diff options
Diffstat (limited to 'src/backend/access/heap/tuptoaster.c')
| -rw-r--r-- | src/backend/access/heap/tuptoaster.c | 31 |
1 files changed, 26 insertions, 5 deletions
diff --git a/src/backend/access/heap/tuptoaster.c b/src/backend/access/heap/tuptoaster.c index 3a9d2ff38ed..f9d1fb36bc8 100644 --- a/src/backend/access/heap/tuptoaster.c +++ b/src/backend/access/heap/tuptoaster.c @@ -35,6 +35,7 @@ #include "access/tuptoaster.h" #include "access/xact.h" #include "catalog/catalog.h" +#include "common/int.h" #include "common/pg_lzcompress.h" #include "miscadmin.h" #include "utils/expandeddatum.h" @@ -252,6 +253,9 @@ heap_tuple_untoast_attr(struct varlena *attr) * * Public entry point to get back part of a toasted value * from compression or external storage. + * + * sliceoffset is where to start (zero or more) + * If slicelength < 0, return everything beyond sliceoffset * ---------- */ struct varlena * @@ -261,8 +265,21 @@ heap_tuple_untoast_attr_slice(struct varlena *attr, struct varlena *preslice; struct varlena *result; char *attrdata; + int32 slicelimit; int32 attrsize; + if (sliceoffset < 0) + elog(ERROR, "invalid sliceoffset: %d", sliceoffset); + + /* + * Compute slicelimit = offset + length, or -1 if we must fetch all of the + * value. In case of integer overflow, we must fetch all. + */ + if (slicelength < 0) + slicelimit = -1; + else if (pg_add_s32_overflow(sliceoffset, slicelength, &slicelimit)) + slicelength = slicelimit = -1; + if (VARATT_IS_EXTERNAL_ONDISK(attr)) { struct varatt_external toast_pointer; @@ -303,8 +320,8 @@ heap_tuple_untoast_attr_slice(struct varlena *attr, struct varlena *tmp = preslice; /* Decompress enough to encompass the slice and the offset */ - if (slicelength > 0 && sliceoffset >= 0) - preslice = toast_decompress_datum_slice(tmp, slicelength + sliceoffset); + if (slicelimit >= 0) + preslice = toast_decompress_datum_slice(tmp, slicelimit); else preslice = toast_decompress_datum(tmp); @@ -330,8 +347,7 @@ heap_tuple_untoast_attr_slice(struct varlena *attr, sliceoffset = 0; slicelength = 0; } - - if (((sliceoffset + slicelength) > attrsize) || slicelength < 0) + else if (slicelength < 0 || slicelimit > attrsize) slicelength = attrsize - sliceoffset; result = (struct varlena *) palloc(slicelength + VARHDRSZ); @@ -2086,7 +2102,12 @@ toast_fetch_datum_slice(struct varlena *attr, int32 sliceoffset, int32 length) length = 0; } - if (((sliceoffset + length) > attrsize) || length < 0) + /* + * Adjust length request if needed. (Note: our sole caller, + * heap_tuple_untoast_attr_slice, protects us against sliceoffset + length + * overflowing.) + */ + else if (((sliceoffset + length) > attrsize) || length < 0) length = attrsize - sliceoffset; result = (struct varlena *) palloc(length + VARHDRSZ); |