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Fix crashes in mgd77magref with a numeric -D #9270

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Merged
Esteban82 merged 4 commits into from
Oct 19, 2026
Merged

Fix crashes in mgd77magref with a numeric -D #9270

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c96232c
Fix segfault, lost sign and multi-record overrun for numeric -D in mg…
Esteban82 Oct 16, 2026
2fef6ca
Free the Dst buffer in Free_Ctrl so every exit path releases it
Esteban82 Oct 16, 2026
d0a4435
Keep the Dst buffer when a segment falls outside the Dst table
Esteban82 Oct 16, 2026
2e03144
Update test
Esteban82 Oct 17, 2026
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3 changes: 1 addition & 2 deletions src/mgd77/cm4_functions.c
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Original file line number Diff line number Diff line change
Expand Up @@ -375,7 +375,6 @@ int MGD77_cm4field (struct GMT_CTRL *GMT, struct MGD77_CM4 *Ctrl, double *p_lon,
if (dstx) Ctrl->CM4_D.dst[0] = intdst(mjdl, mjdh, mjdy[0], msec[0], dstx, &cerr);
if (cerr > 49) {
gmt_M_str_free (dstx);
if (Ctrl->CM4_DATA.n_times > 1) gmt_M_str_free (Ctrl->CM4_D.dst);
clear_mem (mut, gpsq, gssq, gpmg, gsmg, hysq, epsq, essq, ecto, hyto, hq, ht, bkpo, ws, gamf, epmg,
esmg, hymg, f107x, pleg, rcur, gcto_or, gcto_mg);
gmt_M_str_free (msec); gmt_M_str_free (mjdy); free (mjdy);
Expand Down Expand Up @@ -459,7 +458,7 @@ int MGD77_cm4field (struct GMT_CTRL *GMT, struct MGD77_CM4 *Ctrl, double *p_lon,
/* See if we are using a constant time or an array */
if (Ctrl->CM4_DATA.n_times > 1) {
date = p_date[n];
dst = Ctrl->CM4_D.dst[n];
dst = Ctrl->CM4_D.index ? Ctrl->CM4_D.dst[n] : Ctrl->CM4_D.dst[0];
mut_now = mut[n];
}
else {
Expand Down
10 changes: 5 additions & 5 deletions src/mgd77/mgd77magref.c
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Original file line number Diff line number Diff line change
Expand Up @@ -82,6 +82,7 @@ static void Free_Ctrl (struct GMT_CTRL *GMT, struct MGD77MAGREF_CTRL *C) { /* De
if (!C) return;
gmt_M_str_free (C->CM4->CM4_M.path);
gmt_M_str_free (C->CM4->CM4_D.path);
gmt_M_str_free (C->CM4->CM4_D.dst);
gmt_M_str_free (C->CM4->CM4_I.path);
gmt_M_str_free (C->CM4);
gmt_M_free (GMT, C);
Expand Down Expand Up @@ -237,10 +238,10 @@ static int parse (struct GMT_CTRL *GMT, struct MGD77MAGREF_CTRL *Ctrl, struct GM
break;
case 'D':
n_errors += gmt_M_repeated_module_option (API, Ctrl->D.active);
j = 0;
if (opt->arg[j] == '-') j++;
j = (opt->arg[0] == '-') ? 1 : 0;
if ((opt->arg[j] > 47) && (opt->arg[j] < 58)) { /* arg is numeric -> Dst Index */
Ctrl->CM4->CM4_D.dst[0] = atof (&opt->arg[j]);
if (Ctrl->CM4->CM4_D.dst == NULL) Ctrl->CM4->CM4_D.dst = calloc (1U, sizeof(double));
Ctrl->CM4->CM4_D.dst[0] = atof (opt->arg);
Ctrl->CM4->CM4_D.index = false;
}
else {
Expand Down Expand Up @@ -494,7 +495,7 @@ EXTERN_MSC int GMT_mgd77magref (void *V_API, int mode, void *args) {

if (Ctrl->A.fixed_alt) t_col = 2; /* Since we are missing the altitude column */

Ctrl->CM4->CM4_D.dst = calloc (1U, sizeof(double)); /* We need at least a size of one in case a value is given in input */
if (Ctrl->CM4->CM4_D.dst == NULL) Ctrl->CM4->CM4_D.dst = calloc (1U, sizeof(double)); /* We need at least a size of one in case a value is given in input */
if (!Ctrl->A.fixed_time) /* Otherwise we don't print the time */
gmt_set_column_type (GMT, GMT_IO, t_col, GMT_IS_ABSTIME);

Expand Down Expand Up @@ -731,7 +732,6 @@ EXTERN_MSC int GMT_mgd77magref (void *V_API, int mode, void *args) {
}

gmt_M_free (GMT, Out);
gmt_M_str_free (Ctrl->CM4->CM4_D.dst);
gmt_M_free (GMT, Ctrl->CM4->CM4_DATA.out_field);
if (!(Ctrl->A.years || Ctrl->A.fixed_time)) gmt_M_free (GMT, time_years);
if (Ctrl->joint_IGRF_CM4) gmt_M_free (GMT, igrf_xyz);
Expand Down
24 changes: 24 additions & 0 deletions test/mgd77/magref_dst.sh
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Original file line number Diff line number Diff line change
@@ -0,0 +1,24 @@
#!/usr/bin/env bash
#
# gmt mgd77magref -D<dst> with a numeric Dst value used to segfault (the value was stored
# before its buffer was allocated) and dropped the sign of a negative value.

rec="-30 45 0 2000.08700533"
echo "$rec" | gmt mgd77magref -A+y -Fxyz/3 -D8 > pos.txt || exit 1
echo "$rec" | gmt mgd77magref -A+y -Fxyz/3 -D-8 > neg.txt || exit 1
# The sign must matter and the output must be finite
cmp -s pos.txt neg.txt && { echo "-D-8 same as -D8: sign was dropped"; exit 1; }
test -s pos.txt && test -s neg.txt || exit 1

# With several records the single Dst value must apply to every row, not index past it
printf -- "-30 45 0 2000.08700533\n-30 45 0 2000.5\n-30 45 0 2001.2\n" > multi.txt
gmt mgd77magref multi.txt -A+y -Fxyz/3 -D8 > multi_all.txt || exit 1
for i in 1 2 3; do
sed -n ${i}p multi.txt | gmt mgd77magref -A+y -Fxyz/3 -D8
done > multi_one.txt || exit 1
diff multi_all.txt multi_one.txt || exit 1

# A segment rejected for lying outside the Dst table must not break the next segment
printf -- "> bad\n-30 45 0 1900.5\n-30 45 0 1900.6\n> good\n-30 45 0 2000.5\n" > seg.txt
gmt mgd77magref seg.txt -A+y -Fxyz/3 -Vq > seg_out.txt || exit 1
grep -v '^>' seg_out.txt | wc -l | grep -q '^ *1$'
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