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implement an ipfs cat --length flag #4553

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merged 3 commits into from
Jan 12, 2018
Merged

implement an ipfs cat --length flag #4553

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153bb68
implement an ipfs cat --length flag
Stebalien Jan 6, 2018
089496b
test the ipfs cat --length flag
Stebalien Jan 6, 2018
3e0f7cb
fix add-and-cat sharness test on osx
Stebalien Jan 6, 2018
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33 changes: 30 additions & 3 deletions core/commands/cat.go
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Original file line number Diff line number Diff line change
Expand Up @@ -26,6 +26,7 @@ var CatCmd = &cmds.Command{
},
Options: []cmdkit.Option{
cmdkit.IntOption("offset", "o", "Byte offset to begin reading from."),
cmdkit.IntOption("length", "l", "Maximum number of bytes to read."),
},
Run: func(req cmds.Request, res cmds.ResponseEmitter) {
node, err := req.InvocContext().GetNode()
Expand All @@ -50,7 +51,20 @@ var CatCmd = &cmds.Command{
return
}

readers, length, err := cat(req.Context(), node, req.Arguments(), int64(offset))
max, found, err := req.Option("length").Int()
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USE int64. THIS COULD OVERFLOW

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I don't see a int64 option in go-ipfs-cmdkit, we could use a uint instead? We could also add a new option if not.

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I was really just giving @Stebalien crap, he was sitting behind me while i reviewed this and pointed out that this should be an int64

if err != nil {
res.SetError(err, cmdkit.ErrNormal)
return
}
if max < 0 {
res.SetError(fmt.Errorf("Cannot specify negative length."), cmdkit.ErrNormal)
return
}
if !found {
max = -1
}

readers, length, err := cat(req.Context(), node, req.Arguments(), int64(offset), int64(max))
if err != nil {
res.SetError(err, cmdkit.ErrNormal)
return
Expand Down Expand Up @@ -116,9 +130,12 @@ var CatCmd = &cmds.Command{
},
}

func cat(ctx context.Context, node *core.IpfsNode, paths []string, offset int64) ([]io.Reader, uint64, error) {
func cat(ctx context.Context, node *core.IpfsNode, paths []string, offset int64, max int64) ([]io.Reader, uint64, error) {
readers := make([]io.Reader, 0, len(paths))
length := uint64(0)
if max == 0 {
return nil, 0, nil
}
for _, fpath := range paths {
read, err := coreunix.Cat(ctx, node, fpath)
if err != nil {
Expand All @@ -134,8 +151,18 @@ func cat(ctx context.Context, node *core.IpfsNode, paths []string, offset int64)
}
offset = 0

size := uint64(read.Size() - uint64(count))
length += size
if max > 0 && length >= uint64(max) {
var r io.Reader = read
if overshoot := int64(length - uint64(max)); overshoot != 0 {
r = io.LimitReader(read, int64(size)-overshoot)
length = uint64(max)
}
readers = append(readers, r)
break
}
readers = append(readers, read)
length += uint64(read.Size() - uint64(count))
}
return readers, length, nil
}
49 changes: 49 additions & 0 deletions test/sharness/t0040-add-and-cat.sh
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Expand Up @@ -78,6 +78,55 @@ test_add_cat_file() {
test_expect_code 1 ipfs cat --offset -102 "$HASH" > actual
'

test_expect_success "ipfs cat with length succeeds" '
ipfs cat --length 8 "$HASH" >actual
'

test_expect_success "ipfs cat with length output looks good" '
printf "Hello Wo" >expected &&
test_cmp expected actual
'

test_expect_success "ipfs cat multiple hashes with offset and length succeeds" '
ipfs cat --offset 5 --length 15 "$HASH" "$HASH" "$HASH" >actual
'

test_expect_success "ipfs cat multiple hashes with offset and length looks good" '
printf " Worlds!\nHello " >expected &&
test_cmp expected actual
'

test_expect_success "ipfs cat with exact length succeeds" '
ipfs cat --length $(ipfs cat "$HASH" | wc -c) "$HASH" >actual
'

test_expect_success "ipfs cat with exact length looks good" '
echo "Hello Worlds!" >expected &&
test_cmp expected actual
'

test_expect_success "ipfs cat with 0 length succeeds" '
ipfs cat --length 0 "$HASH" >actual
'

test_expect_success "ipfs cat with 0 length looks good" '
: >expected &&
test_cmp expected actual
'

test_expect_success "ipfs cat with oversized length succeeds" '
ipfs cat --length 100 "$HASH" >actual
'

test_expect_success "ipfs cat with oversized length looks good" '
echo "Hello Worlds!" >expected &&
test_cmp expected actual
'

test_expect_success "ipfs cat with negitive length should fail" '
test_expect_code 1 ipfs cat --length -102 "$HASH" > actual
'

test_expect_success "ipfs cat /ipfs/file succeeds" '
ipfs cat /ipfs/$HASH >actual
'
Expand Down