This change adds Doxygen-style comments to the public API functions
in `src/debug.c`, including mrb_packed_int_len, mrb_packed_int_encode,
and mrb_packed_int_decode. The comments explain the purpose of each function,
its parameters, and its return value. This improves the readability
and maintainability of the code.
The function requires the buffer bigger than `mrb_packed_int_len()`
anyway, so we don't need boundary checks for each iteration. Should
makes the function a little bit faster.
It uses BER number compression of delta of instruction positions and line
numbers. BER compression is a variable length number representation.
* `mrb_debug_line_ary`: array of line numbers represented in `uint16_t`.
`[lineno, lineno, ...]`
* `mrb_debug_line_flat_map`: array of `mrb_irep_debug_info_line`, which
is `struct {uint32_t pos; uint16_t lineno}`, for each line.
* `mrb_debug_line_packed_map` [new]: sequence of BER compressed 2
numbers, `pos_delta, lineno_delta`. Deltas are differences from
previous values (starting `0`). `line_entry_counts` represents total
length of a packed map string for this type.
The accuracy is greatly improved by using the C preprocessor to scan C
sources for presym. C preprocessor can perfectly interpret all comments and
preprocessor directives, so it can detect all symbols defined, for example
`mrbgems/mruby-socket/src/const.cstub`.
Also, as described later, this change will greatly improve the accuracy of
presym detection from Ruby sources.
## Result
The number of lines in the `presym` file for all gems is as follows:
```console
Previous: 999 (false positive = 89, undetected = 297)
New: 1207
```
## Build process
The new build process (with presym) is as follows:
1. Build `mrbc` without presym (more on building without presym later).
2. Compile Ruby sources to C struct format with the `mrbc` created in
step 1, and create` mrblib.c` and `gem_init.c`. Note that the symbols
in the created files are output as `MRB_SYM` family macros or
`mrb_intern_lit` instead of IDs (details will be described later).
3. C preprocessor processes C sources including the created files of
step 2 and outputs them as `.i` files. In these files, for example,
`MRB_IVSYM(foo)` is converted to `<@! "@" "foo" !@>` and
`mrb_define_module(mrb, "Foo")` is converted to `<@! "Foo" !@>`.
4. Scan the files created in step 3 and create `presym` and` presym.inc`
files.
The files created in step 2 should output all static symbols defined in Ruby
sources, including local variables, so we can detect all presyms by just
scanning C sources without scanning Ruby sources directly.
Further, by this process, the files to be scanned becomes the same as the
files to be compiled, so that there is no excess or deficiency.
## Related changes
The following changes have been made in relation to realizing this feature.
### Allow build without presym
It enables build without presym to achieve the "Build process: 1". This
incorporates #5202, see its issue for details.
Note that when presym is enabled, even adding a local variable to a Ruby
source may change contents of presym and require recompilation of almost
all C sources. This is inconvenient, especially during trial and error in
development, but this feature is also useful because it does not cause
this problem if presym is disabled.
### Automatically create build target for `mrbc` without presym
The `mrbc` used in the "Build process: 1" will be built by automatically
creating a build target for it. The build name is `SOURCE_BUILD_NAME/mrbc`.
### Constantize output of C struct format by `mrbc`
To realizing the "Build process: 2", as mentioned above, symbol IDs are not
output directly in C struct format output by `mrbc`. As a result, the output
becomes constant regardless of the state of presym at the time of `mrbc`
build, and it is possible to detect symbols of Ruby sources in the same way
as other C sources.
Note that `mrb_intern_lit` is used for symbols that do not become presym,
but in this state, the corresponding element in the symbol array cannot be
statically initialized, so it is initialized at run time (therefore, in this
case, the `const` qualifier is not added to the symbol array).
### Specify arbitrary `mrbc` file
To realizing the "Build process: 2", enabled to specify `mrbc` created by
another build target or pre-built` mrbc`. Use `MRuby::Build#mrbcfile =` to
specify it explicitly. You can omit the "Build process: 1" by specifying
pre-built `mrbc`, and you can always use an optimized build to compile Ruby
sources faster. I think changes that affect the output of `mrbc` are rare,
so in many cases it helps to improve efficiency.
With presym, the build will be a little slower due to more build steps, but
this feature will improve it a bit.
### Create presym files for each build target
This feature was proposed at #5194 and merged once, but was reverted in
5c205e6e due to problems especially with cross-compilation. It has been
introduced again because this change solves the problem.
The presym files will be created below.
* `build/NAME/presym`
* `build/NAME/include/mruby/presym.inc`
### Other changes
* Because presym detection accuracy is greatly improved as mentioned above,
`MRuby::Gem::Specification#cdump?` is set to true by default, and
`disable_cdump` is added instead of `enable_cdump`. Also, support for gem
specific presym files has been discontinued (https://github.com/mruby/mruby/issues/5151#issuecomment-730967232).
* Previously, `mrbc` was automatically created for the `host` build, but it
will not be created if the build target for `mrbc` mentioned above is
automatically created. At this time, `mrbc` file of the `mrbc` build is
copied to` bin/`.
* Two types of `.d` files will be created, `.o.d` and `.i.d`. oThis is
because if `.i` depends on `presym.inc`, the dependency will circulate, so
the `.d` file cannot be shared.
* Changed file created with `enable_cxx_exception` to `X-cxx.cxx` from
`X.cxx` to use the mruby standard Rake rule.
### Note
Almost all C sources will need to be recompiled if there are any changes to
`persym.inc` (if not recompiled properly, it will often result in run-time
error). If `gcc` toolchain is used, dependencies are resolved by the `.d`
file, so it become automatically recompile target, but if not (e.g. MSVC),
it is necessary to manually make it recompile target.
Also, even if `gcc` toolchain is used, it may not become recompile target if
external gems does not use the mruby standard Rake rule. In particular, if
the standard rule is overwritten, such as
https://github.com/mruby/mruby/pull/5112/files, `.d` file will not be read,
so be careful.
commit 2d7d545c4c4bfce7fdcbcbe9baaeb437915742f0
Merge: 625a1249 b178914b
Author: Yukihiro "Matz" Matsumoto <matz@ruby.or.jp>
Date: Fri Jun 5 14:35:13 2020 +0900
Merge branch 'fix-mrb_open-with-nomem' of https://github.com/dearblue/mruby into dearblue-fix-mrb_open-with-nomem
commit b178914b11
Author: dearblue <dearblue@users.noreply.github.com>
Date: Sat Jan 19 22:22:44 2019 +0900
Fix invalid pointer free inside other heap's block
1. `e = mrb_obj_alloc(...)`
2. `e->stack = mrb->c->stack` (`mrb->c->stack` is anywhere in the range `stbase...stend`)
3. And raised exception by `mrb_malloc()`!
4. `mrb_free(e->stack)` by GC part (wrong free)
commit 52e3d5d858
Author: dearblue <dearblue@users.noreply.github.com>
Date: Sat Jan 19 21:55:36 2019 +0900
Fix memory leak for temporary symbols when out of memory
commit 4c5499b88e
Author: dearblue <dearblue@users.noreply.github.com>
Date: Sun Jan 20 11:42:07 2019 +0900
Fix uninitialized pointer dereference for debug section
commit 8e993167de
Author: dearblue <dearblue@users.noreply.github.com>
Date: Sun Jan 20 11:41:09 2019 +0900
Fix memory leak for temporary filenames when out of memory
commit 8b422577e6
Author: dearblue <dearblue@users.noreply.github.com>
Date: Sun Jan 20 10:57:51 2019 +0900
Fix memory leak for irep when out of memory
commit 6b35ebf49a
Author: dearblue <dearblue@users.noreply.github.com>
Date: Sun Jan 20 10:55:50 2019 +0900
Fix uninitialized pointer dereference when do not finished initializing irep
commit 2531f2631e
Author: dearblue <dearblue@users.noreply.github.com>
Date: Sun Jan 20 10:48:15 2019 +0900
Fix NULL pointer dereference when do not finished initializing irep
commit e2d6896eba
Author: dearblue <dearblue@users.noreply.github.com>
Date: Sat Jan 19 12:54:19 2019 +0900
Fix memory leak for irep when out of memory by `mrb_proc_new()`
commit b6214ff8a0
Author: dearblue <dearblue@users.noreply.github.com>
Date: Sat Jan 19 12:53:07 2019 +0900
Fix memory leak for `khash_t` in `kh_init_size()` when out of memory by `kh_alloc()`
commit 19162dd6c1
Author: dearblue <dearblue@users.noreply.github.com>
Date: Sun Jan 20 02:15:07 2019 +0900
Fix memory leak for symbol string when out of memory in `kh_put()`
commit 15e67297ff
Author: dearblue <dearblue@users.noreply.github.com>
Date: Sun Jan 20 02:12:24 2019 +0900
Fix keep wrong symbol index when out of memory
commit 3f8e2b3752
Author: dearblue <dearblue@users.noreply.github.com>
Date: Sun Jan 20 02:08:13 2019 +0900
Fix keep wrong symbol capacity when out of memory
commit a3cfe755ab
Author: dearblue <dearblue@users.noreply.github.com>
Date: Sat Jan 19 10:11:37 2019 +0900
Fix NULL pointer dereference `mrb->c` by `mark_context()`
commit d9c7b6be6e
Author: dearblue <dearblue@users.noreply.github.com>
Date: Sun Jan 20 15:25:09 2019 +0900
Fix protect exception for print error message
commit 100642750e
Author: dearblue <dearblue@users.noreply.github.com>
Date: Sun Jan 20 11:59:02 2019 +0900
Protect exception for mruby core initialization
commit 7a0418304e
Author: dearblue <dearblue@users.noreply.github.com>
Date: Fri Jan 18 20:38:27 2019 +0900
Fix memory leak for string object when out of memory
The `mrb_str_pool()` function has a path to call `malloc()` twice.
If occurs `NoMemoryError` exception in second `malloc()`,
first `malloc()` pointer is not freed.
commit fef1c152ce
Author: dearblue <dearblue@users.noreply.github.com>
Date: Sat Jan 19 13:05:09 2019 +0900
Fix stack overflow when out of memory
As a result of this change, no backtrace information is set
for NoMemoryError (`mrb->nomem_err`).
Detailes:
When generating a backtrace, called `mrb_intern_lit()`,
`mrb_str_new_cstr()` and `mrb_obj_iv_set()` function with
`exc_debug_info()` function in `src/error.c`.
If a `NoMemoryError` exception occurs at this time,
the `exc_debug_info()` function will be called again,
and in the same way `NoMemoryError` exception raised will result
in an infinite loop to occurs stack overflow (and SIGSEGV).
commit da7d7f881b
Author: dearblue <dearblue@users.noreply.github.com>
Date: Sun Jan 20 12:00:38 2019 +0900
Fix NULL pointer dereference `mrb->nomem_err` when not initialized
Add internal functions (not `static`):
* `mrb_raise_nomemory()`
* `mrb_core_init_abort()`
The addresses for packed inline symbols reference `mrb->symbuf` that
could be overridden by the later call of `mrb_sym2name_len`. Since
file names in call stack information are kept as symbols, keeping the
address in the C structures could cause problems like #4342.
This changes small incompatible changes in function prototypes:
* `mrb_parser_get_filename`: return value changed to `mrb_sym`.
* `mrb_debug_get_filename`: add `mrb_state*` as a first argument.
* `mrb_debug_get_line`: ditto.
I believe above functions are almost internal, and no third-party
mrbgem use them.
According to CONTRIBUTING.md,
Don't use C++ style comments
/* This is the prefered comment style */
Use C++ style comments only for temporary comment e.g. commenting out some code lines.
google-labs-jules[bot]