Squashed 'third_party/git/' content from commit cb71568594

git-subtree-dir: third_party/git
git-subtree-split: cb715685942260375e1eb8153b0768a376e4ece7

1 files changed, 367 insertions, 0 deletions

diff --git a/server-info.c b/server-info.c
new file mode 100644
index 000000000000..4d8199b1d916
--- /dev/null
+++ b/server-info.c
@@ -0,0 +1,367 @@
+#include "cache.h"
+#include "dir.h"
+#include "repository.h"
+#include "refs.h"
+#include "object.h"
+#include "commit.h"
+#include "tag.h"
+#include "packfile.h"
+#include "object-store.h"
+#include "strbuf.h"
+
+struct update_info_ctx {
+	FILE *cur_fp;
+	FILE *old_fp; /* becomes NULL if it differs from cur_fp */
+	struct strbuf cur_sb;
+	struct strbuf old_sb;
+};
+
+static void uic_mark_stale(struct update_info_ctx *uic)
+{
+	fclose(uic->old_fp);
+	uic->old_fp = NULL;
+}
+
+static int uic_is_stale(const struct update_info_ctx *uic)
+{
+	return uic->old_fp == NULL;
+}
+
+static int uic_printf(struct update_info_ctx *uic, const char *fmt, ...)
+{
+	va_list ap;
+	int ret = -1;
+
+	va_start(ap, fmt);
+
+	if (uic_is_stale(uic)) {
+		ret = vfprintf(uic->cur_fp, fmt, ap);
+	} else {
+		ssize_t r;
+		struct strbuf *cur = &uic->cur_sb;
+		struct strbuf *old = &uic->old_sb;
+
+		strbuf_reset(cur);
+		strbuf_vinsertf(cur, 0, fmt, ap);
+
+		strbuf_reset(old);
+		strbuf_grow(old, cur->len);
+		r = fread(old->buf, 1, cur->len, uic->old_fp);
+		if (r != cur->len || memcmp(old->buf, cur->buf, r))
+			uic_mark_stale(uic);
+
+		if (fwrite(cur->buf, 1, cur->len, uic->cur_fp) == cur->len)
+			ret = 0;
+	}
+
+	va_end(ap);
+
+	return ret;
+}
+
+/*
+ * Create the file "path" by writing to a temporary file and renaming
+ * it into place. The contents of the file come from "generate", which
+ * should return non-zero if it encounters an error.
+ */
+static int update_info_file(char *path,
+			int (*generate)(struct update_info_ctx *),
+			int force)
+{
+	char *tmp = mkpathdup("%s_XXXXXX", path);
+	int ret = -1;
+	int fd = -1;
+	FILE *to_close;
+	struct update_info_ctx uic = {
+		.cur_fp = NULL,
+		.old_fp = NULL,
+		.cur_sb = STRBUF_INIT,
+		.old_sb = STRBUF_INIT
+	};
+
+	safe_create_leading_directories(path);
+	fd = git_mkstemp_mode(tmp, 0666);
+	if (fd < 0)
+		goto out;
+	to_close = uic.cur_fp = fdopen(fd, "w");
+	if (!uic.cur_fp)
+		goto out;
+	fd = -1;
+
+	/* no problem on ENOENT and old_fp == NULL, it's stale, now */
+	if (!force)
+		uic.old_fp = fopen_or_warn(path, "r");
+
+	/*
+	 * uic_printf will compare incremental comparison aginst old_fp
+	 * and mark uic as stale if needed
+	 */
+	ret = generate(&uic);
+	if (ret)
+		goto out;
+
+	/* new file may be shorter than the old one, check here */
+	if (!uic_is_stale(&uic)) {
+		struct stat st;
+		long new_len = ftell(uic.cur_fp);
+		int old_fd = fileno(uic.old_fp);
+
+		if (new_len < 0) {
+			ret = -1;
+			goto out;
+		}
+		if (fstat(old_fd, &st) || (st.st_size != (size_t)new_len))
+			uic_mark_stale(&uic);
+	}
+
+	uic.cur_fp = NULL;
+	if (fclose(to_close))
+		goto out;
+
+	if (uic_is_stale(&uic)) {
+		if (adjust_shared_perm(tmp) < 0)
+			goto out;
+		if (rename(tmp, path) < 0)
+			goto out;
+	} else {
+		unlink(tmp);
+	}
+	ret = 0;
+
+out:
+	if (ret) {
+		error_errno("unable to update %s", path);
+		if (uic.cur_fp)
+			fclose(uic.cur_fp);
+		else if (fd >= 0)
+			close(fd);
+		unlink(tmp);
+	}
+	free(tmp);
+	if (uic.old_fp)
+		fclose(uic.old_fp);
+	strbuf_release(&uic.old_sb);
+	strbuf_release(&uic.cur_sb);
+	return ret;
+}
+
+static int add_info_ref(const char *path, const struct object_id *oid,
+			int flag, void *cb_data)
+{
+	struct update_info_ctx *uic = cb_data;
+	struct object *o = parse_object(the_repository, oid);
+	if (!o)
+		return -1;
+
+	if (uic_printf(uic, "%s	%s\n", oid_to_hex(oid), path) < 0)
+		return -1;
+
+	if (o->type == OBJ_TAG) {
+		o = deref_tag(the_repository, o, path, 0);
+		if (o)
+			if (uic_printf(uic, "%s	%s^{}\n",
+				oid_to_hex(&o->oid), path) < 0)
+				return -1;
+	}
+	return 0;
+}
+
+static int generate_info_refs(struct update_info_ctx *uic)
+{
+	return for_each_ref(add_info_ref, uic);
+}
+
+static int update_info_refs(int force)
+{
+	char *path = git_pathdup("info/refs");
+	int ret = update_info_file(path, generate_info_refs, force);
+	free(path);
+	return ret;
+}
+
+/* packs */
+static struct pack_info {
+	struct packed_git *p;
+	int old_num;
+	int new_num;
+} **info;
+static int num_pack;
+
+static struct pack_info *find_pack_by_name(const char *name)
+{
+	int i;
+	for (i = 0; i < num_pack; i++) {
+		struct packed_git *p = info[i]->p;
+		if (!strcmp(pack_basename(p), name))
+			return info[i];
+	}
+	return NULL;
+}
+
+/* Returns non-zero when we detect that the info in the
+ * old file is useless.
+ */
+static int parse_pack_def(const char *packname, int old_cnt)
+{
+	struct pack_info *i = find_pack_by_name(packname);
+	if (i) {
+		i->old_num = old_cnt;
+		return 0;
+	}
+	else {
+		/* The file describes a pack that is no longer here */
+		return 1;
+	}
+}
+
+/* Returns non-zero when we detect that the info in the
+ * old file is useless.
+ */
+static int read_pack_info_file(const char *infofile)
+{
+	FILE *fp;
+	struct strbuf line = STRBUF_INIT;
+	int old_cnt = 0;
+	int stale = 1;
+
+	fp = fopen_or_warn(infofile, "r");
+	if (!fp)
+		return 1; /* nonexistent is not an error. */
+
+	while (strbuf_getline(&line, fp) != EOF) {
+		const char *arg;
+
+		if (!line.len)
+			continue;
+
+		if (skip_prefix(line.buf, "P ", &arg)) {
+			/* P name */
+			if (parse_pack_def(arg, old_cnt++))
+				goto out_stale;
+		} else if (line.buf[0] == 'D') {
+			/* we used to emit D but that was misguided. */
+			goto out_stale;
+		} else if (line.buf[0] == 'T') {
+			/* we used to emit T but nobody uses it. */
+			goto out_stale;
+		} else {
+			error("unrecognized: %s", line.buf);
+		}
+	}
+	stale = 0;
+
+ out_stale:
+	strbuf_release(&line);
+	fclose(fp);
+	return stale;
+}
+
+static int compare_info(const void *a_, const void *b_)
+{
+	struct pack_info *const *a = a_;
+	struct pack_info *const *b = b_;
+
+	if (0 <= (*a)->old_num && 0 <= (*b)->old_num)
+		/* Keep the order in the original */
+		return (*a)->old_num - (*b)->old_num;
+	else if (0 <= (*a)->old_num)
+		/* Only A existed in the original so B is obviously newer */
+		return -1;
+	else if (0 <= (*b)->old_num)
+		/* The other way around. */
+		return 1;
+
+	/* then it does not matter but at least keep the comparison stable */
+	if ((*a)->p == (*b)->p)
+		return 0;
+	else if ((*a)->p < (*b)->p)
+		return -1;
+	else
+		return 1;
+}
+
+static void init_pack_info(const char *infofile, int force)
+{
+	struct packed_git *p;
+	int stale;
+	int i;
+	size_t alloc = 0;
+
+	for (p = get_all_packs(the_repository); p; p = p->next) {
+		/* we ignore things on alternate path since they are
+		 * not available to the pullers in general.
+		 */
+		if (!p->pack_local || !file_exists(p->pack_name))
+			continue;
+
+		i = num_pack++;
+		ALLOC_GROW(info, num_pack, alloc);
+		info[i] = xcalloc(1, sizeof(struct pack_info));
+		info[i]->p = p;
+		info[i]->old_num = -1;
+	}
+
+	if (infofile && !force)
+		stale = read_pack_info_file(infofile);
+	else
+		stale = 1;
+
+	for (i = 0; i < num_pack; i++)
+		if (stale)
+			info[i]->old_num = -1;
+
+	/* renumber them */
+	QSORT(info, num_pack, compare_info);
+	for (i = 0; i < num_pack; i++)
+		info[i]->new_num = i;
+}
+
+static void free_pack_info(void)
+{
+	int i;
+	for (i = 0; i < num_pack; i++)
+		free(info[i]);
+	free(info);
+}
+
+static int write_pack_info_file(struct update_info_ctx *uic)
+{
+	int i;
+	for (i = 0; i < num_pack; i++) {
+		if (uic_printf(uic, "P %s\n", pack_basename(info[i]->p)) < 0)
+			return -1;
+	}
+	if (uic_printf(uic, "\n") < 0)
+		return -1;
+	return 0;
+}
+
+static int update_info_packs(int force)
+{
+	char *infofile = mkpathdup("%s/info/packs", get_object_directory());
+	int ret;
+
+	init_pack_info(infofile, force);
+	ret = update_info_file(infofile, write_pack_info_file, force);
+	free_pack_info();
+	free(infofile);
+	return ret;
+}
+
+/* public */
+int update_server_info(int force)
+{
+	/* We would add more dumb-server support files later,
+	 * including index of available pack files and their
+	 * intended audiences.
+	 */
+	int errs = 0;
+
+	errs = errs | update_info_refs(force);
+	errs = errs | update_info_packs(force);
+
+	/* remove leftover rev-cache file if there is any */
+	unlink_or_warn(git_path("info/rev-cache"));
+
+	return errs;
+}