Fix default wstring length

[TonyWelte]

This PR fixes strings containing unicode characters not being escaped properly and their size being inaccurate. For instance on WString it results in the following change

38c38
< static char test_msgs__msg__WStrings__DEFAULT_VALUE__wstring_value_default2[] = "Hell\\xc3\\xb6 w\\xc3\\xb6rld!";
---
> static char test_msgs__msg__WStrings__DEFAULT_VALUE__wstring_value_default2[] = "Hell\xc3\xb6 w\xc3\xb6rld!";
40c40
< static char test_msgs__msg__WStrings__DEFAULT_VALUE__wstring_value_default3[] = "\\xe3\\x83\\x8f\\xe3\\x83\\xad\\xe3\\x83\\xbc\\xe3\\x83\\xaf\\xe3\\x83\\xbc\\xe3\\x83\\xab\\xe3\\x83\\x89";
---
> static char test_msgs__msg__WStrings__DEFAULT_VALUE__wstring_value_default3[] = "\xe3\x83\x8f\xe3\x83\xad\xe3\x83\xbc\xe3\x83\xaf\xe3\x83\xbc\xe3\x83\xab\xe3\x83\x89";
74c74
<     {test_msgs__msg__WStrings__DEFAULT_VALUE__wstring_value_default2, 12, 12},
---
>     {test_msgs__msg__WStrings__DEFAULT_VALUE__wstring_value_default2, 14, 14},
84c84
<     {test_msgs__msg__WStrings__DEFAULT_VALUE__wstring_value_default3, 7, 7},
---
>     {test_msgs__msg__WStrings__DEFAULT_VALUE__wstring_value_default3, 21, 21},
140,141c140,141
<   "wstring wstring_value_default2 \"Hell\\xc3\\xb6 w\\xc3\\xb6rld!\"\n"
<   "wstring wstring_value_default3 \"\\xe3\\x83\\x8f\\xe3\\x83\\xad\\xe3\\x83\\xbc\\xe3\\x83\\xaf\\xe3\\x83\\xbc\\xe3\\x83\\xab\\xe3\\x83\\x89\"\n"
---
>   "wstring wstring_value_default2 \"Hell\xc3\xb6 w\xc3\xb6rld!\"\n"
>   "wstring wstring_value_default3 \"\xe3\x83\x8f\xe3\x83\xad\xe3\x83\xbc\xe3\x83\xaf\xe3\x83\xbc\xe3\x83\xab\xe3\x83\x89\"\n"
161c161
<     {toplevel_type_raw_source, 399, 399},
---
>     {toplevel_type_raw_source, 415, 415},

It also fixes " and ' being over escaped (and some other escaped characters). For instance on https://github.com/Tonywelte/test_interface_files/blob/rolling/msg/Strings.msg (see ros2/test_interface_files#25)

46c46
< static char test_msgs__msg__Strings__DEFAULT_VALUE__string_value_default6[] = "Hello\\\\world!";
---
> static char test_msgs__msg__Strings__DEFAULT_VALUE__string_value_default6[] = "Hello\\world!";
48c48
< static char test_msgs__msg__Strings__DEFAULT_VALUE__string_value_default7[] = "Hello\\tworld!";
---
> static char test_msgs__msg__Strings__DEFAULT_VALUE__string_value_default7[] = "Hello  world!";
61c61
< static char test_msgs__msg__Strings__DEFAULT_VALUE__bounded_string_value_default6[] = "Hello\\\\world!";
---
> static char test_msgs__msg__Strings__DEFAULT_VALUE__bounded_string_value_default6[] = "Hello\\world!";
63c63
< static char test_msgs__msg__Strings__DEFAULT_VALUE__bounded_string_value_default7[] = "Hello\\tworld!";
---
> static char test_msgs__msg__Strings__DEFAULT_VALUE__bounded_string_value_default7[] = "Hello  world!";
250,255c250,255
<   "string string_value_default2 \"Hello\\'world!\"\n"
<   "string string_value_default3 \\'Hello\"world!\\'\n"
<   "string string_value_default4 'Hello\\\\'world!'\n"
<   "string string_value_default5 \"Hello\\\\\"world!\"\n"
<   "string string_value_default6 \"Hello\\\\\\\\world!\"\n"
<   "string string_value_default7 \"Hello\\\\tworld!\"\n"
---
>   "string string_value_default2 \"Hello'world!\"\n"
>   "string string_value_default3 'Hello\"world!'\n"
>   "string string_value_default4 'Hello\\'world!'\n"
>   "string string_value_default5 \"Hello\\\"world!\"\n"
>   "string string_value_default6 \"Hello\\\\world!\"\n"
>   "string string_value_default7 \"Hello\\tworld!\"\n"
260,265c260,265
<   "string<=22 bounded_string_value_default2 \"Hello\\'world!\"\n"
<   "string<=22 bounded_string_value_default3 \\'Hello\"world!\\'\n"
<   "string<=22 bounded_string_value_default4 'Hello\\\\'world!'\n"
<   "string<=22 bounded_string_value_default5 \"Hello\\\\\"world!\"\n"
<   "string<=22 bounded_string_value_default6 \"Hello\\\\\\\\world!\"\n"
<   "string<=22 bounded_string_value_default7 \"Hello\\\\tworld!\"\n"
---
>   "string<=22 bounded_string_value_default2 \"Hello'world!\"\n"
>   "string<=22 bounded_string_value_default3 'Hello\"world!'\n"
>   "string<=22 bounded_string_value_default4 'Hello\\'world!'\n"
>   "string<=22 bounded_string_value_default5 \"Hello\\\"world!\"\n"
>   "string<=22 bounded_string_value_default6 \"Hello\\\\world!\"\n"
>   "string<=22 bounded_string_value_default7 \"Hello\\tworld!\"\n"

Additional notes

• While working on this fix I noticed that rosidl_runtime_c__String states that the capacity should include the null byte but the size shouldn't. None of the string defined by rosidl generator do this. I haven't fixed it in this PR since I'm not sure what needs to be changed. It should be as simple as adding +1 in static_seq but for toplevel_type_raw_source it should be -1. I'm not sure what's the difference.
• A think it should be clarified what escaped characters are supported in default strings. \' and \" are mentioned in https://design.ros2.org/articles/legacy_interface_definition.html but other (\\ and \t) worked in rosidl_generator_cpp but rosidl_generator_c didn't escape them properly. \n doesn't work at all.

Fixes #855

[fujitatomoya]

nit. comments stays where the code is implemented?

Suggested change

	# ASCII characters are encoded as-is
	# Non-ASCII characters are encoded as UTF-8
	if c < 0x80:
	result += chr(c)
	else:
	result += '\\x%02x' % c
	if c < 0x80:
	# ASCII characters are encoded as-is
	result += chr(c)
	else:
	# Non-ASCII characters are encoded as UTF-8
	result += '\\x%02x' % c

[fujitatomoya]

this looks good to me, just a minor nitpick.

i would like to have an another review for this PR before merge.

[fujitatomoya]

Pulls: #862
Gist: https://gist.githubusercontent.com/fujitatomoya/88476ec104d8b6970d44034c3f4a6fac/raw/354a5a9e3a0ddbe768c322cf3f1ae478f06cbdf5/ros2.repos
BUILD args: --packages-above-and-dependencies rosidl_generator_c
TEST args: --packages-above rosidl_generator_c
ROS Distro: rolling
Job: ci_launcher
ci_launcher ran: https://ci.ros2.org/job/ci_launcher/15920

• Linux
• Linux-aarch64
• Linux-rhel
• Windows

[fujitatomoya]

Pulls: #862
Gist: https://gist.githubusercontent.com/fujitatomoya/9157bd03771275331596df97b01c4e91/raw/354a5a9e3a0ddbe768c322cf3f1ae478f06cbdf5/ros2.repos
BUILD args: --packages-above-and-dependencies rosidl_generator_c
TEST args: --packages-above rosidl_generator_c
ROS Distro: rolling
Job: ci_launcher
ci_launcher ran: https://ci.ros2.org/job/ci_launcher/16050

• Linux
• Linux-aarch64
• Linux-rhel
• Windows

[TonyWelte]

Looks like the RHEL build uses an older Python version (before 3.12) which doesn't like strings within fstrings. I've pushed the following modification:

   """Statically define a runtime Sequence or String type."""
   if values:
     if isinstance(values, str):
-      return f'{{{varname}, {len(values.encode('utf-8'))}, {len(values.encode('utf-8'))}}}'
+      utf8_values = values.encode('utf-8')
+      return f'{{{varname}, {len(utf8_values)}, {len(utf8_values)}}}'
     else:
       return f'{{{varname}, {len(values)}, {len(values)}}}'
   return '{NULL, 0, 0}'

[fujitatomoya]

Pulls: #862
Gist: https://gist.githubusercontent.com/fujitatomoya/56af7eafdd1a192e3fc92c458054b5f5/raw/354a5a9e3a0ddbe768c322cf3f1ae478f06cbdf5/ros2.repos
BUILD args: --packages-above-and-dependencies rosidl_generator_c
TEST args: --packages-above rosidl_generator_c
ROS Distro: rolling
Job: ci_launcher
ci_launcher ran: https://ci.ros2.org/job/ci_launcher/16062

• Linux
• Linux-aarch64
• Linux-rhel
• Windows