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Revision a5bf71be4ada0d8e914c23c2fc334ce1899e36c1 authored by Stefan Beller on 22 May 2015, 19:17:52 UTC, committed by Stefan Beller on 22 May 2015, 19:17:52 UTC 
submodule documentation: Reorder introductory paragraphs
 
It's better to start the man page with a description of what submodules
actually are instead of saying what they are not.

Reorder the paragraphs such that
the first short paragraph introduces the submodule concept,
the second paragraph highlights the usage of the submodule command,
the third paragraph giving background information,
and finally the fourth paragraph discusing alternatives such
as subtrees and remotes, which we don't want to be confused with.

This ordering deepens the knowledge on submodules with each paragraph.
First the basic questions like "How/what" will be answered, while the
underlying concepts will be taught at a later time.

Making sure it is not confused with subtrees and remotes is not really
enhancing knowledge of submodules itself, but rather painting the big
picture of git concepts, so you could also argue to have it as the second
paragraph. Personally I think this may confuse readers, specially
newcomers though.

Additionally to reordering the paragraphs, they have been slightly
reworded.

Signed-off-by: Stefan Beller <sbeller@google.com>
1 parent 6c1249c
Raw File
tag.c 
#include "cache.h"
#include "tag.h"
#include "commit.h"
#include "tree.h"
#include "blob.h"

const char *tag_type = "tag";

struct object *deref_tag(struct object *o, const char *warn, int warnlen)
{
	while (o && o->type == OBJ_TAG)
		if (((struct tag *)o)->tagged)
			o = parse_object(((struct tag *)o)->tagged->sha1);
		else
			o = NULL;
	if (!o && warn) {
		if (!warnlen)
			warnlen = strlen(warn);
		error("missing object referenced by '%.*s'", warnlen, warn);
	}
	return o;
}

struct object *deref_tag_noverify(struct object *o)
{
	while (o && o->type == OBJ_TAG) {
		o = parse_object(o->sha1);
		if (o && o->type == OBJ_TAG && ((struct tag *)o)->tagged)
			o = ((struct tag *)o)->tagged;
		else
			o = NULL;
	}
	return o;
}

struct tag *lookup_tag(const unsigned char *sha1)
{
	struct object *obj = lookup_object(sha1);
	if (!obj)
		return create_object(sha1, alloc_tag_node());
	return object_as_type(obj, OBJ_TAG, 0);
}

static unsigned long parse_tag_date(const char *buf, const char *tail)
{
	const char *dateptr;

	while (buf < tail && *buf++ != '>')
		/* nada */;
	if (buf >= tail)
		return 0;
	dateptr = buf;
	while (buf < tail && *buf++ != '\n')
		/* nada */;
	if (buf >= tail)
		return 0;
	/* dateptr < buf && buf[-1] == '\n', so strtoul will stop at buf-1 */
	return strtoul(dateptr, NULL, 10);
}

int parse_tag_buffer(struct tag *item, const void *data, unsigned long size)
{
	unsigned char sha1[20];
	char type[20];
	const char *bufptr = data;
	const char *tail = bufptr + size;
	const char *nl;

	if (item->object.parsed)
		return 0;
	item->object.parsed = 1;

	if (size < 64)
		return -1;
	if (memcmp("object ", bufptr, 7) || get_sha1_hex(bufptr + 7, sha1) || bufptr[47] != '\n')
		return -1;
	bufptr += 48; /* "object " + sha1 + "\n" */

	if (!starts_with(bufptr, "type "))
		return -1;
	bufptr += 5;
	nl = memchr(bufptr, '\n', tail - bufptr);
	if (!nl || sizeof(type) <= (nl - bufptr))
		return -1;
	strncpy(type, bufptr, nl - bufptr);
	type[nl - bufptr] = '\0';
	bufptr = nl + 1;

	if (!strcmp(type, blob_type)) {
		item->tagged = &lookup_blob(sha1)->object;
	} else if (!strcmp(type, tree_type)) {
		item->tagged = &lookup_tree(sha1)->object;
	} else if (!strcmp(type, commit_type)) {
		item->tagged = &lookup_commit(sha1)->object;
	} else if (!strcmp(type, tag_type)) {
		item->tagged = &lookup_tag(sha1)->object;
	} else {
		error("Unknown type %s", type);
		item->tagged = NULL;
	}

	if (bufptr + 4 < tail && starts_with(bufptr, "tag "))
		; 		/* good */
	else
		return -1;
	bufptr += 4;
	nl = memchr(bufptr, '\n', tail - bufptr);
	if (!nl)
		return -1;
	item->tag = xmemdupz(bufptr, nl - bufptr);
	bufptr = nl + 1;

	if (bufptr + 7 < tail && starts_with(bufptr, "tagger "))
		item->date = parse_tag_date(bufptr, tail);
	else
		item->date = 0;

	return 0;
}

int parse_tag(struct tag *item)
{
	enum object_type type;
	void *data;
	unsigned long size;
	int ret;

	if (item->object.parsed)
		return 0;
	data = read_sha1_file(item->object.sha1, &type, &size);
	if (!data)
		return error("Could not read %s",
			     sha1_to_hex(item->object.sha1));
	if (type != OBJ_TAG) {
		free(data);
		return error("Object %s not a tag",
			     sha1_to_hex(item->object.sha1));
	}
	ret = parse_tag_buffer(item, data, size);
	free(data);
	return ret;
}
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