Re: The argument for fs assistance in handling archives (was: silent semantic changes with reiser4)

[Tonnerre]

Salut,

On Wed, Sep 01, 2004 at 01:50:56PM -0700, Linus Torvalds wrote:
> 	#define MAXNAME 1024
> 	int open_cached_view(int base_fd, char *type, char *subname)
> 	{
> 	        struct stat st;
> 	        char filename[PATH_MAX];
> 	        char name[MAXNAME];
> 	        int len, cachefd;
> 	
> 	        if (fstat(base_fd, &st) < 0)
> 	                return -1;
> 	        sprintf(name, "/proc/self/fd/%d", base_fd);
> 	        len = readlink(name, filename, sizeof(filename)-1);
> 	        if (len < 0)
> 	                return -1;
> 	        filename[len] = 0;
> 	
> 	        /* FIXME! Replace '/' with '#' in "type" and "subname" */
> 	        len = snprintf(name, sizeof(name),
> 	                        "%04llx/%04llx/%s/%s/%s",
> 	                        (unsigned long long) st.st_dev,
> 	                        (unsigned long long) st.st_ino,
> 	                        type ? : "default",
> 	                        subname,
> 	                        filename);
> 	        errno = ENAMETOOLONG;
> 	        if (len >= sizeof(name))
> 	                return -1;
> 	        cachefd = open(name, O_RDONLY);
> 	        if (cachefd >= 0) {
> 	                /* Check mtime here - maybe we could have kernel support */
> 	                return cachefd;
> 	        }
> 	        if (errno != ENOENT)
> 	                return -1;
> 	        /*
> 	        .. try to generate cache file here ..
> 	         */

Around of  what I've  had in  mind. Only that  one might  use libmagic
instead of the type argument. The  rest can be done by a corresponding
MIME plugin.

				Tonnerre

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