From: | Bruce Momjian <maillist(at)candle(dot)pha(dot)pa(dot)us> |
---|---|
To: | scrappy(at)hub(dot)org (The Hermit Hacker) |
Cc: | pgsql-hackers(at)postgreSQL(dot)org |
Subject: | Re: [HACKERS] Does this make sense: |
Date: | 1998-12-14 14:55:56 |
Message-ID: | 199812141455.JAA21406@candle.pha.pa.us |
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Thread: | |
Lists: | pgsql-hackers |
>
> char *
> crypt_getpwdfilename()
> {
>
> static char *pfnam = NULL;
>
> if (!pfnam)
> {
> int bufsize;
> bufsize = strlen(DataDir) + strlen(CRYPT_PWD_FILE) + 2;
> pfnam = (char *) palloc(bufsize);
> spprintf(pfnam, bufsize, "%s/%s", DataDir, CRYPT_PWD_FILE);
> }
>
> return pfnam;
> }
>
> Why the check for '!ipfnam'? Seems useless since we are setting it to
> NULL the line before...no?
Actually, no. We are declaring it as static, so the first time the
function is called, it is set to NULL. After that, it is not
initialized for each function call because a static local variable's
value is kept between function calls. It is like a global variable in
its duration, but in local scope.
This is an old trick to run the initialization code only the first time
the function is called.
--
Bruce Momjian | http://www.op.net/~candle
maillist(at)candle(dot)pha(dot)pa(dot)us | (610) 853-3000
+ If your life is a hard drive, | 830 Blythe Avenue
+ Christ can be your backup. | Drexel Hill, Pennsylvania 19026
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