Forked from sds.c in Redis to create a standalone project.

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+/* SDSLib, A C dynamic strings library
+ *
+ * Copyright (c) 2006-2012, Salvatore Sanfilippo <antirez at gmail dot com>
+ * 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 <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <ctype.h>
+#include <assert.h>
+#include "sds.h"
+#include "zmalloc.h"
+
+/* 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.
+ *
+ * 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. */
+sds sdsnewlen(const void *init, size_t initlen) {
+    struct sdshdr *sh;
+
+    if (init) {
+        sh = zmalloc(sizeof(struct sdshdr)+initlen+1);
+    } else {
+        sh = zcalloc(sizeof(struct sdshdr)+initlen+1);
+    }
+    if (sh == NULL) return NULL;
+    sh->len = initlen;
+    sh->free = 0;
+    if (initlen && init)
+        memcpy(sh->buf, init, initlen);
+    sh->buf[initlen] = '\0';
+    return (char*)sh->buf;
+}
+
+/* Create an empty (zero length) sds string. Even in this case the string
+ * always has an implicit null term. */
+sds sdsempty(void) {
+    return sdsnewlen("",0);
+}
+
+/* Create a new sds string starting from a null termined C string. */
+sds sdsnew(const char *init) {
+    size_t initlen = (init == NULL) ? 0 : strlen(init);
+    return sdsnewlen(init, initlen);
+}
+
+/* Duplicate an sds string. */
+sds sdsdup(const sds s) {
+    return sdsnewlen(s, sdslen(s));
+}
+
+/* Free an sds string. No operation is performed if 's' is NULL. */
+void sdsfree(sds s) {
+    if (s == NULL) return;
+    zfree(s-sizeof(struct sdshdr));
+}
+
+/* Set the sds string length to the length as obtained with strlen(), so
+ * considering as content only up to the first null term character.
+ *
+ * This function is useful when the sds string is hacked manually in some
+ * way, like in the following example:
+ *
+ * s = sdsnew("foobar");
+ * s[2] = '\0';
+ * sdsupdatelen(s);
+ * printf("%d\n", sdslen(s));
+ *
+ * The output will be "2", but if we comment out the call to sdsupdatelen()
+ * the output will be "6" as the string was modified but the logical length
+ * remains 6 bytes. */
+void sdsupdatelen(sds s) {
+    struct sdshdr *sh = (void*) (s-(sizeof(struct sdshdr)));
+    int reallen = strlen(s);
+    sh->free += (sh->len-reallen);
+    sh->len = reallen;
+}
+
+/* Modify an sds string on-place to make it empty (zero length).
+ * However all the existing buffer is not discarded but set as free space
+ * so that next append operations will not require allocations up to the
+ * number of bytes previously available. */
+void sdsclear(sds s) {
+    struct sdshdr *sh = (void*) (s-(sizeof(struct sdshdr)));
+    sh->free += sh->len;
+    sh->len = 0;
+    sh->buf[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. */
+sds sdsMakeRoomFor(sds s, size_t addlen) {
+    struct sdshdr *sh, *newsh;
+    size_t free = sdsavail(s);
+    size_t len, newlen;
+
+    if (free >= addlen) return s;
+    len = sdslen(s);
+    sh = (void*) (s-(sizeof(struct sdshdr)));
+    newlen = (len+addlen);
+    if (newlen < SDS_MAX_PREALLOC)
+        newlen *= 2;
+    else
+        newlen += SDS_MAX_PREALLOC;
+    newsh = zrealloc(sh, sizeof(struct sdshdr)+newlen+1);
+    if (newsh == NULL) return NULL;
+
+    newsh->free = newlen - len;
+    return newsh->buf;
+}
+
+/* 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) {
+    struct sdshdr *sh;
+
+    sh = (void*) (s-(sizeof(struct sdshdr)));
+    sh = zrealloc(sh, sizeof(struct sdshdr)+sh->len+1);
+    sh->free = 0;
+    return sh->buf;
+}
+
+/* Return the total size of the allocation of the specifed 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) {
+    struct sdshdr *sh = (void*) (s-(sizeof(struct sdshdr)));
+
+    return sizeof(*sh)+sh->len+sh->free+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, int incr) {
+    struct sdshdr *sh = (void*) (s-(sizeof(struct sdshdr)));
+
+    assert(sh->free >= incr);
+    sh->len += incr;
+    sh->free -= incr;
+    assert(sh->free >= 0);
+    s[sh->len] = '\0';
+}
+
+/* Grow the sds to have the specified length. Bytes that were not part of
+ * the original length of the sds will be set to zero.
+ *
+ * if the specified length is smaller than the current length, no operation
+ * is performed. */
+sds sdsgrowzero(sds s, size_t len) {
+    struct sdshdr *sh = (void*)(s-(sizeof(struct sdshdr)));
+    size_t totlen, curlen = sh->len;
+
+    if (len <= curlen) return s;
+    s = sdsMakeRoomFor(s,len-curlen);
+    if (s == NULL) return NULL;
+
+    /* Make sure added region doesn't contain garbage */
+    sh = (void*)(s-(sizeof(struct sdshdr)));
+    memset(s+curlen,0,(len-curlen+1)); /* also set trailing \0 byte */
+    totlen = sh->len+sh->free;
+    sh->len = len;
+    sh->free = totlen-sh->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) {
+    struct sdshdr *sh;
+    size_t curlen = sdslen(s);
+
+    s = sdsMakeRoomFor(s,len);
+    if (s == NULL) return NULL;
+    sh = (void*) (s-(sizeof(struct sdshdr)));
+    memcpy(s+curlen, t, len);
+    sh->len = curlen+len;
+    sh->free = sh->free-len;
+    s[curlen+len] = '\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. */
+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. */
+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) {
+    struct sdshdr *sh = (void*) (s-(sizeof(struct sdshdr)));
+    size_t totlen = sh->free+sh->len;
+
+    if (totlen < len) {
+        s = sdsMakeRoomFor(s,len-sh->len);
+        if (s == NULL) return NULL;
+        sh = (void*) (s-(sizeof(struct sdshdr)));
+        totlen = sh->free+sh->len;
+    }
+    memcpy(s, t, len);
+    s[len] = '\0';
+    sh->len = len;
+    sh->free = totlen-len;
+    return s;
+}
+
+/* Like sdscpylen() but 't' must be a null-termined string so that the length
+ * of the string is obtained with strlen(). */
+sds sdscpy(sds s, const char *t) {
+    return sdscpylen(s, t, strlen(t));
+}
+
+/* Like sdscatpritf() but gets va_list instead of being variadic. */
+sds sdscatvprintf(sds s, const char *fmt, va_list ap) {
+    va_list cpy;
+    char *buf, *t;
+    size_t buflen = 16;
+
+    while(1) {
+        buf = zmalloc(buflen);
+        if (buf == NULL) return NULL;
+        buf[buflen-2] = '\0';
+        va_copy(cpy,ap);
+        vsnprintf(buf, buflen, fmt, cpy);
+        if (buf[buflen-2] != '\0') {
+            zfree(buf);
+            buflen *= 2;
+            continue;
+        }
+        break;
+    }
+    t = sdscat(s, buf);
+    zfree(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 = sdsempty("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);
+    t = sdscatvprintf(s,fmt,ap);
+    va_end(ap);
+    return t;
+}
+
+/* Remove the part of the string from left and from right composed just of
+ * contiguous characters found in 'cset', that is a null terminted C string.
+ *
+ * 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,"A. :");
+ * printf("%s\n", s);
+ *
+ * Output will be just "Hello World".
+ */
+sds sdstrim(sds s, const char *cset) {
+    struct sdshdr *sh = (void*) (s-(sizeof(struct sdshdr)));
+    char *start, *end, *sp, *ep;
+    size_t len;
+
+    sp = start = s;
+    ep = end = s+sdslen(s)-1;
+    while(sp <= end && strchr(cset, *sp)) sp++;
+    while(ep > start && strchr(cset, *ep)) ep--;
+    len = (sp > ep) ? 0 : ((ep-sp)+1);
+    if (sh->buf != sp) memmove(sh->buf, sp, len);
+    sh->buf[len] = '\0';
+    sh->free = sh->free+(sh->len-len);
+    sh->len = 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"
+ */
+void sdsrange(sds s, int start, int end) {
+    struct sdshdr *sh = (void*) (s-(sizeof(struct sdshdr)));
+    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 >= (signed)len) {
+            newlen = 0;
+        } else if (end >= (signed)len) {
+            end = len-1;
+            newlen = (start > end) ? 0 : (end-start)+1;
+        }
+    } else {
+        start = 0;
+    }
+    if (start && newlen) memmove(sh->buf, sh->buf+start, newlen);
+    sh->buf[newlen] = 0;
+    sh->free = sh->free+(sh->len-newlen);
+    sh->len = newlen;
+}
+
+/* Apply tolower() to every character of the sds string 's'. */
+void sdstolower(sds s) {
+    int 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) {
+    int 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:
+ *
+ *     1 if s1 > s2.
+ *    -1 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;
+    return cmp;
+}
+
+/* Split 's' with separator in 'sep'. An array
+ * of sds strings is returned. *count will be set
+ * by reference to the number of tokens returned.
+ *
+ * On out of memory, zero length string, zero length
+ * separator, NULL is returned.
+ *
+ * Note that 'sep' is able to split a string using
+ * a multi-character separator. For example
+ * sdssplit("foo_-_bar","_-_"); will return two
+ * elements "foo" and "bar".
+ *
+ * This version of the function is binary-safe but
+ * requires length arguments. sdssplit() is just the
+ * same function but for zero-terminated strings.
+ */
+sds *sdssplitlen(const char *s, int len, const char *sep, int seplen, int *count) {
+    int elements = 0, slots = 5, start = 0, j;
+    sds *tokens;
+
+    if (seplen < 1 || len < 0) return NULL;
+
+    tokens = zmalloc(sizeof(sds)*slots);
+    if (tokens == NULL) return NULL;
+
+    if (len == 0) {
+        *count = 0;
+        return tokens;
+    }
+    for (j = 0; j < (len-(seplen-1)); j++) {
+        /* make sure there is room for the next element and the final one */
+        if (slots < elements+2) {
+            sds *newtokens;
+
+            slots *= 2;
+            newtokens = zrealloc(tokens,sizeof(sds)*slots);
+            if (newtokens == NULL) goto cleanup;
+            tokens = newtokens;
+        }
+        /* search the separator */
+        if ((seplen == 1 && *(s+j) == sep[0]) || (memcmp(s+j,sep,seplen) == 0)) {
+            tokens[elements] = sdsnewlen(s+start,j-start);
+            if (tokens[elements] == NULL) goto cleanup;
+            elements++;
+            start = j+seplen;
+            j = j+seplen-1; /* skip the separator */
+        }
+    }
+    /* Add the final element. We are sure there is room in the tokens array. */
+    tokens[elements] = sdsnewlen(s+start,len-start);
+    if (tokens[elements] == NULL) goto cleanup;
+    elements++;
+    *count = elements;
+    return tokens;
+
+cleanup:
+    {
+        int i;
+        for (i = 0; i < elements; i++) sdsfree(tokens[i]);
+        zfree(tokens);
+        *count = 0;
+        return NULL;
+    }
+}
+
+/* Free the result returned by sdssplitlen(), or do nothing if 'tokens' is NULL. */
+void sdsfreesplitres(sds *tokens, int count) {
+    if (!tokens) return;
+    while(count--)
+        sdsfree(tokens[count]);
+    zfree(tokens);
+}
+
+/* Create an sds string from a long long value. It is much faster than:
+ *
+ * sdscatprintf(sdsempty(),"%lld\n", value);
+ */
+sds sdsfromlonglong(long long value) {
+    char buf[32], *p;
+    unsigned long long v;
+
+    v = (value < 0) ? -value : value;
+    p = buf+31; /* point to the last character */
+    do {
+        *p-- = '0'+(v%10);
+        v /= 10;
+    } while(v);
+    if (value < 0) *p-- = '-';
+    p++;
+    return sdsnewlen(p,32-(p-buf));
+}
+
+/* Append to the sds string "s" an escaped string representation where
+ * all the non-printable characters (tested with isprint()) are turned into
+ * escapes in the form "\n\r\a...." or "\x<hex-number>".
+ *
+ * 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 = zrealloc(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 = zmalloc(sizeof(void*));
+            return vector;
+        }
+    }
+
+err:
+    while((*argc)--)
+        sdsfree(vector[*argc]);
+    zfree(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;
+}
+
+#ifdef SDS_TEST_MAIN
+#include <stdio.h>
+#include "testhelp.h"
+
+int main(void) {
+    {
+        struct sdshdr *sh;
+        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 = sdstrim(sdsnew("xxciaoyyy"),"xy");
+        test_cond("sdstrim() correctly trims characters",
+            sdslen(x) == 4 && memcmp(x,"ciao\0",5) == 0)
+
+        y = sdsrange(sdsdup(x),1,1);
+        test_cond("sdsrange(...,1,1)",
+            sdslen(y) == 1 && memcmp(y,"i\0",2) == 0)
+
+        sdsfree(y);
+        y = sdsrange(sdsdup(x),1,-1);
+        test_cond("sdsrange(...,1,-1)",
+            sdslen(y) == 3 && memcmp(y,"iao\0",4) == 0)
+
+        sdsfree(y);
+        y = sdsrange(sdsdup(x),-2,-1);
+        test_cond("sdsrange(...,-2,-1)",
+            sdslen(y) == 2 && memcmp(y,"ao\0",3) == 0)
+
+        sdsfree(y);
+        y = sdsrange(sdsdup(x),2,1);
+        test_cond("sdsrange(...,2,1)",
+            sdslen(y) == 0 && memcmp(y,"\0",1) == 0)
+
+        sdsfree(y);
+        y = sdsrange(sdsdup(x),1,100);
+        test_cond("sdsrange(...,1,100)",
+            sdslen(y) == 3 && memcmp(y,"iao\0",4) == 0)
+
+        sdsfree(y);
+        y = sdsrange(sdsdup(x),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)
+
+        {
+            int oldfree;
+
+            sdsfree(x);
+            x = sdsnew("0");
+            sh = (void*) (x-(sizeof(struct sdshdr)));
+            test_cond("sdsnew() free/len buffers", sh->len == 1 && sh->free == 0);
+            x = sdsMakeRoomFor(x,1);
+            sh = (void*) (x-(sizeof(struct sdshdr)));
+            test_cond("sdsMakeRoomFor()", sh->len == 1 && sh->free > 0);
+            oldfree = sh->free;
+            x[1] = '1';
+            sdsIncrLen(x,1);
+            test_cond("sdsIncrLen() -- content", x[0] == '0' && x[1] == '1');
+            test_cond("sdsIncrLen() -- len", sh->len == 2);
+            test_cond("sdsIncrLen() -- free", sh->free == oldfree-1);
+        }
+    }
+    test_report()
+    return 0;
+}
+#endif
diff --git a/sds.h b/sds.h
new file mode 100644
index 0000000..615c751
--- /dev/null
+++ b/sds.h
@@ -0,0 +1,100 @@
+/* SDSLib, A C dynamic strings library
+ *
+ * Copyright (c) 2006-2010, Salvatore Sanfilippo <antirez at gmail dot com>
+ * 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.
+ */
+
+#ifndef __SDS_H
+#define __SDS_H
+
+#define SDS_MAX_PREALLOC (1024*1024)
+
+#include <sys/types.h>
+#include <stdarg.h>
+
+typedef char *sds;
+
+struct sdshdr {
+    int len;
+    int free;
+    char buf[];
+};
+
+static inline size_t sdslen(const sds s) {
+    struct sdshdr *sh = (void*)(s-(sizeof(struct sdshdr)));
+    return sh->len;
+}
+
+static inline size_t sdsavail(const sds s) {
+    struct sdshdr *sh = (void*)(s-(sizeof(struct sdshdr)));
+    return sh->free;
+}
+
+sds sdsnewlen(const void *init, size_t initlen);
+sds sdsnew(const char *init);
+sds sdsempty(void);
+size_t sdslen(const sds s);
+sds sdsdup(const sds s);
+void sdsfree(sds s);
+size_t sdsavail(const 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 sdstrim(sds s, const char *cset);
+void sdsrange(sds s, int start, int end);
+void sdsupdatelen(sds s);
+void sdsclear(sds s);
+int sdscmp(const sds s1, const sds s2);
+sds *sdssplitlen(const char *s, int 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);
+
+/* Low level functions exposed to the user API */
+sds sdsMakeRoomFor(sds s, size_t addlen);
+void sdsIncrLen(sds s, int incr);
+sds sdsRemoveFreeSpace(sds s);
+size_t sdsAllocSize(sds s);
+
+#endif