PostgreSQL的 initdb 源代码分析之十三

继续分析：

    /* Bootstrap template1 */
    bootstrap_template1();

展开：

我这里读入的文件是：/home/pgsql/project/share/postgres.bki

/*
 * run the BKI script in bootstrap mode to create template1
 */
static void
bootstrap_template1(void)
{
    PG_CMD_DECL;
    char      **line;
    char       *talkargs = "";
    char      **bki_lines;
    char        headerline[MAXPGPATH];
    char        buf[];

    printf(_("creating template1 database in %s/base/1 ... "), pg_data);
    fflush(stdout);

    if (debug)
        talkargs = "-d 5";

    bki_lines = readfile(bki_file);

    /* Check that bki file appears to be of the right version */

    snprintf(headerline, sizeof(headerline), "# PostgreSQL %s\n",
             PG_MAJORVERSION);

    if (strcmp(headerline, *bki_lines) != )
    {
        fprintf(stderr,
                _("%s: input file \"%s\" does not belong to PostgreSQL %s\n"
                  "Check your installation or specify the correct path "
                  "using the option -L.\n"),
                progname, bki_file, PG_VERSION);
        exit_nicely();
    }

    /* Substitute for various symbols used in the BKI file */

    sprintf(buf, "%d", NAMEDATALEN);
    bki_lines = replace_token(bki_lines, "NAMEDATALEN", buf);

    sprintf(buf, "%d", (int) sizeof(Pointer));
    bki_lines = replace_token(bki_lines, "SIZEOF_POINTER", buf);

    bki_lines = replace_token(bki_lines, "ALIGNOF_POINTER",
                              (sizeof(Pointer) == ) ? "i" : "d");

    bki_lines = replace_token(bki_lines, "FLOAT4PASSBYVAL",
                              FLOAT4PASSBYVAL ? "true" : "false");

    bki_lines = replace_token(bki_lines, "FLOAT8PASSBYVAL",
                              FLOAT8PASSBYVAL ? "true" : "false");

    bki_lines = replace_token(bki_lines, "POSTGRES", username);

    bki_lines = replace_token(bki_lines, "ENCODING", encodingid);

    bki_lines = replace_token(bki_lines, "LC_COLLATE", escape_quotes(lc_collate));

    bki_lines = replace_token(bki_lines, "LC_CTYPE", escape_quotes(lc_ctype));

    /*
     * Pass correct LC_xxx environment to bootstrap.
     *
     * The shell script arranged to restore the LC settings afterwards, but
     * there doesn't seem to be any compelling reason to do that.
     */
    snprintf(cmd, sizeof(cmd), "LC_COLLATE=%s", lc_collate);
    putenv(xstrdup(cmd));

    snprintf(cmd, sizeof(cmd), "LC_CTYPE=%s", lc_ctype);
    putenv(xstrdup(cmd));

    unsetenv("LC_ALL");

    /* Also ensure backend isn't confused by this environment var: */
    unsetenv("PGCLIENTENCODING");

    snprintf(cmd, sizeof(cmd),
             "\"%s\" --boot -x1 %s %s",
             backend_exec, boot_options, talkargs);

    PG_CMD_OPEN;

    for (line = bki_lines; *line != NULL; line++)
    {
        PG_CMD_PUTS(*line);
        free(*line);
    }

    PG_CMD_CLOSE;

    free(bki_lines);

    check_ok();
}

其中，  bki_lines = readfile(bki_file) ，是得到了要读取的文件的每一行。

再展开看 replace_token 函数：

这个函数就是用 replacement指向的字符串，替换在 lines所代表的文件内容行数组中所有token值。

比如：

sprintf(buf, "%d", NAMEDATALEN);
bki_lines = replace_token(bki_lines, "NAMEDATALEN", buf);

把 postgres.bki  文件中 类似于

insert OID = 19 ( name 11 10 NAMEDATALEN f b S f t \054 0 18 1003 namein nameout namerecv namesend - - - c p f 0 -1 0 0 _null_ _null_ )

这样的句子，在内存中替换为（根据宏定义、NAMEDATALEN为64）：

insert OID = 19 ( name 11 10 64 f b S f t \054 0 18 1003 namein nameout namerecv namesend - - - c p f 0 -1 0 0 _null_ _null_ )

/*
 * make a copy of the array of lines, with token replaced by replacement
 * the first time it occurs on each line.
 *
 * This does most of what sed was used for in the shell script, but
 * doesn't need any regexp stuff.
 */
static char **
replace_token(char **lines, const char *token, const char *replacement)
{
    int            numlines = ;
    int            i;
    char      **result;
    int            toklen,
                replen,
                diff;

    for (i = ; lines[i]; i++)
        numlines++;

    result = (char **) pg_malloc(numlines * sizeof(char *));

    toklen = strlen(token);
    replen = strlen(replacement);
    diff = replen - toklen;

    for (i = ; i < numlines; i++)
    {
        char       *where;
        char       *newline;
        int            pre;

        /* just copy pointer if NULL or no change needed */
        if (lines[i] == NULL || (where = strstr(lines[i], token)) == NULL)
        {
            result[i] = lines[i];
            continue;
        }

        /* if we get here a change is needed - set up new line */

        newline = (char *) pg_malloc(strlen(lines[i]) + diff + );

        pre = where - lines[i];

        strncpy(newline, lines[i], pre);

        strcpy(newline + pre, replacement);

        strcpy(newline + pre + replen, lines[i] + pre + toklen);

        result[i] = newline;
    }

    return result;
}

综合上述两段，加入调试信息后，可以看到：

---------------replace for   NAMEDATALEN ------start
===============lines[] OLD is : insert OID =  ( name   NAMEDATALEN f b S f t \    namein nameout namerecv namesend - - - c p f  -   _null_ _null_ )

===============result[] NEW is : insert OID =  ( name    f b S f t \    namein nameout namerecv namesend - - - c p f  -   _null_ _null_ )

===============lines[] OLD is : insert (  proname  - NAMEDATALEN   - - f p c t f f t   _null_ _null_)

===============result[] NEW is : insert (  proname  -    - - f p c t f f t   _null_ _null_)

===============lines[] OLD is : insert (  typname  - NAMEDATALEN   - - f p c t f f t   _null_ _null_)

===============result[] NEW is : insert (  typname  -    - - f p c t f f t   _null_ _null_)

===============lines[] OLD is : insert (  attname  - NAMEDATALEN   - - f p c t f f t   _null_ _null_)

===============result[] NEW is : insert (  attname  -    - - f p c t f f t   _null_ _null_)

===============lines[] OLD is : insert (  relname  - NAMEDATALEN   - - f p c t f f t   _null_ _null_)

===============result[] NEW is : insert (  relname  -    - - f p c t f f t   _null_ _null_)

---------------replace for   NAMEDATALEN ------end

---------------replace for   SIZEOF_POINTER ------start
===============lines[] OLD is : insert OID =  ( internal   SIZEOF_POINTER t p P f t \    internal_in internal_out - - - - - ALIGNOF_POINTER p f  -   _null_ _null_ )

===============result[] NEW is : insert OID =  ( internal    t p P f t \    internal_in internal_out - - - - - ALIGNOF_POINTER p f  -   _null_ _null_ )

---------------replace for   SIZEOF_POINTER ------end

---------------replace for   ALIGNOF_POINTER ------start
===============lines[] OLD is : insert OID =  ( internal    t p P f t \    internal_in internal_out - - - - - ALIGNOF_POINTER p f  -   _null_ _null_ )

===============result[] NEW is : insert OID =  ( internal    t p P f t \    internal_in internal_out - - - - - d p f  -   _null_ _null_ )

---------------replace for   ALIGNOF_POINTER ------end

---------------replace for   FLOAT4PASSBYVAL ------start
===============lines[] OLD is : insert OID =  ( float4    FLOAT4PASSBYVAL b N f t \    float4in float4out float4recv float4send - - - i p f  -   _null_ _null_ )

===============result[] NEW is : insert OID =  ( float4    true b N f t \    float4in float4out float4recv float4send - - - i p f  -   _null_ _null_ )

===============lines[] OLD is : insert (  procost  -    - - FLOAT4PASSBYVAL p i t f f t   _null_ _null_)

===============result[] NEW is : insert (  procost  -    - - true p i t f f t   _null_ _null_)

===============lines[] OLD is : insert (  prorows  -    - - FLOAT4PASSBYVAL p i t f f t   _null_ _null_)

===============result[] NEW is : insert (  prorows  -    - - true p i t f f t   _null_ _null_)

===============lines[] OLD is : insert (  reltuples  -    - - FLOAT4PASSBYVAL p i t f f t   _null_ _null_)

===============result[] NEW is : insert (  reltuples  -    - - true p i t f f t   _null_ _null_)

---------------replace for   FLOAT4PASSBYVAL ------end

---------------replace for   FLOAT8PASSBYVAL ------start
===============lines[] OLD is : insert OID =  ( int8    FLOAT8PASSBYVAL b N f t \    int8in int8out int8recv int8send - - - d p f  -   _null_ _null_ )

===============result[] NEW is : insert OID =  ( int8    true b N f t \    int8in int8out int8recv int8send - - - d p f  -   _null_ _null_ )

===============lines[] OLD is : insert OID =  ( float8    FLOAT8PASSBYVAL b N t t \    float8in float8out float8recv float8send - - - d p f  -   _null_ _null_ )

===============result[] NEW is : insert OID =  ( float8    true b N t t \    float8in float8out float8recv float8send - - - d p f  -   _null_ _null_ )

===============lines[] OLD is : insert OID =  ( money    FLOAT8PASSBYVAL b N f t \    cash_in cash_out cash_recv cash_send - - - d p f  -   _null_ _null_ )

===============result[] NEW is : insert OID =  ( money    true b N f t \    cash_in cash_out cash_recv cash_send - - - d p f  -   _null_ _null_ )

===============lines[] OLD is : insert OID =  ( time    FLOAT8PASSBYVAL b D f t \    time_in time_out time_recv time_send timetypmodin timetypmodout - d p f  -   _null_ _null_ )

===============result[] NEW is : insert OID =  ( time    true b D f t \    time_in time_out time_recv time_send timetypmodin timetypmodout - d p f  -   _null_ _null_ )

===============lines[] OLD is : insert OID =  ( timestamp    FLOAT8PASSBYVAL b D f t \    timestamp_in timestamp_out timestamp_recv timestamp_send timestamptypmodin timestamptypmodout - d p f  -   _null_ _null_ )

===============result[] NEW is : insert OID =  ( timestamp    true b D f t \    timestamp_in timestamp_out timestamp_recv timestamp_send timestamptypmodin timestamptypmodout - d p f  -   _null_ _null_ )

===============lines[] OLD is : insert OID =  ( timestamptz    FLOAT8PASSBYVAL b D t t \    timestamptz_in timestamptz_out timestamptz_recv timestamptz_send timestamptztypmodin timestamptztypmodout - d p f  -   _null_ _null_ )

===============result[] NEW is : insert OID =  ( timestamptz    true b D t t \    timestamptz_in timestamptz_out timestamptz_recv timestamptz_send timestamptztypmodin timestamptztypmodout - d p f  -   _null_ _null_ )

---------------replace for   FLOAT4PASSBYVAL ------end

---------------replace for   POSTGRES ------start
===============lines[] OLD is : insert OID =  ( "POSTGRES" t t t t t t t - _null_ _null_ )

===============result[] NEW is : insert OID =  ( "pgsql" t t t t t t t - _null_ _null_ )

---------------replace for   POSTGRES ------end

---------------replace for   ENCODING ------start
===============lines[] OLD is : insert OID =  ( template1  ENCODING "LC_COLLATE" "LC_CTYPE" t t -    _null_)

===============result[] NEW is : insert OID =  ( template1   "LC_COLLATE" "LC_CTYPE" t t -    _null_)

---------------replace for   ENCODING ------end

---------------replace for   LC_COLLATE ------start
===============lines[] OLD is : insert OID =  ( template1   "LC_COLLATE" "LC_CTYPE" t t -    _null_)

===============result[] NEW is : insert OID =  ( template1   "en_US.UTF-8" "LC_CTYPE" t t -    _null_)

---------------replace for   LC_COLLATE ------end

---------------replace for   LC_CTYPE ------start
===============lines[] OLD is : insert OID =  ( template1   "en_US.UTF-8" "LC_CTYPE" t t -    _null_)

===============result[] NEW is : insert OID =  ( template1   "en_US.UTF-8" "en_US.UTF-8" t t -    _null_)

---------------replace for   LC_CTYPE ------end

这些被替换以后的信息，如何被使用呢？

看前面的  bootstrap_template1 函数中的这一段：

    /*
     * Pass correct LC_xxx environment to bootstrap.
     *
     * The shell script arranged to restore the LC settings afterwards, but
     * there doesn't seem to be any compelling reason to do that.
     */
    snprintf(cmd, sizeof(cmd), "LC_COLLATE=%s", lc_collate);
    putenv(xstrdup(cmd));

    snprintf(cmd, sizeof(cmd), "LC_CTYPE=%s", lc_ctype);
    putenv(xstrdup(cmd));

    unsetenv("LC_ALL");

    /* Also ensure backend isn't confused by this environment var: */
    unsetenv("PGCLIENTENCODING");

    snprintf(cmd, sizeof(cmd),
             "\"%s\" --boot -x1 %s %s",
             backend_exec, boot_options, talkargs);

我可以得到 cmd是： "/home/pgsql/project/bin/postgres" --boot -x1 -F

而后面的一段：

则是一次一次的逐行带参数执行 Postgresql.bki中所有行（包括被替换的和没有被替换的行）

可以理解为特殊的模式下，向postgresql 的template 数据库中逐条写入数据。

    PG_CMD_OPEN;

    for (line = bki_lines; *line != NULL; line++)
    {
        PG_CMD_PUTS(*line);
        free(*line);
    }

    PG_CMD_CLOSE;

需要注意的是，对各个系统表的建立，都是在此处，通过执行 postgres.bki文件中的各行脚本来完成的。