Improve behavior of tsearch_readline(), and remove t_readline().

Commit fbeb9da22, which added the tsearch_readline APIs, left
t_readline() in place as a compatibility measure.  But that function
has been unused and deprecated for twelve years now, so that seems
like enough time to remove it.  Doing so, and merging t_readline's
code into tsearch_readline, aids in making several useful
improvements:

* The hard-wired 4K limit on line length in tsearch data files is
removed, by using a StringInfo buffer instead of a fixed-size buffer.

* We can buy back the per-line palloc/pfree added by 3ea7e9550
in the common case where encoding conversion is not required.

* We no longer need a separate pg_verify_mbstr call, as that
functionality was folded into encoding conversion some time ago.

(We could have done some of this stuff while keeping t_readline as a
separate API, but there seems little point, since there's no reason
for anyone to still be using t_readline directly.)

Discussion: https://postgr.es/m/48A4FA71-524E-41B9-953A-FD04EF36E2E7@yesql.se

diff --git a/src/backend/tsearch/dict_thesaurus.c b/src/backend/tsearch/dict_thesaurus.c
index cb0835982d85c7a8e4600abcd5fdf6772654d839..64c979086d1ebe5278e8d29edb23afb0fa68b820 100644 (file)
--- a/src/backend/tsearch/dict_thesaurus.c
+++ b/src/backend/tsearch/dict_thesaurus.c
@@ -286,11 +286,6 @@ thesaurusRead(const char *filename, DictThesaurus *d)
                                        (errcode(ERRCODE_CONFIG_FILE_ERROR),
                                         errmsg("unexpected end of line")));
 
-               /*
-                * Note: currently, tsearch_readline can't return lines exceeding 4KB,
-                * so overflow of the word counts is impossible.  But that may not
-                * always be true, so let's check.
-                */
                if (nwrd != (uint16) nwrd || posinsubst != (uint16) posinsubst)
                        ereport(ERROR,
                                        (errcode(ERRCODE_CONFIG_FILE_ERROR),

diff --git a/src/backend/tsearch/ts_locale.c b/src/backend/tsearch/ts_locale.c
index 9b199d0ac18b3c8fdcdc01b377abbeaab91fb9ac..d362e86d61a260af098f93fd274044c2f8fce3ef 100644 (file)
--- a/src/backend/tsearch/ts_locale.c
+++ b/src/backend/tsearch/ts_locale.c
@@ -14,6 +14,7 @@
 #include "postgres.h"
 
 #include "catalog/pg_collation.h"
+#include "common/string.h"
 #include "storage/fd.h"
 #include "tsearch/ts_locale.h"
 #include "tsearch/ts_public.h"
@@ -128,6 +129,7 @@ tsearch_readline_begin(tsearch_readline_state *stp,
                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;
@@ -145,7 +147,7 @@ tsearch_readline_begin(tsearch_readline_state *stp,
 char *
 tsearch_readline(tsearch_readline_state *stp)
 {
-       char       *result;
+       char       *recoded;
 
        /* Advance line number to use in error reports */
        stp->lineno++;
@@ -153,23 +155,35 @@ tsearch_readline(tsearch_readline_state *stp)
        /* Clear curline, it's no longer relevant */
        if (stp->curline)
        {
-               pfree(stp->curline);
+               if (stp->curline != stp->buf.data)
+                       pfree(stp->curline);
                stp->curline = NULL;
        }
 
        /* Collect next line, if there is one */
-       result = t_readline(stp->fp);
-       if (!result)
+       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 */
+
        /*
-        * Save a copy of the line for possible use in error reports.  (We cannot
-        * just save "result", since it's likely to get pfree'd at some point by
-        * the caller; an error after that would try to access freed 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.)
         */
-       stp->curline = pstrdup(result);
-
-       return result;
+       return pstrdup(recoded);
 }
 
 /*
@@ -181,11 +195,13 @@ tsearch_readline_end(tsearch_readline_state *stp)
        /* Suppress use of curline in any error reported below */
        if (stp->curline)
        {
-               pfree(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 */
@@ -203,8 +219,7 @@ tsearch_readline_callback(void *arg)
 
        /*
         * We can't include the text of the config line for errors that occur
-        * during t_readline() itself.  This is only partly a consequence of our
-        * arms-length use of that routine: the major cause of such errors is
+        * 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.
         */
@@ -220,43 +235,6 @@ tsearch_readline_callback(void *arg)
 }
 
 
-/*
- * 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.
- *
- * Note: direct use of this function is now deprecated.  Go through
- * tsearch_readline() to provide better error reporting.
- */
-char *
-t_readline(FILE *fp)
-{
-       int                     len;
-       char       *recoded;
-       char            buf[4096];              /* lines must not be longer than this */
-
-       if (fgets(buf, sizeof(buf), fp) == NULL)
-               return NULL;
-
-       len = strlen(buf);
-
-       /* Make sure the input is valid UTF-8 */
-       (void) pg_verify_mbstr(PG_UTF8, buf, len, false);
-
-       /* And convert */
-       recoded = pg_any_to_server(buf, len, PG_UTF8);
-       if (recoded == buf)
-       {
-               /*
-                * conversion didn't pstrdup, so we must. We can use the length of the
-                * original string, because no conversion was done.
-                */
-               recoded = pnstrdup(recoded, len);
-       }
-
-       return recoded;
-}
-
 /*
  * lowerstr --- fold null-terminated string to lower case
  *

diff --git a/src/include/tsearch/ts_locale.h b/src/include/tsearch/ts_locale.h
index cc4bd9ab20d49873cc1e35ada22a5319e998f409..f1669fda2111b8cc29a5c0bba7a75ad28b9f143a 100644 (file)
--- a/src/include/tsearch/ts_locale.h
+++ b/src/include/tsearch/ts_locale.h
@@ -15,6 +15,7 @@
 #include <ctype.h>
 #include <limits.h>
 
+#include "lib/stringinfo.h"
 #include "mb/pg_wchar.h"
 #include "utils/pg_locale.h"
 
@@ -33,7 +34,9 @@ typedef struct
        FILE       *fp;
        const char *filename;
        int                     lineno;
-       char       *curline;
+       StringInfoData buf;                     /* current input line, in UTF-8 */
+       char       *curline;            /* current input line, in DB's encoding */
+       /* curline may be NULL, or equal to buf.data, or a palloc'd string */
        ErrorContextCallback cb;
 } tsearch_readline_state;
 
@@ -57,6 +60,4 @@ extern bool tsearch_readline_begin(tsearch_readline_state *stp,
 extern char *tsearch_readline(tsearch_readline_state *stp);
 extern void tsearch_readline_end(tsearch_readline_state *stp);
 
-extern char *t_readline(FILE *fp);
-
 #endif                                                 /* __TSLOCALE_H__ */