Adding upstream version 5:7.2.4.upstream/5%7.2.4

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 951 insertions, 0 deletions

diff --git a/src/t_string.c b/src/t_string.c
new file mode 100644
index 0000000..2bce3ac
--- /dev/null
+++ b/src/t_string.c
@@ -0,0 +1,951 @@
+/*
+ * Copyright (c) 2009-2012, 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 "server.h"
+#include <math.h> /* isnan(), isinf() */
+
+/* Forward declarations */
+int getGenericCommand(client *c);
+
+/*-----------------------------------------------------------------------------
+ * String Commands
+ *----------------------------------------------------------------------------*/
+
+static int checkStringLength(client *c, long long size, long long append) {
+    if (mustObeyClient(c))
+        return C_OK;
+    /* 'uint64_t' cast is there just to prevent undefined behavior on overflow */
+    long long total = (uint64_t)size + append;
+    /* Test configured max-bulk-len represending a limit of the biggest string object,
+     * and also test for overflow. */
+    if (total > server.proto_max_bulk_len || total < size || total < append) {
+        addReplyError(c,"string exceeds maximum allowed size (proto-max-bulk-len)");
+        return C_ERR;
+    }
+    return C_OK;
+}
+
+/* The setGenericCommand() function implements the SET operation with different
+ * options and variants. This function is called in order to implement the
+ * following commands: SET, SETEX, PSETEX, SETNX, GETSET.
+ *
+ * 'flags' changes the behavior of the command (NX, XX or GET, see below).
+ *
+ * 'expire' represents an expire to set in form of a Redis object as passed
+ * by the user. It is interpreted according to the specified 'unit'.
+ *
+ * 'ok_reply' and 'abort_reply' is what the function will reply to the client
+ * if the operation is performed, or when it is not because of NX or
+ * XX flags.
+ *
+ * If ok_reply is NULL "+OK" is used.
+ * If abort_reply is NULL, "$-1" is used. */
+
+#define OBJ_NO_FLAGS 0
+#define OBJ_SET_NX (1<<0)          /* Set if key not exists. */
+#define OBJ_SET_XX (1<<1)          /* Set if key exists. */
+#define OBJ_EX (1<<2)              /* Set if time in seconds is given */
+#define OBJ_PX (1<<3)              /* Set if time in ms in given */
+#define OBJ_KEEPTTL (1<<4)         /* Set and keep the ttl */
+#define OBJ_SET_GET (1<<5)         /* Set if want to get key before set */
+#define OBJ_EXAT (1<<6)            /* Set if timestamp in second is given */
+#define OBJ_PXAT (1<<7)            /* Set if timestamp in ms is given */
+#define OBJ_PERSIST (1<<8)         /* Set if we need to remove the ttl */
+
+/* Forward declaration */
+static int getExpireMillisecondsOrReply(client *c, robj *expire, int flags, int unit, long long *milliseconds);
+
+void setGenericCommand(client *c, int flags, robj *key, robj *val, robj *expire, int unit, robj *ok_reply, robj *abort_reply) {
+    long long milliseconds = 0; /* initialized to avoid any harmness warning */
+    int found = 0;
+    int setkey_flags = 0;
+
+    if (expire && getExpireMillisecondsOrReply(c, expire, flags, unit, &milliseconds) != C_OK) {
+        return;
+    }
+
+    if (flags & OBJ_SET_GET) {
+        if (getGenericCommand(c) == C_ERR) return;
+    }
+
+    found = (lookupKeyWrite(c->db,key) != NULL);
+
+    if ((flags & OBJ_SET_NX && found) ||
+        (flags & OBJ_SET_XX && !found))
+    {
+        if (!(flags & OBJ_SET_GET)) {
+            addReply(c, abort_reply ? abort_reply : shared.null[c->resp]);
+        }
+        return;
+    }
+
+    /* When expire is not NULL, we avoid deleting the TTL so it can be updated later instead of being deleted and then created again. */
+    setkey_flags |= ((flags & OBJ_KEEPTTL) || expire) ? SETKEY_KEEPTTL : 0;
+    setkey_flags |= found ? SETKEY_ALREADY_EXIST : SETKEY_DOESNT_EXIST;
+
+    setKey(c,c->db,key,val,setkey_flags);
+    server.dirty++;
+    notifyKeyspaceEvent(NOTIFY_STRING,"set",key,c->db->id);
+
+    if (expire) {
+        setExpire(c,c->db,key,milliseconds);
+        /* Propagate as SET Key Value PXAT millisecond-timestamp if there is
+         * EX/PX/EXAT flag. */
+        if (!(flags & OBJ_PXAT)) {
+            robj *milliseconds_obj = createStringObjectFromLongLong(milliseconds);
+            rewriteClientCommandVector(c, 5, shared.set, key, val, shared.pxat, milliseconds_obj);
+            decrRefCount(milliseconds_obj);
+        }
+        notifyKeyspaceEvent(NOTIFY_GENERIC,"expire",key,c->db->id);
+    }
+
+    if (!(flags & OBJ_SET_GET)) {
+        addReply(c, ok_reply ? ok_reply : shared.ok);
+    }
+
+    /* Propagate without the GET argument (Isn't needed if we had expire since in that case we completely re-written the command argv) */
+    if ((flags & OBJ_SET_GET) && !expire) {
+        int argc = 0;
+        int j;
+        robj **argv = zmalloc((c->argc-1)*sizeof(robj*));
+        for (j=0; j < c->argc; j++) {
+            char *a = c->argv[j]->ptr;
+            /* Skip GET which may be repeated multiple times. */
+            if (j >= 3 &&
+                (a[0] == 'g' || a[0] == 'G') &&
+                (a[1] == 'e' || a[1] == 'E') &&
+                (a[2] == 't' || a[2] == 'T') && a[3] == '\0')
+                continue;
+            argv[argc++] = c->argv[j];
+            incrRefCount(c->argv[j]);
+        }
+        replaceClientCommandVector(c, argc, argv);
+    }
+}
+
+/*
+ * Extract the `expire` argument of a given GET/SET command as an absolute timestamp in milliseconds.
+ *
+ * "client" is the client that sent the `expire` argument.
+ * "expire" is the `expire` argument to be extracted.
+ * "flags" represents the behavior of the command (e.g. PX or EX).
+ * "unit" is the original unit of the given `expire` argument (e.g. UNIT_SECONDS).
+ * "milliseconds" is output argument.
+ *
+ * If return C_OK, "milliseconds" output argument will be set to the resulting absolute timestamp.
+ * If return C_ERR, an error reply has been added to the given client.
+ */
+static int getExpireMillisecondsOrReply(client *c, robj *expire, int flags, int unit, long long *milliseconds) {
+    int ret = getLongLongFromObjectOrReply(c, expire, milliseconds, NULL);
+    if (ret != C_OK) {
+        return ret;
+    }
+
+    if (*milliseconds <= 0 || (unit == UNIT_SECONDS && *milliseconds > LLONG_MAX / 1000)) {
+        /* Negative value provided or multiplication is gonna overflow. */
+        addReplyErrorExpireTime(c);
+        return C_ERR;
+    }
+
+    if (unit == UNIT_SECONDS) *milliseconds *= 1000;
+
+    if ((flags & OBJ_PX) || (flags & OBJ_EX)) {
+        *milliseconds += commandTimeSnapshot();
+    }
+
+    if (*milliseconds <= 0) {
+        /* Overflow detected. */
+        addReplyErrorExpireTime(c);
+        return C_ERR;
+    }
+
+    return C_OK;
+}
+
+#define COMMAND_GET 0
+#define COMMAND_SET 1
+/*
+ * The parseExtendedStringArgumentsOrReply() function performs the common validation for extended
+ * string arguments used in SET and GET command.
+ *
+ * Get specific commands - PERSIST/DEL
+ * Set specific commands - XX/NX/GET
+ * Common commands - EX/EXAT/PX/PXAT/KEEPTTL
+ *
+ * Function takes pointers to client, flags, unit, pointer to pointer of expire obj if needed
+ * to be determined and command_type which can be COMMAND_GET or COMMAND_SET.
+ *
+ * If there are any syntax violations C_ERR is returned else C_OK is returned.
+ *
+ * Input flags are updated upon parsing the arguments. Unit and expire are updated if there are any
+ * EX/EXAT/PX/PXAT arguments. Unit is updated to millisecond if PX/PXAT is set.
+ */
+int parseExtendedStringArgumentsOrReply(client *c, int *flags, int *unit, robj **expire, int command_type) {
+
+    int j = command_type == COMMAND_GET ? 2 : 3;
+    for (; j < c->argc; j++) {
+        char *opt = c->argv[j]->ptr;
+        robj *next = (j == c->argc-1) ? NULL : c->argv[j+1];
+
+        if ((opt[0] == 'n' || opt[0] == 'N') &&
+            (opt[1] == 'x' || opt[1] == 'X') && opt[2] == '\0' &&
+            !(*flags & OBJ_SET_XX) && (command_type == COMMAND_SET))
+        {
+            *flags |= OBJ_SET_NX;
+        } else if ((opt[0] == 'x' || opt[0] == 'X') &&
+                   (opt[1] == 'x' || opt[1] == 'X') && opt[2] == '\0' &&
+                   !(*flags & OBJ_SET_NX) && (command_type == COMMAND_SET))
+        {
+            *flags |= OBJ_SET_XX;
+        } else if ((opt[0] == 'g' || opt[0] == 'G') &&
+                   (opt[1] == 'e' || opt[1] == 'E') &&
+                   (opt[2] == 't' || opt[2] == 'T') && opt[3] == '\0' &&
+                   (command_type == COMMAND_SET))
+        {
+            *flags |= OBJ_SET_GET;
+        } else if (!strcasecmp(opt, "KEEPTTL") && !(*flags & OBJ_PERSIST) &&
+            !(*flags & OBJ_EX) && !(*flags & OBJ_EXAT) &&
+            !(*flags & OBJ_PX) && !(*flags & OBJ_PXAT) && (command_type == COMMAND_SET))
+        {
+            *flags |= OBJ_KEEPTTL;
+        } else if (!strcasecmp(opt,"PERSIST") && (command_type == COMMAND_GET) &&
+               !(*flags & OBJ_EX) && !(*flags & OBJ_EXAT) &&
+               !(*flags & OBJ_PX) && !(*flags & OBJ_PXAT) &&
+               !(*flags & OBJ_KEEPTTL))
+        {
+            *flags |= OBJ_PERSIST;
+        } else if ((opt[0] == 'e' || opt[0] == 'E') &&
+                   (opt[1] == 'x' || opt[1] == 'X') && opt[2] == '\0' &&
+                   !(*flags & OBJ_KEEPTTL) && !(*flags & OBJ_PERSIST) &&
+                   !(*flags & OBJ_EXAT) && !(*flags & OBJ_PX) &&
+                   !(*flags & OBJ_PXAT) && next)
+        {
+            *flags |= OBJ_EX;
+            *expire = next;
+            j++;
+        } else if ((opt[0] == 'p' || opt[0] == 'P') &&
+                   (opt[1] == 'x' || opt[1] == 'X') && opt[2] == '\0' &&
+                   !(*flags & OBJ_KEEPTTL) && !(*flags & OBJ_PERSIST) &&
+                   !(*flags & OBJ_EX) && !(*flags & OBJ_EXAT) &&
+                   !(*flags & OBJ_PXAT) && next)
+        {
+            *flags |= OBJ_PX;
+            *unit = UNIT_MILLISECONDS;
+            *expire = next;
+            j++;
+        } else if ((opt[0] == 'e' || opt[0] == 'E') &&
+                   (opt[1] == 'x' || opt[1] == 'X') &&
+                   (opt[2] == 'a' || opt[2] == 'A') &&
+                   (opt[3] == 't' || opt[3] == 'T') && opt[4] == '\0' &&
+                   !(*flags & OBJ_KEEPTTL) && !(*flags & OBJ_PERSIST) &&
+                   !(*flags & OBJ_EX) && !(*flags & OBJ_PX) &&
+                   !(*flags & OBJ_PXAT) && next)
+        {
+            *flags |= OBJ_EXAT;
+            *expire = next;
+            j++;
+        } else if ((opt[0] == 'p' || opt[0] == 'P') &&
+                   (opt[1] == 'x' || opt[1] == 'X') &&
+                   (opt[2] == 'a' || opt[2] == 'A') &&
+                   (opt[3] == 't' || opt[3] == 'T') && opt[4] == '\0' &&
+                   !(*flags & OBJ_KEEPTTL) && !(*flags & OBJ_PERSIST) &&
+                   !(*flags & OBJ_EX) && !(*flags & OBJ_EXAT) &&
+                   !(*flags & OBJ_PX) && next)
+        {
+            *flags |= OBJ_PXAT;
+            *unit = UNIT_MILLISECONDS;
+            *expire = next;
+            j++;
+        } else {
+            addReplyErrorObject(c,shared.syntaxerr);
+            return C_ERR;
+        }
+    }
+    return C_OK;
+}
+
+/* SET key value [NX] [XX] [KEEPTTL] [GET] [EX <seconds>] [PX <milliseconds>]
+ *     [EXAT <seconds-timestamp>][PXAT <milliseconds-timestamp>] */
+void setCommand(client *c) {
+    robj *expire = NULL;
+    int unit = UNIT_SECONDS;
+    int flags = OBJ_NO_FLAGS;
+
+    if (parseExtendedStringArgumentsOrReply(c,&flags,&unit,&expire,COMMAND_SET) != C_OK) {
+        return;
+    }
+
+    c->argv[2] = tryObjectEncoding(c->argv[2]);
+    setGenericCommand(c,flags,c->argv[1],c->argv[2],expire,unit,NULL,NULL);
+}
+
+void setnxCommand(client *c) {
+    c->argv[2] = tryObjectEncoding(c->argv[2]);
+    setGenericCommand(c,OBJ_SET_NX,c->argv[1],c->argv[2],NULL,0,shared.cone,shared.czero);
+}
+
+void setexCommand(client *c) {
+    c->argv[3] = tryObjectEncoding(c->argv[3]);
+    setGenericCommand(c,OBJ_EX,c->argv[1],c->argv[3],c->argv[2],UNIT_SECONDS,NULL,NULL);
+}
+
+void psetexCommand(client *c) {
+    c->argv[3] = tryObjectEncoding(c->argv[3]);
+    setGenericCommand(c,OBJ_PX,c->argv[1],c->argv[3],c->argv[2],UNIT_MILLISECONDS,NULL,NULL);
+}
+
+int getGenericCommand(client *c) {
+    robj *o;
+
+    if ((o = lookupKeyReadOrReply(c,c->argv[1],shared.null[c->resp])) == NULL)
+        return C_OK;
+
+    if (checkType(c,o,OBJ_STRING)) {
+        return C_ERR;
+    }
+
+    addReplyBulk(c,o);
+    return C_OK;
+}
+
+void getCommand(client *c) {
+    getGenericCommand(c);
+}
+
+/*
+ * GETEX <key> [PERSIST][EX seconds][PX milliseconds][EXAT seconds-timestamp][PXAT milliseconds-timestamp]
+ *
+ * The getexCommand() function implements extended options and variants of the GET command. Unlike GET
+ * command this command is not read-only.
+ *
+ * The default behavior when no options are specified is same as GET and does not alter any TTL.
+ *
+ * Only one of the below options can be used at a given time.
+ *
+ * 1. PERSIST removes any TTL associated with the key.
+ * 2. EX Set expiry TTL in seconds.
+ * 3. PX Set expiry TTL in milliseconds.
+ * 4. EXAT Same like EX instead of specifying the number of seconds representing the TTL
+ *      (time to live), it takes an absolute Unix timestamp
+ * 5. PXAT Same like PX instead of specifying the number of milliseconds representing the TTL
+ *      (time to live), it takes an absolute Unix timestamp
+ *
+ * Command would either return the bulk string, error or nil.
+ */
+void getexCommand(client *c) {
+    robj *expire = NULL;
+    int unit = UNIT_SECONDS;
+    int flags = OBJ_NO_FLAGS;
+
+    if (parseExtendedStringArgumentsOrReply(c,&flags,&unit,&expire,COMMAND_GET) != C_OK) {
+        return;
+    }
+
+    robj *o;
+
+    if ((o = lookupKeyReadOrReply(c,c->argv[1],shared.null[c->resp])) == NULL)
+        return;
+
+    if (checkType(c,o,OBJ_STRING)) {
+        return;
+    }
+
+    /* Validate the expiration time value first */
+    long long milliseconds = 0;
+    if (expire && getExpireMillisecondsOrReply(c, expire, flags, unit, &milliseconds) != C_OK) {
+        return;
+    }
+
+    /* We need to do this before we expire the key or delete it */
+    addReplyBulk(c,o);
+
+    /* This command is never propagated as is. It is either propagated as PEXPIRE[AT],DEL,UNLINK or PERSIST.
+     * This why it doesn't need special handling in feedAppendOnlyFile to convert relative expire time to absolute one. */
+    if (((flags & OBJ_PXAT) || (flags & OBJ_EXAT)) && checkAlreadyExpired(milliseconds)) {
+        /* When PXAT/EXAT absolute timestamp is specified, there can be a chance that timestamp
+         * has already elapsed so delete the key in that case. */
+        int deleted = dbGenericDelete(c->db, c->argv[1], server.lazyfree_lazy_expire, DB_FLAG_KEY_EXPIRED);
+        serverAssert(deleted);
+        robj *aux = server.lazyfree_lazy_expire ? shared.unlink : shared.del;
+        rewriteClientCommandVector(c,2,aux,c->argv[1]);
+        signalModifiedKey(c, c->db, c->argv[1]);
+        notifyKeyspaceEvent(NOTIFY_GENERIC, "del", c->argv[1], c->db->id);
+        server.dirty++;
+    } else if (expire) {
+        setExpire(c,c->db,c->argv[1],milliseconds);
+        /* Propagate as PXEXPIREAT millisecond-timestamp if there is
+         * EX/PX/EXAT/PXAT flag and the key has not expired. */
+        robj *milliseconds_obj = createStringObjectFromLongLong(milliseconds);
+        rewriteClientCommandVector(c,3,shared.pexpireat,c->argv[1],milliseconds_obj);
+        decrRefCount(milliseconds_obj);
+        signalModifiedKey(c, c->db, c->argv[1]);
+        notifyKeyspaceEvent(NOTIFY_GENERIC,"expire",c->argv[1],c->db->id);
+        server.dirty++;
+    } else if (flags & OBJ_PERSIST) {
+        if (removeExpire(c->db, c->argv[1])) {
+            signalModifiedKey(c, c->db, c->argv[1]);
+            rewriteClientCommandVector(c, 2, shared.persist, c->argv[1]);
+            notifyKeyspaceEvent(NOTIFY_GENERIC,"persist",c->argv[1],c->db->id);
+            server.dirty++;
+        }
+    }
+}
+
+void getdelCommand(client *c) {
+    if (getGenericCommand(c) == C_ERR) return;
+    if (dbSyncDelete(c->db, c->argv[1])) {
+        /* Propagate as DEL command */
+        rewriteClientCommandVector(c,2,shared.del,c->argv[1]);
+        signalModifiedKey(c, c->db, c->argv[1]);
+        notifyKeyspaceEvent(NOTIFY_GENERIC, "del", c->argv[1], c->db->id);
+        server.dirty++;
+    }
+}
+
+void getsetCommand(client *c) {
+    if (getGenericCommand(c) == C_ERR) return;
+    c->argv[2] = tryObjectEncoding(c->argv[2]);
+    setKey(c,c->db,c->argv[1],c->argv[2],0);
+    notifyKeyspaceEvent(NOTIFY_STRING,"set",c->argv[1],c->db->id);
+    server.dirty++;
+
+    /* Propagate as SET command */
+    rewriteClientCommandArgument(c,0,shared.set);
+}
+
+void setrangeCommand(client *c) {
+    robj *o;
+    long offset;
+    sds value = c->argv[3]->ptr;
+
+    if (getLongFromObjectOrReply(c,c->argv[2],&offset,NULL) != C_OK)
+        return;
+
+    if (offset < 0) {
+        addReplyError(c,"offset is out of range");
+        return;
+    }
+
+    o = lookupKeyWrite(c->db,c->argv[1]);
+    if (o == NULL) {
+        /* Return 0 when setting nothing on a non-existing string */
+        if (sdslen(value) == 0) {
+            addReply(c,shared.czero);
+            return;
+        }
+
+        /* Return when the resulting string exceeds allowed size */
+        if (checkStringLength(c,offset,sdslen(value)) != C_OK)
+            return;
+
+        o = createObject(OBJ_STRING,sdsnewlen(NULL, offset+sdslen(value)));
+        dbAdd(c->db,c->argv[1],o);
+    } else {
+        size_t olen;
+
+        /* Key exists, check type */
+        if (checkType(c,o,OBJ_STRING))
+            return;
+
+        /* Return existing string length when setting nothing */
+        olen = stringObjectLen(o);
+        if (sdslen(value) == 0) {
+            addReplyLongLong(c,olen);
+            return;
+        }
+
+        /* Return when the resulting string exceeds allowed size */
+        if (checkStringLength(c,offset,sdslen(value)) != C_OK)
+            return;
+
+        /* Create a copy when the object is shared or encoded. */
+        o = dbUnshareStringValue(c->db,c->argv[1],o);
+    }
+
+    if (sdslen(value) > 0) {
+        o->ptr = sdsgrowzero(o->ptr,offset+sdslen(value));
+        memcpy((char*)o->ptr+offset,value,sdslen(value));
+        signalModifiedKey(c,c->db,c->argv[1]);
+        notifyKeyspaceEvent(NOTIFY_STRING,
+            "setrange",c->argv[1],c->db->id);
+        server.dirty++;
+    }
+    addReplyLongLong(c,sdslen(o->ptr));
+}
+
+void getrangeCommand(client *c) {
+    robj *o;
+    long long start, end;
+    char *str, llbuf[32];
+    size_t strlen;
+
+    if (getLongLongFromObjectOrReply(c,c->argv[2],&start,NULL) != C_OK)
+        return;
+    if (getLongLongFromObjectOrReply(c,c->argv[3],&end,NULL) != C_OK)
+        return;
+    if ((o = lookupKeyReadOrReply(c,c->argv[1],shared.emptybulk)) == NULL ||
+        checkType(c,o,OBJ_STRING)) return;
+
+    if (o->encoding == OBJ_ENCODING_INT) {
+        str = llbuf;
+        strlen = ll2string(llbuf,sizeof(llbuf),(long)o->ptr);
+    } else {
+        str = o->ptr;
+        strlen = sdslen(str);
+    }
+
+    /* Convert negative indexes */
+    if (start < 0 && end < 0 && start > end) {
+        addReply(c,shared.emptybulk);
+        return;
+    }
+    if (start < 0) start = strlen+start;
+    if (end < 0) end = strlen+end;
+    if (start < 0) start = 0;
+    if (end < 0) end = 0;
+    if ((unsigned long long)end >= strlen) end = strlen-1;
+
+    /* Precondition: end >= 0 && end < strlen, so the only condition where
+     * nothing can be returned is: start > end. */
+    if (start > end || strlen == 0) {
+        addReply(c,shared.emptybulk);
+    } else {
+        addReplyBulkCBuffer(c,(char*)str+start,end-start+1);
+    }
+}
+
+void mgetCommand(client *c) {
+    int j;
+
+    addReplyArrayLen(c,c->argc-1);
+    for (j = 1; j < c->argc; j++) {
+        robj *o = lookupKeyRead(c->db,c->argv[j]);
+        if (o == NULL) {
+            addReplyNull(c);
+        } else {
+            if (o->type != OBJ_STRING) {
+                addReplyNull(c);
+            } else {
+                addReplyBulk(c,o);
+            }
+        }
+    }
+}
+
+void msetGenericCommand(client *c, int nx) {
+    int j;
+
+    if ((c->argc % 2) == 0) {
+        addReplyErrorArity(c);
+        return;
+    }
+
+    /* Handle the NX flag. The MSETNX semantic is to return zero and don't
+     * set anything if at least one key already exists. */
+    if (nx) {
+        for (j = 1; j < c->argc; j += 2) {
+            if (lookupKeyWrite(c->db,c->argv[j]) != NULL) {
+                addReply(c, shared.czero);
+                return;
+            }
+        }
+    }
+
+    int setkey_flags = nx ? SETKEY_DOESNT_EXIST : 0;
+    for (j = 1; j < c->argc; j += 2) {
+        c->argv[j+1] = tryObjectEncoding(c->argv[j+1]);
+        setKey(c, c->db, c->argv[j], c->argv[j + 1], setkey_flags);
+        notifyKeyspaceEvent(NOTIFY_STRING,"set",c->argv[j],c->db->id);
+        /* In MSETNX, It could be that we're overriding the same key, we can't be sure it doesn't exist. */
+        if (nx)
+            setkey_flags = SETKEY_ADD_OR_UPDATE;
+    }
+    server.dirty += (c->argc-1)/2;
+    addReply(c, nx ? shared.cone : shared.ok);
+}
+
+void msetCommand(client *c) {
+    msetGenericCommand(c,0);
+}
+
+void msetnxCommand(client *c) {
+    msetGenericCommand(c,1);
+}
+
+void incrDecrCommand(client *c, long long incr) {
+    long long value, oldvalue;
+    robj *o, *new;
+
+    o = lookupKeyWrite(c->db,c->argv[1]);
+    if (checkType(c,o,OBJ_STRING)) return;
+    if (getLongLongFromObjectOrReply(c,o,&value,NULL) != C_OK) return;
+
+    oldvalue = value;
+    if ((incr < 0 && oldvalue < 0 && incr < (LLONG_MIN-oldvalue)) ||
+        (incr > 0 && oldvalue > 0 && incr > (LLONG_MAX-oldvalue))) {
+        addReplyError(c,"increment or decrement would overflow");
+        return;
+    }
+    value += incr;
+
+    if (o && o->refcount == 1 && o->encoding == OBJ_ENCODING_INT &&
+        (value < 0 || value >= OBJ_SHARED_INTEGERS) &&
+        value >= LONG_MIN && value <= LONG_MAX)
+    {
+        new = o;
+        o->ptr = (void*)((long)value);
+    } else {
+        new = createStringObjectFromLongLongForValue(value);
+        if (o) {
+            dbReplaceValue(c->db,c->argv[1],new);
+        } else {
+            dbAdd(c->db,c->argv[1],new);
+        }
+    }
+    signalModifiedKey(c,c->db,c->argv[1]);
+    notifyKeyspaceEvent(NOTIFY_STRING,"incrby",c->argv[1],c->db->id);
+    server.dirty++;
+    addReplyLongLong(c, value);
+}
+
+void incrCommand(client *c) {
+    incrDecrCommand(c,1);
+}
+
+void decrCommand(client *c) {
+    incrDecrCommand(c,-1);
+}
+
+void incrbyCommand(client *c) {
+    long long incr;
+
+    if (getLongLongFromObjectOrReply(c, c->argv[2], &incr, NULL) != C_OK) return;
+    incrDecrCommand(c,incr);
+}
+
+void decrbyCommand(client *c) {
+    long long incr;
+
+    if (getLongLongFromObjectOrReply(c, c->argv[2], &incr, NULL) != C_OK) return;
+    /* Overflow check: negating LLONG_MIN will cause an overflow */
+    if (incr == LLONG_MIN) {
+        addReplyError(c, "decrement would overflow");
+        return;
+    }
+    incrDecrCommand(c,-incr);
+}
+
+void incrbyfloatCommand(client *c) {
+    long double incr, value;
+    robj *o, *new;
+
+    o = lookupKeyWrite(c->db,c->argv[1]);
+    if (checkType(c,o,OBJ_STRING)) return;
+    if (getLongDoubleFromObjectOrReply(c,o,&value,NULL) != C_OK ||
+        getLongDoubleFromObjectOrReply(c,c->argv[2],&incr,NULL) != C_OK)
+        return;
+
+    value += incr;
+    if (isnan(value) || isinf(value)) {
+        addReplyError(c,"increment would produce NaN or Infinity");
+        return;
+    }
+    new = createStringObjectFromLongDouble(value,1);
+    if (o)
+        dbReplaceValue(c->db,c->argv[1],new);
+    else
+        dbAdd(c->db,c->argv[1],new);
+    signalModifiedKey(c,c->db,c->argv[1]);
+    notifyKeyspaceEvent(NOTIFY_STRING,"incrbyfloat",c->argv[1],c->db->id);
+    server.dirty++;
+    addReplyBulk(c,new);
+
+    /* Always replicate INCRBYFLOAT as a SET command with the final value
+     * in order to make sure that differences in float precision or formatting
+     * will not create differences in replicas or after an AOF restart. */
+    rewriteClientCommandArgument(c,0,shared.set);
+    rewriteClientCommandArgument(c,2,new);
+    rewriteClientCommandArgument(c,3,shared.keepttl);
+}
+
+void appendCommand(client *c) {
+    size_t totlen;
+    robj *o, *append;
+
+    o = lookupKeyWrite(c->db,c->argv[1]);
+    if (o == NULL) {
+        /* Create the key */
+        c->argv[2] = tryObjectEncoding(c->argv[2]);
+        dbAdd(c->db,c->argv[1],c->argv[2]);
+        incrRefCount(c->argv[2]);
+        totlen = stringObjectLen(c->argv[2]);
+    } else {
+        /* Key exists, check type */
+        if (checkType(c,o,OBJ_STRING))
+            return;
+
+        /* "append" is an argument, so always an sds */
+        append = c->argv[2];
+        if (checkStringLength(c,stringObjectLen(o),sdslen(append->ptr)) != C_OK)
+            return;
+
+        /* Append the value */
+        o = dbUnshareStringValue(c->db,c->argv[1],o);
+        o->ptr = sdscatlen(o->ptr,append->ptr,sdslen(append->ptr));
+        totlen = sdslen(o->ptr);
+    }
+    signalModifiedKey(c,c->db,c->argv[1]);
+    notifyKeyspaceEvent(NOTIFY_STRING,"append",c->argv[1],c->db->id);
+    server.dirty++;
+    addReplyLongLong(c,totlen);
+}
+
+void strlenCommand(client *c) {
+    robj *o;
+    if ((o = lookupKeyReadOrReply(c,c->argv[1],shared.czero)) == NULL ||
+        checkType(c,o,OBJ_STRING)) return;
+    addReplyLongLong(c,stringObjectLen(o));
+}
+
+/* LCS key1 key2 [LEN] [IDX] [MINMATCHLEN <len>] [WITHMATCHLEN] */
+void lcsCommand(client *c) {
+    uint32_t i, j;
+    long long minmatchlen = 0;
+    sds a = NULL, b = NULL;
+    int getlen = 0, getidx = 0, withmatchlen = 0;
+    robj *obja = NULL, *objb = NULL;
+
+    obja = lookupKeyRead(c->db,c->argv[1]);
+    objb = lookupKeyRead(c->db,c->argv[2]);
+    if ((obja && obja->type != OBJ_STRING) ||
+        (objb && objb->type != OBJ_STRING))
+    {
+        addReplyError(c,
+            "The specified keys must contain string values");
+        /* Don't cleanup the objects, we need to do that
+         * only after calling getDecodedObject(). */
+        obja = NULL;
+        objb = NULL;
+        goto cleanup;
+    }
+    obja = obja ? getDecodedObject(obja) : createStringObject("",0);
+    objb = objb ? getDecodedObject(objb) : createStringObject("",0);
+    a = obja->ptr;
+    b = objb->ptr;
+
+    for (j = 3; j < (uint32_t)c->argc; j++) {
+        char *opt = c->argv[j]->ptr;
+        int moreargs = (c->argc-1) - j;
+
+        if (!strcasecmp(opt,"IDX")) {
+            getidx = 1;
+        } else if (!strcasecmp(opt,"LEN")) {
+            getlen = 1;
+        } else if (!strcasecmp(opt,"WITHMATCHLEN")) {
+            withmatchlen = 1;
+        } else if (!strcasecmp(opt,"MINMATCHLEN") && moreargs) {
+            if (getLongLongFromObjectOrReply(c,c->argv[j+1],&minmatchlen,NULL)
+                != C_OK) goto cleanup;
+            if (minmatchlen < 0) minmatchlen = 0;
+            j++;
+        } else {
+            addReplyErrorObject(c,shared.syntaxerr);
+            goto cleanup;
+        }
+    }
+
+    /* Complain if the user passed ambiguous parameters. */
+    if (getlen && getidx) {
+        addReplyError(c,
+            "If you want both the length and indexes, please just use IDX.");
+        goto cleanup;
+    }
+
+    /* Detect string truncation or later overflows. */
+    if (sdslen(a) >= UINT32_MAX-1 || sdslen(b) >= UINT32_MAX-1) {
+        addReplyError(c, "String too long for LCS");
+        goto cleanup;
+    }
+
+    /* Compute the LCS using the vanilla dynamic programming technique of
+     * building a table of LCS(x,y) substrings. */
+    uint32_t alen = sdslen(a);
+    uint32_t blen = sdslen(b);
+
+    /* Setup an uint32_t array to store at LCS[i,j] the length of the
+     * LCS A0..i-1, B0..j-1. Note that we have a linear array here, so
+     * we index it as LCS[j+(blen+1)*i] */
+    #define LCS(A,B) lcs[(B)+((A)*(blen+1))]
+
+    /* Try to allocate the LCS table, and abort on overflow or insufficient memory. */
+    unsigned long long lcssize = (unsigned long long)(alen+1)*(blen+1); /* Can't overflow due to the size limits above. */
+    unsigned long long lcsalloc = lcssize * sizeof(uint32_t);
+    uint32_t *lcs = NULL;
+    if (lcsalloc < SIZE_MAX && lcsalloc / lcssize == sizeof(uint32_t)) {
+        if (lcsalloc > (size_t)server.proto_max_bulk_len) {
+            addReplyError(c, "Insufficient memory, transient memory for LCS exceeds proto-max-bulk-len");
+            goto cleanup;
+        }
+        lcs = ztrymalloc(lcsalloc);
+    }
+    if (!lcs) {
+        addReplyError(c, "Insufficient memory, failed allocating transient memory for LCS");
+        goto cleanup;
+    }
+
+    /* Start building the LCS table. */
+    for (uint32_t i = 0; i <= alen; i++) {
+        for (uint32_t j = 0; j <= blen; j++) {
+            if (i == 0 || j == 0) {
+                /* If one substring has length of zero, the
+                 * LCS length is zero. */
+                LCS(i,j) = 0;
+            } else if (a[i-1] == b[j-1]) {
+                /* The len LCS (and the LCS itself) of two
+                 * sequences with the same final character, is the
+                 * LCS of the two sequences without the last char
+                 * plus that last char. */
+                LCS(i,j) = LCS(i-1,j-1)+1;
+            } else {
+                /* If the last character is different, take the longest
+                 * between the LCS of the first string and the second
+                 * minus the last char, and the reverse. */
+                uint32_t lcs1 = LCS(i-1,j);
+                uint32_t lcs2 = LCS(i,j-1);
+                LCS(i,j) = lcs1 > lcs2 ? lcs1 : lcs2;
+            }
+        }
+    }
+
+    /* Store the actual LCS string in "result" if needed. We create
+     * it backward, but the length is already known, we store it into idx. */
+    uint32_t idx = LCS(alen,blen);
+    sds result = NULL;        /* Resulting LCS string. */
+    void *arraylenptr = NULL; /* Deferred length of the array for IDX. */
+    uint32_t arange_start = alen, /* alen signals that values are not set. */
+             arange_end = 0,
+             brange_start = 0,
+             brange_end = 0;
+
+    /* Do we need to compute the actual LCS string? Allocate it in that case. */
+    int computelcs = getidx || !getlen;
+    if (computelcs) result = sdsnewlen(SDS_NOINIT,idx);
+
+    /* Start with a deferred array if we have to emit the ranges. */
+    uint32_t arraylen = 0;  /* Number of ranges emitted in the array. */
+    if (getidx) {
+        addReplyMapLen(c,2);
+        addReplyBulkCString(c,"matches");
+        arraylenptr = addReplyDeferredLen(c);
+    }
+
+    i = alen, j = blen;
+    while (computelcs && i > 0 && j > 0) {
+        int emit_range = 0;
+        if (a[i-1] == b[j-1]) {
+            /* If there is a match, store the character and reduce
+             * the indexes to look for a new match. */
+            result[idx-1] = a[i-1];
+
+            /* Track the current range. */
+            if (arange_start == alen) {
+                arange_start = i-1;
+                arange_end = i-1;
+                brange_start = j-1;
+                brange_end = j-1;
+            } else {
+                /* Let's see if we can extend the range backward since
+                 * it is contiguous. */
+                if (arange_start == i && brange_start == j) {
+                    arange_start--;
+                    brange_start--;
+                } else {
+                    emit_range = 1;
+                }
+            }
+            /* Emit the range if we matched with the first byte of
+             * one of the two strings. We'll exit the loop ASAP. */
+            if (arange_start == 0 || brange_start == 0) emit_range = 1;
+            idx--; i--; j--;
+        } else {
+            /* Otherwise reduce i and j depending on the largest
+             * LCS between, to understand what direction we need to go. */
+            uint32_t lcs1 = LCS(i-1,j);
+            uint32_t lcs2 = LCS(i,j-1);
+            if (lcs1 > lcs2)
+                i--;
+            else
+                j--;
+            if (arange_start != alen) emit_range = 1;
+        }
+
+        /* Emit the current range if needed. */
+        uint32_t match_len = arange_end - arange_start + 1;
+        if (emit_range) {
+            if (minmatchlen == 0 || match_len >= minmatchlen) {
+                if (arraylenptr) {
+                    addReplyArrayLen(c,2+withmatchlen);
+                    addReplyArrayLen(c,2);
+                    addReplyLongLong(c,arange_start);
+                    addReplyLongLong(c,arange_end);
+                    addReplyArrayLen(c,2);
+                    addReplyLongLong(c,brange_start);
+                    addReplyLongLong(c,brange_end);
+                    if (withmatchlen) addReplyLongLong(c,match_len);
+                    arraylen++;
+                }
+            }
+            arange_start = alen; /* Restart at the next match. */
+        }
+    }
+
+    /* Signal modified key, increment dirty, ... */
+
+    /* Reply depending on the given options. */
+    if (arraylenptr) {
+        addReplyBulkCString(c,"len");
+        addReplyLongLong(c,LCS(alen,blen));
+        setDeferredArrayLen(c,arraylenptr,arraylen);
+    } else if (getlen) {
+        addReplyLongLong(c,LCS(alen,blen));
+    } else {
+        addReplyBulkSds(c,result);
+        result = NULL;
+    }
+
+    /* Cleanup. */
+    sdsfree(result);
+    zfree(lcs);
+
+cleanup:
+    if (obja) decrRefCount(obja);
+    if (objb) decrRefCount(objb);
+    return;
+}
+