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streaming: filter cascading 

This implements an internal "cascade" filter mechanism that plugs
two filters in series.

Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit is contained in:
Junio C Hamano 2011-05-21 18:28:41 -07:00
parent b84c783917
commit a265a7f95e
1 changed files with 112 additions and 14 deletions
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126
convert.c
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@ -914,6 +914,112 @@ static struct stream_filter lf_to_crlf_filter_singleton = {
};
/*
* Cascade filter
*/
#define FILTER_BUFFER 1024
struct cascade_filter {
struct stream_filter filter;
struct stream_filter *one;
struct stream_filter *two;
char buf[FILTER_BUFFER];
int end, ptr;
};
static int cascade_filter_fn(struct stream_filter *filter,
const char *input, size_t *isize_p,
char *output, size_t *osize_p)
{
struct cascade_filter *cas = (struct cascade_filter *) filter;
size_t filled = 0;
size_t sz = *osize_p;
size_t to_feed, remaining;
/*
* input -- (one) --> buf -- (two) --> output
*/
while (filled < sz) {
remaining = sz - filled;
/* do we already have something to feed two with? */
if (cas->ptr < cas->end) {
to_feed = cas->end - cas->ptr;
if (stream_filter(cas->two,
cas->buf + cas->ptr, &to_feed,
output + filled, &remaining))
return -1;
cas->ptr += (cas->end - cas->ptr) - to_feed;
filled = sz - remaining;
continue;
}
/* feed one from upstream and have it emit into our buffer */
to_feed = input ? *isize_p : 0;
if (input && !to_feed)
break;
remaining = sizeof(cas->buf);
if (stream_filter(cas->one,
input, &to_feed,
cas->buf, &remaining))
return -1;
cas->end = sizeof(cas->buf) - remaining;
cas->ptr = 0;
if (input) {
size_t fed = *isize_p - to_feed;
*isize_p -= fed;
input += fed;
}
/* do we know that we drained one completely? */
if (input || cas->end)
continue;
/* tell two to drain; we have nothing more to give it */
to_feed = 0;
remaining = sz - filled;
if (stream_filter(cas->two,
NULL, &to_feed,
output + filled, &remaining))
return -1;
if (remaining == (sz - filled))
break; /* completely drained two */
filled = sz - remaining;
}
*osize_p -= filled;
return 0;
}
static void cascade_free_fn(struct stream_filter *filter)
{
struct cascade_filter *cas = (struct cascade_filter *)filter;
free_stream_filter(cas->one);
free_stream_filter(cas->two);
free(filter);
}
static struct stream_filter_vtbl cascade_vtbl = {
cascade_filter_fn,
cascade_free_fn,
};
static struct stream_filter *cascade_filter(struct stream_filter *one,
struct stream_filter *two)
{
struct cascade_filter *cascade;
if (!one || is_null_stream_filter(one))
return two;
if (!two || is_null_stream_filter(two))
return one;
cascade = xmalloc(sizeof(*cascade));
cascade->one = one;
cascade->two = two;
cascade->end = cascade->ptr = 0;
cascade->filter.vtbl = &cascade_vtbl;
return (struct stream_filter *)cascade;
}
/*
* ident filter
*/
@ -1083,20 +1189,12 @@ struct stream_filter *get_stream_filter(const char *path, const unsigned char *s
crlf_action = input_crlf_action(ca.crlf_action, ca.eol_attr);
if ((crlf_action == CRLF_BINARY) || (crlf_action == CRLF_INPUT) ||
(crlf_action == CRLF_GUESS && auto_crlf == AUTO_CRLF_FALSE)) {
if (filter) {
free_stream_filter(filter);
return NULL;
}
return &null_filter_singleton;
} else if (output_eol(crlf_action) == EOL_CRLF &&
!(crlf_action == CRLF_AUTO || crlf_action == CRLF_GUESS)) {
if (filter) {
free_stream_filter(filter);
return NULL;
}
return &lf_to_crlf_filter_singleton;
}
(crlf_action == CRLF_GUESS && auto_crlf == AUTO_CRLF_FALSE))
filter = cascade_filter(filter, &null_filter_singleton);
else if (output_eol(crlf_action) == EOL_CRLF &&
!(crlf_action == CRLF_AUTO || crlf_action == CRLF_GUESS))
filter = cascade_filter(filter, &lf_to_crlf_filter_singleton);
return filter;
}