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aff_db.cpp
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aff_db.cpp
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/*
* afflib_db.cpp:
*
* Functions for the manipulation of the AFF database.
*/
#include "affconfig.h"
#include "afflib.h"
#include "afflib_i.h"
#include "aff_db.h"
/****************************************************************
*** Low-level functions
****************************************************************/
/****************************************************************
*** Probe Functions
****************************************************************/
int af_probe_next_seg(AFFILE *af,
char *segname,
size_t segname_len,
unsigned long *arg_, // optional arg
size_t *datasize_, // optional get datasize
size_t *segsize_, // optional get size of entire segment
int do_rewind) // optional rewind af->aseg, otherwise leave at start of segment data
{
if(!af->aseg)(*af->error_reporter)("af_probe_next_segment only works with aff files");
struct af_segment_head segh;
memset(&segh,0,sizeof(segh));
uint64_t start = ftello(af->aseg);
#ifdef __BORLANDC__
fseeko(af->aseg, start, SEEK_SET) ; // Windows is dumb :-(
#endif
if(fread(&segh,sizeof(segh),1,af->aseg)!=1){
return AF_ERROR_EOF;
}
if(strcmp(segh.magic,AF_SEGHEAD)!=0){
snprintf(af->error_str,sizeof(af->error_str),"afflib: segh is corrupt at %" PRIu64,start);
return AF_ERROR_SEGH;
}
unsigned long name_len = ntohl(segh.name_len);
unsigned long datasize = ntohl(segh.data_len);
if(name_len>AF_MAX_NAME_LEN){
snprintf(af->error_str,sizeof(af->error_str),"afflib: name_len=%lu (an outrageous value)",name_len);
return AF_ERROR_NAME;
}
if(name_len+1 > segname_len){
fseeko(af->aseg,start,SEEK_SET); // rewind to start
return -2;
}
if(fread(segname,1,name_len,af->aseg)!=name_len){
fseeko(af->aseg,start,SEEK_SET); // rewind
return -1;
}
segname[name_len] = 0;
if(do_rewind) fseeko(af->aseg,start,SEEK_SET); // rewind
unsigned long segsize = sizeof(struct af_segment_head)
+ sizeof(struct af_segment_tail)
+ name_len + datasize;
if(arg_) *arg_ = ntohl(segh.flag);
if(datasize_) *datasize_ = datasize;
if(segsize_) *segsize_ = segsize;
#ifdef DEBUG
fprintf(stderr,"af_probe_next_seg(segname=%s datasize=%d segsize=%d) do_rewind=%d\n",
segname,datasize,segsize,do_rewind);
#endif
return 0;
}
/* af_backspace:
* moves back one segment in the aff file.
* Returns 0 if success, -1 if we can't back up further.
*/
int af_backspace(AFFILE *af)
{
struct af_segment_tail segt;
uint64_t start = ftello(af->aseg);
if(start==sizeof(AF_HEADER) || start<sizeof(segt)) return -1; // can't backspace further
uint64_t pos_tail = start - sizeof(segt); // backspace to read the tail
fseeko(af->aseg,pos_tail,SEEK_SET);
if(fread(&segt,sizeof(segt),1,af->aseg)!=1){
fseeko(af->aseg,start,SEEK_SET); // put it back
return -1; // can't read segt?
}
/* Verify that this is a segment tail. if it isn't, put the file pointer back and return */
if(memcmp(segt.magic,AF_SEGTAIL,sizeof(AF_SEGTAIL))!=0){
fseeko(af->aseg,start,SEEK_SET);
return -1;
}
/* Now I know how long the segment was. Compute where it started */
uint64_t seg_start = start - ntohl(segt.segment_len);
fseeko(af->aseg,seg_start,SEEK_SET);
return 0;
}
/* find the given segment and return 0 if found.
* Leave the file pointer positioned at the start of the segment.
* Return -1 if segment is not found, and leave pointer at the end
*/
int aff_find_seg(AFFILE *af,const char *segname,
unsigned long *arg,
size_t *datasize,
size_t *segsize)
{
char next_segment_name[AF_MAX_NAME_LEN];
size_t next_segsize = 0;
size_t next_datasize = 0;
unsigned long next_arg;
/* Try to use the TOC to find the segment in question */
struct aff_toc_mem *adm = aff_toc(af,segname);
if(adm){
if(datasize==0 && segsize==0 && arg==0){
/* User was just probing to see if it was present. And it is! */
return 0;
}
fseeko(af->aseg,adm->offset,SEEK_SET);
}
else {
af_rewind_seg(af);
}
while(af_probe_next_seg(af,next_segment_name,sizeof(next_segment_name),
&next_arg,&next_datasize,&next_segsize,1)==0){
if(strcmp(next_segment_name,segname)==0){ // found the segment!
if(datasize) *datasize = next_datasize;
if(segsize) *segsize = next_segsize;
if(arg) *arg = next_arg;
return 0; // return the info
}
fseeko(af->aseg,next_segsize,SEEK_CUR); // skip the segment
}
return -1; // couldn't find segment
}
int af_get_segq(AFFILE *af,const char *name,int64_t *aff_quad)
{
unsigned char buf[8];
size_t bufsize = sizeof(buf);
if(af_get_seg(af,name,0,(unsigned char *)&buf,&bufsize)){
return -1; // couldn't get it...
}
if(bufsize!=sizeof(struct aff_quad)){ // make sure size is good.
return -1;
}
*aff_quad = af_decode_q(buf);
return 0;
}
/* af_update_segq:
* Update the named aff_quad-byte value.
*/
int af_update_segq(AFFILE *af, const char *name, int64_t value)
{
struct aff_quad q;
q.low = htonl((unsigned long)(value & 0xffffffff));
q.high = htonl((unsigned long)(value >> 32));
return af_update_seg(af,name,AF_SEG_QUADWORD,(const u_char *)&q,8);
}

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