diff options
Diffstat (limited to 'pkg/sentry/usermem/addr_range_seq_unsafe.go')
| -rw-r--r-- | pkg/sentry/usermem/addr_range_seq_unsafe.go | 277 |
1 files changed, 0 insertions, 277 deletions
diff --git a/pkg/sentry/usermem/addr_range_seq_unsafe.go b/pkg/sentry/usermem/addr_range_seq_unsafe.go deleted file mode 100644 index c09337c15..000000000 --- a/pkg/sentry/usermem/addr_range_seq_unsafe.go +++ /dev/null @@ -1,277 +0,0 @@ -// Copyright 2018 The gVisor Authors. -// -// Licensed under the Apache License, Version 2.0 (the "License"); -// you may not use this file except in compliance with the License. -// You may obtain a copy of the License at -// -// http://www.apache.org/licenses/LICENSE-2.0 -// -// Unless required by applicable law or agreed to in writing, software -// distributed under the License is distributed on an "AS IS" BASIS, -// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. -// See the License for the specific language governing permissions and -// limitations under the License. - -package usermem - -import ( - "bytes" - "fmt" - "reflect" - "unsafe" -) - -// An AddrRangeSeq represents a sequence of AddrRanges. -// -// AddrRangeSeqs are immutable and may be copied by value. The zero value of -// AddrRangeSeq represents an empty sequence. -// -// An AddrRangeSeq may contain AddrRanges with a length of 0. This is necessary -// since zero-length AddrRanges are significant to MM bounds checks. -type AddrRangeSeq struct { - // If length is 0, then the AddrRangeSeq represents no AddrRanges. - // Invariants: data == 0; offset == 0; limit == 0. - // - // If length is 1, then the AddrRangeSeq represents the single - // AddrRange{offset, offset+limit}. Invariants: data == 0. - // - // Otherwise, length >= 2, and the AddrRangeSeq represents the `length` - // AddrRanges in the array of AddrRanges starting at address `data`, - // starting at `offset` bytes into the first AddrRange and limited to the - // following `limit` bytes. (AddrRanges after `limit` are still iterated, - // but are truncated to a length of 0.) Invariants: data != 0; offset <= - // data[0].Length(); limit > 0; offset+limit <= the combined length of all - // AddrRanges in the array. - data unsafe.Pointer - length int - offset Addr - limit Addr -} - -// AddrRangeSeqOf returns an AddrRangeSeq representing the single AddrRange ar. -func AddrRangeSeqOf(ar AddrRange) AddrRangeSeq { - return AddrRangeSeq{ - length: 1, - offset: ar.Start, - limit: ar.Length(), - } -} - -// AddrRangeSeqFromSlice returns an AddrRangeSeq representing all AddrRanges in -// slice. -// -// Whether the returned AddrRangeSeq shares memory with slice is unspecified; -// clients should avoid mutating slices passed to AddrRangeSeqFromSlice. -// -// Preconditions: The combined length of all AddrRanges in slice <= -// math.MaxInt64. -func AddrRangeSeqFromSlice(slice []AddrRange) AddrRangeSeq { - var limit int64 - for _, ar := range slice { - len64 := int64(ar.Length()) - if len64 < 0 { - panic(fmt.Sprintf("Length of AddrRange %v overflows int64", ar)) - } - sum := limit + len64 - if sum < limit { - panic(fmt.Sprintf("Total length of AddrRanges %v overflows int64", slice)) - } - limit = sum - } - return addrRangeSeqFromSliceLimited(slice, limit) -} - -// Preconditions: The combined length of all AddrRanges in slice <= limit. -// limit >= 0. If len(slice) != 0, then limit > 0. -func addrRangeSeqFromSliceLimited(slice []AddrRange, limit int64) AddrRangeSeq { - switch len(slice) { - case 0: - return AddrRangeSeq{} - case 1: - return AddrRangeSeq{ - length: 1, - offset: slice[0].Start, - limit: Addr(limit), - } - default: - return AddrRangeSeq{ - data: unsafe.Pointer(&slice[0]), - length: len(slice), - limit: Addr(limit), - } - } -} - -// IsEmpty returns true if ars.NumRanges() == 0. -// -// Note that since AddrRangeSeq may contain AddrRanges with a length of zero, -// an AddrRange representing 0 bytes (AddrRangeSeq.NumBytes() == 0) is not -// necessarily empty. -func (ars AddrRangeSeq) IsEmpty() bool { - return ars.length == 0 -} - -// NumRanges returns the number of AddrRanges in ars. -func (ars AddrRangeSeq) NumRanges() int { - return ars.length -} - -// NumBytes returns the number of bytes represented by ars. -func (ars AddrRangeSeq) NumBytes() int64 { - return int64(ars.limit) -} - -// Head returns the first AddrRange in ars. -// -// Preconditions: !ars.IsEmpty(). -func (ars AddrRangeSeq) Head() AddrRange { - if ars.length == 0 { - panic("empty AddrRangeSeq") - } - if ars.length == 1 { - return AddrRange{ars.offset, ars.offset + ars.limit} - } - ar := *(*AddrRange)(ars.data) - ar.Start += ars.offset - if ar.Length() > ars.limit { - ar.End = ar.Start + ars.limit - } - return ar -} - -// Tail returns an AddrRangeSeq consisting of all AddrRanges in ars after the -// first. -// -// Preconditions: !ars.IsEmpty(). -func (ars AddrRangeSeq) Tail() AddrRangeSeq { - if ars.length == 0 { - panic("empty AddrRangeSeq") - } - if ars.length == 1 { - return AddrRangeSeq{} - } - return ars.externalTail() -} - -// Preconditions: ars.length >= 2. -func (ars AddrRangeSeq) externalTail() AddrRangeSeq { - headLen := (*AddrRange)(ars.data).Length() - ars.offset - var tailLimit int64 - if ars.limit > headLen { - tailLimit = int64(ars.limit - headLen) - } - var extSlice []AddrRange - extSliceHdr := (*reflect.SliceHeader)(unsafe.Pointer(&extSlice)) - extSliceHdr.Data = uintptr(ars.data) - extSliceHdr.Len = ars.length - extSliceHdr.Cap = ars.length - return addrRangeSeqFromSliceLimited(extSlice[1:], tailLimit) -} - -// DropFirst returns an AddrRangeSeq equivalent to ars, but with the first n -// bytes omitted. If n > ars.NumBytes(), DropFirst returns an empty -// AddrRangeSeq. -// -// If !ars.IsEmpty() and ars.Head().Length() == 0, DropFirst will always omit -// at least ars.Head(), even if n == 0. This guarantees that the basic pattern -// of: -// -// for !ars.IsEmpty() { -// n, err = doIOWith(ars.Head()) -// if err != nil { -// return err -// } -// ars = ars.DropFirst(n) -// } -// -// works even in the presence of zero-length AddrRanges. -// -// Preconditions: n >= 0. -func (ars AddrRangeSeq) DropFirst(n int) AddrRangeSeq { - if n < 0 { - panic(fmt.Sprintf("invalid n: %d", n)) - } - return ars.DropFirst64(int64(n)) -} - -// DropFirst64 is equivalent to DropFirst but takes an int64. -func (ars AddrRangeSeq) DropFirst64(n int64) AddrRangeSeq { - if n < 0 { - panic(fmt.Sprintf("invalid n: %d", n)) - } - if Addr(n) > ars.limit { - return AddrRangeSeq{} - } - // Handle initial empty AddrRange. - switch ars.length { - case 0: - return AddrRangeSeq{} - case 1: - if ars.limit == 0 { - return AddrRangeSeq{} - } - default: - if rawHeadLen := (*AddrRange)(ars.data).Length(); ars.offset == rawHeadLen { - ars = ars.externalTail() - } - } - for n != 0 { - // Calling ars.Head() here is surprisingly expensive, so inline getting - // the head's length. - var headLen Addr - if ars.length == 1 { - headLen = ars.limit - } else { - headLen = (*AddrRange)(ars.data).Length() - ars.offset - } - if Addr(n) < headLen { - // Dropping ends partway through the head AddrRange. - ars.offset += Addr(n) - ars.limit -= Addr(n) - return ars - } - n -= int64(headLen) - ars = ars.Tail() - } - return ars -} - -// TakeFirst returns an AddrRangeSeq equivalent to ars, but iterating at most n -// bytes. TakeFirst never removes AddrRanges from ars; AddrRanges beyond the -// first n bytes are reduced to a length of zero, but will still be iterated. -// -// Preconditions: n >= 0. -func (ars AddrRangeSeq) TakeFirst(n int) AddrRangeSeq { - if n < 0 { - panic(fmt.Sprintf("invalid n: %d", n)) - } - return ars.TakeFirst64(int64(n)) -} - -// TakeFirst64 is equivalent to TakeFirst but takes an int64. -func (ars AddrRangeSeq) TakeFirst64(n int64) AddrRangeSeq { - if n < 0 { - panic(fmt.Sprintf("invalid n: %d", n)) - } - if ars.limit > Addr(n) { - ars.limit = Addr(n) - } - return ars -} - -// String implements fmt.Stringer.String. -func (ars AddrRangeSeq) String() string { - // This is deliberately chosen to be the same as fmt's automatic stringer - // for []AddrRange. - var buf bytes.Buffer - buf.WriteByte('[') - var sep string - for !ars.IsEmpty() { - buf.WriteString(sep) - sep = " " - buf.WriteString(ars.Head().String()) - ars = ars.Tail() - } - buf.WriteByte(']') - return buf.String() -} |