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a10ae35328
Essentially, the problem is that safemalloc is excruciatingly slow as it checks all allocated blocks for overrun at each memory management primitive, yielding a almost exponential slowdown for the memory management functions (malloc, realloc, free). The overrun check basically consists of verifying some bytes of a block for certain magic keys, which catches some simple forms of overrun. Another minor problem is violation of aliasing rules and that its own internal list of blocks is prone to corruption. Another issue with safemalloc is rather the maintenance cost as the tool has a significant impact on the server code. Given the magnitude of memory debuggers available nowadays, especially those that are provided with the platform malloc implementation, maintenance of a in-house and largely obsolete memory debugger becomes a burden that is not worth the effort due to its slowness and lack of support for detecting more common forms of heap corruption. Since there are third-party tools that can provide the same functionality at a lower or comparable performance cost, the solution is to simply remove safemalloc. Third-party tools can provide the same functionality at a lower or comparable performance cost. The removal of safemalloc also allows a simplification of the malloc wrappers, removing quite a bit of kludge: redefinition of my_malloc, my_free and the removal of the unused second argument of my_free. Since free() always check whether the supplied pointer is null, redudant checks are also removed. Also, this patch adds unit testing for my_malloc and moves my_realloc implementation into the same file as the other memory allocation primitives.
264 lines
6.9 KiB
C
264 lines
6.9 KiB
C
/* Copyright (C) 2000 MySQL AB
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; version 2 of the License.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */
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/* Written by Sinisa Milivojevic <sinisa@mysql.com> */
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#include <my_global.h>
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#ifdef HAVE_COMPRESS
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#include <my_sys.h>
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#ifndef SCO
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#include <m_string.h>
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#endif
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#include <zlib.h>
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/*
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This replaces the packet with a compressed packet
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SYNOPSIS
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my_compress()
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packet Data to compress. This is is replaced with the compressed data.
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len Length of data to compress at 'packet'
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complen out: 0 if packet was not compressed
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RETURN
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1 error. 'len' is not changed'
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0 ok. In this case 'len' contains the size of the compressed packet
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*/
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my_bool my_compress(uchar *packet, size_t *len, size_t *complen)
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{
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DBUG_ENTER("my_compress");
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if (*len < MIN_COMPRESS_LENGTH)
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{
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*complen=0;
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DBUG_PRINT("note",("Packet too short: Not compressed"));
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}
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else
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{
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uchar *compbuf=my_compress_alloc(packet,len,complen);
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if (!compbuf)
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DBUG_RETURN(*complen ? 0 : 1);
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memcpy(packet,compbuf,*len);
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my_free(compbuf);
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}
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DBUG_RETURN(0);
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}
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uchar *my_compress_alloc(const uchar *packet, size_t *len, size_t *complen)
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{
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uchar *compbuf;
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uLongf tmp_complen;
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int res;
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*complen= *len * 120 / 100 + 12;
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if (!(compbuf= (uchar *) my_malloc(*complen, MYF(MY_WME))))
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return 0; /* Not enough memory */
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tmp_complen= (uint) *complen;
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res= compress((Bytef*) compbuf, &tmp_complen, (Bytef*) packet, (uLong) *len);
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*complen= tmp_complen;
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if (res != Z_OK)
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{
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my_free(compbuf);
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return 0;
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}
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if (*complen >= *len)
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{
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*complen= 0;
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my_free(compbuf);
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DBUG_PRINT("note",("Packet got longer on compression; Not compressed"));
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return 0;
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}
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/* Store length of compressed packet in *len */
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swap_variables(size_t, *len, *complen);
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return compbuf;
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}
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/*
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Uncompress packet
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SYNOPSIS
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my_uncompress()
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packet Compressed data. This is is replaced with the orignal data.
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len Length of compressed data
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complen Length of the packet buffer (must be enough for the original
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data)
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RETURN
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1 error
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0 ok. In this case 'complen' contains the updated size of the
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real data.
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*/
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my_bool my_uncompress(uchar *packet, size_t len, size_t *complen)
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{
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uLongf tmp_complen;
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DBUG_ENTER("my_uncompress");
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if (*complen) /* If compressed */
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{
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uchar *compbuf= (uchar *) my_malloc(*complen,MYF(MY_WME));
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int error;
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if (!compbuf)
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DBUG_RETURN(1); /* Not enough memory */
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tmp_complen= (uint) *complen;
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error= uncompress((Bytef*) compbuf, &tmp_complen, (Bytef*) packet,
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(uLong) len);
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*complen= tmp_complen;
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if (error != Z_OK)
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{ /* Probably wrong packet */
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DBUG_PRINT("error",("Can't uncompress packet, error: %d",error));
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my_free(compbuf);
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DBUG_RETURN(1);
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}
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memcpy(packet, compbuf, *complen);
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my_free(compbuf);
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}
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else
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*complen= len;
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DBUG_RETURN(0);
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}
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/*
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Internal representation of the frm blob is:
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ver 4 bytes
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orglen 4 bytes
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complen 4 bytes
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*/
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#define BLOB_HEADER 12
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/*
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packfrm is a method used to compress the frm file for storage in a
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handler. This method was developed for the NDB handler and has been moved
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here to serve also other uses.
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SYNOPSIS
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packfrm()
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data Data reference to frm file data.
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len Length of frm file data
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out:pack_data Reference to the pointer to the packed frm data
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out:pack_len Length of packed frm file data
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NOTES
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data is replaced with compressed content
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RETURN VALUES
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0 Success
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>0 Failure
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*/
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int packfrm(uchar *data, size_t len,
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uchar **pack_data, size_t *pack_len)
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{
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int error;
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size_t org_len, comp_len, blob_len;
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uchar *blob;
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DBUG_ENTER("packfrm");
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DBUG_PRINT("enter", ("data: 0x%lx len: %lu", (long) data, (ulong) len));
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error= 1;
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org_len= len;
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if (my_compress((uchar*)data, &org_len, &comp_len))
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goto err;
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DBUG_PRINT("info", ("org_len: %lu comp_len: %lu", (ulong) org_len,
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(ulong) comp_len));
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DBUG_DUMP("compressed", data, org_len);
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error= 2;
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blob_len= BLOB_HEADER + org_len;
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if (!(blob= (uchar*) my_malloc(blob_len,MYF(MY_WME))))
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goto err;
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/* Store compressed blob in machine independent format */
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int4store(blob, 1);
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int4store(blob+4, (uint32) len);
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int4store(blob+8, (uint32) org_len); /* compressed length */
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/* Copy frm data into blob, already in machine independent format */
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memcpy(blob+BLOB_HEADER, data, org_len);
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*pack_data= blob;
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*pack_len= blob_len;
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error= 0;
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DBUG_PRINT("exit", ("pack_data: 0x%lx pack_len: %lu",
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(long) *pack_data, (ulong) *pack_len));
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err:
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DBUG_RETURN(error);
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}
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/*
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unpackfrm is a method used to decompress the frm file received from a
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handler. This method was developed for the NDB handler and has been moved
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here to serve also other uses for other clustered storage engines.
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SYNOPSIS
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unpackfrm()
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pack_data Data reference to packed frm file data
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out:unpack_data Reference to the pointer to the unpacked frm data
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out:unpack_len Length of unpacked frm file data
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RETURN VALUES¨
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0 Success
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>0 Failure
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*/
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int unpackfrm(uchar **unpack_data, size_t *unpack_len,
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const uchar *pack_data)
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{
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uchar *data;
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size_t complen, orglen;
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ulong ver;
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DBUG_ENTER("unpackfrm");
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DBUG_PRINT("enter", ("pack_data: 0x%lx", (long) pack_data));
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ver= uint4korr(pack_data);
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orglen= uint4korr(pack_data+4);
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complen= uint4korr(pack_data+8);
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DBUG_PRINT("blob",("ver: %lu complen: %lu orglen: %lu",
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ver, (ulong) complen, (ulong) orglen));
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DBUG_DUMP("blob->data", pack_data + BLOB_HEADER, complen);
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if (ver != 1)
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DBUG_RETURN(1);
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if (!(data= my_malloc(max(orglen, complen), MYF(MY_WME))))
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DBUG_RETURN(2);
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memcpy(data, pack_data + BLOB_HEADER, complen);
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if (my_uncompress(data, complen, &orglen))
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{
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my_free(data);
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DBUG_RETURN(3);
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}
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*unpack_data= data;
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*unpack_len= orglen;
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DBUG_PRINT("exit", ("frmdata: 0x%lx len: %lu", (long) *unpack_data,
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(ulong) *unpack_len));
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DBUG_RETURN(0);
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}
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#endif /* HAVE_COMPRESS */
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