/*
** Describe the usages of a b-tree page
*/
static void page_usage_btree(
int pgno, /* Page to describe */
int parent, /* Parent of this page. 0 for root pages */
int idx, /* Which child of the parent */
const char *zName /* Name of the table */
){
unsigned char *a;
const char *zType = "corrupt node";
int nCell;
int i;
int hdr = pgno==1 ? 100 : 0;
if( pgno<=0 || pgno>mxPage ) return;
a = getContent((pgno-1)*pagesize, pagesize);
switch( a[hdr] ){
case 2: zType = "interior node of index"; break;
case 5: zType = "interior node of table"; break;
case 10: zType = "leaf of index"; break;
case 13: zType = "leaf of table"; break;
}
if( parent ){
page_usage_msg(pgno, "%s [%s], child %d of page %d",
zType, zName, idx, parent);
}else{
page_usage_msg(pgno, "root %s [%s]", zType, zName);
}
nCell = a[hdr+3]*256 + a[hdr+4];
if( a[hdr]==2 || a[hdr]==5 ){
int cellstart = hdr+12;
unsigned int child;
for(i=0; i<nCell; i++){
int ofst;
ofst = cellstart + i*2;
ofst = a[ofst]*256 + a[ofst+1];
child = decodeInt32(a+ofst);
page_usage_btree(child, pgno, i, zName);
}
child = decodeInt32(a+cellstart-4);
page_usage_btree(child, pgno, i, zName);
}
if( a[hdr]==2 || a[hdr]==10 || a[hdr]==13 ){
int cellstart = hdr + 8 + 4*(a[hdr]<=5);
for(i=0; i<nCell; i++){
int ofst;
ofst = cellstart + i*2;
ofst = a[ofst]*256 + a[ofst+1];
page_usage_cell(a[hdr], a+ofst, pgno, i);
}
}
free(a);
}
/*
** Determine pages used as PTRMAP pages
*/
static void page_usage_ptrmap(unsigned char *a){
if( a[55] ){
int usable = pagesize - a[20];
int pgno = 2;
int perPage = usable/5;
while( pgno<=mxPage ){
page_usage_msg(pgno, "PTRMAP page covering %d..%d",
pgno+1, pgno+perPage);
pgno += perPage + 1;
}
}
}
/*
** Determine page usage by the freelist
*/
static void page_usage_freelist(int pgno){
unsigned char *a;
int cnt = 0;
int i;
int n;
int iNext;
int parent = 1;
while( pgno>0 && pgno<=mxPage && (cnt++)<mxPage ){
page_usage_msg(pgno, "freelist trunk #%d child of %d", cnt, parent);
a = getContent((pgno-1)*pagesize, pagesize);
iNext = decodeInt32(a);
n = decodeInt32(a+4);
for(i=0; i<n; i++){
int child = decodeInt32(a + (i*4+8));
page_usage_msg(child, "freelist leaf, child %d of trunk page %d",
i, pgno);
}
free(a);
parent = pgno;
pgno = iNext;
}
}
/*
** Find overflow pages of a cell and describe their usage.
*/
static void page_usage_cell(
unsigned char cType, /* Page type */
unsigned char *a, /* Cell content */
int pgno, /* page containing the cell */
int cellno /* Index of the cell on the page */
){
int i;
int nDesc = 0;
int n = 0;
i64 nPayload;
i64 rowid;
int nLocal;
i = 0;
if( cType<=5 ){
a += 4;
n += 4;
}
if( cType!=5 ){
i = decodeVarint(a, &nPayload);
a += i;
n += i;
nLocal = localPayload(nPayload, cType);
}else{
nPayload = nLocal = 0;
}
if( cType==5 || cType==13 ){
i = decodeVarint(a, &rowid);
a += i;
n += i;
}
if( nLocal<nPayload ){
int ovfl = decodeInt32(a+nLocal);
int cnt = 0;
while( ovfl && (cnt++)<mxPage ){
page_usage_msg(ovfl, "overflow %d from cell %d of page %d",
cnt, cellno, pgno);
a = getContent((ovfl-1)*pagesize, 4);
ovfl = decodeInt32(a);
free(a);
}
}
}
