[GRASS-git] [OSGeo/grass] 822943: r.clump: Fail with the clump limit instead of over...

[R Sai Pranav]

  Branch: refs/heads/main
  Home:   https://github.com/OSGeo/grass
  Commit: 8229439fe70f67ab86df4ad4f66ff9fba7ecc288
      https://github.com/OSGeo/grass/commit/8229439fe70f67ab86df4ad4f66ff9fba7ecc288
  Author: R Sai Pranav <rajasaipranav0 at gmail.com>
  Date:   2026-09-23 (Wed, 23 Sep 2026)

  Changed paths:
    M raster/r.clump/clump.c

  Log Message:
  -----------
  r.clump: Fail with the clump limit instead of overflowing the index (#7853)

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

r.clump asked G_realloc() for 18446744065119617024 bytes and stopped with
a memory error, which reads as a memory problem when it is not one.

label and nalloc are both 32 bit. nalloc starts at INCR and grows in INCR
steps, so it lands exactly on 2^31 and wraps to INT_MIN, and
nalloc * sizeof(CELL) then converts to (size_t)(INT_MIN * 4), which is
18446744065119617024 - the number in the report.

Clump IDs are raster values of type CELL, so as @metzm said on the issue
the limit of one CELL cannot be raised. Report it as the limit it is
instead, and stop INCR short of INT_MAX so nalloc cannot overflow either.

Fixes #6412

* r.clump: Reword the clump limit message

Per review: say "the maximum supported number of clumps". Re-wrapped the
string so the lines stay within 80 columns.



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