, const char *p, size_t len);
sds *sdssplitargs(const char *line, int *argc);
sds sdsmapchars(sds s, const char *from, const char *to, size_t setlen);
sds sdsjoin(char **argv, int argc, char *sep);
sds sdsjoinsds(sds *argv, int argc, const char *sep, size_t seplen);
/* Low level functions exposed to the user API */
sds sdsMakeRoomFor(sds s, size_t addlen);
void sdsIncrLen(sds s, ssize_t incr);
sds sdsRemoveFreeSpace(sds s);
size_t sdsAllocSize(sds s);
void *sdsAllocPtr(sds s);
/* Export the allocator used by SDS to the program using SDS.
* Sometimes the program SDS is linked to, may use a different set of
* allocators, but may want to allocate or free things that SDS will
* respectively free or allocate. */
void *sds_malloc(size_t size);
void *sds_realloc(void *ptr, size_t size);
void sds_free(void *ptr);
#ifdef REDIS_TEST
int sdsTest(int argc, char *argv[]);
#endif
#endif
sds.c带注释
/* SDSLib 2.0 -- A C dynamic strings library
*
* Copyright (c) 2006-2015, Salvatore Sanfilippo
* Copyright (c) 2015, Oran Agra
* Copyright (c) 2015, Redis Labs, Inc
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* * Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
* * 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.
* * Neither the name of Redis 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 OWNER 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.
*/
#include
#include
#include
#include
#include
#include
#include "sds.h"
#include "sdsalloc.h"
const char *SDS_NOINIT = "SDS_NOINIT";
//根据sds类型获取对应结构的内存容量
static inline int sdsHdrSize(char type) {
switch(type&SDS_TYPE_MASK) {
case SDS_TYPE_5:
return sizeof(struct sdshdr5);
case SDS_TYPE_8:
return sizeof(struct sdshdr8);
case SDS_TYPE_16:
return sizeof(struct sdshdr16);
case SDS_TYPE_32:
return sizeof(struct sdshdr32);
case SDS_TYPE_64:
return sizeof(struct sdshdr64);
}
return 0;
}
//根据数据大小获取对应的sds类型
static inline char sdsReqType(size_t string_size) {
if (string_size < 1<<5) //32
return SDS_TYPE_5;
if (string_size < 1<<8) //256
return SDS_TYPE_8;
if (string_size < 1<<16) //65536bit 64k
return SDS_TYPE_16;
#if (LONG_MAX == LLONG_MAX)
if (string_size < 1ll<<32)
return SDS_TYPE_32;
return SDS_TYPE_64;
#else
return SDS_TYPE_32; //4GB
#endif
}
/* Create a new sds string with the content specified by the 'init' pointer
* and 'initlen'.
* If NULL is used for 'init' the string is initialized with zero bytes.
* If SDS_NOINIT is used, the buffer is left uninitialized;
*
* The string is always null-termined (all the sds strings are, always) so
* even if you create an sds string with:
*
* mystring = sdsnewlen("abc",3);
*
* You can print the string with printf() as there is an implicit \0 at the
* end of the string. However the string is binary safe and can contain
* \0 characters in the middle, as the length is stored in the sds header. */
/*创建一个新的sds*/
sds sdsnewlen(const void *init, size_t initlen) {
void *sh;
sds s;
// 根据initlen决定创建哪种sds结构(struct的flags)
char type = sdsReqType(initlen);
// 空字符串使用sdshdr8而不是sdshdr5
if (type == SDS_TYPE_5 && initlen == 0) type = SDS_TYPE_8;
// sizeof(struct type)
int hdrlen = sdsHdrSize(type);
/* flags pointer. */
unsigned char *fp;
/* 申请 sdshdr初始化大小 + 字符串长度 + 1大小的存储空间 */
sh = s_malloc(hdrlen+initlen+1);
if (sh == NULL) return NULL;
/* init == "SDS_NOINIT" 直接复制null */
if (init==SDS_NOINIT)
init = NULL;
else if (!init)
/* 初始化内存空间 */
memset(sh, 0, hdrlen+initlen+1);
s = (char*)sh+hdrlen; // buf[]头地址指针
fp = ((unsigned char*)s)-1; // struct紧凑存储，buf指针前一即为flags地址
switch(type) {
case SDS_TYPE_5: {
*fp = type | (initlen << SDS_TYPE_BITS);
break;
}
case SDS_TYPE_8: {
SDS_HDR_VAR(8,s); //根据buf[0]获取到struct sds##T指针赋值给sh
sh->len = initlen; //设置len
sh->alloc = initlen; // 设置alloc
*fp = type; //设置type
break;
}
case SDS_TYPE_16: {
SDS_HDR_VAR(16,s);
sh->len = initlen;
sh->alloc = initlen;
*fp = type;
break;
}
case SDS_TYPE_32: {
SDS_HDR_VAR(32,s);
sh->len = initlen;
sh->alloc = initlen;
*fp = type;
break;
}
case SDS_TYPE_64: {
SDS_HDR_VAR(64,s);
sh->len = initlen;
sh->alloc = initlen;
*fp = type;
break;
}
}
if (initlen && init)
memcpy(s, init, initlen); // 把init的initlen个字节复制到存储区s
s[initlen] = '\0'; //最后一位设为\0
return s;
}
// 创建一个空sds，len=0
sds sdsempty(void) {
return sdsnewlen("",0);
}
// 创建一个包含指定字符串的sds
sds sdsnew(const char *init) {
size_t initlen = (init == NULL) ? 0 : strlen(init);
return sdsnewlen(init, initlen);
}
// 创建一个给定sds 的副本
sds sdsdup(const sds s) {
return sdsnewlen(s, sdslen(s));
}
// 释放给定的sds
void sdsfree(sds s) {
if (s == NULL) return;
s_free((char*)s-sdsHdrSize(s[-1]));
}
// 设置s所在sds##T结构体的len属性为s从头到第一个'\0'的长度(不包括'\0'在内)
void sdsupdatelen(sds s) {
size_t reallen = strlen(s);
sdssetlen(s, reallen);
}
/* 清空sds保存的字符串，将len设为0，s[0]='\0' */
void sdsclear(sds s) {
sdssetlen(s, 0);
s[0] = '\0';
}
/* Enlarge the free space at the end of the sds string so that the caller
* is sure that after calling this function can overwrite up to addlen
* bytes after the end of the string, plus one more byte for nul term.
*
* Note: this does not change the *length* of the sds string as returned
* by sdslen(), but only the free buffer space we have. */
/* 开辟额外空间，保证追加操作 */
sds sdsMakeRoomFor(sds s, size_t addlen) {
void *sh, *newsh;
size_t avail = sdsavail(s); // 可用空间长度 alloc-len
size_t len, newlen;
char type, oldtype = s[-1] & SDS_TYPE_MASK;
int hdrlen;
/* 如果空间足够直接返回 */
if (avail >= addlen) return s;
len = sdslen(s); // 获取s长度
sh = (char*)s-sdsHdrSize(oldtype); // 获取s所在的结构体的指针
newlen = (len+addlen);
if (newlen < SDS_MAX_PREALLOC) // 如果需要分配的内存小于1024*1024（1M）就分配两倍内存
newlen *= 2;
else
newlen += SDS_MAX_PREALLOC; // 大于1M分配就分配len+1M
type = sdsReqType(newlen); // 获取新字符串的SDS类型
/* Don't use type 5: the user is appending to the string and type 5 is
* not able to remember empty space, so sdsMakeRoomFor() must be called
* at every appending operation. */
if (type == SDS_TYPE_5) type = SDS_TYPE_8;
hdrlen = sdsHdrSize(type); // 新的SDS类型的初始化内存大小
if (oldtype==type) { //类型未改变
// 在原有基础上realloc，sh为需要分配的内存空间指针，新大小为hdrlen+newlen+1
newsh = s_realloc(sh, hdrlen+newlen+1);
if (newsh == NULL) return NULL;
s = (char*)newsh+hdrlen;
} else {
/* SDS类型改变后，s前面的部分size就改变了，因此需要重新分配内存，不能复用 */
newsh = s_malloc(hdrlen+newlen+1); // 类型发生变化需要重新malloc
if (newsh == NULL) return NULL;
memcpy((char*)newsh+hdrlen, s, len+1); // 将老字符串拷贝到新的内存快中
s_free(sh); // 释放源字符串的内存
s = (char*)newsh+hdrlen;
s[-1] = type; // 设置sds->flags
sdssetlen(s, len); // 设置 sds->len
}
sdssetalloc(s, newlen); // 设置 sds->alloc
return s;
}
/* Reallocate the sds string so that it has no free space at the end. The
* contained string remains not altered, but next concatenation operations
* will require a reallocation.
*
* After the call, the passed sds string is no longer valid and all the
* references must be substituted with the new pointer returned by the call. */
/* */
sds sdsRemoveFreeSpace(sds s) {
void *sh, *newsh;
char type, oldtype = s[-1] & SDS_TYPE_MASK;
int hdrlen, oldhdrlen = sdsHdrSize(oldtype);
size_t len = sdslen(s);
size_t avail = sdsavail(s);
sh = (char*)s-oldhdrlen;
/* Return ASAP if there is no space left. */
if (avail == 0) return s;
/* Check what would be the minimum SDS header that is just good enough to
* fit this string. */
type = sdsReqType(len);
hdrlen = sdsHdrSize(type);
/* If the type is the same, or at least a large enough type is still
* required, we just realloc(), letting the allocator to do the copy
* only if really needed. Otherwise if the change is huge, we manually
* reallocate the string to use the different header type. */
if (oldtype==type || type > SDS_TYPE_8) {
newsh = s_realloc(sh, oldhdrlen+len+1);
if (newsh == NULL) return NULL;
s = (char*)newsh+oldhdrlen;
} else {
newsh = s_malloc(hdrlen+len+1);
if (newsh == NULL) return NULL;
memcpy((char*)newsh+hdrlen, s, len+1);
s_free(sh);
s = (char*)newsh+hdrlen;
s[-1] = type;
sdssetlen(s, len);
}
sdssetalloc(s, len);
return s;
}
/* Return the total size of the allocation of the specified sds string,
* including:
* 1) The sds header before the pointer.
* 2) The string.
* 3) The free buffer at the end if any.
* 4) The implicit null term.
*/
size_t sdsAllocSize(sds s) {
size_t alloc = sdsalloc(s);
return sdsHdrSize(s[-1])+alloc+1;
}
/* Return the pointer of the actual SDS allocation (normally SDS strings
* are referenced by the start of the string buffer). */
void *sdsAllocPtr(sds s) {
return (void*) (s-sdsHdrSize(s[-1]));
}
/* Increment the sds length and decrements the left free space at the
* end of the string according to 'incr'. Also set the null term
* in the new end of the string.
*
* This function is used in order to fix the string length after the
* user calls sdsMakeRoomFor(), writes something after the end of
* the current string, and finally needs to set the new length.
*
* Note: it is possible to use a negative increment in order to
* right-trim the string.
*
* Usage example:
*
* Using sdsIncrLen() and sdsMakeRoomFor() it is possible to mount the
* following schema, to cat bytes coming from the kernel to the end of an
* sds string without copying into an intermediate buffer:
*
* oldlen = sdslen(s);
* s = sdsMakeRoomFor(s, BUFFER_SIZE);
* nread = read(fd, s+oldlen, BUFFER_SIZE);
* ... check for nread <= 0 and handle it ...
* sdsIncrLen(s, nread);
*/
void sdsIncrLen(sds s, ssize_t incr) {
unsigned char flags = s[-1]; // SDS类型
size_t len;
switch(flags&SDS_TYPE_MASK) {
case SDS_TYPE_5: {
unsigned char *fp = ((unsigned char*)s)-1;
unsigned char oldlen = SDS_TYPE_5_LEN(flags);
assert((incr > 0 && oldlen+incr < 32) || (incr < 0 && oldlen >= (unsigned int)(-incr)));
*fp = SDS_TYPE_5 | ((oldlen+incr) << SDS_TYPE_BITS);
len = oldlen+incr;
break;
}
case SDS_TYPE_8: {
SDS_HDR_VAR(8,s); // 获取指向结构体的指针
assert((incr >= 0 && sh->alloc-sh->len >= incr) || (incr < 0 && sh->len >= (unsigned int)(-incr)));
len = (sh->len += incr); // 新的len
break;
}
case SDS_TYPE_16: {
SDS_HDR_VAR(16,s);
assert((incr >= 0 && sh->alloc-sh->len >= incr) || (incr < 0 && sh->len >= (unsigned int)(-incr)));
len = (sh->len += incr);
break;
}
case SDS_TYPE_32: {
SDS_HDR_VAR(32,s);
assert((incr >= 0 && sh->alloc-sh->len >= (unsigned int)incr) || (incr < 0 && sh->len >= (unsigned int)(-incr)));
len = (sh->len += incr);
break;
}
case SDS_TYPE_64: {
SDS_HDR_VAR(64,s);
assert((incr >= 0 && sh->alloc-sh->len >= (uint64_t)incr) || (incr < 0 && sh->len >= (uint64_t)(-incr)));
len = (sh->len += incr);
break;
}
default: len = 0; /* Just to avoid compilation warnings. */
}
s[len] = '\0';
}
/* 用空字符将sds扩展到指定长度，如果要扩展的长度小于s的长度，直接返回*/
sds sdsgrowzero(sds s, size_t len) {
size_t curlen = sdslen(s); // 未扩展前s长度
if (len <= curlen) return s; // 如果要扩展的长度小于s的长度，直接返回
s = sdsMakeRoomFor(s,len-curlen); /* 开辟额外空间，保证追加操作 */
if (s == NULL) return NULL;
/* Make sure added region doesn't contain garbage */
memset(s+curlen,0,(len-curlen+1)); // 将s+curlen地址开始的字符串，用0填充， 包括结尾的\0 */
sdssetlen(s, len); // 将SDS的len成员设置为新的len
return s;
}
/* Append the specified binary-safe string pointed by 't' of 'len' bytes to the
* end of the specified sds string 's'.
*
* After the call, the passed sds string is no longer valid and all the
* references must be substituted with the new pointer returned by the call. */
sds sdscatlen(sds s, const void *t, size_t len) {
size_t curlen = sdslen(s); // 获取当前字符串长度
s = sdsMakeRoomFor(s,len);
if (s == NULL) return NULL;
memcpy(s+curlen, t, len); // 内存拷贝
sdssetlen(s, curlen+len); // 设置sds的len
s[curlen+len] = '\0'; // 在buf的末尾追加一个\0
return s;
}
/* Append the specified null termianted C string to the sds string 's'.
*
* After the call, the passed sds string is no longer valid and all the
* references must be substituted with the new pointer returned by the call. */
// 将给定字符串拼接到s的末尾
sds sdscat(sds s, const char *t) {
return sdscatlen(s, t, strlen(t));
}
/* Append the specified sds 't' to the existing sds 's'.
*
* After the call, the modified sds string is no longer valid and all the
* references must be substituted with the new pointer returned by the call. */
// 将给定sds拼接到另一个sds s的末尾
sds sdscatsds(sds s, const sds t) {
return sdscatlen(s, t, sdslen(t));
}
/* Destructively modify the sds string 's' to hold the specified binary
* safe string pointed by 't' of length 'len' bytes. */
sds sdscpylen(sds s, const char *t, size_t len) {
if (sdsalloc(s) < len) {
s = sdsMakeRoomFor(s,len-sdslen(s));
if (s == NULL) return NULL;
}
memcpy(s, t, len);
s[len] = '\0';
sdssetlen(s, len);
return s;
}
/* 将给定字符串复制到s所在的SDS中，覆盖原有内容 */
sds sdscpy(sds s, const char *t) {
return sdscpylen(s, t, strlen(t));
}
/* Helper for sdscatlonglong() doing the actual number -> string
* conversion. 's' must point to a string with room for at least
* SDS_LLSTR_SIZE bytes.
*
* The function returns the length of the null-terminated string
* representation stored at 's'. */
#define SDS_LLSTR_SIZE 21
int sdsll2str(char *s, long long value) {
char *p, aux;
unsigned long long v;
size_t l;
/* Generate the string representation, this method produces
* an reversed string. */
v = (value < 0) ? -value : value;
p = s;
do {
*p++ = '0'+(v%10);
v /= 10;
} while(v);
if (value < 0) *p++ = '-';
/* Compute length and add null term. */
l = p-s;
*p = '\0';
/* Reverse the string. */
p--;
while(s < p) {
aux = *s;
*s = *p;
*p = aux;
s++;
p--;
}
return l;
}
/* Identical sdsll2str(), but for unsigned long long type. */
int sdsull2str(char *s, unsigned long long v) {
char *p, aux;
size_t l;
/* Generate the string representation, this method produces
* an reversed string. */
p = s;
do {
*p++ = '0'+(v%10);
v /= 10;
} while(v);
/* Compute length and add null term. */
l = p-s;
*p = '\0';
/* Reverse the string. */
p--;
while(s < p) {
aux = *s;
*s = *p;
*p = aux;
s++;
p--;
}
return l;
}
/* Create an sds string from a long long value. It is much faster than:
*
* sdscatprintf(sdsempty(),"%lld\n", value);
*/
// 获取long long 类型的value的字符串类型
sds sdsfromlonglong(long long value) {
char buf[SDS_LLSTR_SIZE];
int len = sdsll2str(buf,value);
return sdsnewlen(buf,len);
}
/* Like sdscatprintf() but gets va_list instead of being variadic. */
/*
* fmt：格式化字符串，如"%d %s"
*
*/
sds sdscatvprintf(sds s, const char *fmt, va_list ap) {
va_list cpy;
char staticbuf[1024], *buf = staticbuf, *t;
size_t buflen = strlen(fmt)*2;
// 如果buflen大于staticbuf，那么不要staticbuf
if (buflen > sizeof(staticbuf)) {
buf = s_malloc(buflen); // 重新分配内存给buf
if (buf == NULL) return NULL;
} else {
buflen = sizeof(staticbuf);
}
/* Try with buffers two times bigger every time we fail to
* fit the string in the current buffer size. */
while(1) {
buf[buflen-2] = '\0'; // 用来判断之后的buf是否超出范围
va_copy(cpy,ap); // 将可变参数ap复制到cpy
vsnprintf(buf, buflen, fmt, cpy); // 根据格式化字符串fmt，格式化cpy，并输出到buf数组，长度为buflen
va_end(cpy); // 释放相应资源，结束对ap的操作
if (buf[buflen-2] != '\0') { // 复制到buf的内容超过buf的范围
if (buf != staticbuf) s_free(buf); // 释放无用内存
buflen *= 2;
buf = s_malloc(buflen); // 重新分配buf内存空间
if (buf == NULL) return NULL; // 分配失败返回null
continue; // 循环直到可以容纳所有的ap参数
}
break;
}
/* Finally concat the obtained string to the SDS string and return it. */
t = sdscat(s, buf);
if (buf != staticbuf) s_free(buf);
return t;
}
/* Append to the sds string 's' a string obtained using printf-alike format
* specifier.
*
* After the call, the modified sds string is no longer valid and all the
* references must be substituted with the new pointer returned by the call.
*
* Example:
*
* s = sdsnew("Sum is: ");
* s = sdscatprintf(s,"%d+%d = %d",a,b,a+b).
*
* Often you need to create a string from scratch with the printf-alike
* format. When this is the need, just use sdsempty() as the target string:
*
* s = sdscatprintf(sdsempty(), "... your format ...", args);
*/
sds sdscatprintf(sds s, const char *fmt, ...) {
va_list ap;
char *t;
va_start(ap, fmt); // 初始化变量，ap指向最后一个固定参数
t = sdscatvprintf(s,fmt,ap);
va_end(ap); // 释放资源
return t;
}
/* This function is similar to sdscatprintf, but much faster as it does
* not rely on sprintf() family functions implemented by the libc that
* are often very slow. Moreover directly handling the sds string as
* new data is concatenated provides a performance improvement.
*
* However this function only handles an incompatible subset of printf-alike
* format specifiers:
*
* %s - C String
* %S - SDS string
* %i - signed int
* %I - 64 bit signed integer (long long, int64_t)
* %u - unsigned int
* %U - 64 bit unsigned integer (unsigned long long, uint64_t)
* %% - Verbatim "%" character.
*/
sds sdscatfmt(sds s, char const *fmt, ...) {
size_t initlen = sdslen(s);
const char *f = fmt;
long i;
va_list ap;
/* To avoid continuous reallocations, let's start with a buffer that
* can hold at least two times the format string itself. It's not the
* best heuristic but seems to work in practice. */
s = sdsMakeRoomFor(s, initlen + strlen(fmt)*2);
va_start(ap,fmt);
f = fmt; /* Next format specifier byte to process. */
i = initlen; /* Position of the next byte to write to dest str. */
while(*f) {
char next, *str;
size_t l;
long long num;
unsigned long long unum;
/* Make sure there is always space for at least 1 char. */
if (sdsavail(s)==0) {
s = sdsMakeRoomFor(s,1);
}
switch(*f) {
case '%':
next = *(f+1);
f++;
switch(next) {
case 's':
case 'S':
str = va_arg(ap,char*);
l = (next == 's') ? strlen(str) : sdslen(str);
if (sdsavail(s) < l) {
s = sdsMakeRoomFor(s,l);
}
memcpy(s+i,str,l);
sdsinclen(s,l);
i += l;
break;
case 'i':
case 'I':
if (next == 'i')
num = va_arg(ap,int);
else
num = va_arg(ap,long long);
{
char buf[SDS_LLSTR_SIZE];
l = sdsll2str(buf,num);
if (sdsavail(s) < l) {
s = sdsMakeRoomFor(s,l);
}
memcpy(s+i,buf,l);
sdsinclen(s,l);
i += l;
}
break;
case 'u':
case 'U':
if (next == 'u')
unum = va_arg(ap,unsigned int);
else
unum = va_arg(ap,unsigned long long);
{
char buf[SDS_LLSTR_SIZE];
l = sdsull2str(buf,unum);
if (sdsavail(s) < l) {
s = sdsMakeRoomFor(s,l);
}
memcpy(s+i,buf,l);
sdsinclen(s,l);
i += l;
}
break;
default: /* Handle %% and generally %. */
s[i++] = next;
sdsinclen(s,1);
break;
}
break;
default:
s[i++] = *f;
sdsinclen(s,1);
break;
}
f++;
}
va_end(ap);
/* Add null-term */
s[i] = '\0';
return s;
}
/* 从sds两端分别移除所有在cset指向字符串中出现的字符
* After the call, the modified sds string is no longer valid and all the
* references must be substituted with the new pointer returned by the call.
*
* Example:
*
* s = sdsnew("AA...AA.a.aa.aHelloWorld :::");
* s = sdstrim(s,"Aa. :");
* printf("%s\n", s);
*
* Output will be just "HelloWorld".
*/
sds sdstrim(sds s, const char *cset) {
char *start, *end, *sp, *ep;
size_t len;
sp = start = s;
ep = end = s+sdslen(s)-1;
while(sp <= end && strchr(cset, *sp)) sp++; // 从头到尾遍历
while(ep > sp && strchr(cset, *ep)) ep--; // 反向遍历
len = (sp > ep) ? 0 : ((ep-sp)+1); //
if (s != sp) memmove(s, sp, len);
s[len] = '\0';
sdssetlen(s,len);
return s;
}
/* Turn the string into a smaller (or equal) string containing only the
* substring specified by the 'start' and 'end' indexes.
*
* start and end can be negative, where -1 means the last character of the
* string, -2 the penultimate character, and so forth.
*
* The interval is inclusive, so the start and end characters will be part
* of the resulting string.
*
* The string is modified in-place.
*
* Example:
*
* s = sdsnew("Hello World");
* sdsrange(s,1,-1); => "ello World"
*/
// 保留s中[start,end]区间内的数据
void sdsrange(sds s, ssize_t start, ssize_t end) {
size_t newlen, len = sdslen(s);
if (len == 0) return;
if (start < 0) {
start = len+start;
if (start < 0) start = 0;
}
if (end < 0) {
end = len+end;
if (end < 0) end = 0;
}
newlen = (start > end) ? 0 : (end-start)+1;
if (newlen != 0) {
if (start >= (ssize_t)len) {
newlen = 0;
} else if (end >= (ssize_t)len) {
end = len-1;
newlen = (start > end) ? 0 : (end-start)+1;
}
} else {
start = 0;
}
if (start && newlen) memmove(s, s+start, newlen);
s[newlen] = 0;
sdssetlen(s,newlen);
}
/* Apply tolower() to every character of the sds string 's'. */
void sdstolower(sds s) {
size_t len = sdslen(s), j;
for (j = 0; j < len; j++) s[j] = tolower(s[j]);
}
/* Apply toupper() to every character of the sds string 's'. */
void sdstoupper(sds s) {
size_t len = sdslen(s), j;
for (j = 0; j < len; j++) s[j] = toupper(s[j]);
}
/* Compare two sds strings s1 and s2 with memcmp().
*
* Return value:
*
* positive if s1 > s2.
* negative if s1 < s2.
* 0 if s1 and s2 are exactly the same binary string.
*
* If two strings share exactly the same prefix, but one of the two has
* additional characters, the longer string is considered to be greater than
* the smaller one. */
int sdscmp(const sds s1, const sds s2) {
size_t l1, l2, minlen;
int cmp;
l1 = sdslen(s1);
l2 = sdslen(s2);
minlen = (l1 < l2) ? l1 : l2;
cmp = memcmp(s1,s2,minlen);
if (cmp == 0) return l1>l2? 1: (l1".
*
* After the call, the modified sds string is no longer valid and all the
* references must be substituted with the new pointer returned by the call. */
sds sdscatrepr(sds s, const char *p, size_t len) {
s = sdscatlen(s,"\"",1);
while(len--) {
switch(*p) {
case '\\':
case '"':
s = sdscatprintf(s,"\\%c",*p);
break;
case '\n': s = sdscatlen(s,"\\n",2); break;
case '\r': s = sdscatlen(s,"\\r",2); break;
case '\t': s = sdscatlen(s,"\\t",2); break;
case '\a': s = sdscatlen(s,"\\a",2); break;
case '\b': s = sdscatlen(s,"\\b",2); break;
default:
if (isprint(*p))
s = sdscatprintf(s,"%c",*p);
else
s = sdscatprintf(s,"\\x%02x",(unsigned char)*p);
break;
}
p++;
}
return sdscatlen(s,"\"",1);
}
/* Helper function for sdssplitargs() that returns non zero if 'c'
* is a valid hex digit. */
int is_hex_digit(char c) {
return (c >= '0' && c <= '9') || (c >= 'a' && c <= 'f') ||
(c >= 'A' && c <= 'F');
}
/* Helper function for sdssplitargs() that converts a hex digit into an
* integer from 0 to 15 */
int hex_digit_to_int(char c) {
switch(c) {
case '0': return 0;
case '1': return 1;
case '2': return 2;
case '3': return 3;
case '4': return 4;
case '5': return 5;
case '6': return 6;
case '7': return 7;
case '8': return 8;
case '9': return 9;
case 'a': case 'A': return 10;
case 'b': case 'B': return 11;
case 'c': case 'C': return 12;
case 'd': case 'D': return 13;
case 'e': case 'E': return 14;
case 'f': case 'F': return 15;
default: return 0;
}
}
/* Split a line into arguments, where every argument can be in the
* following programming-language REPL-alike form:
*
* foo bar "newline are supported\n" and "\xff\x00otherstuff"
*
* The number of arguments is stored into *argc, and an array
* of sds is returned.
*
* The caller should free the resulting array of sds strings with
* sdsfreesplitres().
*
* Note that sdscatrepr() is able to convert back a string into
* a quoted string in the same format sdssplitargs() is able to parse.
*
* The function returns the allocated tokens on success, even when the
* input string is empty, or NULL if the input contains unbalanced
* quotes or closed quotes followed by non space characters
* as in: "foo"bar or "foo'
*/
sds *sdssplitargs(const char *line, int *argc) {
const char *p = line;
char *current = NULL;
char **vector = NULL;
*argc = 0;
while(1) {
/* skip blanks */
while(*p && isspace(*p)) p++;
if (*p) {
/* get a token */
int inq=0; /* set to 1 if we are in "quotes" */
int insq=0; /* set to 1 if we are in 'single quotes' */
int done=0;
if (current == NULL) current = sdsempty();
while(!done) {
if (inq) {
if (*p == '\\' && *(p+1) == 'x' &&
is_hex_digit(*(p+2)) &&
is_hex_digit(*(p+3)))
{
unsigned char byte;
byte = (hex_digit_to_int(*(p+2))*16)+
hex_digit_to_int(*(p+3));
current = sdscatlen(current,(char*)&byte,1);
p += 3;
} else if (*p == '\\' && *(p+1)) {
char c;
p++;
switch(*p) {
case 'n': c = '\n'; break;
case 'r': c = '\r'; break;
case 't': c = '\t'; break;
case 'b': c = '\b'; break;
case 'a': c = '\a'; break;
default: c = *p; break;
}
current = sdscatlen(current,&c,1);
} else if (*p == '"') {
/* closing quote must be followed by a space or
* nothing at all. */
if (*(p+1) && !isspace(*(p+1))) goto err;
done=1;
} else if (!*p) {
/* unterminated quotes */
goto err;
} else {
current = sdscatlen(current,p,1);
}
} else if (insq) {
if (*p == '\\' && *(p+1) == '\'') {
p++;
current = sdscatlen(current,"'",1);
} else if (*p == '\'') {
/* closing quote must be followed by a space or
* nothing at all. */
if (*(p+1) && !isspace(*(p+1))) goto err;
done=1;
} else if (!*p) {
/* unterminated quotes */
goto err;
} else {
current = sdscatlen(current,p,1);
}
} else {
switch(*p) {
case ' ':
case '\n':
case '\r':
case '\t':
case '\0':
done=1;
break;
case '"':
inq=1;
break;
case '\'':
insq=1;
break;
default:
current = sdscatlen(current,p,1);
break;
}
}
if (*p) p++;
}
/* add the token to the vector */
vector = s_realloc(vector,((*argc)+1)*sizeof(char*));
vector[*argc] = current;
(*argc)++;
current = NULL;
} else {
/* Even on empty input string return something not NULL. */
if (vector == NULL) vector = s_malloc(sizeof(void*));
return vector;
}
}
err:
while((*argc)--)
sdsfree(vector[*argc]);
s_free(vector);
if (current) sdsfree(current);
*argc = 0;
return NULL;
}
/* Modify the string substituting all the occurrences of the set of
* characters specified in the 'from' string to the corresponding character
* in the 'to' array.
*
* For instance: sdsmapchars(mystring, "ho", "01", 2)
* will have the effect of turning the string "hello" into "0ell1".
*
* The function returns the sds string pointer, that is always the same
* as the input pointer since no resize is needed. */
sds sdsmapchars(sds s, const char *from, const char *to, size_t setlen) {
size_t j, i, l = sdslen(s);
for (j = 0; j < l; j++) {
for (i = 0; i < setlen; i++) {
if (s[j] == from[i]) {
s[j] = to[i];
break;
}
}
}
return s;
}
/* Join an array of C strings using the specified separator (also a C string).
* Returns the result as an sds string. */
sds sdsjoin(char **argv, int argc, char *sep) {
sds join = sdsempty();
int j;
for (j = 0; j < argc; j++) {
join = sdscat(join, argv[j]);
if (j != argc-1) join = sdscat(join,sep);
}
return join;
}
/* Like sdsjoin, but joins an array of SDS strings. */
sds sdsjoinsds(sds *argv, int argc, const char *sep, size_t seplen) {
sds join = sdsempty();
int j;
for (j = 0; j < argc; j++) {
join = sdscatsds(join, argv[j]);
if (j != argc-1) join = sdscatlen(join,sep,seplen);
}
return join;
}
/* Wrappers to the allocators used by SDS. Note that SDS will actually
* just use the macros defined into sdsalloc.h in order to avoid to pay
* the overhead of function calls. Here we define these wrappers only for
* the programs SDS is linked to, if they want to touch the SDS internals
* even if they use a different allocator. */
void *sds_malloc(size_t size) { return s_malloc(size); }
void *sds_realloc(void *ptr, size_t size) { return s_realloc(ptr,size); }
void sds_free(void *ptr) { s_free(ptr); }
#if defined(SDS_TEST_MAIN)
#include
#include "testhelp.h"
#include "limits.h"
#define UNUSED(x) (void)(x)
int sdsTest(void) {
{
sds x = sdsnew("foo"), y;
test_cond("Create a string and obtain the length",
sdslen(x) == 3 && memcmp(x,"foo\0",4) == 0)
sdsfree(x);
x = sdsnewlen("foo",2);
test_cond("Create a string with specified length",
sdslen(x) == 2 && memcmp(x,"fo\0",3) == 0)
x = sdscat(x,"bar");
test_cond("Strings concatenation",
sdslen(x) == 5 && memcmp(x,"fobar\0",6) == 0);
x = sdscpy(x,"a");
test_cond("sdscpy() against an originally longer string",
sdslen(x) == 1 && memcmp(x,"a\0",2) == 0)
x = sdscpy(x,"xyzxxxxxxxxxxyyyyyyyyyykkkkkkkkkk");
test_cond("sdscpy() against an originally shorter string",
sdslen(x) == 33 &&
memcmp(x,"xyzxxxxxxxxxxyyyyyyyyyykkkkkkkkkk\0",33) == 0)
sdsfree(x);
x = sdscatprintf(sdsempty(),"%d",123);
test_cond("sdscatprintf() seems working in the base case",
sdslen(x) == 3 && memcmp(x,"123\0",4) == 0)
sdsfree(x);
x = sdsnew("--");
x = sdscatfmt(x, "Hello %s World %I,%I--", "Hi!", LLONG_MIN,LLONG_MAX);
test_cond("sdscatfmt() seems working in the base case",
sdslen(x) == 60 &&
memcmp(x,"--Hello Hi! World -9223372036854775808,"
"9223372036854775807--",60) == 0)
printf("[%s]\n",x);
sdsfree(x);
x = sdsnew("--");
x = sdscatfmt(x, "%u,%U--", UINT_MAX, ULLONG_MAX);
test_cond("sdscatfmt() seems working with unsigned numbers",
sdslen(x) == 35 &&
memcmp(x,"--4294967295,18446744073709551615--",35) == 0)
sdsfree(x);
x = sdsnew(" x ");
sdstrim(x," x");
test_cond("sdstrim() works when all chars match",
sdslen(x) == 0)
sdsfree(x);
x = sdsnew(" x ");
sdstrim(x," ");
test_cond("sdstrim() works when a single char remains",
sdslen(x) == 1 && x[0] == 'x')
sdsfree(x);
x = sdsnew("xxciaoyyy");
sdstrim(x,"xy");
test_cond("sdstrim() correctly trims characters",
sdslen(x) == 4 && memcmp(x,"ciao\0",5) == 0)
y = sdsdup(x);
sdsrange(y,1,1);
test_cond("sdsrange(...,1,1)",
sdslen(y) == 1 && memcmp(y,"i\0",2) == 0)
sdsfree(y);
y = sdsdup(x);
sdsrange(y,1,-1);
test_cond("sdsrange(...,1,-1)",
sdslen(y) == 3 && memcmp(y,"iao\0",4) == 0)
sdsfree(y);
y = sdsdup(x);
sdsrange(y,-2,-1);
test_cond("sdsrange(...,-2,-1)",
sdslen(y) == 2 && memcmp(y,"ao\0",3) == 0)
sdsfree(y);
y = sdsdup(x);
sdsrange(y,2,1);
test_cond("sdsrange(...,2,1)",
sdslen(y) == 0 && memcmp(y,"\0",1) == 0)
sdsfree(y);
y = sdsdup(x);
sdsrange(y,1,100);
test_cond("sdsrange(...,1,100)",
sdslen(y) == 3 && memcmp(y,"iao\0",4) == 0)
sdsfree(y);
y = sdsdup(x);
sdsrange(y,100,100);
test_cond("sdsrange(...,100,100)",
sdslen(y) == 0 && memcmp(y,"\0",1) == 0)
sdsfree(y);
sdsfree(x);
x = sdsnew("foo");
y = sdsnew("foa");
test_cond("sdscmp(foo,foa)", sdscmp(x,y) > 0)
sdsfree(y);
sdsfree(x);
x = sdsnew("bar");
y = sdsnew("bar");
test_cond("sdscmp(bar,bar)", sdscmp(x,y) == 0)
sdsfree(y);
sdsfree(x);
x = sdsnew("aar");
y = sdsnew("bar");
test_cond("sdscmp(bar,bar)", sdscmp(x,y) < 0)
sdsfree(y);
sdsfree(x);
x = sdsnewlen("\a\n\0foo\r",7);
y = sdscatrepr(sdsempty(),x,sdslen(x));
test_cond("sdscatrepr(...data...)",
memcmp(y,"\"\\a\\n\\x00foo\\r\"",15) == 0)
{
unsigned int oldfree;
char *p;
int step = 10, j, i;
sdsfree(x);
sdsfree(y);
x = sdsnew("0");
test_cond("sdsnew() free/len buffers", sdslen(x) == 1 && sdsavail(x) == 0);
/* Run the test a few times in order to hit the first two
* SDS header types. */
for (i = 0; i < 10; i++) {
int oldlen = sdslen(x);
x = sdsMakeRoomFor(x,step);
int type = x[-1]&SDS_TYPE_MASK;
test_cond("sdsMakeRoomFor() len", sdslen(x) == oldlen);
if (type != SDS_TYPE_5) {
test_cond("sdsMakeRoomFor() free", sdsavail(x) >= step);
oldfree = sdsavail(x);
}
p = x+oldlen;
for (j = 0; j < step; j++) {
p[j] = 'A'+j;
}
sdsIncrLen(x,step);
}
test_cond("sdsMakeRoomFor() content",
memcmp("0ABCDEFGHIJABCDEFGHIJABCDEFGHIJABCDEFGHIJABCDEFGHIJABCDEFGHIJABCDEFGHIJABCDEFGHIJABCDEFGHIJABCDEFGHIJ",x,101) == 0);
test_cond("sdsMakeRoomFor() final length",sdslen(x)==101);
sdsfree(x);
}
}
test_report()
return 0;
}
#endif
#ifdef SDS_TEST_MAIN
int main(void) {
return sdsTest();
}
#endif