On Thu, Jun 7, 2018 at 4:03 PM, Derrick Stolee <stolee@xxxxxxxxx> wrote:
> As we build the multi-pack-index feature by adding chunks at a time,
> we want to test that the data is being written correctly.
>
> Create struct midxed_git to store an in-memory representation of a
A word play on 'packed_git'? Amusing. Some more descriptive name would
be better though. midxed looks almost like random letters thrown
together.
> multi-pack-index and a memory-map of the binary file. Initialize this
> struct in load_midxed_git(object_dir).
> +static int read_midx_file(const char *object_dir)
> +{
> + struct midxed_git *m = load_midxed_git(object_dir);
> +
> + if (!m)
> + return 0;
This looks like an error case, please don't just return zero,
typically used to say "success". I don't know if this command stays
"for debugging purposes" until the end. Of course in that case it does
not really matter.
> +struct midxed_git *load_midxed_git(const char *object_dir)
> +{
> + struct midxed_git *m;
> + int fd;
> + struct stat st;
> + size_t midx_size;
> + void *midx_map;
> + const char *midx_name = get_midx_filename(object_dir);
mem leak? This function returns allocated memory if I remember correctly.
> +
> + fd = git_open(midx_name);
> + if (fd < 0)
> + return NULL;
do an error_errno() so we know what went wrong at least.
> + if (fstat(fd, &st)) {
> + close(fd);
> + return NULL;
same here, we should know why fstat() fails.
> + }
> + midx_size = xsize_t(st.st_size);
> +
> + if (midx_size < MIDX_MIN_SIZE) {
> + close(fd);
> + die("multi-pack-index file %s is too small", midx_name);
_()
The use of die() should be discouraged though. Many people still try
(or wish) to libify code and new die() does not help. I think error()
here would be enough then you can return NULL. Or you can go fancier
and store the error string in a strbuf like refs code.
> + }
> +
> + midx_map = xmmap(NULL, midx_size, PROT_READ, MAP_PRIVATE, fd, 0);
> +
> + m = xcalloc(1, sizeof(*m) + strlen(object_dir) + 1);
> + strcpy(m->object_dir, object_dir);
> + m->data = midx_map;
> +
> + m->signature = get_be32(m->data);
> + if (m->signature != MIDX_SIGNATURE) {
> + error("multi-pack-index signature %X does not match signature %X",
> + m->signature, MIDX_SIGNATURE);
_(). Maybe 0x%08x instead of %x
> + goto cleanup_fail;
> + }
> +
> + m->version = *(m->data + 4);
m->data[4] instead? shorter and easier to understand.
Same comment on "*(m->data + x)" and error() without _() for the rest.
> + if (m->version != MIDX_VERSION) {
> + error("multi-pack-index version %d not recognized",
> + m->version);
_()
> + goto cleanup_fail;
> + }
> +
> + m->hash_version = *(m->data + 5);
m->data[5]
> +cleanup_fail:
> + FREE_AND_NULL(m);
> + munmap(midx_map, midx_size);
> + close(fd);
> + exit(1);
It's bad enough that you die() but exit() in this code seems too much.
Please just return NULL and let the caller handle the error.
> diff --git a/midx.h b/midx.h
> index 3a63673952..a1d18ed991 100644
> --- a/midx.h
> +++ b/midx.h
> @@ -1,4 +1,13 @@
> +#ifndef MIDX_H
> +#define MIDX_H
> +
> +#include "git-compat-util.h"
> #include "cache.h"
> +#include "object-store.h"
I don't really think you need object-store here (git-compat-util.h
too). "struct mixed_git;" would be enough for load_midxed_git
declaration below.
> #include "packfile.h"
>
> +struct midxed_git *load_midxed_git(const char *object_dir);
> +
> int write_midx_file(const char *object_dir);
> +
> +#endif
> diff --git a/object-store.h b/object-store.h
> index d683112fd7..77cb82621a 100644
> --- a/object-store.h
> +++ b/object-store.h
> @@ -84,6 +84,25 @@ struct packed_git {
> char pack_name[FLEX_ARRAY]; /* more */
> };
>
> +struct midxed_git {
> + struct midxed_git *next;
Do we really have multiple midx files?
> +
> + int fd;
> +
> + const unsigned char *data;
> + size_t data_len;
> +
> + uint32_t signature;
> + unsigned char version;
> + unsigned char hash_version;
> + unsigned char hash_len;
> + unsigned char num_chunks;
> + uint32_t num_packs;
> + uint32_t num_objects;
> +
> + char object_dir[FLEX_ARRAY];
Why do you need to keep object_dir when it could be easily retrieved
when the repo is available?
> +};
> +
> struct raw_object_store {
> /*
> * Path to the repository's object store.
--
Duy
