407 lines
12 KiB
C
407 lines
12 KiB
C
/*
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*******************************************************************************
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*
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* Copyright (C) 1999, International Business Machines
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* Corporation and others. All Rights Reserved.
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*
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*******************************************************************************
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*
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*
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* ucnv_io.c:
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* initializes global variables and defines functions pertaining to file access,
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* and name resolution aspect of the library.
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*
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* new implementation:
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*
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* created on: 1999nov22
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* created by: Markus W. Scherer
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*
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* Use the binary cnvalias.dat (created from convrtrs.txt) to work
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* with aliases for converter names.
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********************************************************************************
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*/
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#include "unicode/utypes.h"
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#include "umutex.h"
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#include "cstring.h"
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#include "cmemory.h"
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#include "ucnv_io.h"
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#include "unicode/udata.h"
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/* Format of cnvalias.dat ------------------------------------------------------
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*
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* cnvalias.dat is a binary, memory-mappable form of convrtrs.txt .
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* It contains two sorted tables and a block of zero-terminated strings.
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* Each table is preceded by the number of table entries.
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*
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* The first table maps from aliases to converter indexes.
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* The converter names themselves are listed as aliases in this table.
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* Each entry in this table has an offset to the alias and
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* an index of the converter in the converter table.
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*
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* The second table lists only the converters themselves.
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* Each entry in this table has an offset to the converter name and
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* the number of aliases, including the converter itself.
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* A count of 1 means that there is no alias, only the converter name.
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*
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* In the block of strings after the tables, each converter name is directly
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* followed by its aliases. All offsets to strings are offsets from the
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* beginning of the data.
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*
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* More formal file data structure (data format 2.0):
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*
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* uint16_t aliasCount;
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* uint16_t aliasOffsets[aliasCount];
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* uint16_t converterIndexes[aliasCount];
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*
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* uint16_t converterCount;
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* struct {
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* uint16_t converterOffset;
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* uint16_t aliasCount;
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* } converters[converterCount];
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*
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* char strings[]={
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* "Converter0\0Alias1\0Alias2\0...Converter1\0Converter2\0Alias0\Alias1\0..."
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* };
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*/
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#define DATA_NAME "cnvalias"
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#define DATA_TYPE "dat"
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static UDataMemory *aliasData=NULL;
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static const uint16_t *aliasTable=NULL;
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static UBool
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isAcceptable(void *context,
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const char *type, const char *name,
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const UDataInfo *pInfo) {
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return
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pInfo->size>=20 &&
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pInfo->isBigEndian==U_IS_BIG_ENDIAN &&
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pInfo->charsetFamily==U_CHARSET_FAMILY &&
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pInfo->dataFormat[0]==0x43 && /* dataFormat="CvAl" */
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pInfo->dataFormat[1]==0x76 &&
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pInfo->dataFormat[2]==0x41 &&
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pInfo->dataFormat[3]==0x6c &&
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pInfo->formatVersion[0]==2;
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}
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static UBool
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haveAliasData(UErrorCode *pErrorCode) {
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if(pErrorCode==NULL || U_FAILURE(*pErrorCode)) {
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return FALSE;
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}
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/* load converter alias data from file if necessary */
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if(aliasData==NULL) {
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UDataMemory *data;
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const uint16_t *table=NULL;
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/* open the data outside the mutex block */
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data=udata_openChoice(NULL, DATA_TYPE, DATA_NAME, isAcceptable, NULL, pErrorCode);
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if(U_FAILURE(*pErrorCode)) {
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return FALSE;
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}
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table=(const uint16_t *)udata_getMemory(data);
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/* in the mutex block, set the data for this process */
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umtx_lock(NULL);
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if(aliasData==NULL) {
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aliasData=data;
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data=NULL;
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aliasTable=table;
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table=NULL;
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}
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umtx_unlock(NULL);
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/* if a different thread set it first, then close the extra data */
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if(data!=NULL) {
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udata_close(data); /* NULL if it was set correctly */
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}
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}
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return TRUE;
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}
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static UBool
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isAlias(const char *alias, UErrorCode *pErrorCode) {
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if(alias==NULL) {
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*pErrorCode=U_ILLEGAL_ARGUMENT_ERROR;
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return FALSE;
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} else if(*alias==0) {
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return FALSE;
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} else {
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return TRUE;
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}
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}
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/**
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* Do a fuzzy compare of a two converter/alias names. The comparison
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* is case-insensitive. It also ignores the characters '-', '_', and
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* ' ' (dash, underscore, and space). Thus the strings "UTF-8",
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* "utf_8", and "Utf 8" are exactly equivalent.
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*
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* This is a symmetrical (commutative) operation; order of arguments
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* is insignificant. This is an important property for sorting the
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* list (when the list is preprocessed into binary form) and for
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* performing binary searches on it at run time.
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*
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* @param name1 a converter name or alias, zero-terminated
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* @param name2 a converter name or alias, zero-terminated
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* @return 0 if the names match, or a negative value if the name1
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* lexically precedes name2, or a positive value if the name1
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* lexically follows name2.
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*/
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U_CFUNC int
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charsetNameCmp(const char *name1, const char *name2) {
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int rc;
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unsigned char c1, c2;
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for (;;) {
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/* Ignore delimiters '-', '_', and ' ' */
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while ((c1 = (unsigned char)*name1) == '-'
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|| c1 == '_' || c1 == ' ') ++name1;
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while ((c2 = (unsigned char)*name2) == '-'
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|| c2 == '_' || c2 == ' ') ++name2;
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/* If we reach the ends of both strings then they match */
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if ((c1|c2)==0) {
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return 0;
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}
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/* Case-insensitive comparison */
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rc = (int)(unsigned char)uprv_tolower(c1) -
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(int)(unsigned char)uprv_tolower(c2);
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if (rc!=0) {
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return rc;
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}
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++name1;
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++name2;
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}
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}
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/*
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* search for an alias
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* return NULL or a pointer to the converter table entry
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*/
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static const uint16_t *
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findAlias(const char *alias) {
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char name[100];
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const uint16_t *p=aliasTable;
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uint16_t i, start, limit;
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limit=*p++;
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if(limit==0) {
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/* there are no aliases */
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return NULL;
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}
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/* convert the alias name to lowercase to do case-insensitive comparisons */
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for(i=0; i<sizeof(name)-1 && *alias!=0; ++i) {
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name[i]=uprv_tolower(*alias++);
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}
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name[i]=0;
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/* do a binary search for the alias */
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start=0;
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while(start<limit-1) {
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i=(start+limit)/2;
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if(charsetNameCmp(name, (const char *)aliasTable+p[i])<0) {
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limit=i;
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} else {
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start=i;
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}
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}
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/* did we really find it? */
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if(charsetNameCmp(name, (const char *)aliasTable+p[start])==0) {
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limit=*(p-1); /* aliasCount */
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p+=limit; /* advance to the second column of the alias table */
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i=p[start]; /* converter index */
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return
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p+limit+ /* beginning of converter table */
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1+ /* skip its count */
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2*i; /* go to this converter's entry and return a pointer to it */
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} else {
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return NULL;
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}
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}
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U_CFUNC const char *
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ucnv_io_getConverterName(const char *alias, UErrorCode *pErrorCode) {
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if(haveAliasData(pErrorCode) && isAlias(alias, pErrorCode)) {
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const uint16_t *p=findAlias(alias);
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if(p!=NULL) {
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return (const char *)aliasTable+*p;
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}
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}
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return NULL;
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}
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U_CFUNC uint16_t
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ucnv_io_getAliases(const char *alias, const char **aliases, UErrorCode *pErrorCode) {
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if(haveAliasData(pErrorCode) && isAlias(alias, pErrorCode)) {
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const uint16_t *p=findAlias(alias);
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if(p!=NULL) {
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*aliases=(const char *)aliasTable+*p;
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return *(p+1);
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}
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}
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return 0;
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}
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U_CFUNC const char *
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ucnv_io_getAlias(const char *alias, uint16_t n, UErrorCode *pErrorCode) {
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if(haveAliasData(pErrorCode) && isAlias(alias, pErrorCode)) {
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const uint16_t *p=findAlias(alias);
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if(p!=NULL) {
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uint16_t count=*(p+1);
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if(n<count) {
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const char *aliases=(const char *)aliasTable+*p;
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while(n>0) {
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/* skip a name, first the canonical converter name */
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aliases+=uprv_strlen(aliases)+1;
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--n;
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}
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return aliases;
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}
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}
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}
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return NULL;
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}
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U_CFUNC uint16_t
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ucnv_io_countAvailableConverters(UErrorCode *pErrorCode) {
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if(haveAliasData(pErrorCode)) {
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return aliasTable[1+2*(*aliasTable)];
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}
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return 0;
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}
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U_CFUNC const char *
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ucnv_io_getAvailableConverter(uint16_t n, UErrorCode *pErrorCode) {
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if(haveAliasData(pErrorCode)) {
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const uint16_t *p=aliasTable+1+2*(*aliasTable);
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if(n<*p) {
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return (const char *)aliasTable+p[1+2*n];
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}
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}
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return NULL;
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}
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U_CFUNC void
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ucnv_io_fillAvailableConverters(const char **aliases, UErrorCode *pErrorCode) {
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if(haveAliasData(pErrorCode)) {
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const uint16_t *p=aliasTable+1+2*(*aliasTable);
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uint16_t count=*p++;
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while(count>0) {
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*aliases++=(const char *)aliasTable+*p;
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p+=2;
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--count;
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}
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}
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}
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U_CFUNC uint16_t
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ucnv_io_countAvailableAliases(UErrorCode *pErrorCode) {
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if(haveAliasData(pErrorCode)) {
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return *aliasTable;
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}
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return 0;
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}
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#if 0
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/*
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* We are not currently using these functions, so I am commenting them out
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* to reduce the binary file size and improve the code coverage;
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* I do not currently want to remove this entirely because it may be useful
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* in the future and also serves to some degree as another piece of
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* documentation of the data structure.
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*/
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U_CFUNC const char *
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ucnv_io_getAvailableAlias(uint16_t n, UErrorCode *pErrorCode) {
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if(haveAliasData(pErrorCode) && n<*aliasTable) {
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return (const char *)aliasTable+*(aliasTable+1+n);
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}
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return NULL;
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}
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U_CFUNC void
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ucnv_io_fillAvailableAliases(const char **aliases, UErrorCode *pErrorCode) {
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if(haveAliasData(pErrorCode)) {
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const uint16_t *p=aliasTable;
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uint16_t count=*p++;
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while(count>0) {
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*aliases++=(const char *)aliasTable+*p;
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++p;
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--count;
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}
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}
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}
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#endif
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/* default converter name --------------------------------------------------- */
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/*
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* In order to be really thread-safe, the get function would have to take
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* a buffer parameter and copy the current string inside a mutex block.
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* This implementation only tries to be really thread-safe while
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* setting the name.
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* It assumes that setting a pointer is atomic.
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*/
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static char defaultConverterNameBuffer[100];
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static const char *defaultConverterName = NULL;
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U_CFUNC const char *
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ucnv_io_getDefaultConverterName() {
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/* local variable to be thread-safe */
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const char *name=defaultConverterName;
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if(name==NULL) {
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const char *codepage=uprv_getDefaultCodepage();
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if(codepage!=NULL) {
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UErrorCode errorCode=U_ZERO_ERROR;
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name=ucnv_io_getConverterName(codepage, &errorCode);
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if(U_FAILURE(errorCode) || name==NULL) {
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name=codepage;
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}
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defaultConverterName=name;
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}
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}
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return name;
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}
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U_CFUNC void
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ucnv_io_setDefaultConverterName(const char *converterName) {
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if(converterName==NULL) {
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/* reset to the default codepage */
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defaultConverterName=NULL;
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} else {
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UErrorCode errorCode=U_ZERO_ERROR;
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const char *name=ucnv_io_getConverterName(converterName, &errorCode);
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if(U_SUCCESS(errorCode) && name!=NULL) {
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defaultConverterName=name;
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} else {
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/* do not set the name if the alias lookup failed and it is too long */
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int32_t length=uprv_strlen(converterName);
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if(length<sizeof(defaultConverterNameBuffer)) {
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/* it was not found as an alias, so copy it - accept an empty name */
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UBool didLock;
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if(defaultConverterName==defaultConverterNameBuffer) {
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umtx_lock(NULL);
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didLock=TRUE;
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} else {
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didLock=FALSE;
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}
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uprv_memcpy(defaultConverterNameBuffer, converterName, length);
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defaultConverterNameBuffer[length]=0;
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defaultConverterName=defaultConverterNameBuffer;
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if(didLock) {
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umtx_unlock(NULL);
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}
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}
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}
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}
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}
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