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diff --git a/docs/migration.rst b/docs/migration.rst new file mode 100644 index 0000000..fdc1d8c --- /dev/null +++ b/docs/migration.rst @@ -0,0 +1,320 @@ +===================================== +Nanopb: Migration from older versions +===================================== + +.. include :: menu.rst + +This document details all the breaking changes that have been made to nanopb +since its initial release. For each change, the rationale and required +modifications of user applications are explained. Also any error indications +are included, in order to make it easier to find this document. + +.. contents :: + +Nanopb-0.3.9.1, 0.4.0 (2018-xx-xx) +================================== + +Fix handling of string and bytes default values +----------------------------------------------- + +**Rationale:** Previously nanopb didn't properly decode special character +escapes like \\200 emitted by protoc. This caused these escapes to end up +verbatim in the default values in .pb.c file. + +**Changes:** Escapes are now decoded, and e.g. "\\200" or "\\x80" results in +{0x80} for bytes field and "\\x80" for string field. + +**Required actions:** If code has previously relied on '\\' in default value +being passed through verbatim, it must now be changed to '\\\\'. + +Nanopb-0.3.8 (2017-03-05) +========================= + +Fully drain substreams before closing +------------------------------------- + +**Rationale:** If the substream functions were called directly and the caller +did not completely empty the substring before closing it, the parent stream +would be put into an incorrect state. + +**Changes:** *pb_close_string_substream* can now error and returns a boolean. + +**Required actions:** Add error checking onto any call to +*pb_close_string_substream*. + +Change oneof format in .pb.c files +---------------------------------- + +**Rationale:** Previously two oneofs in a single message would be erroneously +handled as part of the same union. + +**Changes:** Oneofs fields now use special *PB_DATAOFFSET_UNION* offset type +in generated .pb.c files to distinguish whether they are the first or following +field inside an union. + +**Required actions:** Regenerate *.pb.c/.pb.h* files with new nanopb version if +oneofs are used. + +Nanopb-0.3.5 (2016-02-13) +========================= + +Add support for platforms without uint8_t +----------------------------------------- +**Rationale:** Some platforms cannot access 8-bit sized values directly, and +do not define *uint8_t*. Nanopb previously didn't support these platforms. + +**Changes:** References to *uint8_t* were replaced with several alternatives, +one of them being a new *pb_byte_t* typedef. This in turn uses *uint_least8_t* +which means the smallest available type. + +**Required actions:** If your platform does not have a standards-compliant +*stdint.h*, it may lack the definition for *[u]int_least8_t*. This must be +added manually, example can be found in *extra/pb_syshdr.h*. + +**Error indications:** Compiler error: "unknown type name 'uint_least8_t'". + +Nanopb-0.3.2 (2015-01-24) +========================= + +Add support for OneOfs +---------------------- +**Rationale:** Previously nanopb did not support the *oneof* construct in +*.proto* files. Those fields were generated as regular *optional* fields. + +**Changes:** OneOfs are now generated as C unions. Callback fields are not +supported inside oneof and generator gives an error. + +**Required actions:** The generator option *no_unions* can be used to restore old +behaviour and to allow callbacks to be used. To use unions, one change is +needed: use *which_xxxx* field to detect which field is present, instead +of *has_xxxx*. Compare the value against *MyStruct_myfield_tag*. + +**Error indications:** Generator error: "Callback fields inside of oneof are +not supported". Compiler error: "Message" has no member named "has_xxxx". + +Nanopb-0.3.0 (2014-08-26) +========================= + +Separate field iterator logic to pb_common.c +-------------------------------------------- +**Rationale:** Originally, the field iteration logic was simple enough to be +duplicated in *pb_decode.c* and *pb_encode.c*. New field types have made the +logic more complex, which required the creation of a new file to contain the +common functionality. + +**Changes:** There is a new file, *pb_common.c*, which must be included in +builds. + +**Required actions:** Add *pb_common.c* to build rules. This file is always +required. Either *pb_decode.c* or *pb_encode.c* can still be left out if some +functionality is not needed. + +**Error indications:** Linker error: undefined reference to +*pb_field_iter_begin*, *pb_field_iter_next* or similar. + +Change data type of field counts to pb_size_t +--------------------------------------------- +**Rationale:** Often nanopb is used with small arrays, such as 255 items or +less. Using a full *size_t* field to store the array count wastes memory if +there are many arrays. There already exists parameters *PB_FIELD_16BIT* and +*PB_FIELD_32BIT* which tell nanopb what is the maximum size of arrays in use. + +**Changes:** Generator will now use *pb_size_t* for the array *_count* fields. +The size of the type will be controlled by the *PB_FIELD_16BIT* and +*PB_FIELD_32BIT* compilation time options. + +**Required actions:** Regenerate all *.pb.h* files. In some cases casts to the +*pb_size_t* type may need to be added in the user code when accessing the +*_count* fields. + +**Error indications:** Incorrect data at runtime, crashes. But note that other +changes in the same version already require regenerating the files and have +better indications of errors, so this is only an issue for development +versions. + +Renamed some macros and identifiers +----------------------------------- +**Rationale:** Some names in nanopb core were badly chosen and conflicted with +ISO C99 reserved names or lacked a prefix. While they haven't caused trouble +so far, it is reasonable to switch to non-conflicting names as these are rarely +used from user code. + +**Changes:** The following identifier names have changed: + + * Macros: + + * STATIC_ASSERT(x) -> PB_STATIC_ASSERT(x) + * UNUSED(x) -> PB_UNUSED(x) + + * Include guards: + + * _PB_filename_ -> PB_filename_INCLUDED + + * Structure forward declaration tags: + + * _pb_field_t -> pb_field_s + * _pb_bytes_array_t -> pb_bytes_array_s + * _pb_callback_t -> pb_callback_s + * _pb_extension_type_t -> pb_extension_type_s + * _pb_extension_t -> pb_extension_s + * _pb_istream_t -> pb_istream_s + * _pb_ostream_t -> pb_ostream_s + +**Required actions:** Regenerate all *.pb.c* files. If you use any of the above +identifiers in your application code, perform search-replace to the new name. + +**Error indications:** Compiler errors on lines with the macro/type names. + +Nanopb-0.2.9 (2014-08-09) +========================= + +Change semantics of generator -e option +--------------------------------------- +**Rationale:** Some compilers do not accept filenames with two dots (like +in default extension .pb.c). The *-e* option to the generator allowed changing +the extension, but not skipping the extra dot. + +**Changes:** The *-e* option in generator will no longer add the prepending +dot. The default value has been adjusted accordingly to *.pb.c* to keep the +default behaviour the same as before. + +**Required actions:** Only if using the generator -e option. Add dot before +the parameter value on the command line. + +**Error indications:** File not found when trying to compile generated files. + +Nanopb-0.2.7 (2014-04-07) +========================= + +Changed pointer-type bytes field datatype +----------------------------------------- +**Rationale:** In the initial pointer encoding support since nanopb-0.2.5, +the bytes type used a separate *pb_bytes_ptr_t* type to represent *bytes* +fields. This made it easy to encode data from a separate, user-allocated +buffer. However, it made the internal logic more complex and was inconsistent +with the other types. + +**Changes:** Dynamically allocated bytes fields now have the *pb_bytes_array_t* +type, just like statically allocated ones. + +**Required actions:** Only if using pointer-type fields with the bytes datatype. +Change any access to *msg->field.size* to *msg->field->size*. Change any +allocation to reserve space of amount *PB_BYTES_ARRAY_T_ALLOCSIZE(n)*. If the +data pointer was begin assigned from external source, implement the field using +a callback function instead. + +**Error indications:** Compiler error: unknown type name *pb_bytes_ptr_t*. + +Nanopb-0.2.4 (2013-11-07) +========================= + +Remove the NANOPB_INTERNALS compilation option +---------------------------------------------- +**Rationale:** Having the option in the headers required the functions to +be non-static, even if the option is not used. This caused errors on some +static analysis tools. + +**Changes:** The *#ifdef* and associated functions were removed from the +header. + +**Required actions:** Only if the *NANOPB_INTERNALS* option was previously +used. Actions are as listed under nanopb-0.1.3 and nanopb-0.1.6. + +**Error indications:** Compiler warning: implicit declaration of function +*pb_dec_string*, *pb_enc_string*, or similar. + +Nanopb-0.2.1 (2013-04-14) +========================= + +Callback function signature +--------------------------- +**Rationale:** Previously the auxilary data to field callbacks was passed +as *void\**. This allowed passing of any data, but made it unnecessarily +complex to return a pointer from callback. + +**Changes:** The callback function parameter was changed to *void\*\**. + +**Required actions:** You can continue using the old callback style by +defining *PB_OLD_CALLBACK_STYLE*. Recommended action is to: + + * Change the callback signatures to contain *void\*\** for decoders and + *void \* const \** for encoders. + * Change the callback function body to use *\*arg* instead of *arg*. + +**Error indications:** Compiler warning: assignment from incompatible +pointer type, when initializing *funcs.encode* or *funcs.decode*. + +Nanopb-0.2.0 (2013-03-02) +========================= + +Reformatted generated .pb.c file using macros +--------------------------------------------- +**Rationale:** Previously the generator made a list of C *pb_field_t* +initializers in the .pb.c file. This led to a need to regenerate all .pb.c +files after even small changes to the *pb_field_t* definition. + +**Changes:** Macros were added to pb.h which allow for cleaner definition +of the .pb.c contents. By changing the macro definitions, changes to the +field structure are possible without breaking compatibility with old .pb.c +files. + +**Required actions:** Regenerate all .pb.c files from the .proto sources. + +**Error indications:** Compiler warning: implicit declaration of function +*pb_delta_end*. + +Changed pb_type_t definitions +----------------------------- +**Rationale:** The *pb_type_t* was previously an enumeration type. This +caused warnings on some compilers when using bitwise operations to set flags +inside the values. + +**Changes:** The *pb_type_t* was changed to *typedef uint8_t*. The values +were changed to *#define*. Some value names were changed for consistency. + +**Required actions:** Only if you directly access the `pb_field_t` contents +in your own code, something which is not usually done. Needed changes: + + * Change *PB_HTYPE_ARRAY* to *PB_HTYPE_REPEATED*. + * Change *PB_HTYPE_CALLBACK* to *PB_ATYPE()* and *PB_ATYPE_CALLBACK*. + +**Error indications:** Compiler error: *PB_HTYPE_ARRAY* or *PB_HTYPE_CALLBACK* +undeclared. + +Nanopb-0.1.6 (2012-09-02) +========================= + +Refactored field decoder interface +---------------------------------- +**Rationale:** Similarly to field encoders in nanopb-0.1.3. + +**Changes:** New functions with names *pb_decode_\** were added. + +**Required actions:** By defining NANOPB_INTERNALS, you can still keep using +the old functions. Recommended action is to replace any calls with the newer +*pb_decode_\** equivalents. + +**Error indications:** Compiler warning: implicit declaration of function +*pb_dec_string*, *pb_dec_varint*, *pb_dec_submessage* or similar. + +Nanopb-0.1.3 (2012-06-12) +========================= + +Refactored field encoder interface +---------------------------------- +**Rationale:** The old *pb_enc_\** functions were designed mostly for the +internal use by the core. Because they are internally accessed through +function pointers, their signatures had to be common. This led to a confusing +interface for external users. + +**Changes:** New functions with names *pb_encode_\** were added. These have +easier to use interfaces. The old functions are now only thin wrappers for +the new interface. + +**Required actions:** By defining NANOPB_INTERNALS, you can still keep using +the old functions. Recommended action is to replace any calls with the newer +*pb_encode_\** equivalents. + +**Error indications:** Compiler warning: implicit declaration of function +*pb_enc_string*, *pb_enc_varint, *pb_enc_submessage* or similar. + |