[ruby-core:114070] [Ruby master Bug#19753] IO::Buffer#get_string can't handle negative offset
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/
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/
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/
Issue #19753 has been updated by noteflakes (Sharon Rosner). nobu (Nobuyoshi Nakada) wrote in #note-3:
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"`.
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/
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/
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/
Issue #19753 has been updated by nagachika (Tomoyuki Chikanaga). https://github.com/nagachika/ruby/commit/7d325d1b2ea7b6ef7debd6a29ad97c93311... 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/
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/
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/
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/
participants (5)
-
ioquatix (Samuel Williams) -
jeremyevans0 (Jeremy Evans)
-
nagachika (Tomoyuki Chikanaga)
-
nobu (Nobuyoshi Nakada)
-
noteflakes (Sharon Rosner)