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MISRA.md

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MISRA Compliance

The POSIX platform implementations of transport interfaces, clock utility and retry utils conform to the MISRA C:2012 guidelines, with some noted exceptions. Compliance is checked with Coverity static analysis. Deviations from the MISRA standard are listed below:

Ignored by Coverity Configuration

Deviation Category Justification
Directive 4.5 Advisory Allow names that MISRA considers ambiguous (such as LogInfo and LogError)
Directive 4.8 Advisory Allow inclusion of unused types. Header files for a specific port, which are needed by all files, may define types that are not used by a specific file.
Directive 4.9 Advisory Allow inclusion of function like macros. The assert macro is used throughout the library for parameter validation, and logging is done using function like macros.
Rule 2.3 Advisory Allow unused types. Library headers may define types intended for the application's use, but not used within the library files.
Rule 2.4 Advisory Allow unused tags. Some compilers warn if types are not tagged.
Rule 2.5 Advisory Allow unused macros. Library headers may define macros intended for the application's use, but are not used by a specific file.
Rule 3.1 Required Allow nested comments. C++ style // comments are used in example code within Doxygen documentation blocks.
Rule 11.5 Advisory Allow casts from void *. Fields may be passed as void *, requiring a cast to the correct data type before use.
Rule 21.1 Required Allow use of all macro names. For compatibility, libraries may define macros introduced in C99 for use with C90 compilers.
Rule 21.2 Required Allow use of all macro and identifier names. For compatibility, libraries may define macros introduced in C99 for use with C90 compilers.

Flagged by Coverity

Deviation Category Justification
Rule 5.6 Required The header file transport_interface.h is present in each library repository that depends on the transport interface. This is to be able to independently compile the library repository build targets. When all the targets are analyzed together, Coverity flags the type duplication caused by multiple copies of header files in this repository as violations. However, this violation will not be flagged if each library repository build target is analyzed individually.
Rule 5.7 Required The network context struct is defined by each transport implementation; however, only one transport implementation is needed by an application at a time. If the transport implementations are analyzed one at a time by Coverity, this violation will not be flagged.
Rule 8.7 Advisory API functions are not used by the library outside of the files they are defined; however, they must be externally visible in order to be used by an application.
Rule 8.13 Advisory The object pointed to by pNetworkContext is not modified by POSIX sockets or OpenSSL, but other implementations of TransportRecv_t and TransportSend_t may do so.

Suppressed with Coverity Comments

Deviation Category Justification
Directive 4.6 Advisory Basic numerical types are used in platform implementations, since the POSIX platform functions and OpenSSL functions used in the platform implementations take arguments of these types.
Rule 10.1 Required A POSIX-specific macro utility FD_SET is flagged for this violation. This macro utility, whose implementation is supplied by the system, is used in the transport implementation.
Rule 10.8 Required A POSIX-specific macro utility FD_SET is flagged for this violation. This macro utility, whose implementation is supplied by the system, is used in the transport implementation.
Rule 11.3 Required The transport implementation casts an object pointer to a pointer of a different object type. This cast is supported in POSIX, and is used to obtain IP addresses from address records.
Rule 11.8 Required An OpenSSL API SSL_set_tlsext_host_name, which is used in the TLS transport implementation, internally casts a string literal to a void * pointer.
Rule 13.4 Required A POSIX-specific macro utility FD_SET is flagged for this violation. This macro utility, whose implementation is supplied by the system, is used in the transport implementation.
Rule 14.4 Required A POSIX-specific macro utility FD_ZERO is flagged for this violation. This macro utility, whose implementation is supplied by the system, is used in the transport implementation.
Rule 21.6 Required The Standard Library input/output functions for opening and closing files are used by the OpenSSL transport implementation, since the OpenSSL API PEM_read_X509 to read PEM files takes FILE * as an argument. The standard C library file handling functions are also used in POSIX platform implementation of OTA.