Hi Ævar, (catching up after a week away, and noticed your patch today..) On 20/12/2021 12:10, Ævar Arnfjörð Bjarmason wrote: > Add a convenience function to wrap the xsnprintf() command that > generates loose object headers. This code was copy/pasted in various > parts of the codebase, let's define it in one place and re-use it from > there. > > All except one caller of it had a valid "enum object_type" for us, > it's only write_object_file_prepare() which might need to deal with > "git hash-object --literally" and a potential garbage type. Let's have > the primary API use an "enum object_type", and define an *_extended() > function that can take an arbitrary "const char *" for the type. I recently completed a PR in the Git for Windows build that is focused on "git hash-object --literally" as a starter for LLP64 large file (>4GB) compatibility. (https://github.com/git-for-windows/git/pull/3533), which Dscho has merged (cc'd). I'm not sure that the `extended` version will work as expected across the test suite as multiple fake object types are tried, though I only skimmed the patch. I'd support the general thrust, but just wanted to synchronise any changes. Philip > > See [1] for the discussion that prompted this patch, i.e. new code in > object-file.c that wanted to copy/paste the xsnprintf() invocation. > > 1. https://lore.kernel.org/git/211213.86bl1l9bfz.gmgdl@xxxxxxxxxxxxxxxxxxx/ > > Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@xxxxxxxxx> > --- > > On Fri, Dec 17 2021, Han Xin wrote: > >> From: Han Xin <hanxin.hx@xxxxxxxxxxxxxxx> >> >> There are 3 places where "xsnprintf" is used to generate the object >> header, and I originally planned to add a fourth in the latter patch. >> >> According to Ævar Arnfjörð Bjarmason’s suggestion, although it's just >> one line, it's also code that's very central to git, so reafactor them >> into a function which will help later readability. >> >> Helped-by: Ævar Arnfjörð Bjarmason <avarab@xxxxxxxxx> >> Signed-off-by: Han Xin <hanxin.hx@xxxxxxxxxxxxxxx> > I came up with this after my comment on the earlier round suggesting > to factor out that header formatting. I don't know if this more > thorough approach is worth it or if you'd like to replace your change > with this one, but just posting it here as an RFC. > > builtin/index-pack.c | 3 +-- > bulk-checkin.c | 4 ++-- > cache.h | 21 +++++++++++++++++++++ > http-push.c | 2 +- > object-file.c | 14 +++++++++++--- > 5 files changed, 36 insertions(+), 8 deletions(-) > > diff --git a/builtin/index-pack.c b/builtin/index-pack.c > index c23d01de7dc..900c6539f68 100644 > --- a/builtin/index-pack.c > +++ b/builtin/index-pack.c > @@ -449,8 +449,7 @@ static void *unpack_entry_data(off_t offset, unsigned long size, > int hdrlen; > > if (!is_delta_type(type)) { > - hdrlen = xsnprintf(hdr, sizeof(hdr), "%s %"PRIuMAX, > - type_name(type),(uintmax_t)size) + 1; > + hdrlen = format_loose_header(hdr, sizeof(hdr), type, (uintmax_t)size); > the_hash_algo->init_fn(&c); > the_hash_algo->update_fn(&c, hdr, hdrlen); > } else > diff --git a/bulk-checkin.c b/bulk-checkin.c > index 8785b2ac806..446dea7c516 100644 > --- a/bulk-checkin.c > +++ b/bulk-checkin.c > @@ -220,8 +220,8 @@ static int deflate_to_pack(struct bulk_checkin_state *state, > if (seekback == (off_t) -1) > return error("cannot find the current offset"); > > - header_len = xsnprintf((char *)obuf, sizeof(obuf), "%s %" PRIuMAX, > - type_name(type), (uintmax_t)size) + 1; > + header_len = format_loose_header((char *)obuf, sizeof(obuf), > + type, (uintmax_t)size); > the_hash_algo->init_fn(&ctx); > the_hash_algo->update_fn(&ctx, obuf, header_len); > > diff --git a/cache.h b/cache.h > index d5cafba17d4..ccece21a4a2 100644 > --- a/cache.h > +++ b/cache.h > @@ -1309,6 +1309,27 @@ enum unpack_loose_header_result unpack_loose_header(git_zstream *stream, > unsigned long bufsiz, > struct strbuf *hdrbuf); > > +/** > + * format_loose_header() is a thin wrapper around s xsnprintf() that > + * writes the initial "<type> <obj-len>" part of the loose object > + * header. It returns the size that snprintf() returns + 1. > + * > + * The format_loose_header_extended() function allows for writing a > + * type_name that's not one of the "enum object_type" types. This is > + * used for "git hash-object --literally". Pass in a OBJ_NONE as the > + * type, and a non-NULL "type_str" to do that. > + * > + * format_loose_header() is a convenience wrapper for > + * format_loose_header_extended(). > + */ > +int format_loose_header_extended(char *str, size_t size, enum object_type type, > + const char *type_str, size_t objsize); > +static inline int format_loose_header(char *str, size_t size, > + enum object_type type, size_t objsize) > +{ > + return format_loose_header_extended(str, size, type, NULL, objsize); > +} > + > /** > * parse_loose_header() parses the starting "<type> <len>\0" of an > * object. If it doesn't follow that format -1 is returned. To check > diff --git a/http-push.c b/http-push.c > index 3309aaf004a..d1a8619e0af 100644 > --- a/http-push.c > +++ b/http-push.c > @@ -363,7 +363,7 @@ static void start_put(struct transfer_request *request) > git_zstream stream; > > unpacked = read_object_file(&request->obj->oid, &type, &len); > - hdrlen = xsnprintf(hdr, sizeof(hdr), "%s %"PRIuMAX , type_name(type), (uintmax_t)len) + 1; > + hdrlen = format_loose_header(hdr, sizeof(hdr), type, (uintmax_t)len); > > /* Set it up */ > git_deflate_init(&stream, zlib_compression_level); > diff --git a/object-file.c b/object-file.c > index eac67f6f5f9..d94609ee48d 100644 > --- a/object-file.c > +++ b/object-file.c > @@ -1009,6 +1009,14 @@ void *xmmap(void *start, size_t length, > return ret; > } > > +int format_loose_header_extended(char *str, size_t size, enum object_type type, > + const char *typestr, size_t objsize) > +{ > + const char *s = type == OBJ_NONE ? typestr : type_name(type); > + > + return xsnprintf(str, size, "%s %"PRIuMAX, s, (uintmax_t)objsize) + 1; > +} > + > /* > * With an in-core object data in "map", rehash it to make sure the > * object name actually matches "oid" to detect object corruption. > @@ -1037,7 +1045,7 @@ int check_object_signature(struct repository *r, const struct object_id *oid, > return -1; > > /* Generate the header */ > - hdrlen = xsnprintf(hdr, sizeof(hdr), "%s %"PRIuMAX , type_name(obj_type), (uintmax_t)size) + 1; > + hdrlen = format_loose_header(hdr, sizeof(hdr), obj_type, size); > > /* Sha1.. */ > r->hash_algo->init_fn(&c); > @@ -1737,7 +1745,7 @@ static void write_object_file_prepare(const struct git_hash_algo *algo, > git_hash_ctx c; > > /* Generate the header */ > - *hdrlen = xsnprintf(hdr, *hdrlen, "%s %"PRIuMAX , type, (uintmax_t)len)+1; > + *hdrlen = format_loose_header_extended(hdr, *hdrlen, OBJ_NONE, type, len); > > /* Sha1.. */ > algo->init_fn(&c); > @@ -2009,7 +2017,7 @@ int force_object_loose(const struct object_id *oid, time_t mtime) > buf = read_object(the_repository, oid, &type, &len); > if (!buf) > return error(_("cannot read object for %s"), oid_to_hex(oid)); > - hdrlen = xsnprintf(hdr, sizeof(hdr), "%s %"PRIuMAX , type_name(type), (uintmax_t)len) + 1; > + hdrlen = format_loose_header(hdr, sizeof(hdr), type, len); > ret = write_loose_object(oid, hdr, hdrlen, buf, len, mtime, 0); > free(buf); >
