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Changed the memory allocation strategy for NmapOutputTable from

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estimating the worst-possible-case memory usage (the longest row
length times the number of rows) to a more reasonable dynamic
allocation of memory.  Now the buffer is started at 512 bytes and
approximately doubled each time it fills.  512 bytes is a compromise
that was determined empirically.  Most regular scans use less than 512
bytes.  Scans with -sV and especially -sC tend to use a few k of
memory.

See http://seclists.org/nmap-dev/2009/q1/0782.html for the tests.
This commit is contained in:
bmenrigh
2009-03-24 21:18:01 +00:00
parent 3af559b852
commit 1d732258c8
2 changed files with 21 additions and 43 deletions
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60
NmapOutputTable.cc
View File

@@ -214,33 +214,6 @@ void NmapOutputTable::addItemFormatted(unsigned int row,
}
}
// Returns the maximum size neccessary to create a printableTable() (the
// actual size could be less);
int NmapOutputTable::printableSize() {
struct NmapOutputTableCell *cell;
int rowlen = 0;
unsigned int i;
for(i = 0; i < numColumns; i++) {
rowlen += maxColLen[i];
}
/* Add the delimeter between each column, and the final newline */
rowlen += numColumns;
// if one of the fullrow tables is larger than the single column
// roles then the maximal rowlen needs to be adjusted.
for(i = 0; i < numRows; i++) {
cell = getCellAddy(i, 0);
if(cell->fullrow && cell->strlength + 1 > rowlen)
rowlen = cell->strlength + 1; /* Account for the newline with the +1 */
}
return rowlen * numRows;
}
/* True if every column in nrow is empty */
bool NmapOutputTable::emptyRow(unsigned int nrow) {
NmapOutputTableCell *cell;
@@ -267,18 +240,16 @@ bool NmapOutputTable::emptyRow(unsigned int nrow) {
// All blank rows are removed from the returned string
char *NmapOutputTable::printableTable(int *size) {
unsigned int col, row;
int maxsz = printableSize();
char *p;
int p = 0; /* The offset into tableout */
int clen = 0;
int i;
struct NmapOutputTableCell *cell;
int validthisrow;
if (maxsz >= tableoutsz) {
tableoutsz = maxsz + 1;
tableout = (char *) safe_realloc(tableout, tableoutsz);
if (tableoutsz == 0) {
tableoutsz = 512; /* Start us off with half a k */
tableout = (char *) safe_malloc(tableoutsz);
}
p = tableout;
for(row = 0; row < numRows; row++) {
validthisrow = 0;
@@ -288,27 +259,38 @@ char *NmapOutputTable::printableTable(int *size) {
cell = getCellAddy(row, 0);
if(cell->fullrow && cell->strlength > 0) {
memcpy(p, cell->str, cell->strlength);
/* Full rows are easy, just make sure we have the space + \n\0 */
if (cell->strlength + p + 2 > tableoutsz) {
tableoutsz = (cell->strlength + p + 2) * 2;
tableout = (char *) safe_realloc(tableout, tableoutsz);
}
memcpy(tableout + p, cell->str, cell->strlength);
p += cell->strlength;
} else {
for(col = 0; col < numColumns; col++) {
cell = getCellAddy(row, col);
clen = maxColLen[col];
/* Cells get padded with an extra space + \n\0 */
if (clen + p + 3 > tableoutsz) {
tableoutsz = (cell->strlength + p + 2) * 2;
tableout = (char *) safe_realloc(tableout, tableoutsz);
}
if (cell->strlength > 0) {
memcpy(p, cell->str, cell->strlength);
memcpy(tableout + p, cell->str, cell->strlength);
p += cell->strlength;
validthisrow++;
}
// No point leaving trailing spaces ...
if (validthisrow < itemsInRow[row]) {
for(i=cell->strlength; i <= clen; i++) // one extra because of space between columns
*(p++) = ' ';
*(tableout + p++) = ' ';
}
}
}
*(p++) = '\n';
*(tableout + p++) = '\n';
}
*p = '\0';
if (size) *size = p - tableout;
*(tableout + p) = '\0';
if (size) *size = p;
return tableout;
}

4
NmapOutputTable.h
View File

@@ -142,10 +142,6 @@ class NmapOutputTable {
void addItemFormatted(unsigned int row, unsigned int column, bool fullrow, const char *fmt, ...)
__attribute__ ((format (printf, 4, 5)));
// Returns the maximum size neccessary to create a printableTable() (the
// actual size could be less);
int printableSize();
// This function sticks the entire table into a character buffer.
// Note that the buffer is likely to be reused if you call the
// function again, and it will also be invalidated if you free the