[ruby-core:114070] [Ruby master Bug#19753] IO::Buffer#get_string can't handle negative offset
3 Jul
2023
3 Jul
'23
7:14 a.m.
Issue #19753 has been reported by noteflakes (Sharon Rosner).
----------------------------------------
Bug #19753: IO::Buffer#get_string can't handle negative offset
https://bugs.ruby-lang.org/issues/19753
* Author: noteflakes (Sharon Rosner)
* Status: Open
* Priority: Normal
* ruby -v: 3.2
* Backport: 3.0: UNKNOWN, 3.1: UNKNOWN, 3.2: UNKNOWN
----------------------------------------
```ruby
irb(main):001:0> b = IO::Buffer.for('abc')
=>
#<IO::Buffer 0x00007f858f5450c0+3 EXTERNAL READONLY SLICE>
...
irb(main):002:0> b.get_string(-1)
=> "\x00abc"
irb(main):003:0> b.get_string(-1000, 3)
(irb):3:in `get_string': Specified offset+length exceeds data size! (ArgumentError)
from (irb):3:in `<main>'
from /home/sharon/.rbenv/versions/3.2.0/lib/ruby/gems/3.2.0/gems/irb-1.7.1/exe/irb:9:in
`<top (required)>'
from /home/sharon/.rbenv/versions/3.2.0/bin/irb:25:in `load'
from /home/sharon/.rbenv/versions/3.2.0/bin/irb:25:in `<main>'
```
Using a negative offset returns garbage in the string but it also might segfault:
```ruby
irb(main):003:0> b = IO::Buffer.map(File.open('sgt-nodes.sql', 'r+'))
=> #<IO::Buffer 0x00007f189de14000+2008858 EXTERNAL MAPPED SHARED>
irb(main):004:0> b.get_string(-1000)
(irb):4: [BUG] Segmentation fault at 0x00007f189de13c18
ruby 3.2.0 (2022-12-25 revision a528908271) [x86_64-linux]
-- Control frame information -----------------------------------------------
c:0021 p:---- s:0109 e:000108 CFUNC :get_string
...
```
## Expected behaviour
I think it might be nice to have `#get_string` behave like other methods taking an offset,
like `String#[]`. For example:
```ruby
irb(main):001:0> b = IO::Buffer.for('abc')
=>
#<IO::Buffer 0x00007f858f5450c0+3 EXTERNAL READONLY SLICE>
...
irb(main):002:0> b.get_string(-1)
=> "c"
irb(main):003:0> b.get_string(-2)
=> "bc"
irb(main):003:0> b.get_string(-1000)
=> "abc"
irb(main):003:0> b.get_string(-1000, 2)
=> "ab"
```
--
https://bugs.ruby-lang.org/
3 Jul
3 Jul
8:35 a.m.
New subject: [ruby-core:114071] [Ruby master Bug#19753] IO::Buffer#get_string can't handle negative offset
Issue #19753 has been updated by noteflakes (Sharon Rosner).
PR here: https://github.com/ruby/ruby/pull/8015
----------------------------------------
Bug #19753: IO::Buffer#get_string can't handle negative offset
https://bugs.ruby-lang.org/issues/19753#change-103743
* Author: noteflakes (Sharon Rosner)
* Status: Open
* Priority: Normal
* ruby -v: 3.2
* Backport: 3.0: UNKNOWN, 3.1: UNKNOWN, 3.2: UNKNOWN
----------------------------------------
```ruby
irb(main):001:0> b = IO::Buffer.for('abc')
=>
#<IO::Buffer 0x00007f858f5450c0+3 EXTERNAL READONLY SLICE>
...
irb(main):002:0> b.get_string(-1)
=> "\x00abc"
irb(main):003:0> b.get_string(-1000, 3)
(irb):3:in `get_string': Specified offset+length exceeds data size! (ArgumentError)
from (irb):3:in `<main>'
from /home/sharon/.rbenv/versions/3.2.0/lib/ruby/gems/3.2.0/gems/irb-1.7.1/exe/irb:9:in
`<top (required)>'
from /home/sharon/.rbenv/versions/3.2.0/bin/irb:25:in `load'
from /home/sharon/.rbenv/versions/3.2.0/bin/irb:25:in `<main>'
```
Using a negative offset returns garbage in the string but it also might segfault:
```ruby
irb(main):003:0> b = IO::Buffer.map(File.open('sgt-nodes.sql', 'r+'))
=> #<IO::Buffer 0x00007f189de14000+2008858 EXTERNAL MAPPED SHARED>
irb(main):004:0> b.get_string(-1000)
(irb):4: [BUG] Segmentation fault at 0x00007f189de13c18
ruby 3.2.0 (2022-12-25 revision a528908271) [x86_64-linux]
-- Control frame information -----------------------------------------------
c:0021 p:---- s:0109 e:000108 CFUNC :get_string
...
```
## Expected behaviour
I think it might be nice to have `#get_string` behave like other methods taking an offset,
like `String#[]`, so a negative offset means counting backwards from the end of the
buffer. For example:
```ruby
irb(main):001:0> b = IO::Buffer.for('abc')
=>
#<IO::Buffer 0x00007f858f5450c0+3 EXTERNAL READONLY SLICE>
...
irb(main):002:0> b.get_string(-1)
=> "c"
irb(main):003:0> b.get_string(-2)
=> "bc"
irb(main):003:0> b.get_string(-1000)
=> "abc"
irb(main):003:0> b.get_string(-1000, 2)
=> "ab"
```
--
https://bugs.ruby-lang.org/
12:07 p.m.
New subject: [ruby-core:114073] [Ruby master Bug#19753] IO::Buffer#get_string can't handle negative offset
Issue #19753 has been updated by nobu (Nobuyoshi Nakada).
Status changed from Open to Assigned
Assignee set to ioquatix (Samuel Williams)
Backport changed from 3.0: UNKNOWN, 3.1: UNKNOWN, 3.2: UNKNOWN to 3.0: DONTNEED, 3.1:
REQUIRED, 3.2: REQUIRED
noteflakes (Sharon Rosner) wrote:
```ruby
irb(main):003:0> b.get_string(-1000)
=> "abc"
I think this should raise an `ArgumentError`.
```ruby
irb(main):003:0> b.get_string(-1000, 2)
=> "ab"
```
At least, it should not be `"ab"`.
----------------------------------------
Bug #19753: IO::Buffer#get_string can't handle negative offset
https://bugs.ruby-lang.org/issues/19753#change-103746
* Author: noteflakes (Sharon Rosner)
* Status: Assigned
* Priority: Normal
* Assignee: ioquatix (Samuel Williams)
* ruby -v: 3.2
* Backport: 3.0: DONTNEED, 3.1: REQUIRED, 3.2: REQUIRED
----------------------------------------
```ruby
irb(main):001:0> b = IO::Buffer.for('abc')
=>
#<IO::Buffer 0x00007f858f5450c0+3 EXTERNAL READONLY SLICE>
...
irb(main):002:0> b.get_string(-1)
=> "\x00abc"
irb(main):003:0> b.get_string(-1000, 3)
(irb):3:in `get_string': Specified offset+length exceeds data size! (ArgumentError)
from (irb):3:in `<main>'
from /home/sharon/.rbenv/versions/3.2.0/lib/ruby/gems/3.2.0/gems/irb-1.7.1/exe/irb:9:in
`<top (required)>'
from /home/sharon/.rbenv/versions/3.2.0/bin/irb:25:in `load'
from /home/sharon/.rbenv/versions/3.2.0/bin/irb:25:in `<main>'
```
Using a negative offset returns garbage in the string but it also might segfault:
```ruby
irb(main):003:0> b = IO::Buffer.map(File.open('sgt-nodes.sql', 'r+'))
=> #<IO::Buffer 0x00007f189de14000+2008858 EXTERNAL MAPPED SHARED>
irb(main):004:0> b.get_string(-1000)
(irb):4: [BUG] Segmentation fault at 0x00007f189de13c18
ruby 3.2.0 (2022-12-25 revision a528908271) [x86_64-linux]
-- Control frame information -----------------------------------------------
c:0021 p:---- s:0109 e:000108 CFUNC :get_string
...
```
## Expected behaviour
I think it might be nice to have `#get_string` behave like other methods taking an offset,
like `String#[]`, so a negative offset means counting backwards from the end of the
buffer. For example:
```ruby
irb(main):001:0> b = IO::Buffer.for('abc')
=>
#<IO::Buffer 0x00007f858f5450c0+3 EXTERNAL READONLY SLICE>
...
irb(main):002:0> b.get_string(-1)
=> "c"
irb(main):003:0> b.get_string(-2)
=> "bc"
irb(main):003:0> b.get_string(-1000)
=> "abc"
irb(main):003:0> b.get_string(-1000, 2)
=> "ab"
```
--
https://bugs.ruby-lang.org/
4 Jul
4 Jul
5:47 a.m.
New subject: [ruby-core:114081] [Ruby master Bug#19753] IO::Buffer#get_string can't handle negative offset
Issue #19753 has been updated by noteflakes (Sharon Rosner).
nobu (Nobuyoshi Nakada) wrote in #note-3:
Well now that I look at `String#[]` and `Array#[]` they return `nil` when `offset <
-size`:
```ruby
irb(main):001:0> s = 'abc'
=> "abc"
irb(main):002:0> s[-3]
=> "a"
irb(main):003:0> s[-4]
=> nil
irb(main):004:0> a = [1,2,3]
=> [1, 2, 3]
irb(main):005:0> a[-4]
=> nil
irb(main):006:0> a[-4, 2]
=> nil
```
Would a similar behaviour be acceptable for `IO::Buffer`?
----------------------------------------
Bug #19753: IO::Buffer#get_string can't handle negative offset
https://bugs.ruby-lang.org/issues/19753#change-103752
* Author: noteflakes (Sharon Rosner)
* Status: Assigned
* Priority: Normal
* Assignee: ioquatix (Samuel Williams)
* ruby -v: 3.2
* Backport: 3.0: DONTNEED, 3.1: REQUIRED, 3.2: REQUIRED
----------------------------------------
```ruby
irb(main):001:0> b = IO::Buffer.for('abc')
=>
#<IO::Buffer 0x00007f858f5450c0+3 EXTERNAL READONLY SLICE>
...
irb(main):002:0> b.get_string(-1)
=> "\x00abc"
irb(main):003:0> b.get_string(-1000, 3)
(irb):3:in `get_string': Specified offset+length exceeds data size! (ArgumentError)
from (irb):3:in `<main>'
from /home/sharon/.rbenv/versions/3.2.0/lib/ruby/gems/3.2.0/gems/irb-1.7.1/exe/irb:9:in
`<top (required)>'
from /home/sharon/.rbenv/versions/3.2.0/bin/irb:25:in `load'
from /home/sharon/.rbenv/versions/3.2.0/bin/irb:25:in `<main>'
```
Using a negative offset returns garbage in the string but it also might segfault:
```ruby
irb(main):003:0> b = IO::Buffer.map(File.open('sgt-nodes.sql', 'r+'))
=> #<IO::Buffer 0x00007f189de14000+2008858 EXTERNAL MAPPED SHARED>
irb(main):004:0> b.get_string(-1000)
(irb):4: [BUG] Segmentation fault at 0x00007f189de13c18
ruby 3.2.0 (2022-12-25 revision a528908271) [x86_64-linux]
-- Control frame information -----------------------------------------------
c:0021 p:---- s:0109 e:000108 CFUNC :get_string
...
```
## Expected behaviour
I think it might be nice to have `#get_string` behave like other methods taking an offset,
like `String#[]`, so a negative offset means counting backwards from the end of the
buffer. For example:
```ruby
irb(main):001:0> b = IO::Buffer.for('abc')
=>
#<IO::Buffer 0x00007f858f5450c0+3 EXTERNAL READONLY SLICE>
...
irb(main):002:0> b.get_string(-1)
=> "c"
irb(main):003:0> b.get_string(-2)
=> "bc"
irb(main):003:0> b.get_string(-1000)
=> "abc"
irb(main):003:0> b.get_string(-1000, 2)
=> "ab"
```
--
https://bugs.ruby-lang.org/
irb(main):003:0> b.get_string(-1000)
=> "abc"
I think this should raise an `ArgumentError`.
```ruby
irb(main):003:0> b.get_string(-1000, 2)
=> "ab"
```
At least, it should not be `"ab"`.
26 Oct
26 Oct
12:36 a.m.
New subject: [ruby-core:115172] [Ruby master Bug#19753] IO::Buffer#get_string can't handle negative offset
Issue #19753 has been updated by jeremyevans0 (Jeremy Evans).
Status changed from Assigned to Closed
This appears to be fixed by commit:a095740fed2a05a04806a1d3827bcaba02e45720, as you now
get: `Offset can't be negative! (ArgumentError)` for `b.get_string(-1)`
----------------------------------------
Bug #19753: IO::Buffer#get_string can't handle negative offset
https://bugs.ruby-lang.org/issues/19753#change-105081
* Author: noteflakes (Sharon Rosner)
* Status: Closed
* Priority: Normal
* Assignee: ioquatix (Samuel Williams)
* ruby -v: 3.2
* Backport: 3.0: DONTNEED, 3.1: REQUIRED, 3.2: REQUIRED
----------------------------------------
```ruby
irb(main):001:0> b = IO::Buffer.for('abc')
=>
#<IO::Buffer 0x00007f858f5450c0+3 EXTERNAL READONLY SLICE>
...
irb(main):002:0> b.get_string(-1)
=> "\x00abc"
irb(main):003:0> b.get_string(-1000, 3)
(irb):3:in `get_string': Specified offset+length exceeds data size! (ArgumentError)
from (irb):3:in `<main>'
from /home/sharon/.rbenv/versions/3.2.0/lib/ruby/gems/3.2.0/gems/irb-1.7.1/exe/irb:9:in
`<top (required)>'
from /home/sharon/.rbenv/versions/3.2.0/bin/irb:25:in `load'
from /home/sharon/.rbenv/versions/3.2.0/bin/irb:25:in `<main>'
```
Using a negative offset returns garbage in the string but it also might segfault:
```ruby
irb(main):003:0> b = IO::Buffer.map(File.open('sgt-nodes.sql', 'r+'))
=> #<IO::Buffer 0x00007f189de14000+2008858 EXTERNAL MAPPED SHARED>
irb(main):004:0> b.get_string(-1000)
(irb):4: [BUG] Segmentation fault at 0x00007f189de13c18
ruby 3.2.0 (2022-12-25 revision a528908271) [x86_64-linux]
-- Control frame information -----------------------------------------------
c:0021 p:---- s:0109 e:000108 CFUNC :get_string
...
```
## Expected behaviour
I think it might be nice to have `#get_string` behave like other methods taking an offset,
like `String#[]`, so a negative offset means counting backwards from the end of the
buffer. For example:
```ruby
irb(main):001:0> b = IO::Buffer.for('abc')
=>
#<IO::Buffer 0x00007f858f5450c0+3 EXTERNAL READONLY SLICE>
...
irb(main):002:0> b.get_string(-1)
=> "c"
irb(main):003:0> b.get_string(-2)
=> "bc"
irb(main):003:0> b.get_string(-1000)
=> "abc"
irb(main):003:0> b.get_string(-1000, 2)
=> "ab"
```
--
https://bugs.ruby-lang.org/
2:01 a.m.
New subject: [ruby-core:115174] [Ruby master Bug#19753] IO::Buffer#get_string can't handle negative offset
Issue #19753 has been updated by ioquatix (Samuel Williams).
@jeremyevans0 Thanks for reviewing the fix, yes, this should be closed.
----------------------------------------
Bug #19753: IO::Buffer#get_string can't handle negative offset
https://bugs.ruby-lang.org/issues/19753#change-105085
* Author: noteflakes (Sharon Rosner)
* Status: Closed
* Priority: Normal
* Assignee: ioquatix (Samuel Williams)
* ruby -v: 3.2
* Backport: 3.0: DONTNEED, 3.1: REQUIRED, 3.2: REQUIRED
----------------------------------------
```ruby
irb(main):001:0> b = IO::Buffer.for('abc')
=>
#<IO::Buffer 0x00007f858f5450c0+3 EXTERNAL READONLY SLICE>
...
irb(main):002:0> b.get_string(-1)
=> "\x00abc"
irb(main):003:0> b.get_string(-1000, 3)
(irb):3:in `get_string': Specified offset+length exceeds data size! (ArgumentError)
from (irb):3:in `<main>'
from /home/sharon/.rbenv/versions/3.2.0/lib/ruby/gems/3.2.0/gems/irb-1.7.1/exe/irb:9:in
`<top (required)>'
from /home/sharon/.rbenv/versions/3.2.0/bin/irb:25:in `load'
from /home/sharon/.rbenv/versions/3.2.0/bin/irb:25:in `<main>'
```
Using a negative offset returns garbage in the string but it also might segfault:
```ruby
irb(main):003:0> b = IO::Buffer.map(File.open('sgt-nodes.sql', 'r+'))
=> #<IO::Buffer 0x00007f189de14000+2008858 EXTERNAL MAPPED SHARED>
irb(main):004:0> b.get_string(-1000)
(irb):4: [BUG] Segmentation fault at 0x00007f189de13c18
ruby 3.2.0 (2022-12-25 revision a528908271) [x86_64-linux]
-- Control frame information -----------------------------------------------
c:0021 p:---- s:0109 e:000108 CFUNC :get_string
...
```
## Expected behaviour
I think it might be nice to have `#get_string` behave like other methods taking an offset,
like `String#[]`, so a negative offset means counting backwards from the end of the
buffer. For example:
```ruby
irb(main):001:0> b = IO::Buffer.for('abc')
=>
#<IO::Buffer 0x00007f858f5450c0+3 EXTERNAL READONLY SLICE>
...
irb(main):002:0> b.get_string(-1)
=> "c"
irb(main):003:0> b.get_string(-2)
=> "bc"
irb(main):003:0> b.get_string(-1000)
=> "abc"
irb(main):003:0> b.get_string(-1000, 2)
=> "ab"
```
--
https://bugs.ruby-lang.org/
16 May
16 May
11:20 a.m.
New subject: [ruby-core:117897] [Ruby master Bug#19753] IO::Buffer#get_string can't handle negative offset
Issue #19753 has been updated by nagachika (Tomoyuki Chikanaga).
https://github.com/nagachika/ruby/commit/7d325d1b2ea7b6ef7debd6a29ad97c9331… Here is
the changeset to backport into ruby_3_2 branch, including style change and refactoring
(data -> buffer).
I have resolved some conflict by hand.
@ioquatix Would you kindly review the backport commit?
----------------------------------------
Bug #19753: IO::Buffer#get_string can't handle negative offset
https://bugs.ruby-lang.org/issues/19753#change-108315
* Author: noteflakes (Sharon Rosner)
* Status: Closed
* Assignee: ioquatix (Samuel Williams)
* ruby -v: 3.2
* Backport: 3.0: DONTNEED, 3.1: REQUIRED, 3.2: REQUIRED
----------------------------------------
```ruby
irb(main):001:0> b = IO::Buffer.for('abc')
=>
#<IO::Buffer 0x00007f858f5450c0+3 EXTERNAL READONLY SLICE>
...
irb(main):002:0> b.get_string(-1)
=> "\x00abc"
irb(main):003:0> b.get_string(-1000, 3)
(irb):3:in `get_string': Specified offset+length exceeds data size! (ArgumentError)
from (irb):3:in `<main>'
from /home/sharon/.rbenv/versions/3.2.0/lib/ruby/gems/3.2.0/gems/irb-1.7.1/exe/irb:9:in
`<top (required)>'
from /home/sharon/.rbenv/versions/3.2.0/bin/irb:25:in `load'
from /home/sharon/.rbenv/versions/3.2.0/bin/irb:25:in `<main>'
```
Using a negative offset returns garbage in the string but it also might segfault:
```ruby
irb(main):003:0> b = IO::Buffer.map(File.open('sgt-nodes.sql', 'r+'))
=> #<IO::Buffer 0x00007f189de14000+2008858 EXTERNAL MAPPED SHARED>
irb(main):004:0> b.get_string(-1000)
(irb):4: [BUG] Segmentation fault at 0x00007f189de13c18
ruby 3.2.0 (2022-12-25 revision a528908271) [x86_64-linux]
-- Control frame information -----------------------------------------------
c:0021 p:---- s:0109 e:000108 CFUNC :get_string
...
```
## Expected behaviour
I think it might be nice to have `#get_string` behave like other methods taking an offset,
like `String#[]`, so a negative offset means counting backwards from the end of the
buffer. For example:
```ruby
irb(main):001:0> b = IO::Buffer.for('abc')
=>
#<IO::Buffer 0x00007f858f5450c0+3 EXTERNAL READONLY SLICE>
...
irb(main):002:0> b.get_string(-1)
=> "c"
irb(main):003:0> b.get_string(-2)
=> "bc"
irb(main):003:0> b.get_string(-1000)
=> "abc"
irb(main):003:0> b.get_string(-1000, 2)
=> "ab"
```
--
https://bugs.ruby-lang.org/
1:23 p.m.
New subject: [ruby-core:117898] [Ruby master Bug#19753] IO::Buffer#get_string can't handle negative offset
Issue #19753 has been updated by nagachika (Tomoyuki Chikanaga).
I have cherry-picked some additional refactoring commits and open pull request
https://github.com/ruby/ruby/pull/10778.
----------------------------------------
Bug #19753: IO::Buffer#get_string can't handle negative offset
https://bugs.ruby-lang.org/issues/19753#change-108316
* Author: noteflakes (Sharon Rosner)
* Status: Closed
* Assignee: ioquatix (Samuel Williams)
* ruby -v: 3.2
* Backport: 3.0: DONTNEED, 3.1: REQUIRED, 3.2: REQUIRED
----------------------------------------
```ruby
irb(main):001:0> b = IO::Buffer.for('abc')
=>
#<IO::Buffer 0x00007f858f5450c0+3 EXTERNAL READONLY SLICE>
...
irb(main):002:0> b.get_string(-1)
=> "\x00abc"
irb(main):003:0> b.get_string(-1000, 3)
(irb):3:in `get_string': Specified offset+length exceeds data size! (ArgumentError)
from (irb):3:in `<main>'
from /home/sharon/.rbenv/versions/3.2.0/lib/ruby/gems/3.2.0/gems/irb-1.7.1/exe/irb:9:in
`<top (required)>'
from /home/sharon/.rbenv/versions/3.2.0/bin/irb:25:in `load'
from /home/sharon/.rbenv/versions/3.2.0/bin/irb:25:in `<main>'
```
Using a negative offset returns garbage in the string but it also might segfault:
```ruby
irb(main):003:0> b = IO::Buffer.map(File.open('sgt-nodes.sql', 'r+'))
=> #<IO::Buffer 0x00007f189de14000+2008858 EXTERNAL MAPPED SHARED>
irb(main):004:0> b.get_string(-1000)
(irb):4: [BUG] Segmentation fault at 0x00007f189de13c18
ruby 3.2.0 (2022-12-25 revision a528908271) [x86_64-linux]
-- Control frame information -----------------------------------------------
c:0021 p:---- s:0109 e:000108 CFUNC :get_string
...
```
## Expected behaviour
I think it might be nice to have `#get_string` behave like other methods taking an offset,
like `String#[]`, so a negative offset means counting backwards from the end of the
buffer. For example:
```ruby
irb(main):001:0> b = IO::Buffer.for('abc')
=>
#<IO::Buffer 0x00007f858f5450c0+3 EXTERNAL READONLY SLICE>
...
irb(main):002:0> b.get_string(-1)
=> "c"
irb(main):003:0> b.get_string(-2)
=> "bc"
irb(main):003:0> b.get_string(-1000)
=> "abc"
irb(main):003:0> b.get_string(-1000, 2)
=> "ab"
```
--
https://bugs.ruby-lang.org/
4:15 p.m.
New subject: [ruby-core:117899] [Ruby master Bug#19753] IO::Buffer#get_string can't handle negative offset
Issue #19753 has been updated by ioquatix (Samuel Williams).
Thanks so much, I will revie wit.
----------------------------------------
Bug #19753: IO::Buffer#get_string can't handle negative offset
https://bugs.ruby-lang.org/issues/19753#change-108317
* Author: noteflakes (Sharon Rosner)
* Status: Closed
* Assignee: ioquatix (Samuel Williams)
* ruby -v: 3.2
* Backport: 3.0: DONTNEED, 3.1: REQUIRED, 3.2: REQUIRED
----------------------------------------
```ruby
irb(main):001:0> b = IO::Buffer.for('abc')
=>
#<IO::Buffer 0x00007f858f5450c0+3 EXTERNAL READONLY SLICE>
...
irb(main):002:0> b.get_string(-1)
=> "\x00abc"
irb(main):003:0> b.get_string(-1000, 3)
(irb):3:in `get_string': Specified offset+length exceeds data size! (ArgumentError)
from (irb):3:in `<main>'
from /home/sharon/.rbenv/versions/3.2.0/lib/ruby/gems/3.2.0/gems/irb-1.7.1/exe/irb:9:in
`<top (required)>'
from /home/sharon/.rbenv/versions/3.2.0/bin/irb:25:in `load'
from /home/sharon/.rbenv/versions/3.2.0/bin/irb:25:in `<main>'
```
Using a negative offset returns garbage in the string but it also might segfault:
```ruby
irb(main):003:0> b = IO::Buffer.map(File.open('sgt-nodes.sql', 'r+'))
=> #<IO::Buffer 0x00007f189de14000+2008858 EXTERNAL MAPPED SHARED>
irb(main):004:0> b.get_string(-1000)
(irb):4: [BUG] Segmentation fault at 0x00007f189de13c18
ruby 3.2.0 (2022-12-25 revision a528908271) [x86_64-linux]
-- Control frame information -----------------------------------------------
c:0021 p:---- s:0109 e:000108 CFUNC :get_string
...
```
## Expected behaviour
I think it might be nice to have `#get_string` behave like other methods taking an offset,
like `String#[]`, so a negative offset means counting backwards from the end of the
buffer. For example:
```ruby
irb(main):001:0> b = IO::Buffer.for('abc')
=>
#<IO::Buffer 0x00007f858f5450c0+3 EXTERNAL READONLY SLICE>
...
irb(main):002:0> b.get_string(-1)
=> "c"
irb(main):003:0> b.get_string(-2)
=> "bc"
irb(main):003:0> b.get_string(-1000)
=> "abc"
irb(main):003:0> b.get_string(-1000, 2)
=> "ab"
```
--
https://bugs.ruby-lang.org/
18 May
18 May
12:10 p.m.
New subject: [ruby-core:117915] [Ruby master Bug#19753] IO::Buffer#get_string can't handle negative offset
Issue #19753 has been updated by nagachika (Tomoyuki Chikanaga).
Backport changed from 3.0: DONTNEED, 3.1: REQUIRED, 3.2: REQUIRED to 3.0: DONTNEED, 3.1:
REQUIRED, 3.2: DONE
Backported by https://github.com/ruby/ruby/pull/10778
----------------------------------------
Bug #19753: IO::Buffer#get_string can't handle negative offset
https://bugs.ruby-lang.org/issues/19753#change-108331
* Author: noteflakes (Sharon Rosner)
* Status: Closed
* Assignee: ioquatix (Samuel Williams)
* ruby -v: 3.2
* Backport: 3.0: DONTNEED, 3.1: REQUIRED, 3.2: DONE
----------------------------------------
```ruby
irb(main):001:0> b = IO::Buffer.for('abc')
=>
#<IO::Buffer 0x00007f858f5450c0+3 EXTERNAL READONLY SLICE>
...
irb(main):002:0> b.get_string(-1)
=> "\x00abc"
irb(main):003:0> b.get_string(-1000, 3)
(irb):3:in `get_string': Specified offset+length exceeds data size! (ArgumentError)
from (irb):3:in `<main>'
from /home/sharon/.rbenv/versions/3.2.0/lib/ruby/gems/3.2.0/gems/irb-1.7.1/exe/irb:9:in
`<top (required)>'
from /home/sharon/.rbenv/versions/3.2.0/bin/irb:25:in `load'
from /home/sharon/.rbenv/versions/3.2.0/bin/irb:25:in `<main>'
```
Using a negative offset returns garbage in the string but it also might segfault:
```ruby
irb(main):003:0> b = IO::Buffer.map(File.open('sgt-nodes.sql', 'r+'))
=> #<IO::Buffer 0x00007f189de14000+2008858 EXTERNAL MAPPED SHARED>
irb(main):004:0> b.get_string(-1000)
(irb):4: [BUG] Segmentation fault at 0x00007f189de13c18
ruby 3.2.0 (2022-12-25 revision a528908271) [x86_64-linux]
-- Control frame information -----------------------------------------------
c:0021 p:---- s:0109 e:000108 CFUNC :get_string
...
```
## Expected behaviour
I think it might be nice to have `#get_string` behave like other methods taking an offset,
like `String#[]`, so a negative offset means counting backwards from the end of the
buffer. For example:
```ruby
irb(main):001:0> b = IO::Buffer.for('abc')
=>
#<IO::Buffer 0x00007f858f5450c0+3 EXTERNAL READONLY SLICE>
...
irb(main):002:0> b.get_string(-1)
=> "c"
irb(main):003:0> b.get_string(-2)
=> "bc"
irb(main):003:0> b.get_string(-1000)
=> "abc"
irb(main):003:0> b.get_string(-1000, 2)
=> "ab"
```
--
https://bugs.ruby-lang.org/
1
days inactive
321
days old
9 comments
5 participants
participants (5)
-
ioquatix (Samuel Williams) -
jeremyevans0 (Jeremy Evans)
-
nagachika (Tomoyuki Chikanaga)
-
nobu (Nobuyoshi Nakada)
-
noteflakes (Sharon Rosner)