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Avoid memcpy()-ing 0-length vectors #6820

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Merged
aitap merged 3 commits into from
Feb 23, 2025
Merged

Avoid memcpy()-ing 0-length vectors #6820

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52924e9
Avoid memcpy()-ing 0-length vectors
aitap Feb 17, 2025
94fcf92
Update src/dogroups.c
aitap Feb 23, 2025
4773ceb
Use early returns for 0-length cases
aitap Feb 23, 2025
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5 changes: 5 additions & 0 deletions src/dogroups.c
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Original file line number Diff line number Diff line change
Expand Up @@ -535,6 +535,11 @@ SEXP growVector(SEXP x, const R_len_t newlen)
if (isNull(x)) error(_("growVector passed NULL"));
PROTECT(newx = allocVector(TYPEOF(x), newlen)); // TO DO: R_realloc(?) here?
if (newlen < len) len=newlen; // i.e. shrink
if (!len) { // cannot memcpy invalid pointer, #6819
keepattr(newx, x);
UNPROTECT(1);
return newx;
}
switch (TYPEOF(x)) {
case RAWSXP: memcpy(RAW(newx), RAW(x), len*SIZEOF(x)); break;
case LGLSXP: memcpy(LOGICAL(newx), LOGICAL(x), len*SIZEOF(x)); break;
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11 changes: 8 additions & 3 deletions src/utils.c
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Original file line number Diff line number Diff line change
Expand Up @@ -222,6 +222,14 @@ SEXP copyAsPlain(SEXP x) {
}
const int64_t n = XLENGTH(x);
SEXP ans = PROTECT(allocVector(TYPEOF(x), n));
// aside: unlike R's duplicate we do not copy truelength here; important for dogroups.c which uses negative truelenth to mark its specials
if (ALTREP(ans))
internal_error(__func__, "copyAsPlain returning ALTREP for type '%s'", type2char(TYPEOF(x))); // # nocov
if (!n) { // cannot memcpy invalid pointer, #6819
DUPLICATE_ATTRIB(ans, x);
UNPROTECT(1);
return ans;
}
switch (TYPEOF(x)) {
case RAWSXP:
memcpy(RAW(ans), RAW(x), n*sizeof(Rbyte));
Expand Down Expand Up @@ -250,9 +258,6 @@ SEXP copyAsPlain(SEXP x) {
internal_error(__func__, "type '%s' not supported in %s", type2char(TYPEOF(x)), "copyAsPlain()"); // # nocov
}
DUPLICATE_ATTRIB(ans, x);
// aside: unlike R's duplicate we do not copy truelength here; important for dogroups.c which uses negative truelenth to mark its specials
if (ALTREP(ans))
internal_error(__func__, "copyAsPlain returning ALTREP for type '%s'", type2char(TYPEOF(x))); // # nocov
UNPROTECT(1);
return ans;
}
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