filter.c

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/*-------------------------------------------------------------------------
 *
 * filter.c
 *      Implementation of simple filter file parser
 *
 * Portions Copyright (c) 1996-2024, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 * IDENTIFICATION
 *    src/bin/pg_dump/filter.c
 *
 *-------------------------------------------------------------------------
 */
#include "postgres_fe.h"
 
#include "common/logging.h"
#include "common/string.h"
#include "filter.h"
#include "lib/stringinfo.h"
#include "pqexpbuffer.h"
 
#define     is_keyword_str(cstr, str, bytes) \
    ((strlen(cstr) == (bytes)) && (pg_strncasecmp((cstr), (str), (bytes)) == 0))
 
/*
 * Following routines are called from pg_dump, pg_dumpall and pg_restore.
 * Since the implementation of exit_nicely is application specific, each
 * application need to pass a function pointer to the exit_nicely function to
 * use for exiting on errors.
 */
 
/*
 * Opens filter's file and initialize fstate structure.
 */
void
filter_init(FilterStateData *fstate, const char *filename, exit_function f_exit)
{
    fstate->filename = filename;
    fstate->lineno = 0;
    fstate->exit_nicely = f_exit;
    initStringInfo(&fstate->linebuff);
 
    if (strcmp(filename, "-") != 0)
    {
        fstate->fp = fopen(filename, "r");
        if (!fstate->fp)
        {
            pg_log_error("could not open filter file \"%s\": %m", filename);
            fstate->exit_nicely(1);
        }
    }
    else
        fstate->fp = stdin;
}
 
/*
 * Release allocated resources for the given filter.
 */
void
filter_free(FilterStateData *fstate)
{
    if (!fstate)
        return;
 
    free(fstate->linebuff.data);
    fstate->linebuff.data = NULL;
 
    if (fstate->fp && fstate->fp != stdin)
    {
        if (fclose(fstate->fp) != 0)
            pg_log_error("could not close filter file \"%s\": %m", fstate->filename);
 
        fstate->fp = NULL;
    }
}
 
/*
 * Translate FilterObjectType enum to string. The main purpose is for error
 * message formatting.
 */
const char *
filter_object_type_name(FilterObjectType fot)
{
    switch (fot)
    {
        case FILTER_OBJECT_TYPE_NONE:
            return "comment or empty line";
        case FILTER_OBJECT_TYPE_TABLE_DATA:
            return "table data";
        case FILTER_OBJECT_TYPE_TABLE_DATA_AND_CHILDREN:
            return "table data and children";
        case FILTER_OBJECT_TYPE_DATABASE:
            return "database";
        case FILTER_OBJECT_TYPE_EXTENSION:
            return "extension";
        case FILTER_OBJECT_TYPE_FOREIGN_DATA:
            return "foreign data";
        case FILTER_OBJECT_TYPE_FUNCTION:
            return "function";
        case FILTER_OBJECT_TYPE_INDEX:
            return "index";
        case FILTER_OBJECT_TYPE_SCHEMA:
            return "schema";
        case FILTER_OBJECT_TYPE_TABLE:
            return "table";
        case FILTER_OBJECT_TYPE_TABLE_AND_CHILDREN:
            return "table and children";
        case FILTER_OBJECT_TYPE_TRIGGER:
            return "trigger";
    }
 
    /* should never get here */
    pg_unreachable();
}
 
/*
 * Returns true when keyword is one of supported object types, and
 * set related objtype. Returns false, when keyword is not assigned
 * with known object type.
 */
static bool
get_object_type(const char *keyword, int size, FilterObjectType *objtype)
{
    if (is_keyword_str("table_data", keyword, size))
        *objtype = FILTER_OBJECT_TYPE_TABLE_DATA;
    else if (is_keyword_str("table_data_and_children", keyword, size))
        *objtype = FILTER_OBJECT_TYPE_TABLE_DATA_AND_CHILDREN;
    else if (is_keyword_str("database", keyword, size))
        *objtype = FILTER_OBJECT_TYPE_DATABASE;
    else if (is_keyword_str("extension", keyword, size))
        *objtype = FILTER_OBJECT_TYPE_EXTENSION;
    else if (is_keyword_str("foreign_data", keyword, size))
        *objtype = FILTER_OBJECT_TYPE_FOREIGN_DATA;
    else if (is_keyword_str("function", keyword, size))
        *objtype = FILTER_OBJECT_TYPE_FUNCTION;
    else if (is_keyword_str("index", keyword, size))
        *objtype = FILTER_OBJECT_TYPE_INDEX;
    else if (is_keyword_str("schema", keyword, size))
        *objtype = FILTER_OBJECT_TYPE_SCHEMA;
    else if (is_keyword_str("table", keyword, size))
        *objtype = FILTER_OBJECT_TYPE_TABLE;
    else if (is_keyword_str("table_and_children", keyword, size))
        *objtype = FILTER_OBJECT_TYPE_TABLE_AND_CHILDREN;
    else if (is_keyword_str("trigger", keyword, size))
        *objtype = FILTER_OBJECT_TYPE_TRIGGER;
    else
        return false;
 
    return true;
}
 
 
void
pg_log_filter_error(FilterStateData *fstate, const char *fmt,...)
{
    va_list     argp;
    char        buf[256];
 
    va_start(argp, fmt);
    vsnprintf(buf, sizeof(buf), fmt, argp);
    va_end(argp);
 
    if (fstate->fp == stdin)
        pg_log_error("invalid format in filter read from standard input on line %d: %s",
                     fstate->lineno, buf);
    else
        pg_log_error("invalid format in filter read from file \"%s\" on line %d: %s",
                     fstate->filename, fstate->lineno, buf);
}
 
/*
 * filter_get_keyword - read the next filter keyword from buffer
 *
 * Search for keywords (limited to ascii alphabetic characters) in
 * the passed in line buffer. Returns NULL when the buffer is empty or the first
 * char is not alpha. The char '_' is allowed, except as the first character.
 * The length of the found keyword is returned in the size parameter.
 */
static const char *
filter_get_keyword(const char **line, int *size)
{
    const char *ptr = *line;
    const char *result = NULL;
 
    /* Set returned length preemptively in case no keyword is found */
    *size = 0;
 
    /* Skip initial whitespace */
    while (isspace((unsigned char) *ptr))
        ptr++;
 
    if (isalpha((unsigned char) *ptr))
    {
        result = ptr++;
 
        while (isalpha((unsigned char) *ptr) || *ptr == '_')
            ptr++;
 
        *size = ptr - result;
    }
 
    *line = ptr;
 
    return result;
}
 
/*
 * read_quoted_string - read quoted possibly multi line string
 *
 * Reads a quoted string which can span over multiple lines and returns a
 * pointer to next char after ending double quotes; it will exit on errors.
 */
static const char *
read_quoted_string(FilterStateData *fstate,
                   const char *str,
                   PQExpBuffer pattern)
{
    appendPQExpBufferChar(pattern, '"');
    str++;
 
    while (1)
    {
        /*
         * We can ignore \r or \n chars because the string is read by
         * pg_get_line_buf, so these chars should be just trailing chars.
         */
        if (*str == '\r' || *str == '\n')
        {
            str++;
            continue;
        }
 
        if (*str == '\0')
        {
            Assert(fstate->linebuff.data);
 
            if (!pg_get_line_buf(fstate->fp, &fstate->linebuff))
            {
                if (ferror(fstate->fp))
                    pg_log_error("could not read from filter file \"%s\": %m",
                                 fstate->filename);
                else
                    pg_log_filter_error(fstate, _("unexpected end of file"));
 
                fstate->exit_nicely(1);
            }
 
            str = fstate->linebuff.data;
 
            appendPQExpBufferChar(pattern, '\n');
            fstate->lineno++;
        }
 
        if (*str == '"')
        {
            appendPQExpBufferChar(pattern, '"');
            str++;
 
            if (*str == '"')
            {
                appendPQExpBufferChar(pattern, '"');
                str++;
            }
            else
                break;
        }
        else if (*str == '\\')
        {
            str++;
            if (*str == 'n')
                appendPQExpBufferChar(pattern, '\n');
            else if (*str == '\\')
                appendPQExpBufferChar(pattern, '\\');
 
            str++;
        }
        else
            appendPQExpBufferChar(pattern, *str++);
    }
 
    return str;
}
 
/*
 * read_pattern - reads on object pattern from input
 *
 * This function will parse any valid identifier (quoted or not, qualified or
 * not), which can also includes the full signature for routines.
 * Note that this function takes special care to sanitize the detected
 * identifier (removing extraneous whitespaces or other unnecessary
 * characters).  This is necessary as most backup/restore filtering functions
 * only recognize identifiers if they are written exactly the same way as
 * they are output by the server.
 *
 * Returns a pointer to next character after the found identifier and exits
 * on error.
 */
static const char *
read_pattern(FilterStateData *fstate, const char *str, PQExpBuffer pattern)
{
    bool        skip_space = true;
    bool        found_space = false;
 
    /* Skip initial whitespace */
    while (isspace((unsigned char) *str))
        str++;
 
    if (*str == '\0')
    {
        pg_log_filter_error(fstate, _("missing object name pattern"));
        fstate->exit_nicely(1);
    }
 
    while (*str && *str != '#')
    {
        while (*str && !isspace((unsigned char) *str) && !strchr("#,.()\"", *str))
        {
            /*
             * Append space only when it is allowed, and when it was found in
             * original string.
             */
            if (!skip_space && found_space)
            {
                appendPQExpBufferChar(pattern, ' ');
                skip_space = true;
            }
 
            appendPQExpBufferChar(pattern, *str++);
        }
 
        skip_space = false;
 
        if (*str == '"')
        {
            if (found_space)
                appendPQExpBufferChar(pattern, ' ');
 
            str = read_quoted_string(fstate, str, pattern);
        }
        else if (*str == ',')
        {
            appendPQExpBufferStr(pattern, ", ");
            skip_space = true;
            str++;
        }
        else if (*str && strchr(".()", *str))
        {
            appendPQExpBufferChar(pattern, *str++);
            skip_space = true;
        }
 
        found_space = false;
 
        /* skip ending whitespaces */
        while (isspace((unsigned char) *str))
        {
            found_space = true;
            str++;
        }
    }
 
    return str;
}
 
/*
 * filter_read_item - Read command/type/pattern triplet from a filter file
 *
 * This will parse one filter item from the filter file, and while it is a
 * row based format a pattern may span more than one line due to how object
 * names can be constructed.  The expected format of the filter file is:
 *
 * <command> <object_type> <pattern>
 *
 * command can be "include" or "exclude".
 *
 * Supported object types are described by enum FilterObjectType
 * (see function get_object_type).
 *
 * pattern can be any possibly-quoted and possibly-qualified identifier.  It
 * follows the same rules as other object include and exclude functions so it
 * can also use wildcards.
 *
 * Returns true when one filter item was successfully read and parsed.  When
 * object name contains \n chars, then more than one line from input file can
 * be processed.  Returns false when the filter file reaches EOF. In case of
 * error, the function will emit an appropriate error message and exit.
 */
bool
filter_read_item(FilterStateData *fstate,
                 char **objname,
                 FilterCommandType *comtype,
                 FilterObjectType *objtype)
{
    if (pg_get_line_buf(fstate->fp, &fstate->linebuff))
    {
        const char *str = fstate->linebuff.data;
        const char *keyword;
        int         size;
        PQExpBufferData pattern;
 
        fstate->lineno++;
 
        /* Skip initial white spaces */
        while (isspace((unsigned char) *str))
            str++;
 
        /*
         * Skip empty lines or lines where the first non-whitespace character
         * is a hash indicating a comment.
         */
        if (*str != '\0' && *str != '#')
        {
            /*
             * First we expect sequence of two keywords, {include|exclude}
             * followed by the object type to operate on.
             */
            keyword = filter_get_keyword(&str, &size);
            if (!keyword)
            {
                pg_log_filter_error(fstate,
                                    _("no filter command found (expected \"include\" or \"exclude\")"));
                fstate->exit_nicely(1);
            }
 
            if (is_keyword_str("include", keyword, size))
                *comtype = FILTER_COMMAND_TYPE_INCLUDE;
            else if (is_keyword_str("exclude", keyword, size))
                *comtype = FILTER_COMMAND_TYPE_EXCLUDE;
            else
            {
                pg_log_filter_error(fstate,
                                    _("invalid filter command (expected \"include\" or \"exclude\")"));
                fstate->exit_nicely(1);
            }
 
            keyword = filter_get_keyword(&str, &size);
            if (!keyword)
            {
                pg_log_filter_error(fstate, _("missing filter object type"));
                fstate->exit_nicely(1);
            }
 
            if (!get_object_type(keyword, size, objtype))
            {
                pg_log_filter_error(fstate,
                                    _("unsupported filter object type: \"%.*s\""), size, keyword);
                fstate->exit_nicely(1);
            }
 
            initPQExpBuffer(&pattern);
 
            str = read_pattern(fstate, str, &pattern);
            *objname = pattern.data;
        }
        else
        {
            *objname = NULL;
            *comtype = FILTER_COMMAND_TYPE_NONE;
            *objtype = FILTER_OBJECT_TYPE_NONE;
        }
 
        return true;
    }
 
    if (ferror(fstate->fp))
    {
        pg_log_error("could not read from filter file \"%s\": %m", fstate->filename);
        fstate->exit_nicely(1);
    }
 
    return false;
}