ts_locale.c

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/*-------------------------------------------------------------------------
 *
 * ts_locale.c
 *      locale compatibility layer for tsearch
 *
 * Portions Copyright (c) 1996-2025, PostgreSQL Global Development Group
 *
 *
 * IDENTIFICATION
 *    src/backend/tsearch/ts_locale.c
 *
 *-------------------------------------------------------------------------
 */
#include "postgres.h"
 
#include "common/string.h"
#include "storage/fd.h"
#include "tsearch/ts_locale.h"
 
static void tsearch_readline_callback(void *arg);
 
 
/*
 * The reason these functions use a 3-wchar_t output buffer, not 2 as you
 * might expect, is that on Windows "wchar_t" is 16 bits and what we'll be
 * getting from char2wchar() is UTF16 not UTF32.  A single input character
 * may therefore produce a surrogate pair rather than just one wchar_t;
 * we also need room for a trailing null.  When we do get a surrogate pair,
 * we pass just the first code to iswdigit() etc, so that these functions will
 * always return false for characters outside the Basic Multilingual Plane.
 */
#define WC_BUF_LEN  3
 
int
t_isalpha(const char *ptr)
{
    int         clen = pg_mblen(ptr);
    wchar_t     character[WC_BUF_LEN];
    pg_locale_t mylocale = 0;   /* TODO */
 
    if (clen == 1 || database_ctype_is_c)
        return isalpha(TOUCHAR(ptr));
 
    char2wchar(character, WC_BUF_LEN, ptr, clen, mylocale);
 
    return iswalpha((wint_t) character[0]);
}
 
int
t_isalnum(const char *ptr)
{
    int         clen = pg_mblen(ptr);
    wchar_t     character[WC_BUF_LEN];
    pg_locale_t mylocale = 0;   /* TODO */
 
    if (clen == 1 || database_ctype_is_c)
        return isalnum(TOUCHAR(ptr));
 
    char2wchar(character, WC_BUF_LEN, ptr, clen, mylocale);
 
    return iswalnum((wint_t) character[0]);
}
 
 
/*
 * Set up to read a file using tsearch_readline().  This facility is
 * better than just reading the file directly because it provides error
 * context pointing to the specific line where a problem is detected.
 *
 * Expected usage is:
 *
 *      tsearch_readline_state trst;
 *
 *      if (!tsearch_readline_begin(&trst, filename))
 *          ereport(ERROR,
 *                  (errcode(ERRCODE_CONFIG_FILE_ERROR),
 *                   errmsg("could not open stop-word file \"%s\": %m",
 *                          filename)));
 *      while ((line = tsearch_readline(&trst)) != NULL)
 *          process line;
 *      tsearch_readline_end(&trst);
 *
 * Note that the caller supplies the ereport() for file open failure;
 * this is so that a custom message can be provided.  The filename string
 * passed to tsearch_readline_begin() must remain valid through
 * tsearch_readline_end().
 */
bool
tsearch_readline_begin(tsearch_readline_state *stp,
                       const char *filename)
{
    if ((stp->fp = AllocateFile(filename, "r")) == NULL)
        return false;
    stp->filename = filename;
    stp->lineno = 0;
    initStringInfo(&stp->buf);
    stp->curline = NULL;
    /* Setup error traceback support for ereport() */
    stp->cb.callback = tsearch_readline_callback;
    stp->cb.arg = stp;
    stp->cb.previous = error_context_stack;
    error_context_stack = &stp->cb;
    return true;
}
 
/*
 * Read the next line from a tsearch data file (expected to be in UTF-8), and
 * convert it to database encoding if needed. The returned string is palloc'd.
 * NULL return means EOF.
 */
char *
tsearch_readline(tsearch_readline_state *stp)
{
    char       *recoded;
 
    /* Advance line number to use in error reports */
    stp->lineno++;
 
    /* Clear curline, it's no longer relevant */
    if (stp->curline)
    {
        if (stp->curline != stp->buf.data)
            pfree(stp->curline);
        stp->curline = NULL;
    }
 
    /* Collect next line, if there is one */
    if (!pg_get_line_buf(stp->fp, &stp->buf))
        return NULL;
 
    /* Validate the input as UTF-8, then convert to DB encoding if needed */
    recoded = pg_any_to_server(stp->buf.data, stp->buf.len, PG_UTF8);
 
    /* Save the correctly-encoded string for possible error reports */
    stp->curline = recoded;     /* might be equal to buf.data */
 
    /*
     * We always return a freshly pstrdup'd string.  This is clearly necessary
     * if pg_any_to_server() returned buf.data, and we need a second copy even
     * if encoding conversion did occur.  The caller is entitled to pfree the
     * returned string at any time, which would leave curline pointing to
     * recycled storage, causing problems if an error occurs after that point.
     * (It's preferable to return the result of pstrdup instead of the output
     * of pg_any_to_server, because the conversion result tends to be
     * over-allocated.  Since callers might save the result string directly
     * into a long-lived dictionary structure, we don't want it to be a larger
     * palloc chunk than necessary.  We'll reclaim the conversion result on
     * the next call.)
     */
    return pstrdup(recoded);
}
 
/*
 * Close down after reading a file with tsearch_readline()
 */
void
tsearch_readline_end(tsearch_readline_state *stp)
{
    /* Suppress use of curline in any error reported below */
    if (stp->curline)
    {
        if (stp->curline != stp->buf.data)
            pfree(stp->curline);
        stp->curline = NULL;
    }
 
    /* Release other resources */
    pfree(stp->buf.data);
    FreeFile(stp->fp);
 
    /* Pop the error context stack */
    error_context_stack = stp->cb.previous;
}
 
/*
 * Error context callback for errors occurring while reading a tsearch
 * configuration file.
 */
static void
tsearch_readline_callback(void *arg)
{
    tsearch_readline_state *stp = (tsearch_readline_state *) arg;
 
    /*
     * We can't include the text of the config line for errors that occur
     * during tsearch_readline() itself.  The major cause of such errors is
     * encoding violations, and we daren't try to print error messages
     * containing badly-encoded data.
     */
    if (stp->curline)
        errcontext("line %d of configuration file \"%s\": \"%s\"",
                   stp->lineno,
                   stp->filename,
                   stp->curline);
    else
        errcontext("line %d of configuration file \"%s\"",
                   stp->lineno,
                   stp->filename);
}