Revision f6a1e1e288d13472f5f7fe2b907bb8c0bd69a018 authored by Jim Hill on 18 May 2015, 00:41:45 UTC, committed by Junio C Hamano on 18 May 2015, 17:15:20 UTC
`git add` of an empty file with a filter pops complaints from `copy_fd` about a bad file descriptor. This traces back to these lines in sha1_file.c:index_core: if (!size) { ret = index_mem(sha1, NULL, size, type, path, flags); The problem here is that content to be added to the index can be supplied from an fd, or from a memory buffer, or from a pathname. This call is supplying a NULL buffer pointer and a zero size. Downstream logic takes the complete absence of a buffer to mean the data is to be found elsewhere -- for instance, these, from convert.c: if (params->src) { write_err = (write_in_full(child_process.in, params->src, params->size) < 0); } else { write_err = copy_fd(params->fd, child_process.in); } ~If there's a buffer, write from that, otherwise the data must be coming from an open fd.~ Perfectly reasonable logic in a routine that's going to write from either a buffer or an fd. So change `index_core` to supply an empty buffer when indexing an empty file. There's a patch out there that instead changes the logic quoted above to take a `-1` fd to mean "use the buffer", but it seems to me that the distinction between a missing buffer and an empty one carries intrinsic semantics, where the logic change is adapting the code to handle incorrect arguments. Signed-off-by: Jim Hill <gjthill@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
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delta.h
#ifndef DELTA_H
#define DELTA_H
/* opaque object for delta index */
struct delta_index;
/*
* create_delta_index: compute index data from given buffer
*
* This returns a pointer to a struct delta_index that should be passed to
* subsequent create_delta() calls, or to free_delta_index(). A NULL pointer
* is returned on failure. The given buffer must not be freed or altered
* before free_delta_index() is called. The returned pointer must be freed
* using free_delta_index().
*/
extern struct delta_index *
create_delta_index(const void *buf, unsigned long bufsize);
/*
* free_delta_index: free the index created by create_delta_index()
*
* Given pointer must be what create_delta_index() returned, or NULL.
*/
extern void free_delta_index(struct delta_index *index);
/*
* sizeof_delta_index: returns memory usage of delta index
*
* Given pointer must be what create_delta_index() returned, or NULL.
*/
extern unsigned long sizeof_delta_index(struct delta_index *index);
/*
* create_delta: create a delta from given index for the given buffer
*
* This function may be called multiple times with different buffers using
* the same delta_index pointer. If max_delta_size is non-zero and the
* resulting delta is to be larger than max_delta_size then NULL is returned.
* On success, a non-NULL pointer to the buffer with the delta data is
* returned and *delta_size is updated with its size. The returned buffer
* must be freed by the caller.
*/
extern void *
create_delta(const struct delta_index *index,
const void *buf, unsigned long bufsize,
unsigned long *delta_size, unsigned long max_delta_size);
/*
* diff_delta: create a delta from source buffer to target buffer
*
* If max_delta_size is non-zero and the resulting delta is to be larger
* than max_delta_size then NULL is returned. On success, a non-NULL
* pointer to the buffer with the delta data is returned and *delta_size is
* updated with its size. The returned buffer must be freed by the caller.
*/
static inline void *
diff_delta(const void *src_buf, unsigned long src_bufsize,
const void *trg_buf, unsigned long trg_bufsize,
unsigned long *delta_size, unsigned long max_delta_size)
{
struct delta_index *index = create_delta_index(src_buf, src_bufsize);
if (index) {
void *delta = create_delta(index, trg_buf, trg_bufsize,
delta_size, max_delta_size);
free_delta_index(index);
return delta;
}
return NULL;
}
/*
* patch_delta: recreate target buffer given source buffer and delta data
*
* On success, a non-NULL pointer to the target buffer is returned and
* *trg_bufsize is updated with its size. On failure a NULL pointer is
* returned. The returned buffer must be freed by the caller.
*/
extern void *patch_delta(const void *src_buf, unsigned long src_size,
const void *delta_buf, unsigned long delta_size,
unsigned long *dst_size);
/* the smallest possible delta size is 4 bytes */
#define DELTA_SIZE_MIN 4
/*
* This must be called twice on the delta data buffer, first to get the
* expected source buffer size, and again to get the target buffer size.
*/
static inline unsigned long get_delta_hdr_size(const unsigned char **datap,
const unsigned char *top)
{
const unsigned char *data = *datap;
unsigned long cmd, size = 0;
int i = 0;
do {
cmd = *data++;
size |= (cmd & 0x7f) << i;
i += 7;
} while (cmd & 0x80 && data < top);
*datap = data;
return size;
}
#endif
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