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Merge branch 'rs/xdiff-context-length-fix' 

The xdiff code on 32-bit platform misbehaved when an insanely large
context size is given, which has been corrected.

* rs/xdiff-context-length-fix:
  xdiff: avoid arithmetic overflow in xdl_get_hunk()
maint
Junio C Hamano 2025-03-29 16:39:10 +09:00
parent f76fe4ab06 d39e28e68c
commit 6767149eca
2 changed files with 17 additions and 1 deletions
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10
t/t4055-diff-context.sh
View File

@ -89,4 +89,14 @@ test_expect_success '-U0 is valid, so is diff.context=0' '
grep "^+MODIFIED" output grep "^+MODIFIED" output
' '


test_expect_success '-U2147483647 works' '
echo APPENDED >>x &&
test_line_count = 16 x &&
git diff -U2147483647 >output &&
test_line_count = 22 output &&
grep "^-ADDED" output &&
grep "^+MODIFIED" output &&
grep "^+APPENDED" output
'

test_done test_done

8
xdiff/xemit.c
View File

@ -43,6 +43,10 @@ static int xdl_emit_record(xdfile_t *xdf, long ri, char const *pre, xdemitcb_t *
return 0; return 0;
} }


static long saturating_add(long a, long b)
{
return signed_add_overflows(a, b) ? LONG_MAX : a + b;
}


/* /*
* Starting at the passed change atom, find the latest change atom to be included * Starting at the passed change atom, find the latest change atom to be included
@ -52,7 +56,9 @@ static int xdl_emit_record(xdfile_t *xdf, long ri, char const *pre, xdemitcb_t *
xdchange_t *xdl_get_hunk(xdchange_t **xscr, xdemitconf_t const *xecfg) xdchange_t *xdl_get_hunk(xdchange_t **xscr, xdemitconf_t const *xecfg)
{ {
xdchange_t *xch, *xchp, *lxch; xdchange_t *xch, *xchp, *lxch;
long max_common = 2 * xecfg->ctxlen + xecfg->interhunkctxlen; long max_common = saturating_add(saturating_add(xecfg->ctxlen,
xecfg->ctxlen),
xecfg->interhunkctxlen);
long max_ignorable = xecfg->ctxlen; long max_ignorable = xecfg->ctxlen;
long ignored = 0; /* number of ignored blank lines */ long ignored = 0; /* number of ignored blank lines */