sbester

#include <stdio.h>
#include <math.h>
#include <errno.h>

int main(int argc, char * argv[])
{
        FILE *myd_file;
    FILE *del_file;
        unsigned char *record=NULL;
        size_t reclength=0;
        unsigned long long offset=0;
        unsigned long long recnum=0;
        unsigned long long numdeleted=0;
        unsigned long long numpresent=0;

        if(argc != 4)
        {
                printf("usage: ./undeleter /path/to/original.MYD /path/to/recovered.MYD record_length\n");
                printf("example: to recover table history and place deleted records into a table called history_recovered, having record length of 42 (as shown in show table status:\n");
                printf("./undeleter /data/test/history.MYD /data/test/history_recovered.MYD 42\n\n");
                return 1;
        }

        myd_file=fopen(argv[1],"rb");
        if(NULL == myd_file)
        {
                printf("failed to open input table from file '%s', errno=%d\n",argv[1],errno);
                return 1;
        }

        del_file=fopen(argv[2],"wb");
        if(NULL == del_file)
        {
                printf("failed to open output table from file '%s', errno=%d\n",argv[2],errno);
                fclose(myd_file);
                return 1;
        }

        reclength=atoi(argv[3]);
        printf("allocating a block of memory for records, %lu bytes\n",reclength);
        record=(unsigned char*)calloc(reclength,1);
        if(NULL == record)
        {
                printf("failed to allocate memory for a single record block\n");
                fclose(myd_file);
                fclose(del_file);
                return 1;
        }

        printf("starting to read records\n");
        while(!feof(myd_file))
        {
                if(fread(record,reclength,1,myd_file) < 1)
                        continue;

                if(record[0] == 0)
                {
                        numdeleted++;
                        record[0]=0xc0; //reset the delete flag
                        printf("found deleted record at offset %lu\n",offset);
                        if(fwrite(record,reclength,1,del_file) < 1)
                        {
                                printf("error trying to write record to '%s', errno=%d\n",argv[2],errno);
                        }
                }
                else
                {
                        numpresent++;
                }
                offset+=reclength;
        }

        fclose(myd_file);
        fclose(del_file);
        free(record);

        printf("-----------------\n");
        printf("    completed    \n");
        printf("-----------------\n");
        printf("records copied into '%s': %lu\n",argv[2],numdeleted);
        printf("records present in '%s': %lu\n\n",argv[1],numpresent);
        printf("next steps:\n");
        printf("1. remove the MYI for '%s'\n",argv[2]);
        printf("2. make sure '%s' definition .frm is created without any unique or PK keys\n",argv[2]);
        printf("3. repair table <recovered table> use_frm\n");
        printf("\n\n");

        return 0;
}