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ash: [REDIR] Replace GPL noclobberopen code with the FreeBSD version

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Upstream commit:

    Date: Thu, 10 Mar 2011 16:52:13 +0800
    [REDIR] Replace GPL noclobberopen code with the FreeBSD version

    Replace noclobberopen() from bash with the FreeBSD code for noclobber
    opens.

    This also reduces code size by eliminating an unnecessary check.

    Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

function                                             old     new   delta
changepath                                           192     194      +2
localcmd                                             366     364      -2
expmeta                                              521     517      -4
redirect                                            1210    1135     -75
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 1/3 up/down: 2/-81)             Total: -79 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
This commit is contained in:
Denys Vlasenko 2017-07-25 17:47:48 +02:00
parent 2990aa45d1
commit f1a5cb0548
1 changed files with 17 additions and 64 deletions
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81
shell/ash.c
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@ -5174,68 +5174,6 @@ stoppedjobs(void)
#define EMPTY -2 /* marks an unused slot in redirtab */
#define CLOSED -3 /* marks a slot of previously-closed fd */
/*
* Open a file in noclobber mode.
* The code was copied from bash.
*/
static int
noclobberopen(const char *fname)
{
int r, fd;
struct stat finfo, finfo2;
/*
* If the file exists and is a regular file, return an error
* immediately.
*/
r = stat(fname, &finfo);
if (r == 0 && S_ISREG(finfo.st_mode)) {
errno = EEXIST;
return -1;
}
/*
* If the file was not present (r != 0), make sure we open it
* exclusively so that if it is created before we open it, our open
* will fail. Make sure that we do not truncate an existing file.
* Note that we don't turn on O_EXCL unless the stat failed -- if the
* file was not a regular file, we leave O_EXCL off.
*/
if (r != 0)
return open(fname, O_WRONLY|O_CREAT|O_EXCL, 0666);
fd = open(fname, O_WRONLY|O_CREAT, 0666);
/* If the open failed, return the file descriptor right away. */
if (fd < 0)
return fd;
/*
* OK, the open succeeded, but the file may have been changed from a
* non-regular file to a regular file between the stat and the open.
* We are assuming that the O_EXCL open handles the case where FILENAME
* did not exist and is symlinked to an existing file between the stat
* and open.
*/
/*
* If we can open it and fstat the file descriptor, and neither check
* revealed that it was a regular file, and the file has not been
* replaced, return the file descriptor.
*/
if (fstat(fd, &finfo2) == 0
&& !S_ISREG(finfo2.st_mode)
&& finfo.st_dev == finfo2.st_dev
&& finfo.st_ino == finfo2.st_ino
) {
return fd;
}
/* The file has been replaced. badness. */
close(fd);
errno = EEXIST;
return -1;
}
/*
* Handle here documents. Normally we fork off a process to write the
* data to a pipe. If the document is short, we can stuff the data in
@ -5280,6 +5218,7 @@ openhere(union node *redir)
static int
openredirect(union node *redir)
{
struct stat sb;
char *fname;
int f;
@ -5319,9 +5258,23 @@ openredirect(union node *redir)
#endif
/* Take care of noclobber mode. */
if (Cflag) {
f = noclobberopen(fname);
if (f < 0)
if (stat(fname, &sb) < 0) {
f = open(fname, O_WRONLY|O_CREAT|O_EXCL, 0666);
if (f < 0)
goto ecreate;
} else if (!S_ISREG(sb.st_mode)) {
f = open(fname, O_WRONLY, 0666);
if (f < 0)
goto ecreate;
if (fstat(f, &sb) < 0 && S_ISREG(sb.st_mode)) {
close(f);
errno = EEXIST;
goto ecreate;
}
} else {
errno = EEXIST;
goto ecreate;
}
break;
}
/* FALLTHROUGH */