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r.clump: Fail with the clump limit instead of overflowing the index #7853

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r.clump: Fail with the clump limit instead of overflowing the index #7853

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1875e35
r.clump: Fail with the clump limit instead of overflowing the index
Pranav-error Aug 26, 2026
132fcd8
r.clump: Reword the clump limit message
Pranav-error Sep 1, 2026
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22 changes: 21 additions & 1 deletion raster/r.clump/clump.c
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Original file line number Diff line number Diff line change
Expand Up @@ -26,9 +26,15 @@
#include <grass/glocale.h>
#include "local_proto.h"
#include <errno.h>
#include <limits.h>
#include <string.h>

#define INCR 1024
#define INCR 1024

/* Clump IDs are stored as CELL, a 32 bit signed integer, so the number of
* clumps cannot exceed the largest CELL value. Stopping INCR short of that
* also keeps nalloc, which grows in INCR steps, from overflowing. */
#define MAX_LABEL (INT_MAX - INCR)

int print_time(time_t *);

Expand Down Expand Up @@ -311,6 +317,13 @@ CELL clump(int *in_fd, int out_fd, int diag, int minsize)
if (NEW == 0 || OLD == NEW) { /* ok */
if (OLD == 0) {
/* start a new clump */
if (label >= MAX_LABEL)
G_fatal_error(
_("Too many clumps: the maximum supported number "
"of clumps is %d. Reduce the extent or the "
"resolution of the computational region, or use "
"a threshold to merge similar cells."),
MAX_LABEL);
label++;
cur_clump[col] = label;
if (label >= nalloc) {
Expand Down Expand Up @@ -641,6 +654,13 @@ CELL clump_n(int *in_fd, char **inname, int nin, double threshold, int out_fd,
if (NEW == 0 || OLD == NEW) { /* ok */
if (OLD == 0) {
/* start a new clump */
if (label >= MAX_LABEL)
G_fatal_error(
_("Too many clumps: the maximum supported number "
"of clumps is %d. Reduce the extent or the "
"resolution of the computational region, or use "
"a threshold to merge similar cells."),
MAX_LABEL);
label++;
cur_clump[col] = label;
if (label >= nalloc) {
Expand Down
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