[ruby-core:120465] [Ruby master Bug#20998] rb_str_locktmp() changes flags of frozen strings and string literals

[ruby-core:120465] [Ruby master Bug#20998] rb_str_locktmp() changes flags of frozen strings and string literals

[Eregon (Benoit Daloze) via ruby-core]

Issue #20998 has been reported by Eregon (Benoit Daloze).

----------------------------------------
Bug #20998: rb_str_locktmp() changes flags of frozen strings and string literals
https://bugs.ruby-lang.org/issues/20998

* Author: Eregon (Benoit Daloze)
* Status: Open
* ruby -v: ruby 3.4.1 (2024-12-25 revision 48d4efcb85) +PRISM [x86_64-linux]
* Backport: 3.1: UNKNOWN, 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: UNKNOWN
----------------------------------------
```ruby
# frozen_string_literal: true
# BOILERPLATE START

require 'tmpdir'
require 'rbconfig'

def inline_c_extension(c_code)
  Dir.mktmpdir('inline_c_extension') do |dir|
    File.write("#{dir}/cext.c", c_code)
    File.write("#{dir}/extconf.rb", <<~RUBY)
    require 'mkmf'
    create_makefile('cext')
    RUBY

    out = IO.popen([RbConfig.ruby, 'extconf.rb'], chdir: dir, &:read)
    raise "ruby extconf.rb failed: #{$?.inspect}\n#{out}" unless $?.success?

    out = IO.popen(['make'], chdir: dir, &:read)
    raise "make failed: #{$?.inspect}\n#{out}" unless $?.success?

    require "#{dir}/cext.#{RbConfig::CONFIG['DLEXT']}"
  end
end

inline_c_extension <<~C
#include "ruby.h"

static VALUE foo(VALUE self, VALUE str) {
  rb_str_locktmp(str);
  return str;
}

void Init_cext(void) {
  VALUE c = rb_define_class("Foo", rb_cObject);
  rb_define_singleton_method(c, "foo", foo, 1);
}
C

# BOILERPLATE END

a = "str"

# imagine a million line of codes in between

b = "str"

Foo.foo(a)

b << "."
# can't modify string; temporarily locked (RuntimeError)
# What? Who "locked" that immutable frozen string literal?
# It should be: can't modify frozen String: "str" (FrozenError)
```

Same problem with:
```ruby
Foo.foo("abc")

# imagine a million line of codes in between

Foo.foo("abc") # emporal locking already locked string (RuntimeError)
```

Related: https://github.com/oracle/truffleruby/issues/3752

It seems a clear bug to mutate a frozen string (with visible side effects), even more so for shared frozen string literals.

I think rb_str_locktmp() should raise (a FrozenError, as it's effectively attempting to mutate it, same as calling `rb_str_modify()`) if called on a frozen string, because it makes little sense, I think "locking a string" only makes sense for mutable strings.

The alternative would be to noop on frozen strings for rb_str_locktmp() and rb_str_unlocktmp(), I think that's susprising, and potentially hiding more bugs, e.g. if one by mistake tries to mutate the RSTRING_PTR() or so.
Any attempt to mutate a frozen string should fail, so might as well fail early.



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[ruby-core:120493] [Ruby master Bug#20998] rb_str_locktmp() changes flags of frozen strings and string literals

[nobu (Nobuyoshi Nakada) via ruby-core]

Issue #20998 has been updated by nobu (Nobuyoshi Nakada).


There isn’t a case that locking a string just to avoid being modified or moved, but not to mutate it?

----------------------------------------
Bug #20998: rb_str_locktmp() changes flags of frozen strings and string literals
https://bugs.ruby-lang.org/issues/20998#change-111278

* Author: Eregon (Benoit Daloze)
* Status: Open
* ruby -v: ruby 3.4.1 (2024-12-25 revision 48d4efcb85) +PRISM [x86_64-linux]
* Backport: 3.1: UNKNOWN, 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: UNKNOWN
----------------------------------------
```ruby
# frozen_string_literal: true
# BOILERPLATE START

require 'tmpdir'
require 'rbconfig'

def inline_c_extension(c_code)
  Dir.mktmpdir('inline_c_extension') do |dir|
    File.write("#{dir}/cext.c", c_code)
    File.write("#{dir}/extconf.rb", <<~RUBY)
    require 'mkmf'
    create_makefile('cext')
    RUBY

    out = IO.popen([RbConfig.ruby, 'extconf.rb'], chdir: dir, &:read)
    raise "ruby extconf.rb failed: #{$?.inspect}\n#{out}" unless $?.success?

    out = IO.popen(['make'], chdir: dir, &:read)
    raise "make failed: #{$?.inspect}\n#{out}" unless $?.success?

    require "#{dir}/cext.#{RbConfig::CONFIG['DLEXT']}"
  end
end

inline_c_extension <<~C
#include "ruby.h"

static VALUE foo(VALUE self, VALUE str) {
  rb_str_locktmp(str);
  return str;
}

void Init_cext(void) {
  VALUE c = rb_define_class("Foo", rb_cObject);
  rb_define_singleton_method(c, "foo", foo, 1);
}
C

# BOILERPLATE END

a = "str"
Foo.foo(a)

# imagine a million lines of code in between

b = "str"

b << "."
# can't modify string; temporarily locked (RuntimeError)
# What? Who "locked" that immutable frozen string literal?
# It should be: can't modify frozen String: "str" (FrozenError)
```

Same problem with:
```ruby
Foo.foo("abc")

# imagine a million lines of code in between

Foo.foo("abc") # temporal locking already locked string (RuntimeError)
```

Related: https://github.com/oracle/truffleruby/issues/3752

It seems a clear bug to mutate a frozen string (with visible side effects), even more so for shared frozen string literals.

I think rb_str_locktmp() should raise (a FrozenError, as it's effectively attempting to mutate it, same as calling `rb_str_modify()`) if called on a frozen string, because it makes little sense, I think "locking a string" only makes sense for mutable strings.

The alternative would be to noop on frozen strings for rb_str_locktmp() and rb_str_unlocktmp(), I think that's susprising, and potentially hiding more bugs, e.g. if one by mistake tries to mutate the RSTRING_PTR() or so, and also rb_str_locktmp() wouldn't imply the flag is set after it returns.
Any attempt to mutate a frozen string should fail, so might as well fail early.



-- 
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[ruby-core:120495] [Ruby master Bug#20998] rb_str_locktmp() changes flags of frozen strings and string literals

[Eregon (Benoit Daloze) via ruby-core]

Issue #20998 has been updated by Eregon (Benoit Daloze).


I'm not aware of any such case, and `.freeze` seems much better for that use case.

----------------------------------------
Bug #20998: rb_str_locktmp() changes flags of frozen strings and string literals
https://bugs.ruby-lang.org/issues/20998#change-111282

* Author: Eregon (Benoit Daloze)
* Status: Open
* ruby -v: ruby 3.4.1 (2024-12-25 revision 48d4efcb85) +PRISM [x86_64-linux]
* Backport: 3.1: UNKNOWN, 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: UNKNOWN
----------------------------------------
```ruby
# frozen_string_literal: true
# BOILERPLATE START

require 'tmpdir'
require 'rbconfig'

def inline_c_extension(c_code)
  Dir.mktmpdir('inline_c_extension') do |dir|
    File.write("#{dir}/cext.c", c_code)
    File.write("#{dir}/extconf.rb", <<~RUBY)
    require 'mkmf'
    create_makefile('cext')
    RUBY

    out = IO.popen([RbConfig.ruby, 'extconf.rb'], chdir: dir, &:read)
    raise "ruby extconf.rb failed: #{$?.inspect}\n#{out}" unless $?.success?

    out = IO.popen(['make'], chdir: dir, &:read)
    raise "make failed: #{$?.inspect}\n#{out}" unless $?.success?

    require "#{dir}/cext.#{RbConfig::CONFIG['DLEXT']}"
  end
end

inline_c_extension <<~C
#include "ruby.h"

static VALUE foo(VALUE self, VALUE str) {
  rb_str_locktmp(str);
  return str;
}

void Init_cext(void) {
  VALUE c = rb_define_class("Foo", rb_cObject);
  rb_define_singleton_method(c, "foo", foo, 1);
}
C

# BOILERPLATE END

a = "str"
Foo.foo(a)

# imagine a million lines of code in between

b = "str"

b << "."
# can't modify string; temporarily locked (RuntimeError)
# What? Who "locked" that immutable frozen string literal?
# It should be: can't modify frozen String: "str" (FrozenError)
```

Same problem with:
```ruby
Foo.foo("abc")

# imagine a million lines of code in between

Foo.foo("abc") # temporal locking already locked string (RuntimeError)
```

Related: https://github.com/oracle/truffleruby/issues/3752

It seems a clear bug to mutate a frozen string (with visible side effects), even more so for shared frozen string literals.

I think rb_str_locktmp() should raise (a FrozenError, as it's effectively attempting to mutate it, same as calling `rb_str_modify()`) if called on a frozen string, because it makes little sense, I think "locking a string" only makes sense for mutable strings.

The alternative would be to noop on frozen strings for rb_str_locktmp() and rb_str_unlocktmp(), I think that's susprising, and potentially hiding more bugs, e.g. if one by mistake tries to mutate the RSTRING_PTR() or so, and also rb_str_locktmp() wouldn't imply the flag is set after it returns.
Any attempt to mutate a frozen string should fail, so might as well fail early.



-- 
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 ______________________________________________
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 To unsubscribe send an email to ruby-core-leave@ml.ruby-lang.org
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[ruby-core:120497] [Ruby master Bug#20998] rb_str_locktmp() changes flags of frozen strings and string literals

[byroot (Jean Boussier) via ruby-core]

Issue #20998 has been updated by byroot (Jean Boussier).


Actually yes, I think it's not an uncommon use case?

e.g. if you need to write a given string into a socket or something like that, you may want to lock it to ensure a concurrent thread won't modify it.

I think `zlic.c` uses it this way?



----------------------------------------
Bug #20998: rb_str_locktmp() changes flags of frozen strings and string literals
https://bugs.ruby-lang.org/issues/20998#change-111289

* Author: Eregon (Benoit Daloze)
* Status: Open
* ruby -v: ruby 3.4.1 (2024-12-25 revision 48d4efcb85) +PRISM [x86_64-linux]
* Backport: 3.1: UNKNOWN, 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: UNKNOWN
----------------------------------------
```ruby
# frozen_string_literal: true
# BOILERPLATE START

require 'tmpdir'
require 'rbconfig'

def inline_c_extension(c_code)
  Dir.mktmpdir('inline_c_extension') do |dir|
    File.write("#{dir}/cext.c", c_code)
    File.write("#{dir}/extconf.rb", <<~RUBY)
    require 'mkmf'
    create_makefile('cext')
    RUBY

    out = IO.popen([RbConfig.ruby, 'extconf.rb'], chdir: dir, &:read)
    raise "ruby extconf.rb failed: #{$?.inspect}\n#{out}" unless $?.success?

    out = IO.popen(['make'], chdir: dir, &:read)
    raise "make failed: #{$?.inspect}\n#{out}" unless $?.success?

    require "#{dir}/cext.#{RbConfig::CONFIG['DLEXT']}"
  end
end

inline_c_extension <<~C
#include "ruby.h"

static VALUE foo(VALUE self, VALUE str) {
  rb_str_locktmp(str);
  return str;
}

void Init_cext(void) {
  VALUE c = rb_define_class("Foo", rb_cObject);
  rb_define_singleton_method(c, "foo", foo, 1);
}
C

# BOILERPLATE END

a = "str"
Foo.foo(a)

# imagine a million lines of code in between

b = "str"

b << "."
# can't modify string; temporarily locked (RuntimeError)
# What? Who "locked" that immutable frozen string literal?
# It should be: can't modify frozen String: "str" (FrozenError)
```

Same problem with:
```ruby
Foo.foo("abc")

# imagine a million lines of code in between

Foo.foo("abc") # temporal locking already locked string (RuntimeError)
```

Related: https://github.com/oracle/truffleruby/issues/3752

It seems a clear bug to mutate a frozen string (with visible side effects), even more so for shared frozen string literals.

I think rb_str_locktmp() should raise (a FrozenError, as it's effectively attempting to mutate it, same as calling `rb_str_modify()`) if called on a frozen string, because it makes little sense, I think "locking a string" only makes sense for mutable strings.

The alternative would be to noop on frozen strings for rb_str_locktmp() and rb_str_unlocktmp(), I think that's susprising, and potentially hiding more bugs, e.g. if one by mistake tries to mutate the RSTRING_PTR() or so, and also rb_str_locktmp() wouldn't imply the flag is set after it returns.
Any attempt to mutate a frozen string should fail, so might as well fail early.



-- 
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 ______________________________________________
 ruby-core mailing list -- ruby-core@ml.ruby-lang.org
 To unsubscribe send an email to ruby-core-leave@ml.ruby-lang.org
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[ruby-core:120499] [Ruby master Bug#20998] rb_str_locktmp() changes flags of frozen strings and string literals

[Eregon (Benoit Daloze) via ruby-core]

Issue #20998 has been updated by Eregon (Benoit Daloze).


@byroot but that's mutating the string, @nobu is asking for a case not mutating the string, which I think there is none.

----------------------------------------
Bug #20998: rb_str_locktmp() changes flags of frozen strings and string literals
https://bugs.ruby-lang.org/issues/20998#change-111292

* Author: Eregon (Benoit Daloze)
* Status: Open
* ruby -v: ruby 3.4.1 (2024-12-25 revision 48d4efcb85) +PRISM [x86_64-linux]
* Backport: 3.1: UNKNOWN, 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: UNKNOWN
----------------------------------------
```ruby
# frozen_string_literal: true
# BOILERPLATE START

require 'tmpdir'
require 'rbconfig'

def inline_c_extension(c_code)
  Dir.mktmpdir('inline_c_extension') do |dir|
    File.write("#{dir}/cext.c", c_code)
    File.write("#{dir}/extconf.rb", <<~RUBY)
    require 'mkmf'
    create_makefile('cext')
    RUBY

    out = IO.popen([RbConfig.ruby, 'extconf.rb'], chdir: dir, &:read)
    raise "ruby extconf.rb failed: #{$?.inspect}\n#{out}" unless $?.success?

    out = IO.popen(['make'], chdir: dir, &:read)
    raise "make failed: #{$?.inspect}\n#{out}" unless $?.success?

    require "#{dir}/cext.#{RbConfig::CONFIG['DLEXT']}"
  end
end

inline_c_extension <<~C
#include "ruby.h"

static VALUE foo(VALUE self, VALUE str) {
  rb_str_locktmp(str);
  return str;
}

void Init_cext(void) {
  VALUE c = rb_define_class("Foo", rb_cObject);
  rb_define_singleton_method(c, "foo", foo, 1);
}
C

# BOILERPLATE END

a = "str"
Foo.foo(a)

# imagine a million lines of code in between

b = "str"

b << "."
# can't modify string; temporarily locked (RuntimeError)
# What? Who "locked" that immutable frozen string literal?
# It should be: can't modify frozen String: "str" (FrozenError)
```

Same problem with:
```ruby
Foo.foo("abc")

# imagine a million lines of code in between

Foo.foo("abc") # temporal locking already locked string (RuntimeError)
```

Related: https://github.com/oracle/truffleruby/issues/3752

It seems a clear bug to mutate a frozen string (with visible side effects), even more so for shared frozen string literals.

I think rb_str_locktmp() should raise (a FrozenError, as it's effectively attempting to mutate it, same as calling `rb_str_modify()`) if called on a frozen string, because it makes little sense, I think "locking a string" only makes sense for mutable strings.

The alternative would be to noop on frozen strings for rb_str_locktmp() and rb_str_unlocktmp(), I think that's susprising, and potentially hiding more bugs, e.g. if one by mistake tries to mutate the RSTRING_PTR() or so, and also rb_str_locktmp() wouldn't imply the flag is set after it returns.
Any attempt to mutate a frozen string should fail, so might as well fail early.



-- 
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 ______________________________________________
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 To unsubscribe send an email to ruby-core-leave@ml.ruby-lang.org
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[ruby-core:120500] [Ruby master Bug#20998] rb_str_locktmp() changes flags of frozen strings and string literals

[Eregon (Benoit Daloze) via ruby-core]

Issue #20998 has been updated by Eregon (Benoit Daloze).


https://github.com/ruby/ruby/blob/975461bf885b8fb791cf048ad39c79924d28e4e9/ext/zlib/zlib.c#L1056 but I'm not quite sure how that String is used.
It seems clearly wrong that two threads using Zlib with a frozen String literal (which happens to have the same contents/characters for both threads) would fail with `temporal locking already locked string (RuntimeError)` though.
So what should we do then when rb_str_locktmp() is called on a frozen string?

----------------------------------------
Bug #20998: rb_str_locktmp() changes flags of frozen strings and string literals
https://bugs.ruby-lang.org/issues/20998#change-111293

* Author: Eregon (Benoit Daloze)
* Status: Open
* ruby -v: ruby 3.4.1 (2024-12-25 revision 48d4efcb85) +PRISM [x86_64-linux]
* Backport: 3.1: UNKNOWN, 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: UNKNOWN
----------------------------------------
```ruby
# frozen_string_literal: true
# BOILERPLATE START

require 'tmpdir'
require 'rbconfig'

def inline_c_extension(c_code)
  Dir.mktmpdir('inline_c_extension') do |dir|
    File.write("#{dir}/cext.c", c_code)
    File.write("#{dir}/extconf.rb", <<~RUBY)
    require 'mkmf'
    create_makefile('cext')
    RUBY

    out = IO.popen([RbConfig.ruby, 'extconf.rb'], chdir: dir, &:read)
    raise "ruby extconf.rb failed: #{$?.inspect}\n#{out}" unless $?.success?

    out = IO.popen(['make'], chdir: dir, &:read)
    raise "make failed: #{$?.inspect}\n#{out}" unless $?.success?

    require "#{dir}/cext.#{RbConfig::CONFIG['DLEXT']}"
  end
end

inline_c_extension <<~C
#include "ruby.h"

static VALUE foo(VALUE self, VALUE str) {
  rb_str_locktmp(str);
  return str;
}

void Init_cext(void) {
  VALUE c = rb_define_class("Foo", rb_cObject);
  rb_define_singleton_method(c, "foo", foo, 1);
}
C

# BOILERPLATE END

a = "str"
Foo.foo(a)

# imagine a million lines of code in between

b = "str"

b << "."
# can't modify string; temporarily locked (RuntimeError)
# What? Who "locked" that immutable frozen string literal?
# It should be: can't modify frozen String: "str" (FrozenError)
```

Same problem with:
```ruby
Foo.foo("abc")

# imagine a million lines of code in between

Foo.foo("abc") # temporal locking already locked string (RuntimeError)
```

Related: https://github.com/oracle/truffleruby/issues/3752

It seems a clear bug to mutate a frozen string (with visible side effects), even more so for shared frozen string literals.

I think rb_str_locktmp() should raise (a FrozenError, as it's effectively attempting to mutate it, same as calling `rb_str_modify()`) if called on a frozen string, because it makes little sense, I think "locking a string" only makes sense for mutable strings.

The alternative would be to noop on frozen strings for rb_str_locktmp() and rb_str_unlocktmp(), I think that's susprising, and potentially hiding more bugs, e.g. if one by mistake tries to mutate the RSTRING_PTR() or so, and also rb_str_locktmp() wouldn't imply the flag is set after it returns.
Any attempt to mutate a frozen string should fail, so might as well fail early.



-- 
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 To unsubscribe send an email to ruby-core-leave@ml.ruby-lang.org
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[ruby-core:120520] [Ruby master Bug#20998] rb_str_locktmp() changes flags of frozen strings and string literals

[byroot (Jean Boussier) via ruby-core]

Issue #20998 has been updated by byroot (Jean Boussier).


> It seems clearly wrong that two threads using Zlib with a frozen String literal (which happens to have the same contents/characters for both threads) would fail with temporal locking already locked string (RuntimeError) though.

That I totally agree.


----------------------------------------
Bug #20998: rb_str_locktmp() changes flags of frozen strings and string literals
https://bugs.ruby-lang.org/issues/20998#change-111325

* Author: Eregon (Benoit Daloze)
* Status: Open
* ruby -v: ruby 3.4.1 (2024-12-25 revision 48d4efcb85) +PRISM [x86_64-linux]
* Backport: 3.1: UNKNOWN, 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: UNKNOWN
----------------------------------------
```ruby
# frozen_string_literal: true
# BOILERPLATE START

require 'tmpdir'
require 'rbconfig'

def inline_c_extension(c_code)
  Dir.mktmpdir('inline_c_extension') do |dir|
    File.write("#{dir}/cext.c", c_code)
    File.write("#{dir}/extconf.rb", <<~RUBY)
    require 'mkmf'
    create_makefile('cext')
    RUBY

    out = IO.popen([RbConfig.ruby, 'extconf.rb'], chdir: dir, &:read)
    raise "ruby extconf.rb failed: #{$?.inspect}\n#{out}" unless $?.success?

    out = IO.popen(['make'], chdir: dir, &:read)
    raise "make failed: #{$?.inspect}\n#{out}" unless $?.success?

    require "#{dir}/cext.#{RbConfig::CONFIG['DLEXT']}"
  end
end

inline_c_extension <<~C
#include "ruby.h"

static VALUE foo(VALUE self, VALUE str) {
  rb_str_locktmp(str);
  return str;
}

void Init_cext(void) {
  VALUE c = rb_define_class("Foo", rb_cObject);
  rb_define_singleton_method(c, "foo", foo, 1);
}
C

# BOILERPLATE END

a = "str"
Foo.foo(a)

# imagine a million lines of code in between

b = "str"

b << "."
# can't modify string; temporarily locked (RuntimeError)
# What? Who "locked" that immutable frozen string literal?
# It should be: can't modify frozen String: "str" (FrozenError)
```

Same problem with:
```ruby
Foo.foo("abc")

# imagine a million lines of code in between

Foo.foo("abc") # temporal locking already locked string (RuntimeError)
```

Related: https://github.com/oracle/truffleruby/issues/3752

It seems a clear bug to mutate a frozen string (with visible side effects), even more so for shared frozen string literals.

I think rb_str_locktmp() should raise (a FrozenError, as it's effectively attempting to mutate it, same as calling `rb_str_modify()`) if called on a frozen string, because it makes little sense, I think "locking a string" only makes sense for mutable strings.

The alternative would be to noop on frozen strings for rb_str_locktmp() and rb_str_unlocktmp(), I think that's susprising, and potentially hiding more bugs, e.g. if one by mistake tries to mutate the RSTRING_PTR() or so, and also rb_str_locktmp() wouldn't imply the flag is set after it returns.
Any attempt to mutate a frozen string should fail, so might as well fail early.



-- 
https://bugs.ruby-lang.org/
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 To unsubscribe send an email to ruby-core-leave@ml.ruby-lang.org
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[ruby-core:120583] [Ruby master Bug#20998] rb_str_locktmp() changes flags of frozen strings and string literals

[Eregon (Benoit Daloze) via ruby-core]

Issue #20998 has been updated by Eregon (Benoit Daloze).


@nobu @byroot So do you think rb_str_locktmp() should noop on frozen strings (since they can't change anyway), or it should raise because the usage seems somewhat dubious?
I'm fine with either, I'd just like a decision so we can do the same in TruffleRuby.
(the current status is broken so that's worse than either fix)

----------------------------------------
Bug #20998: rb_str_locktmp() changes flags of frozen strings and string literals
https://bugs.ruby-lang.org/issues/20998#change-111408

* Author: Eregon (Benoit Daloze)
* Status: Open
* ruby -v: ruby 3.4.1 (2024-12-25 revision 48d4efcb85) +PRISM [x86_64-linux]
* Backport: 3.1: UNKNOWN, 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: UNKNOWN
----------------------------------------
```ruby
# frozen_string_literal: true
# BOILERPLATE START

require 'tmpdir'
require 'rbconfig'

def inline_c_extension(c_code)
  Dir.mktmpdir('inline_c_extension') do |dir|
    File.write("#{dir}/cext.c", c_code)
    File.write("#{dir}/extconf.rb", <<~RUBY)
    require 'mkmf'
    create_makefile('cext')
    RUBY

    out = IO.popen([RbConfig.ruby, 'extconf.rb'], chdir: dir, &:read)
    raise "ruby extconf.rb failed: #{$?.inspect}\n#{out}" unless $?.success?

    out = IO.popen(['make'], chdir: dir, &:read)
    raise "make failed: #{$?.inspect}\n#{out}" unless $?.success?

    require "#{dir}/cext.#{RbConfig::CONFIG['DLEXT']}"
  end
end

inline_c_extension <<~C
#include "ruby.h"

static VALUE foo(VALUE self, VALUE str) {
  rb_str_locktmp(str);
  return str;
}

void Init_cext(void) {
  VALUE c = rb_define_class("Foo", rb_cObject);
  rb_define_singleton_method(c, "foo", foo, 1);
}
C

# BOILERPLATE END

a = "str"
Foo.foo(a)

# imagine a million lines of code in between

b = "str"

b << "."
# can't modify string; temporarily locked (RuntimeError)
# What? Who "locked" that immutable frozen string literal?
# It should be: can't modify frozen String: "str" (FrozenError)
```

Same problem with:
```ruby
Foo.foo("abc")

# imagine a million lines of code in between

Foo.foo("abc") # temporal locking already locked string (RuntimeError)
```

Related: https://github.com/oracle/truffleruby/issues/3752

It seems a clear bug to mutate a frozen string (with visible side effects), even more so for shared frozen string literals.

I think rb_str_locktmp() should raise (a FrozenError, as it's effectively attempting to mutate it, same as calling `rb_str_modify()`) if called on a frozen string, because it makes little sense, I think "locking a string" only makes sense for mutable strings.

The alternative would be to noop on frozen strings for rb_str_locktmp() and rb_str_unlocktmp(), I think that's susprising, and potentially hiding more bugs, e.g. if one by mistake tries to mutate the RSTRING_PTR() or so, and also rb_str_locktmp() wouldn't imply the flag is set after it returns.
Any attempt to mutate a frozen string should fail, so might as well fail early.



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[ruby-core:120585] [Ruby master Bug#20998] rb_str_locktmp() changes flags of frozen strings and string literals

[byroot (Jean Boussier) via ruby-core]

Issue #20998 has been updated by byroot (Jean Boussier).


I prefer the noop solution, as it makes it a much easier to use API. But no strong opinion.

----------------------------------------
Bug #20998: rb_str_locktmp() changes flags of frozen strings and string literals
https://bugs.ruby-lang.org/issues/20998#change-111410

* Author: Eregon (Benoit Daloze)
* Status: Open
* ruby -v: ruby 3.4.1 (2024-12-25 revision 48d4efcb85) +PRISM [x86_64-linux]
* Backport: 3.1: UNKNOWN, 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: UNKNOWN
----------------------------------------
```ruby
# frozen_string_literal: true
# BOILERPLATE START

require 'tmpdir'
require 'rbconfig'

def inline_c_extension(c_code)
  Dir.mktmpdir('inline_c_extension') do |dir|
    File.write("#{dir}/cext.c", c_code)
    File.write("#{dir}/extconf.rb", <<~RUBY)
    require 'mkmf'
    create_makefile('cext')
    RUBY

    out = IO.popen([RbConfig.ruby, 'extconf.rb'], chdir: dir, &:read)
    raise "ruby extconf.rb failed: #{$?.inspect}\n#{out}" unless $?.success?

    out = IO.popen(['make'], chdir: dir, &:read)
    raise "make failed: #{$?.inspect}\n#{out}" unless $?.success?

    require "#{dir}/cext.#{RbConfig::CONFIG['DLEXT']}"
  end
end

inline_c_extension <<~C
#include "ruby.h"

static VALUE foo(VALUE self, VALUE str) {
  rb_str_locktmp(str);
  return str;
}

void Init_cext(void) {
  VALUE c = rb_define_class("Foo", rb_cObject);
  rb_define_singleton_method(c, "foo", foo, 1);
}
C

# BOILERPLATE END

a = "str"
Foo.foo(a)

# imagine a million lines of code in between

b = "str"

b << "."
# can't modify string; temporarily locked (RuntimeError)
# What? Who "locked" that immutable frozen string literal?
# It should be: can't modify frozen String: "str" (FrozenError)
```

Same problem with:
```ruby
Foo.foo("abc")

# imagine a million lines of code in between

Foo.foo("abc") # temporal locking already locked string (RuntimeError)
```

Related: https://github.com/oracle/truffleruby/issues/3752

It seems a clear bug to mutate a frozen string (with visible side effects), even more so for shared frozen string literals.

I think rb_str_locktmp() should raise (a FrozenError, as it's effectively attempting to mutate it, same as calling `rb_str_modify()`) if called on a frozen string, because it makes little sense, I think "locking a string" only makes sense for mutable strings.

The alternative would be to noop on frozen strings for rb_str_locktmp() and rb_str_unlocktmp(), I think that's susprising, and potentially hiding more bugs, e.g. if one by mistake tries to mutate the RSTRING_PTR() or so, and also rb_str_locktmp() wouldn't imply the flag is set after it returns.
Any attempt to mutate a frozen string should fail, so might as well fail early.



-- 
https://bugs.ruby-lang.org/
 ______________________________________________
 ruby-core mailing list -- ruby-core@ml.ruby-lang.org
 To unsubscribe send an email to ruby-core-leave@ml.ruby-lang.org
 ruby-core info -- https://ml.ruby-lang.org/mailman3/lists/ruby-core.ml.ruby-lang.org/