| Implementation notes: | |
| This is a true OS/400 implementation, not a PASE implementation (for PASE, | |
| use an AIX implementation). | |
| The biggest problem with OS/400 is EBCDIC. The current libxml2 implementation | |
| uses UTF-8 internally. To ease encoding conversion between the calling | |
| applications and libxml2, supplementary "convert and latch" functions are | |
| provided (See below). To bind the EBCDIC OS/400 system calls and libxml2, | |
| an ASCII run-time environment (QADRT) has been used and wrapper functions have | |
| been designed. | |
| Other problems are: | |
| - Source code line length: to be stored in DB2 members, source files may not | |
| have lines longer than 100 characters. Some header and documentation files | |
| have been modified accordingly. | |
| - va_list dereferencing: the OS/400 implementation of va_list type is an array | |
| but the compiler forbids explicit array dereferencing. Source files have | |
| been updated accordingly. | |
| - Depending on the compilation/execution environment, it is possible that | |
| stdin/stdout/stderr are not associated with a file descriptor; as a side | |
| effect, open() may return a file descriptor value 0, 1 or 2 that is NOT | |
| a C standard file. Thus using such a number may be inaccurate. | |
| - iconv_open() arguments: OS/400 uses non-standard encoding names and does not | |
| support standard names. For this reason, a name wrapper has been designed. | |
| - dlopen() (support for xmodule): the function and its corollaries are not | |
| provided by the OS/400 library. However a local implementation is provided. | |
| Compiling on OS/400: | |
| _ As a prerequisite, QADRT development environment must be installed. | |
| _ Install the libxml2 source directory in IFS. | |
| _ Enter shell (QSH) | |
| _ Change current directory to the libxml2 installation directory | |
| _ Change current directory to ./os400 | |
| _ Edit file iniscript.sh. You may want to change tunable configuration | |
| parameters, like debug info generation, optimisation level, listing option, | |
| target library, zlib availability, etc. | |
| _ Copy any file in the current directory to makelog (i.e.: | |
| cp initscript.sh makelog): this is intended to create the makelog file with | |
| an ASCII CCSID! | |
| _ Enter the command "sh make.sh >makelog 2>&1' | |
| _ Examine the makelog file to check for compilation errors. | |
| Leaving file initscript.sh unchanged, this will produce the following | |
| OS/400 objects: | |
| _ Library LIBXML2. All other objects will be stored in this library. | |
| _ Modules for all libxml2 units, with full debug info and no code optimization. | |
| _ Binding directory LIBXML2_A, to be used at calling program link time for | |
| statically binding the modules (specify BNDSRVPGM(QADRTTS QGLDCLNT QGLDBRDR) | |
| when creating a program using LIBXML2_A). | |
| _ Service program LIBXML2. To be used at calling program run-time | |
| when this program has dynamically bound libxml2 at link time. | |
| _ Binding directory LIBXML2. To be used to dynamically bind libxml2 when | |
| linking a calling program. | |
| _ Source file LIBXML. It contains all the header members needed to compile a | |
| C/C++ module using libxml2. | |
| _ Standard and additional C/C++ libxml2 header members (possibly renamed) in | |
| file LIBXML. | |
| _ IFS directory /libxml2 with subdirectory include/libxml containing all | |
| C/C++ header files for IFS-based compilation. | |
| _ Source file LIBXMLRPG. It contains all the include members needed to compile a | |
| ILE/RPG module/program using libxml2 (ILE/RPG binding). | |
| _ ILE/RPG binding include members (possibly renamed) in file LIBXMLRPG. | |
| _ IFS subdirectory /libxml2/include/libxmlrpg containing all ILE/RPG include | |
| files for IFS-based compilation. | |
| Renamed header files in DB2 members: | |
| DB2 member names are limited to 10 characters, thus the following C/C++ | |
| header members are renamed as: | |
| parserInternals.h --> PARSERINTE | |
| schemasInternals.h --> SCHEMASINT | |
| xmlautomata.h --> XMLAUTOMAT | |
| xmlschemastype.h --> SCHMTYPES | |
| xpathInternals.h --> XPATHINTER | |
| IFS header files are NOT renamed. | |
| ILE/RPG headers are processed likewise. | |
| Special programming consideration: | |
| QADRT being used, the following points must be considered: | |
| _ If static binding is used, service program QADRTTS must be linked too. | |
| _ The EBCDIC CCSID used by QADRT is 37 by default, NOT THE JOB'S CCSID. If | |
| another EBCDIC CCSID is required, it must be set via a locale through a call | |
| to setlocale_a (QADRT's setlocale() ASCII wrapper) with category LC_ALL or | |
| LC_CTYPE, or by setting environment variable QADRT_ENV_LOCALE to the locale | |
| object path before executing the program. | |
| _ Always use *IFSIO or *IFS64IO to compile calling programs. | |
| Supplementary (non libxml2 standard) support procedures for OS/400. | |
| As cited above, there are some procedures to ease encoding conversion of | |
| libxml2 function arguments and results: the mechanism is based on | |
| dictionaries. The functions convert a string, latch the result in a dictionary | |
| to ensure its persistence and return its address. It is the caller's | |
| responsibility to clean the dictionary when it becomes too big or disappears. | |
| The procedures are: | |
| #include <libxml/transcode.h> | |
| const char * xmlTranscodeResult(const xmlChar * s, | |
| const char * encoding, | |
| xmlDictPtr * dict, | |
| void (*freeproc)(const void *)); | |
| const xmlChar * xmlTranscodeString(const char * s, | |
| const char * encoding, | |
| xmlDictPtr * dict); | |
| const xmlChar * xmlTranscodeWString(const char * s, | |
| const char * encoding, | |
| xmlDictPtr * dict); | |
| const xmlChar * xmlTranscodeWString(const char * s, | |
| const char * encoding, | |
| xmlDictPtr * dict); | |
| where: | |
| s is the string to translate. | |
| encoding is the alternate character encoding. If null, the current job's | |
| encoding (CCSID) is used. | |
| dict is the address of the latching directory. If NULL, the procedure | |
| functions as a simple non-latching encoding converter and | |
| its result value should be freed by the caller. | |
| freeproc is a procedure to release the original string, or NULL. | |
| xmlTranscodeResult() converts from UTF-8 to the given alternate encoding. | |
| xmlTranscodeString() converts from the given 8-bit encoding to UTF-8 (note that | |
| UTF-8 itself is considered as a 8-bit encoding). | |
| xmlTranscodeWString() converts from the given 16-bit encoding to UTF-8. | |
| xmlTranscodeHString() converts from the given 32-bit encoding to UTF-8. | |
| To shorten statements using these functions, shorthands are defined: | |
| xmlTR for xmlTranscodeResult | |
| xmlTS for xmlTranscodeString | |
| xmlTW for xmlTranscodeWString | |
| xmlTH for xmlTranscodeHstring | |
| These shorthands may be disabled by defining XML_NO_SHORT_NAMES before | |
| libxml/transcode.h inclusion. | |
| A directory pointer must be preset to NULL before the first call using it to | |
| one of the above procedure. | |
| To release a latching directory, use function | |
| void xmlZapDict(xmlDictPtr * dict); | |
| Example: | |
| #include <libxml/transcode.h> | |
| #include <libxml/tree.h> | |
| xmlDocPtr mySimpleXMLDoc(char * element, char * text) | |
| { | |
| xmlDocPtr doc; | |
| xmlNodePtr node; | |
| xmlDictPtr dict = NULL; | |
| /* element and text are encoded in the current job's encoding. */ | |
| doc = xmlNewDoc(); | |
| xmlNewTextChild((xmlNodePtr) doc, NULL, xmlTS(element, NULL, | |
| &dict), xmlTS(text, NULL, &dict)); | |
| xmlZapDict(&dict); | |
| return doc; | |
| } | |
| Additionally, a formatter into latched/dynamic storage is provided: | |
| const char * xmlVasprintf(xmlDictPtr * dict, | |
| const char * encoding, | |
| const xmlChar * fmt, | |
| va_list args); | |
| xmllint and xmlcatalog programs: | |
| These programs are fully implemented at the qshell level, with standard | |
| command line options. Links to these are installed in sub-directory bin of | |
| the IFS installation directory. | |
| CL command interfaces to these programs are also provided with limited | |
| support. In particular, interactive mode is not supported and argument count | |
| and lengths are limited by the CL command syntax. | |
| ILE/RPG binding: | |
| All standard types and procedures are provided. Since ILE/RPG does not | |
| support macros, they have not been ported. However some of them are emulated | |
| as functions: these are the more useful ones (xmlXPathNodeSetGetLength, | |
| xmlXPathNodeSetItem, xmlXPathNodeSetIsEmpty, htmlDefaultSubelement, | |
| htmlElementAllowedHereDesc, htmlRequiredAttrs) and the global/threaded | |
| variables access macros. These variables can be read with function | |
| get_xxx(void), where xxxx is the name of the variable; they may be set by | |
| calling function set_xxxx(value), where value is of the same type as the | |
| variable. | |
| The C va_list is not implemented as such in ILE/RPG. Functions implementing | |
| va_list and associated methods are provided: | |
| /include "libxmlrpg/xmlstdarg" | |
| d xmlVaStart pr | |
| d list like(xmlVaList) | |
| d lastargaddr * value | |
| d lastargsize 10u 0 value | |
| d xmlVaArg pr | |
| d list like(xmlVaList) | |
| d dest * value | |
| d argsize 10i 0 value | |
| d xmlVaEnd pr | |
| d list like(xmlVaList) | |