Add support for ETag in 'plain' view

When downloading a blob identified by its path, the client might want
to know if the blob has been modified since a previous download of the
same path. To this end, an ETag containing the blob SHA1 seems to be
ideal.

Todo: add support for HEAD requests...

Suggested-by: Owen Taylor <otaylor@redhat.com>
Signed-off-by: Lars Hjemli <hjemli@gmail.com>

4 files changed, 5 insertions, 0 deletions

diff --git a/cgit.c b/cgit.c
index 64d95f9..411e421 100644
--- a/cgit.c
+++ b/cgit.c
@@ -113,192 +113,193 @@ void config_cb(const char *name, const char *value)
 		ctx.repo->defbranch = xstrdup(value);
 	else if (ctx.repo && !strcmp(name, "repo.snapshots"))
 		ctx.repo->snapshots = ctx.cfg.snapshots & cgit_parse_snapshots_mask(value); /* XXX: &? */
 	else if (ctx.repo && !strcmp(name, "repo.enable-log-filecount"))
 		ctx.repo->enable_log_filecount = ctx.cfg.enable_log_filecount * atoi(value);
 	else if (ctx.repo && !strcmp(name, "repo.enable-log-linecount"))
 		ctx.repo->enable_log_linecount = ctx.cfg.enable_log_linecount * atoi(value);
 	else if (ctx.repo && !strcmp(name, "repo.max-stats"))
 		ctx.repo->max_stats = cgit_find_stats_period(value, NULL);
 	else if (ctx.repo && !strcmp(name, "repo.module-link"))
 		ctx.repo->module_link= xstrdup(value);
 	else if (ctx.repo && !strcmp(name, "repo.readme") && value != NULL) {
 		if (*value == '/')
 			ctx.repo->readme = xstrdup(value);
 		else
 			ctx.repo->readme = xstrdup(fmt("%s/%s", ctx.repo->path, value));
 	} else if (!strcmp(name, "include"))
 		parse_configfile(value, config_cb);
 }
 
 static void querystring_cb(const char *name, const char *value)
 {
 	if (!strcmp(name,"r")) {
 		ctx.qry.repo = xstrdup(value);
 		ctx.repo = cgit_get_repoinfo(value);
 	} else if (!strcmp(name, "p")) {
 		ctx.qry.page = xstrdup(value);
 	} else if (!strcmp(name, "url")) {
 		ctx.qry.url = xstrdup(value);
 		cgit_parse_url(value);
 	} else if (!strcmp(name, "qt")) {
 		ctx.qry.grep = xstrdup(value);
 	} else if (!strcmp(name, "q")) {
 		ctx.qry.search = xstrdup(value);
 	} else if (!strcmp(name, "h")) {
 		ctx.qry.head = xstrdup(value);
 		ctx.qry.has_symref = 1;
 	} else if (!strcmp(name, "id")) {
 		ctx.qry.sha1 = xstrdup(value);
 		ctx.qry.has_sha1 = 1;
 	} else if (!strcmp(name, "id2")) {
 		ctx.qry.sha2 = xstrdup(value);
 		ctx.qry.has_sha1 = 1;
 	} else if (!strcmp(name, "ofs")) {
 		ctx.qry.ofs = atoi(value);
 	} else if (!strcmp(name, "path")) {
 		ctx.qry.path = trim_end(value, '/');
 	} else if (!strcmp(name, "name")) {
 		ctx.qry.name = xstrdup(value);
 	} else if (!strcmp(name, "mimetype")) {
 		ctx.qry.mimetype = xstrdup(value);
 	} else if (!strcmp(name, "s")){
 		ctx.qry.sort = xstrdup(value);
 	} else if (!strcmp(name, "showmsg")) {
 		ctx.qry.showmsg = atoi(value);
 	} else if (!strcmp(name, "period")) {
 		ctx.qry.period = xstrdup(value);
 	}
 }
 
 static void prepare_context(struct cgit_context *ctx)
 {
 	memset(ctx, 0, sizeof(ctx));
 	ctx->cfg.agefile = "info/web/last-modified";
 	ctx->cfg.nocache = 0;
 	ctx->cfg.cache_size = 0;
 	ctx->cfg.cache_dynamic_ttl = 5;
 	ctx->cfg.cache_max_create_time = 5;
 	ctx->cfg.cache_repo_ttl = 5;
 	ctx->cfg.cache_root = CGIT_CACHE_ROOT;
 	ctx->cfg.cache_root_ttl = 5;
 	ctx->cfg.cache_static_ttl = -1;
 	ctx->cfg.css = "/cgit.css";
 	ctx->cfg.logo = "/git-logo.png";
 	ctx->cfg.local_time = 0;
 	ctx->cfg.max_repo_count = 50;
 	ctx->cfg.max_commit_count = 50;
 	ctx->cfg.max_lock_attempts = 5;
 	ctx->cfg.max_msg_len = 80;
 	ctx->cfg.max_repodesc_len = 80;
 	ctx->cfg.max_stats = 0;
 	ctx->cfg.module_link = "./?repo=%s&page=commit&id=%s";
 	ctx->cfg.renamelimit = -1;
 	ctx->cfg.robots = "index, nofollow";
 	ctx->cfg.root_title = "Git repository browser";
 	ctx->cfg.root_desc = "a fast webinterface for the git dscm";
 	ctx->cfg.script_name = CGIT_SCRIPT_NAME;
 	ctx->cfg.summary_branches = 10;
 	ctx->cfg.summary_log = 10;
 	ctx->cfg.summary_tags = 10;
 	ctx->page.mimetype = "text/html";
 	ctx->page.charset = PAGE_ENCODING;
 	ctx->page.filename = NULL;
 	ctx->page.size = 0;
 	ctx->page.modified = time(NULL);
 	ctx->page.expires = ctx->page.modified;
+	ctx->page.etag = NULL;
 }
 
 struct refmatch {
 	char *req_ref;
 	char *first_ref;
 	int match;
 };
 
 int find_current_ref(const char *refname, const unsigned char *sha1,
 		     int flags, void *cb_data)
 {
 	struct refmatch *info;
 
 	info = (struct refmatch *)cb_data;
 	if (!strcmp(refname, info->req_ref))
 		info->match = 1;
 	if (!info->first_ref)
 		info->first_ref = xstrdup(refname);
 	return info->match;
 }
 
 char *find_default_branch(struct cgit_repo *repo)
 {
 	struct refmatch info;
 	char *ref;
 
 	info.req_ref = repo->defbranch;
 	info.first_ref = NULL;
 	info.match = 0;
 	for_each_branch_ref(find_current_ref, &info);
 	if (info.match)
 		ref = info.req_ref;
 	else
 		ref = info.first_ref;
 	if (ref)
 		ref = xstrdup(ref);
 	return ref;
 }
 
 static int prepare_repo_cmd(struct cgit_context *ctx)
 {
 	char *tmp;
 	unsigned char sha1[20];
 	int nongit = 0;
 
 	setenv("GIT_DIR", ctx->repo->path, 1);
 	setup_git_directory_gently(&nongit);
 	if (nongit) {
 		ctx->page.title = fmt("%s - %s", ctx->cfg.root_title,
 				      "config error");
 		tmp = fmt("Not a git repository: '%s'", ctx->repo->path);
 		ctx->repo = NULL;
 		cgit_print_http_headers(ctx);
 		cgit_print_docstart(ctx);
 		cgit_print_pageheader(ctx);
 		cgit_print_error(tmp);
 		cgit_print_docend();
 		return 1;
 	}
 	ctx->page.title = fmt("%s - %s", ctx->repo->name, ctx->repo->desc);
 
 	if (!ctx->qry.head) {
 		ctx->qry.nohead = 1;
 		ctx->qry.head = find_default_branch(ctx->repo);
 		ctx->repo->defbranch = ctx->qry.head;
 	}
 
 	if (!ctx->qry.head) {
 		cgit_print_http_headers(ctx);
 		cgit_print_docstart(ctx);
 		cgit_print_pageheader(ctx);
 		cgit_print_error("Repository seems to be empty");
 		cgit_print_docend();
 		return 1;
 	}
 
 	if (get_sha1(ctx->qry.head, sha1)) {
 		tmp = xstrdup(ctx->qry.head);
 		ctx->qry.head = ctx->repo->defbranch;
 		cgit_print_http_headers(ctx);
 		cgit_print_docstart(ctx);
 		cgit_print_pageheader(ctx);
 		cgit_print_error(fmt("Invalid branch: %s", tmp));
 		cgit_print_docend();
 		return 1;
 	}
 	return 0;
 }
 
 static void process_request(void *cbdata)
 {
 	struct cgit_context *ctx = cbdata;
 	struct cgit_cmd *cmd;
 
 	cmd = cgit_get_cmd(ctx);
 	if (!cmd) {
diff --git a/cgit.h b/cgit.h
index 5f7af51..2bfbe7b 100644
--- a/cgit.h
+++ b/cgit.h
@@ -87,160 +87,161 @@ struct commitinfo {
 
 struct taginfo {
 	char *tagger;
 	char *tagger_email;
 	unsigned long tagger_date;
 	char *msg;
 };
 
 struct refinfo {
 	const char *refname;
 	struct object *object;
 	union {
 		struct taginfo *tag;
 		struct commitinfo *commit;
 	};
 };
 
 struct reflist {
 	struct refinfo **refs;
 	int alloc;
 	int count;
 };
 
 struct cgit_query {
 	int has_symref;
 	int has_sha1;
 	char *raw;
 	char *repo;
 	char *page;
 	char *search;
 	char *grep;
 	char *head;
 	char *sha1;
 	char *sha2;
 	char *path;
 	char *name;
 	char *mimetype;
 	char *url;
 	char *period;
 	int   ofs;
 	int nohead;
 	char *sort;
 	int showmsg;
 };
 
 struct cgit_config {
 	char *agefile;
 	char *cache_root;
 	char *clone_prefix;
 	char *css;
 	char *favicon;
 	char *footer;
 	char *header;
 	char *index_header;
 	char *index_info;
 	char *logo;
 	char *logo_link;
 	char *module_link;
 	char *repo_group;
 	char *robots;
 	char *root_title;
 	char *root_desc;
 	char *root_readme;
 	char *script_name;
 	char *virtual_root;
 	int cache_size;
 	int cache_dynamic_ttl;
 	int cache_max_create_time;
 	int cache_repo_ttl;
 	int cache_root_ttl;
 	int cache_static_ttl;
 	int enable_index_links;
 	int enable_log_filecount;
 	int enable_log_linecount;
 	int local_time;
 	int max_repo_count;
 	int max_commit_count;
 	int max_lock_attempts;
 	int max_msg_len;
 	int max_repodesc_len;
 	int max_stats;
 	int nocache;
 	int renamelimit;
 	int snapshots;
 	int summary_branches;
 	int summary_log;
 	int summary_tags;
 };
 
 struct cgit_page {
 	time_t modified;
 	time_t expires;
 	size_t size;
 	char *mimetype;
 	char *charset;
 	char *filename;
+	char *etag;
 	char *title;
 };
 
 struct cgit_context {
 	struct cgit_query qry;
 	struct cgit_config cfg;
 	struct cgit_repo *repo;
 	struct cgit_page page;
 };
 
 struct cgit_snapshot_format {
 	const char *suffix;
 	const char *mimetype;
 	write_archive_fn_t write_func;
 	int bit;
 };
 
 extern const char *cgit_version;
 
 extern struct cgit_repolist cgit_repolist;
 extern struct cgit_context ctx;
 extern const struct cgit_snapshot_format cgit_snapshot_formats[];
 
 extern struct cgit_repo *cgit_add_repo(const char *url);
 extern struct cgit_repo *cgit_get_repoinfo(const char *url);
 extern void cgit_repo_config_cb(const char *name, const char *value);
 
 extern int chk_zero(int result, char *msg);
 extern int chk_positive(int result, char *msg);
 extern int chk_non_negative(int result, char *msg);
 
 extern char *trim_end(const char *str, char c);
 extern char *strlpart(char *txt, int maxlen);
 extern char *strrpart(char *txt, int maxlen);
 
 extern void cgit_add_ref(struct reflist *list, struct refinfo *ref);
 extern int cgit_refs_cb(const char *refname, const unsigned char *sha1,
 			int flags, void *cb_data);
 
 extern void *cgit_free_commitinfo(struct commitinfo *info);
 
 extern int cgit_diff_files(const unsigned char *old_sha1,
 			   const unsigned char *new_sha1,
 			   unsigned long *old_size, unsigned long *new_size,
 			   int *binary, linediff_fn fn);
 
 extern void cgit_diff_tree(const unsigned char *old_sha1,
 			   const unsigned char *new_sha1,
 			   filepair_fn fn, const char *prefix);
 
 extern void cgit_diff_commit(struct commit *commit, filepair_fn fn);
 
 extern char *fmt(const char *format,...);
 
 extern struct commitinfo *cgit_parse_commit(struct commit *commit);
 extern struct taginfo *cgit_parse_tag(struct tag *tag);
 extern void cgit_parse_url(const char *url);
 
 extern const char *cgit_repobasename(const char *reponame);
 
 extern int cgit_parse_snapshots_mask(const char *str);
 
 
 #endif /* CGIT_H */
diff --git a/ui-plain.c b/ui-plain.c
index 5addd9e..f73cd14 100644
--- a/ui-plain.c
+++ b/ui-plain.c
@@ -1,79 +1,80 @@
 /* ui-plain.c: functions for output of plain blobs by path
  *
  * Copyright (C) 2008 Lars Hjemli
  *
  * Licensed under GNU General Public License v2
  *   (see COPYING for full license text)
  */
 
 #include "cgit.h"
 #include "html.h"
 #include "ui-shared.h"
 
 char *curr_rev;
 char *match_path;
 int match;
 
 static void print_object(const unsigned char *sha1, const char *path)
 {
 	enum object_type type;
 	char *buf;
 	unsigned long size;
 
 	type = sha1_object_info(sha1, &size);
 	if (type == OBJ_BAD) {
 		html_status(404, "Not found", 0);
 		return;
 	}
 
 	buf = read_sha1_file(sha1, &type, &size);
 	if (!buf) {
 		html_status(404, "Not found", 0);
 		return;
 	}
 	ctx.page.mimetype = "text/plain";
 	ctx.page.filename = fmt("%s", path);
 	ctx.page.size = size;
+	ctx.page.etag = sha1_to_hex(sha1);
 	cgit_print_http_headers(&ctx);
 	html_raw(buf, size);
 	match = 1;
 }
 
 static int walk_tree(const unsigned char *sha1, const char *base, int baselen,
 		     const char *pathname, unsigned mode, int stage,
 		     void *cbdata)
 {
 	if (S_ISDIR(mode))
 		return READ_TREE_RECURSIVE;
 
 	if (S_ISREG(mode))
 		print_object(sha1, pathname);
 
 	return 0;
 }
 
 void cgit_print_plain(struct cgit_context *ctx)
 {
 	const char *rev = ctx->qry.sha1;
 	unsigned char sha1[20];
 	struct commit *commit;
 	const char *paths[] = {ctx->qry.path, NULL};
 
 	if (!rev)
 		rev = ctx->qry.head;
 
 	curr_rev = xstrdup(rev);
 	if (get_sha1(rev, sha1)) {
 		html_status(404, "Not found", 0);
 		return;
 	}
 	commit = lookup_commit_reference(sha1);
 	if (!commit || parse_commit(commit)) {
 		html_status(404, "Not found", 0);
 		return;
 	}
 	match_path = ctx->qry.path;
 	read_tree_recursive(commit->tree, NULL, 0, 0, paths, walk_tree, NULL);
 	if (!match)
 		html_status(404, "Not found", 0);
 }
diff --git a/ui-shared.c b/ui-shared.c
index de77bbf..86a7d29 100644
--- a/ui-shared.c
+++ b/ui-shared.c
@@ -375,192 +375,194 @@ void cgit_stats_link(char *name, char *title, char *class, char *head,
 	reporevlink("stats", name, title, class, head, NULL, path);
 }
 
 void cgit_object_link(struct object *obj)
 {
 	char *page, *shortrev, *fullrev, *name;
 
 	fullrev = sha1_to_hex(obj->sha1);
 	shortrev = xstrdup(fullrev);
 	shortrev[10] = '\0';
 	if (obj->type == OBJ_COMMIT) {
                 cgit_commit_link(fmt("commit %s...", shortrev), NULL, NULL,
 				 ctx.qry.head, fullrev);
 		return;
 	} else if (obj->type == OBJ_TREE)
 		page = "tree";
 	else if (obj->type == OBJ_TAG)
 		page = "tag";
 	else
 		page = "blob";
 	name = fmt("%s %s...", typename(obj->type), shortrev);
 	reporevlink(page, name, NULL, NULL, ctx.qry.head, fullrev, NULL);
 }
 
 void cgit_print_date(time_t secs, char *format, int local_time)
 {
 	char buf[64];
 	struct tm *time;
 
 	if (!secs)
 		return;
 	if(local_time)
 		time = localtime(&secs);
 	else
 		time = gmtime(&secs);
 	strftime(buf, sizeof(buf)-1, format, time);
 	html_txt(buf);
 }
 
 void cgit_print_age(time_t t, time_t max_relative, char *format)
 {
 	time_t now, secs;
 
 	if (!t)
 		return;
 	time(&now);
 	secs = now - t;
 
 	if (secs > max_relative && max_relative >= 0) {
 		cgit_print_date(t, format, ctx.cfg.local_time);
 		return;
 	}
 
 	if (secs < TM_HOUR * 2) {
 		htmlf("<span class='age-mins'>%.0f min.</span>",
 		      secs * 1.0 / TM_MIN);
 		return;
 	}
 	if (secs < TM_DAY * 2) {
 		htmlf("<span class='age-hours'>%.0f hours</span>",
 		      secs * 1.0 / TM_HOUR);
 		return;
 	}
 	if (secs < TM_WEEK * 2) {
 		htmlf("<span class='age-days'>%.0f days</span>",
 		      secs * 1.0 / TM_DAY);
 		return;
 	}
 	if (secs < TM_MONTH * 2) {
 		htmlf("<span class='age-weeks'>%.0f weeks</span>",
 		      secs * 1.0 / TM_WEEK);
 		return;
 	}
 	if (secs < TM_YEAR * 2) {
 		htmlf("<span class='age-months'>%.0f months</span>",
 		      secs * 1.0 / TM_MONTH);
 		return;
 	}
 	htmlf("<span class='age-years'>%.0f years</span>",
 	      secs * 1.0 / TM_YEAR);
 }
 
 void cgit_print_http_headers(struct cgit_context *ctx)
 {
 	if (ctx->page.mimetype && ctx->page.charset)
 		htmlf("Content-Type: %s; charset=%s\n", ctx->page.mimetype,
 		      ctx->page.charset);
 	else if (ctx->page.mimetype)
 		htmlf("Content-Type: %s\n", ctx->page.mimetype);
 	if (ctx->page.size)
 		htmlf("Content-Length: %ld\n", ctx->page.size);
 	if (ctx->page.filename)
 		htmlf("Content-Disposition: inline; filename=\"%s\"\n",
 		      ctx->page.filename);
 	htmlf("Last-Modified: %s\n", http_date(ctx->page.modified));
 	htmlf("Expires: %s\n", http_date(ctx->page.expires));
+	if (ctx->page.etag)
+		htmlf("ETag: \"%s\"\n", ctx->page.etag);
 	html("\n");
 }
 
 void cgit_print_docstart(struct cgit_context *ctx)
 {
 	char *host = cgit_hosturl();
 	html(cgit_doctype);
 	html("<html xmlns='http://www.w3.org/1999/xhtml' xml:lang='en' lang='en'>\n");
 	html("<head>\n");
 	html("<title>");
 	html_txt(ctx->page.title);
 	html("</title>\n");
 	htmlf("<meta name='generator' content='cgit %s'/>\n", cgit_version);
 	if (ctx->cfg.robots && *ctx->cfg.robots)
 		htmlf("<meta name='robots' content='%s'/>\n", ctx->cfg.robots);
 	html("<link rel='stylesheet' type='text/css' href='");
 	html_attr(ctx->cfg.css);
 	html("'/>\n");
 	if (ctx->cfg.favicon) {
 		html("<link rel='shortcut icon' href='");
 		html_attr(ctx->cfg.favicon);
 		html("'/>\n");
 	}
 	if (host && ctx->repo) {
 		html("<link rel='alternate' title='Atom feed' href='http://");
 		html_attr(cgit_hosturl());
 		html_attr(cgit_fileurl(ctx->repo->url, "atom", ctx->qry.path,
 				       fmt("h=%s", ctx->qry.head)));
 		html("' type='application/atom+xml'/>");
 	}
 	html("</head>\n");
 	html("<body>\n");
 	if (ctx->cfg.header)
 		html_include(ctx->cfg.header);
 }
 
 void cgit_print_docend()
 {
 	html("</div>");
 	if (ctx.cfg.footer)
 		html_include(ctx.cfg.footer);
 	else {
 		htmlf("<div class='footer'>generated  by cgit %s at ",
 			cgit_version);
 		cgit_print_date(time(NULL), FMT_LONGDATE, ctx.cfg.local_time);
 		html("</div>\n");
 	}
 	html("</body>\n</html>\n");
 }
 
 int print_branch_option(const char *refname, const unsigned char *sha1,
 			int flags, void *cb_data)
 {
 	char *name = (char *)refname;
 	html_option(name, name, ctx.qry.head);
 	return 0;
 }
 
 int print_archive_ref(const char *refname, const unsigned char *sha1,
 		       int flags, void *cb_data)
 {
 	struct tag *tag;
 	struct taginfo *info;
 	struct object *obj;
 	char buf[256], *url;
 	unsigned char fileid[20];
 	int *header = (int *)cb_data;
 
 	if (prefixcmp(refname, "refs/archives"))
 		return 0;
 	strncpy(buf, refname+14, sizeof(buf));
 	obj = parse_object(sha1);
 	if (!obj)
 		return 1;
 	if (obj->type == OBJ_TAG) {
 		tag = lookup_tag(sha1);
 		if (!tag || parse_tag(tag) || !(info = cgit_parse_tag(tag)))
 			return 0;
 		hashcpy(fileid, tag->tagged->sha1);
 	} else if (obj->type != OBJ_BLOB) {
 		return 0;
 	} else {
 		hashcpy(fileid, sha1);
 	}
 	if (!*header) {
 		html("<h1>download</h1>\n");
 		*header = 1;
 	}
 	url = cgit_pageurl(ctx.qry.repo, "blob",
 			   fmt("id=%s&amp;path=%s", sha1_to_hex(fileid),
 			       buf));
 	html_link_open(url, NULL, "menu");
 	html_txt(strlpart(buf, 20));
 	html_link_close();
 	return 0;
 }