mirror of
https://github.com/netbirdio/gvisor.git
synced 2026-05-22 17:12:49 -07:00
Adin Scannell
0e2f1b7abd
Because the abi will depend on the core types for marshalling (usermem, context, safemem, safecopy), these need to be flattened from the sentry directory. These packages contain no sentry-specific details. PiperOrigin-RevId: 291811289
66 lines
1.9 KiB
Go
66 lines
1.9 KiB
Go
// Copyright 2018 The gVisor Authors.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package fs
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import (
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"math"
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"gvisor.dev/gvisor/pkg/usermem"
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)
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// OffsetPageEnd returns the file offset rounded up to the nearest
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// page boundary. OffsetPageEnd panics if rounding up causes overflow,
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// which shouldn't be possible given that offset is an int64.
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func OffsetPageEnd(offset int64) uint64 {
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end, ok := usermem.Addr(offset).RoundUp()
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if !ok {
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panic("impossible overflow")
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}
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return uint64(end)
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}
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// ReadEndOffset returns an exclusive end offset for a read operation
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// so that the read does not overflow an int64 nor size.
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//
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// Parameters:
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// - offset: the starting offset of the read.
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// - length: the number of bytes to read.
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// - size: the size of the file.
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//
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// Postconditions: The returned offset is >= offset.
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func ReadEndOffset(offset int64, length int64, size int64) int64 {
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if offset >= size {
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return offset
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}
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end := offset + length
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// Don't overflow.
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if end < offset || end > size {
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end = size
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}
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return end
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}
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// WriteEndOffset returns an exclusive end offset for a write operation
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// so that the write does not overflow an int64.
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//
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// Parameters:
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// - offset: the starting offset of the write.
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// - length: the number of bytes to write.
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//
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// Postconditions: The returned offset is >= offset.
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func WriteEndOffset(offset int64, length int64) int64 {
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return ReadEndOffset(offset, length, math.MaxInt64)
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}
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