Add support for environment variable expansion

This patch teaches cgit to expand environment variables in certain
cgitrc option values (cache_root, scan-path, include) plus when
finding the location of cgitrc itself.

One use case for this feature is virtual hosting - e.g. by setting
$CGIT_CONFIG='/etc/cgitrc/$HTTP_HOST' in httpd.conf, all virtual
hosts automatically gets their own cgitrc.

Signed-off-by: Lars Hjemli <hjemli@gmail.com>

3 files changed, 78 insertions, 5 deletions

diff --git a/cgit.c b/cgit.c
index 9305d0a..37154e3 100644
--- a/cgit.c
+++ b/cgit.c
@@ -1,732 +1,732 @@
 /* cgit.c: cgi for the git scm
  *
  * Copyright (C) 2006 Lars Hjemli
  *
  * Licensed under GNU General Public License v2
  *   (see COPYING for full license text)
  */
 
 #include "cgit.h"
 #include "cache.h"
 #include "cmd.h"
 #include "configfile.h"
 #include "html.h"
 #include "ui-shared.h"
 #include "ui-stats.h"
 #include "scan-tree.h"
 
 const char *cgit_version = CGIT_VERSION;
 
 void add_mimetype(const char *name, const char *value)
 {
         struct string_list_item *item;
 
         item = string_list_insert(xstrdup(name), &ctx.cfg.mimetypes);
         item->util = xstrdup(value);
 }
 
 struct cgit_filter *new_filter(const char *cmd, int extra_args)
 {
         struct cgit_filter *f;
 
         if (!cmd || !cmd[0])
                 return NULL;
 
         f = xmalloc(sizeof(struct cgit_filter));
         f->cmd = xstrdup(cmd);
         f->argv = xmalloc((2 + extra_args) * sizeof(char *));
         f->argv[0] = f->cmd;
         f->argv[1] = NULL;
         return f;
 }
 
 static void process_cached_repolist(const char *path);
 
 void repo_config(struct cgit_repo *repo, const char *name, const char *value)
 {
         if (!strcmp(name, "name"))
                 repo->name = xstrdup(value);
         else if (!strcmp(name, "clone-url"))
                 repo->clone_url = xstrdup(value);
         else if (!strcmp(name, "desc"))
                 repo->desc = xstrdup(value);
         else if (!strcmp(name, "owner"))
                 repo->owner = xstrdup(value);
         else if (!strcmp(name, "defbranch"))
                 repo->defbranch = xstrdup(value);
         else if (!strcmp(name, "snapshots"))
                 repo->snapshots = ctx.cfg.snapshots & cgit_parse_snapshots_mask(value);
         else if (!strcmp(name, "enable-log-filecount"))
                 repo->enable_log_filecount = ctx.cfg.enable_log_filecount * atoi(value);
         else if (!strcmp(name, "enable-log-linecount"))
                 repo->enable_log_linecount = ctx.cfg.enable_log_linecount * atoi(value);
         else if (!strcmp(name, "enable-remote-branches"))
                 repo->enable_remote_branches = atoi(value);
         else if (!strcmp(name, "max-stats"))
                 repo->max_stats = cgit_find_stats_period(value, NULL);
         else if (!strcmp(name, "module-link"))
                 repo->module_link= xstrdup(value);
         else if (!strcmp(name, "section"))
                 repo->section = xstrdup(value);
         else if (!strcmp(name, "readme") && value != NULL) {
                 if (*value == '/')
                         repo->readme = xstrdup(value);
                 else
                         repo->readme = xstrdup(fmt("%s/%s", repo->path, value));
         } else if (ctx.cfg.enable_filter_overrides) {
                 if (!strcmp(name, "about-filter"))
                         repo->about_filter = new_filter(value, 0);
                 else if (!strcmp(name, "commit-filter"))
                         repo->commit_filter = new_filter(value, 0);
                 else if (!strcmp(name, "source-filter"))
                         repo->source_filter = new_filter(value, 1);
         }
 }
 
 void config_cb(const char *name, const char *value)
 {
         if (!strcmp(name, "section") || !strcmp(name, "repo.group"))
                 ctx.cfg.section = xstrdup(value);
         else if (!strcmp(name, "repo.url"))
                 ctx.repo = cgit_add_repo(value);
         else if (ctx.repo && !strcmp(name, "repo.path"))
                 ctx.repo->path = trim_end(value, '/');
         else if (ctx.repo && !prefixcmp(name, "repo."))
                 repo_config(ctx.repo, name + 5, value);
         else if (!strcmp(name, "root-title"))
                 ctx.cfg.root_title = xstrdup(value);
         else if (!strcmp(name, "root-desc"))
                 ctx.cfg.root_desc = xstrdup(value);
         else if (!strcmp(name, "root-readme"))
                 ctx.cfg.root_readme = xstrdup(value);
         else if (!strcmp(name, "css"))
                 ctx.cfg.css = xstrdup(value);
         else if (!strcmp(name, "favicon"))
                 ctx.cfg.favicon = xstrdup(value);
         else if (!strcmp(name, "footer"))
                 ctx.cfg.footer = xstrdup(value);
         else if (!strcmp(name, "head-include"))
                 ctx.cfg.head_include = xstrdup(value);
         else if (!strcmp(name, "header"))
                 ctx.cfg.header = xstrdup(value);
         else if (!strcmp(name, "logo"))
                 ctx.cfg.logo = xstrdup(value);
         else if (!strcmp(name, "index-header"))
                 ctx.cfg.index_header = xstrdup(value);
         else if (!strcmp(name, "index-info"))
                 ctx.cfg.index_info = xstrdup(value);
         else if (!strcmp(name, "logo-link"))
                 ctx.cfg.logo_link = xstrdup(value);
         else if (!strcmp(name, "module-link"))
                 ctx.cfg.module_link = xstrdup(value);
         else if (!strcmp(name, "virtual-root")) {
                 ctx.cfg.virtual_root = trim_end(value, '/');
                 if (!ctx.cfg.virtual_root && (!strcmp(value, "/")))
                         ctx.cfg.virtual_root = "";
         } else if (!strcmp(name, "nocache"))
                 ctx.cfg.nocache = atoi(value);
         else if (!strcmp(name, "noplainemail"))
                 ctx.cfg.noplainemail = atoi(value);
         else if (!strcmp(name, "noheader"))
                 ctx.cfg.noheader = atoi(value);
         else if (!strcmp(name, "snapshots"))
                 ctx.cfg.snapshots = cgit_parse_snapshots_mask(value);
         else if (!strcmp(name, "enable-filter-overrides"))
                 ctx.cfg.enable_filter_overrides = atoi(value);
         else if (!strcmp(name, "enable-index-links"))
                 ctx.cfg.enable_index_links = atoi(value);
         else if (!strcmp(name, "enable-log-filecount"))
                 ctx.cfg.enable_log_filecount = atoi(value);
         else if (!strcmp(name, "enable-log-linecount"))
                 ctx.cfg.enable_log_linecount = atoi(value);
         else if (!strcmp(name, "enable-remote-branches"))
                 ctx.cfg.enable_remote_branches = atoi(value);
         else if (!strcmp(name, "enable-tree-linenumbers"))
                 ctx.cfg.enable_tree_linenumbers = atoi(value);
         else if (!strcmp(name, "max-stats"))
                 ctx.cfg.max_stats = cgit_find_stats_period(value, NULL);
         else if (!strcmp(name, "cache-size"))
                 ctx.cfg.cache_size = atoi(value);
         else if (!strcmp(name, "cache-root"))
-                ctx.cfg.cache_root = xstrdup(value);
+                ctx.cfg.cache_root = xstrdup(expand_macros(value));
         else if (!strcmp(name, "cache-root-ttl"))
                 ctx.cfg.cache_root_ttl = atoi(value);
         else if (!strcmp(name, "cache-repo-ttl"))
                 ctx.cfg.cache_repo_ttl = atoi(value);
         else if (!strcmp(name, "cache-scanrc-ttl"))
                 ctx.cfg.cache_scanrc_ttl = atoi(value);
         else if (!strcmp(name, "cache-static-ttl"))
                 ctx.cfg.cache_static_ttl = atoi(value);
         else if (!strcmp(name, "cache-dynamic-ttl"))
                 ctx.cfg.cache_dynamic_ttl = atoi(value);
         else if (!strcmp(name, "about-filter"))
                 ctx.cfg.about_filter = new_filter(value, 0);
         else if (!strcmp(name, "commit-filter"))
                 ctx.cfg.commit_filter = new_filter(value, 0);
         else if (!strcmp(name, "embedded"))
                 ctx.cfg.embedded = atoi(value);
         else if (!strcmp(name, "max-message-length"))
                 ctx.cfg.max_msg_len = atoi(value);
         else if (!strcmp(name, "max-repodesc-length"))
                 ctx.cfg.max_repodesc_len = atoi(value);
         else if (!strcmp(name, "max-blob-size"))
                 ctx.cfg.max_blob_size = atoi(value);
         else if (!strcmp(name, "max-repo-count"))
                 ctx.cfg.max_repo_count = atoi(value);
         else if (!strcmp(name, "max-commit-count"))
                 ctx.cfg.max_commit_count = atoi(value);
         else if (!strcmp(name, "scan-path"))
                 if (!ctx.cfg.nocache && ctx.cfg.cache_size)
-                        process_cached_repolist(value);
+                        process_cached_repolist(expand_macros(value));
                 else
-                        scan_tree(value, repo_config);
+                        scan_tree(expand_macros(value), repo_config);
         else if (!strcmp(name, "source-filter"))
                 ctx.cfg.source_filter = new_filter(value, 1);
         else if (!strcmp(name, "summary-log"))
                 ctx.cfg.summary_log = atoi(value);
         else if (!strcmp(name, "summary-branches"))
                 ctx.cfg.summary_branches = atoi(value);
         else if (!strcmp(name, "summary-tags"))
                 ctx.cfg.summary_tags = atoi(value);
         else if (!strcmp(name, "side-by-side-diffs"))
                 ctx.cfg.ssdiff = atoi(value);
         else if (!strcmp(name, "agefile"))
                 ctx.cfg.agefile = xstrdup(value);
         else if (!strcmp(name, "renamelimit"))
                 ctx.cfg.renamelimit = atoi(value);
         else if (!strcmp(name, "robots"))
                 ctx.cfg.robots = xstrdup(value);
         else if (!strcmp(name, "clone-prefix"))
                 ctx.cfg.clone_prefix = xstrdup(value);
         else if (!strcmp(name, "local-time"))
                 ctx.cfg.local_time = atoi(value);
         else if (!prefixcmp(name, "mimetype."))
                 add_mimetype(name + 9, value);
         else if (!strcmp(name, "include"))
-                parse_configfile(value, config_cb);
+                parse_configfile(expand_macros(value), config_cb);
 }
 
 static void querystring_cb(const char *name, const char *value)
 {
         if (!value)
                 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")) {
                 if (*value == '/')
                         value++;
                 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);
         } else if (!strcmp(name, "ss")) {
                 ctx.qry.ssdiff = atoi(value);
         }
 }
 
 char *xstrdupn(const char *str)
 {
         return (str ? xstrdup(str) : NULL);
 }
 
 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_scanrc_ttl = 15;
         ctx->cfg.cache_static_ttl = -1;
         ctx->cfg.css = "/cgit.css";
         ctx->cfg.logo = "/cgit.png";
         ctx->cfg.local_time = 0;
         ctx->cfg.enable_tree_linenumbers = 1;
         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_blob_size = 0;
         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.section = "";
         ctx->cfg.summary_branches = 10;
         ctx->cfg.summary_log = 10;
         ctx->cfg.summary_tags = 10;
         ctx->cfg.ssdiff = 0;
         ctx->env.cgit_config = xstrdupn(getenv("CGIT_CONFIG"));
         ctx->env.http_host = xstrdupn(getenv("HTTP_HOST"));
         ctx->env.https = xstrdupn(getenv("HTTPS"));
         ctx->env.no_http = xstrdupn(getenv("NO_HTTP"));
         ctx->env.path_info = xstrdupn(getenv("PATH_INFO"));
         ctx->env.query_string = xstrdupn(getenv("QUERY_STRING"));
         ctx->env.request_method = xstrdupn(getenv("REQUEST_METHOD"));
         ctx->env.script_name = xstrdupn(getenv("SCRIPT_NAME"));
         ctx->env.server_name = xstrdupn(getenv("SERVER_NAME"));
         ctx->env.server_port = xstrdupn(getenv("SERVER_PORT"));
         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;
         memset(&ctx->cfg.mimetypes, 0, sizeof(struct string_list));
         if (ctx->env.script_name)
                 ctx->cfg.script_name = ctx->env.script_name;
         if (ctx->env.query_string)
                 ctx->qry.raw = ctx->env.query_string;
         if (!ctx->env.cgit_config)
                 ctx->env.cgit_config = CGIT_CONFIG;
 }
 
 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;
                 ctx->page.status = 404;
                 ctx->page.statusmsg = "not found";
                 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) {
                 ctx->page.title = "cgit error";
                 cgit_print_http_headers(ctx);
                 cgit_print_docstart(ctx);
                 cgit_print_pageheader(ctx);
                 cgit_print_error("Invalid request");
                 cgit_print_docend();
                 return;
         }
 
         if (cmd->want_repo && !ctx->repo) {
                 cgit_print_http_headers(ctx);
                 cgit_print_docstart(ctx);
                 cgit_print_pageheader(ctx);
                 cgit_print_error(fmt("No repository selected"));
                 cgit_print_docend();
                 return;
         }
 
         if (ctx->repo && prepare_repo_cmd(ctx))
                 return;
 
         if (cmd->want_layout) {
                 cgit_print_http_headers(ctx);
                 cgit_print_docstart(ctx);
                 cgit_print_pageheader(ctx);
         }
 
         cmd->fn(ctx);
 
         if (cmd->want_layout)
                 cgit_print_docend();
 }
 
 int cmp_repos(const void *a, const void *b)
 {
         const struct cgit_repo *ra = a, *rb = b;
         return strcmp(ra->url, rb->url);
 }
 
 char *build_snapshot_setting(int bitmap)
 {
         const struct cgit_snapshot_format *f;
         char *result = xstrdup("");
         char *tmp;
         int len;
 
         for (f = cgit_snapshot_formats; f->suffix; f++) {
                 if (f->bit & bitmap) {
                         tmp = result;
                         result = xstrdup(fmt("%s%s ", tmp, f->suffix));
                         free(tmp);
                 }
         }
         len = strlen(result);
         if (len)
                 result[len - 1] = '\0';
         return result;
 }
 
 char *get_first_line(char *txt)
 {
         char *t = xstrdup(txt);
         char *p = strchr(t, '\n');
         if (p)
                 *p = '\0';
         return t;
 }
 
 void print_repo(FILE *f, struct cgit_repo *repo)
 {
         fprintf(f, "repo.url=%s\n", repo->url);
         fprintf(f, "repo.name=%s\n", repo->name);
         fprintf(f, "repo.path=%s\n", repo->path);
         if (repo->owner)
                 fprintf(f, "repo.owner=%s\n", repo->owner);
         if (repo->desc) {
                 char *tmp = get_first_line(repo->desc);
                 fprintf(f, "repo.desc=%s\n", tmp);
                 free(tmp);
         }
         if (repo->readme)
                 fprintf(f, "repo.readme=%s\n", repo->readme);
         if (repo->defbranch)
                 fprintf(f, "repo.defbranch=%s\n", repo->defbranch);
         if (repo->module_link)
                 fprintf(f, "repo.module-link=%s\n", repo->module_link);
         if (repo->section)
                 fprintf(f, "repo.section=%s\n", repo->section);
         if (repo->clone_url)
                 fprintf(f, "repo.clone-url=%s\n", repo->clone_url);
         fprintf(f, "repo.enable-log-filecount=%d\n",
                 repo->enable_log_filecount);
         fprintf(f, "repo.enable-log-linecount=%d\n",
                 repo->enable_log_linecount);
         if (repo->about_filter && repo->about_filter != ctx.cfg.about_filter)
                 fprintf(f, "repo.about-filter=%s\n", repo->about_filter->cmd);
         if (repo->commit_filter && repo->commit_filter != ctx.cfg.commit_filter)
                 fprintf(f, "repo.commit-filter=%s\n", repo->commit_filter->cmd);
         if (repo->source_filter && repo->source_filter != ctx.cfg.source_filter)
                 fprintf(f, "repo.source-filter=%s\n", repo->source_filter->cmd);
         if (repo->snapshots != ctx.cfg.snapshots) {
                 char *tmp = build_snapshot_setting(repo->snapshots);
                 fprintf(f, "repo.snapshots=%s\n", tmp);
                 free(tmp);
         }
         if (repo->max_stats != ctx.cfg.max_stats)
                 fprintf(f, "repo.max-stats=%s\n",
                         cgit_find_stats_periodname(repo->max_stats));
         fprintf(f, "\n");
 }
 
 void print_repolist(FILE *f, struct cgit_repolist *list, int start)
 {
         int i;
 
         for(i = start; i < list->count; i++)
                 print_repo(f, &list->repos[i]);
 }
 
 /* Scan 'path' for git repositories, save the resulting repolist in 'cached_rc'
  * and return 0 on success.
  */
 static int generate_cached_repolist(const char *path, const char *cached_rc)
 {
         char *locked_rc;
         int idx;
         FILE *f;
 
         locked_rc = xstrdup(fmt("%s.lock", cached_rc));
         f = fopen(locked_rc, "wx");
         if (!f) {
                 /* Inform about the error unless the lockfile already existed,
                  * since that only means we've got concurrent requests.
                  */
                 if (errno != EEXIST)
                         fprintf(stderr, "[cgit] Error opening %s: %s (%d)\n",
                                 locked_rc, strerror(errno), errno);
                 return errno;
         }
         idx = cgit_repolist.count;
         scan_tree(path, repo_config);
         print_repolist(f, &cgit_repolist, idx);
         if (rename(locked_rc, cached_rc))
                 fprintf(stderr, "[cgit] Error renaming %s to %s: %s (%d)\n",
                         locked_rc, cached_rc, strerror(errno), errno);
         fclose(f);
         return 0;
 }
 
 static void process_cached_repolist(const char *path)
 {
         struct stat st;
         char *cached_rc;
         time_t age;
 
         cached_rc = xstrdup(fmt("%s/rc-%8x", ctx.cfg.cache_root,
                 hash_str(path)));
 
         if (stat(cached_rc, &st)) {
                 /* Nothing is cached, we need to scan without forking. And
                  * if we fail to generate a cached repolist, we need to
                  * invoke scan_tree manually.
                  */
                 if (generate_cached_repolist(path, cached_rc))
                         scan_tree(path, repo_config);
                 return;
         }
 
         parse_configfile(cached_rc, config_cb);
 
         /* If the cached configfile hasn't expired, lets exit now */
         age = time(NULL) - st.st_mtime;
         if (age <= (ctx.cfg.cache_scanrc_ttl * 60))
                 return;
 
         /* The cached repolist has been parsed, but it was old. So lets
          * rescan the specified path and generate a new cached repolist
          * in a child-process to avoid latency for the current request.
          */
         if (fork())
                 return;
 
         exit(generate_cached_repolist(path, cached_rc));
 }
 
 static void cgit_parse_args(int argc, const char **argv)
 {
         int i;
         int scan = 0;
 
         for (i = 1; i < argc; i++) {
                 if (!strncmp(argv[i], "--cache=", 8)) {
                         ctx.cfg.cache_root = xstrdup(argv[i]+8);
                 }
                 if (!strcmp(argv[i], "--nocache")) {
                         ctx.cfg.nocache = 1;
                 }
                 if (!strcmp(argv[i], "--nohttp")) {
                         ctx.env.no_http = "1";
                 }
                 if (!strncmp(argv[i], "--query=", 8)) {
                         ctx.qry.raw = xstrdup(argv[i]+8);
                 }
                 if (!strncmp(argv[i], "--repo=", 7)) {
                         ctx.qry.repo = xstrdup(argv[i]+7);
                 }
                 if (!strncmp(argv[i], "--page=", 7)) {
                         ctx.qry.page = xstrdup(argv[i]+7);
                 }
                 if (!strncmp(argv[i], "--head=", 7)) {
                         ctx.qry.head = xstrdup(argv[i]+7);
                         ctx.qry.has_symref = 1;
                 }
                 if (!strncmp(argv[i], "--sha1=", 7)) {
                         ctx.qry.sha1 = xstrdup(argv[i]+7);
                         ctx.qry.has_sha1 = 1;
                 }
                 if (!strncmp(argv[i], "--ofs=", 6)) {
                         ctx.qry.ofs = atoi(argv[i]+6);
                 }
                 if (!strncmp(argv[i], "--scan-tree=", 12) ||
                     !strncmp(argv[i], "--scan-path=", 12)) {
                         /* HACK: the global snapshot bitmask defines the
                          * set of allowed snapshot formats, but the config
                          * file hasn't been parsed yet so the mask is
                          * currently 0. By setting all bits high before
                          * scanning we make sure that any in-repo cgitrc
                          * snapshot setting is respected by scan_tree().
                          * BTW: we assume that there'll never be more than
                          * 255 different snapshot formats supported by cgit...
                          */
                         ctx.cfg.snapshots = 0xFF;
                         scan++;
                         scan_tree(argv[i] + 12, repo_config);
                 }
         }
         if (scan) {
                 qsort(cgit_repolist.repos, cgit_repolist.count,
                         sizeof(struct cgit_repo), cmp_repos);
                 print_repolist(stdout, &cgit_repolist, 0);
                 exit(0);
         }
 }
 
 static int calc_ttl()
 {
         if (!ctx.repo)
                 return ctx.cfg.cache_root_ttl;
 
         if (!ctx.qry.page)
                 return ctx.cfg.cache_repo_ttl;
 
         if (ctx.qry.has_symref)
                 return ctx.cfg.cache_dynamic_ttl;
 
         if (ctx.qry.has_sha1)
                 return ctx.cfg.cache_static_ttl;
 
         return ctx.cfg.cache_repo_ttl;
 }
 
 int main(int argc, const char **argv)
 {
         const char *path;
         char *qry;
         int err, ttl;
 
         prepare_context(&ctx);
         cgit_repolist.length = 0;
         cgit_repolist.count = 0;
         cgit_repolist.repos = NULL;
 
         cgit_parse_args(argc, argv);
-        parse_configfile(ctx.env.cgit_config, config_cb);
+        parse_configfile(expand_macros(ctx.env.cgit_config), config_cb);
         ctx.repo = NULL;
         http_parse_querystring(ctx.qry.raw, querystring_cb);
 
         /* If virtual-root isn't specified in cgitrc, lets pretend
          * that virtual-root equals SCRIPT_NAME.
          */
         if (!ctx.cfg.virtual_root)
                 ctx.cfg.virtual_root = ctx.cfg.script_name;
 
         /* If no url parameter is specified on the querystring, lets
          * use PATH_INFO as url. This allows cgit to work with virtual
          * urls without the need for rewriterules in the webserver (as
          * long as PATH_INFO is included in the cache lookup key).
          */
         path = ctx.env.path_info;
         if (!ctx.qry.url && path) {
                 if (path[0] == '/')
                         path++;
                 ctx.qry.url = xstrdup(path);
                 if (ctx.qry.raw) {
                         qry = ctx.qry.raw;
                         ctx.qry.raw = xstrdup(fmt("%s?%s", path, qry));
                         free(qry);
                 } else
                         ctx.qry.raw = xstrdup(ctx.qry.url);
                 cgit_parse_url(ctx.qry.url);
         }
 
         ttl = calc_ttl();
         ctx.page.expires += ttl*60;
         if (ctx.env.request_method && !strcmp(ctx.env.request_method, "HEAD"))
                 ctx.cfg.nocache = 1;
         if (ctx.cfg.nocache)
                 ctx.cfg.cache_size = 0;
         err = cache_process(ctx.cfg.cache_size, ctx.cfg.cache_root,
                             ctx.qry.raw, ttl, process_request, &ctx);
         if (err)
                 cgit_print_error(fmt("Error processing page: %s (%d)",
                                      strerror(err), err));
         return err;
 }
diff --git a/cgit.h b/cgit.h
index cd4af72..568e0c0 100644
--- a/cgit.h
+++ b/cgit.h
@@ -1,299 +1,301 @@
 #ifndef CGIT_H
 #define CGIT_H
 
 
 #include <git-compat-util.h>
 #include <cache.h>
 #include <grep.h>
 #include <object.h>
 #include <tree.h>
 #include <commit.h>
 #include <tag.h>
 #include <diff.h>
 #include <diffcore.h>
 #include <refs.h>
 #include <revision.h>
 #include <log-tree.h>
 #include <archive.h>
 #include <string-list.h>
 #include <xdiff-interface.h>
 #include <xdiff/xdiff.h>
 #include <utf8.h>
 
 
 /*
  * Dateformats used on misc. pages
  */
 #define FMT_LONGDATE "%Y-%m-%d %H:%M:%S (%Z)"
 #define FMT_SHORTDATE "%Y-%m-%d"
 #define FMT_ATOMDATE "%Y-%m-%dT%H:%M:%SZ"
 
 
 /*
  * Limits used for relative dates
  */
 #define TM_MIN    60
 #define TM_HOUR  (TM_MIN * 60)
 #define TM_DAY   (TM_HOUR * 24)
 #define TM_WEEK  (TM_DAY * 7)
 #define TM_YEAR  (TM_DAY * 365)
 #define TM_MONTH (TM_YEAR / 12.0)
 
 
 /*
  * Default encoding
  */
 #define PAGE_ENCODING "UTF-8"
 
 typedef void (*configfn)(const char *name, const char *value);
 typedef void (*filepair_fn)(struct diff_filepair *pair);
 typedef void (*linediff_fn)(char *line, int len);
 
 struct cgit_filter {
         char *cmd;
         char **argv;
         int old_stdout;
         int pipe_fh[2];
         int pid;
         int exitstatus;
 };
 
 struct cgit_repo {
         char *url;
         char *name;
         char *path;
         char *desc;
         char *owner;
         char *defbranch;
         char *module_link;
         char *readme;
         char *section;
         char *clone_url;
         int snapshots;
         int enable_log_filecount;
         int enable_log_linecount;
         int enable_remote_branches;
         int max_stats;
         time_t mtime;
         struct cgit_filter *about_filter;
         struct cgit_filter *commit_filter;
         struct cgit_filter *source_filter;
 };
 
 typedef void (*repo_config_fn)(struct cgit_repo *repo, const char *name,
               const char *value);
 
 struct cgit_repolist {
         int length;
         int count;
         struct cgit_repo *repos;
 };
 
 struct commitinfo {
         struct commit *commit;
         char *author;
         char *author_email;
         unsigned long author_date;
         char *committer;
         char *committer_email;
         unsigned long committer_date;
         char *subject;
         char *msg;
         char *msg_encoding;
 };
 
 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;
         int ssdiff;
 };
 
 struct cgit_config {
         char *agefile;
         char *cache_root;
         char *clone_prefix;
         char *css;
         char *favicon;
         char *footer;
         char *head_include;
         char *header;
         char *index_header;
         char *index_info;
         char *logo;
         char *logo_link;
         char *module_link;
         char *robots;
         char *root_title;
         char *root_desc;
         char *root_readme;
         char *script_name;
         char *section;
         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_scanrc_ttl;
         int cache_static_ttl;
         int embedded;
         int enable_filter_overrides;
         int enable_index_links;
         int enable_log_filecount;
         int enable_log_linecount;
         int enable_remote_branches;
         int enable_tree_linenumbers;
         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_blob_size;
         int max_stats;
         int nocache;
         int noplainemail;
         int noheader;
         int renamelimit;
         int snapshots;
         int summary_branches;
         int summary_log;
         int summary_tags;
         int ssdiff;
         struct string_list mimetypes;
         struct cgit_filter *about_filter;
         struct cgit_filter *commit_filter;
         struct cgit_filter *source_filter;
 };
 
 struct cgit_page {
         time_t modified;
         time_t expires;
         size_t size;
         char *mimetype;
         char *charset;
         char *filename;
         char *etag;
         char *title;
         int status;
         char *statusmsg;
 };
 
 struct cgit_environment {
         char *cgit_config;
         char *http_host;
         char *https;
         char *no_http;
         char *path_info;
         char *query_string;
         char *request_method;
         char *script_name;
         char *server_name;
         char *server_port;
 };
 
 struct cgit_context {
         struct cgit_environment env;
         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);
 
 extern int cgit_open_filter(struct cgit_filter *filter);
 extern int cgit_close_filter(struct cgit_filter *filter);
 
 extern int readfile(const char *path, char **buf, size_t *size);
 
+extern char *expand_macros(const char *txt);
+
 #endif /* CGIT_H */
diff --git a/shared.c b/shared.c
index 5f46793..76d26dd 100644
--- a/shared.c
+++ b/shared.c
@@ -1,425 +1,496 @@
 /* shared.c: global vars + some callback functions
  *
  * Copyright (C) 2006 Lars Hjemli
  *
  * Licensed under GNU General Public License v2
  *   (see COPYING for full license text)
  */
 
 #include "cgit.h"
 
 struct cgit_repolist cgit_repolist;
 struct cgit_context ctx;
 int cgit_cmd;
 
 int chk_zero(int result, char *msg)
 {
         if (result != 0)
                 die("%s: %s", msg, strerror(errno));
         return result;
 }
 
 int chk_positive(int result, char *msg)
 {
         if (result <= 0)
                 die("%s: %s", msg, strerror(errno));
         return result;
 }
 
 int chk_non_negative(int result, char *msg)
 {
             if (result < 0)
                     die("%s: %s",msg, strerror(errno));
         return result;
 }
 
 struct cgit_repo *cgit_add_repo(const char *url)
 {
         struct cgit_repo *ret;
 
         if (++cgit_repolist.count > cgit_repolist.length) {
                 if (cgit_repolist.length == 0)
                         cgit_repolist.length = 8;
                 else
                         cgit_repolist.length *= 2;
                 cgit_repolist.repos = xrealloc(cgit_repolist.repos,
                                                cgit_repolist.length *
                                                sizeof(struct cgit_repo));
         }
 
         ret = &cgit_repolist.repos[cgit_repolist.count-1];
         memset(ret, 0, sizeof(struct cgit_repo));
         ret->url = trim_end(url, '/');
         ret->name = ret->url;
         ret->path = NULL;
         ret->desc = "[no description]";
         ret->owner = NULL;
         ret->section = ctx.cfg.section;
         ret->defbranch = "master";
         ret->snapshots = ctx.cfg.snapshots;
         ret->enable_log_filecount = ctx.cfg.enable_log_filecount;
         ret->enable_log_linecount = ctx.cfg.enable_log_linecount;
         ret->enable_remote_branches = ctx.cfg.enable_remote_branches;
         ret->max_stats = ctx.cfg.max_stats;
         ret->module_link = ctx.cfg.module_link;
         ret->readme = NULL;
         ret->mtime = -1;
         ret->about_filter = ctx.cfg.about_filter;
         ret->commit_filter = ctx.cfg.commit_filter;
         ret->source_filter = ctx.cfg.source_filter;
         return ret;
 }
 
 struct cgit_repo *cgit_get_repoinfo(const char *url)
 {
         int i;
         struct cgit_repo *repo;
 
         for (i=0; i<cgit_repolist.count; i++) {
                 repo = &cgit_repolist.repos[i];
                 if (!strcmp(repo->url, url))
                         return repo;
         }
         return NULL;
 }
 
 void *cgit_free_commitinfo(struct commitinfo *info)
 {
         free(info->author);
         free(info->author_email);
         free(info->committer);
         free(info->committer_email);
         free(info->subject);
         free(info->msg);
         free(info->msg_encoding);
         free(info);
         return NULL;
 }
 
 char *trim_end(const char *str, char c)
 {
         int len;
         char *s, *t;
 
         if (str == NULL)
                 return NULL;
         t = (char *)str;
         len = strlen(t);
         while(len > 0 && t[len - 1] == c)
                 len--;
 
         if (len == 0)
                 return NULL;
 
         c = t[len];
         t[len] = '\0';
         s = xstrdup(t);
         t[len] = c;
         return s;
 }
 
 char *strlpart(char *txt, int maxlen)
 {
         char *result;
 
         if (!txt)
                 return txt;
 
         if (strlen(txt) <= maxlen)
                 return txt;
         result = xmalloc(maxlen + 1);
         memcpy(result, txt, maxlen - 3);
         result[maxlen-1] = result[maxlen-2] = result[maxlen-3] = '.';
         result[maxlen] = '\0';
         return result;
 }
 
 char *strrpart(char *txt, int maxlen)
 {
         char *result;
 
         if (!txt)
                 return txt;
 
         if (strlen(txt) <= maxlen)
                 return txt;
         result = xmalloc(maxlen + 1);
         memcpy(result + 3, txt + strlen(txt) - maxlen + 4, maxlen - 3);
         result[0] = result[1] = result[2] = '.';
         return result;
 }
 
 void cgit_add_ref(struct reflist *list, struct refinfo *ref)
 {
         size_t size;
 
         if (list->count >= list->alloc) {
                 list->alloc += (list->alloc ? list->alloc : 4);
                 size = list->alloc * sizeof(struct refinfo *);
                 list->refs = xrealloc(list->refs, size);
         }
         list->refs[list->count++] = ref;
 }
 
 struct refinfo *cgit_mk_refinfo(const char *refname, const unsigned char *sha1)
 {
         struct refinfo *ref;
 
         ref = xmalloc(sizeof (struct refinfo));
         ref->refname = xstrdup(refname);
         ref->object = parse_object(sha1);
         switch (ref->object->type) {
         case OBJ_TAG:
                 ref->tag = cgit_parse_tag((struct tag *)ref->object);
                 break;
         case OBJ_COMMIT:
                 ref->commit = cgit_parse_commit((struct commit *)ref->object);
                 break;
         }
         return ref;
 }
 
 int cgit_refs_cb(const char *refname, const unsigned char *sha1, int flags,
                   void *cb_data)
 {
         struct reflist *list = (struct reflist *)cb_data;
         struct refinfo *info = cgit_mk_refinfo(refname, sha1);
 
         if (info)
                 cgit_add_ref(list, info);
         return 0;
 }
 
 void cgit_diff_tree_cb(struct diff_queue_struct *q,
                        struct diff_options *options, void *data)
 {
         int i;
 
         for (i = 0; i < q->nr; i++) {
                 if (q->queue[i]->status == 'U')
                         continue;
                 ((filepair_fn)data)(q->queue[i]);
         }
 }
 
 static int load_mmfile(mmfile_t *file, const unsigned char *sha1)
 {
         enum object_type type;
 
         if (is_null_sha1(sha1)) {
                 file->ptr = (char *)"";
                 file->size = 0;
         } else {
                 file->ptr = read_sha1_file(sha1, &type, 
                                            (unsigned long *)&file->size);
         }
         return 1;
 }
 
 /*
  * Receive diff-buffers from xdiff and concatenate them as
  * needed across multiple callbacks.
  *
  * This is basically a copy of xdiff-interface.c/xdiff_outf(),
  * ripped from git and modified to use globals instead of
  * a special callback-struct.
  */
 char *diffbuf = NULL;
 int buflen = 0;
 
 int filediff_cb(void *priv, mmbuffer_t *mb, int nbuf)
 {
         int i;
 
         for (i = 0; i < nbuf; i++) {
                 if (mb[i].ptr[mb[i].size-1] != '\n') {
                         /* Incomplete line */
                         diffbuf = xrealloc(diffbuf, buflen + mb[i].size);
                         memcpy(diffbuf + buflen, mb[i].ptr, mb[i].size);
                         buflen += mb[i].size;
                         continue;
                 }
 
                 /* we have a complete line */
                 if (!diffbuf) {
                         ((linediff_fn)priv)(mb[i].ptr, mb[i].size);
                         continue;
                 }
                 diffbuf = xrealloc(diffbuf, buflen + mb[i].size);
                 memcpy(diffbuf + buflen, mb[i].ptr, mb[i].size);
                 ((linediff_fn)priv)(diffbuf, buflen + mb[i].size);
                 free(diffbuf);
                 diffbuf = NULL;
                 buflen = 0;
         }
         if (diffbuf) {
                 ((linediff_fn)priv)(diffbuf, buflen);
                 free(diffbuf);
                 diffbuf = NULL;
                 buflen = 0;
         }
         return 0;
 }
 
 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)
 {
         mmfile_t file1, file2;
         xpparam_t diff_params;
         xdemitconf_t emit_params;
         xdemitcb_t emit_cb;
 
         if (!load_mmfile(&file1, old_sha1) || !load_mmfile(&file2, new_sha1))
                 return 1;
 
         *old_size = file1.size;
         *new_size = file2.size;
 
         if ((file1.ptr && buffer_is_binary(file1.ptr, file1.size)) ||
             (file2.ptr && buffer_is_binary(file2.ptr, file2.size))) {
                 *binary = 1;
                 return 0;
         }
 
         memset(&diff_params, 0, sizeof(diff_params));
         memset(&emit_params, 0, sizeof(emit_params));
         memset(&emit_cb, 0, sizeof(emit_cb));
         diff_params.flags = XDF_NEED_MINIMAL;
         emit_params.ctxlen = 3;
         emit_params.flags = XDL_EMIT_FUNCNAMES;
         emit_cb.outf = filediff_cb;
         emit_cb.priv = fn;
         xdl_diff(&file1, &file2, &diff_params, &emit_params, &emit_cb);
         return 0;
 }
 
 void cgit_diff_tree(const unsigned char *old_sha1,
                     const unsigned char *new_sha1,
                     filepair_fn fn, const char *prefix)
 {
         struct diff_options opt;
         int ret;
         int prefixlen;
 
         diff_setup(&opt);
         opt.output_format = DIFF_FORMAT_CALLBACK;
         opt.detect_rename = 1;
         opt.rename_limit = ctx.cfg.renamelimit;
         DIFF_OPT_SET(&opt, RECURSIVE);
         opt.format_callback = cgit_diff_tree_cb;
         opt.format_callback_data = fn;
         if (prefix) {
                 opt.nr_paths = 1;
                 opt.paths = &prefix;
                 prefixlen = strlen(prefix);
                 opt.pathlens = &prefixlen;
         }
         diff_setup_done(&opt);
 
         if (old_sha1 && !is_null_sha1(old_sha1))
                 ret = diff_tree_sha1(old_sha1, new_sha1, "", &opt);
         else
                 ret = diff_root_tree_sha1(new_sha1, "", &opt);
         diffcore_std(&opt);
         diff_flush(&opt);
 }
 
 void cgit_diff_commit(struct commit *commit, filepair_fn fn)
 {
         unsigned char *old_sha1 = NULL;
 
         if (commit->parents)
                 old_sha1 = commit->parents->item->object.sha1;
         cgit_diff_tree(old_sha1, commit->object.sha1, fn, NULL);
 }
 
 int cgit_parse_snapshots_mask(const char *str)
 {
         const struct cgit_snapshot_format *f;
         static const char *delim = " \t,:/|;";
         int tl, sl, rv = 0;
 
         /* favor legacy setting */
         if(atoi(str))
                 return 1;
         for(;;) {
                 str += strspn(str,delim);
                 tl = strcspn(str,delim);
                 if (!tl)
                         break;
                 for (f = cgit_snapshot_formats; f->suffix; f++) {
                         sl = strlen(f->suffix);
                         if((tl == sl && !strncmp(f->suffix, str, tl)) ||
                            (tl == sl-1 && !strncmp(f->suffix+1, str, tl-1))) {
                                 rv |= f->bit;
                                 break;
                         }
                 }
                 str += tl;
         }
         return rv;
 }
 
 int cgit_open_filter(struct cgit_filter *filter)
 {
 
         filter->old_stdout = chk_positive(dup(STDOUT_FILENO),
                 "Unable to duplicate STDOUT");
         chk_zero(pipe(filter->pipe_fh), "Unable to create pipe to subprocess");
         filter->pid = chk_non_negative(fork(), "Unable to create subprocess");
         if (filter->pid == 0) {
                 close(filter->pipe_fh[1]);
                 chk_non_negative(dup2(filter->pipe_fh[0], STDIN_FILENO),
                         "Unable to use pipe as STDIN");
                 execvp(filter->cmd, filter->argv);
                 die("Unable to exec subprocess %s: %s (%d)", filter->cmd,
                         strerror(errno), errno);
         }
         close(filter->pipe_fh[0]);
         chk_non_negative(dup2(filter->pipe_fh[1], STDOUT_FILENO),
                 "Unable to use pipe as STDOUT");
         close(filter->pipe_fh[1]);
         return 0;
 }
 
 int cgit_close_filter(struct cgit_filter *filter)
 {
         chk_non_negative(dup2(filter->old_stdout, STDOUT_FILENO),
                 "Unable to restore STDOUT");
         close(filter->old_stdout);
         if (filter->pid < 0)
                 return 0;
         waitpid(filter->pid, &filter->exitstatus, 0);
         if (WIFEXITED(filter->exitstatus) && !WEXITSTATUS(filter->exitstatus))
                 return 0;
         die("Subprocess %s exited abnormally", filter->cmd);
 }
 
 /* Read the content of the specified file into a newly allocated buffer,
  * zeroterminate the buffer and return 0 on success, errno otherwise.
  */
 int readfile(const char *path, char **buf, size_t *size)
 {
         int fd, e;
         struct stat st;
 
         fd = open(path, O_RDONLY);
         if (fd == -1)
                 return errno;
         if (fstat(fd, &st)) {
                 e = errno;
                 close(fd);
                 return e;
         }
         if (!S_ISREG(st.st_mode)) {
                 close(fd);
                 return EISDIR;
         }
         *buf = xmalloc(st.st_size + 1);
         *size = read_in_full(fd, *buf, st.st_size);
         e = errno;
         (*buf)[*size] = '\0';
         close(fd);
         return (*size == st.st_size ? 0 : e);
 }
+
+int is_token_char(char c)
+{
+        return isalnum(c) || c == '_';
+}
+
+/* Replace name with getenv(name), return pointer to zero-terminating char
+ */
+char *expand_macro(char *name, int maxlength)
+{
+        char *value;
+        int len;
+
+        len = 0;
+        value = getenv(name);
+        if (value) {
+                len = strlen(value);
+                if (len > maxlength)
+                        len = maxlength;
+                strncpy(name, value, len);
+        }
+        return name + len;
+}
+
+#define EXPBUFSIZE (1024 * 8)
+
+/* Replace all tokens prefixed by '$' in the specified text with the
+ * value of the named environment variable.
+ * NB: the return value is a static buffer, i.e. it must be strdup'd
+ * by the caller.
+ */
+char *expand_macros(const char *txt)
+{
+        static char result[EXPBUFSIZE];
+        char *p, *start;
+        int len;
+
+        p = result;
+        start = NULL;
+        while (p < result + EXPBUFSIZE - 1 && txt && *txt) {
+                *p = *txt;
+                if (start) {
+                        if (!is_token_char(*txt)) {
+                                if (p - start > 0) {
+                                        *p = '\0';
+                                        len = result + EXPBUFSIZE - start - 1;
+                                        p = expand_macro(start, len) - 1;
+                                }
+                                start = NULL;
+                                txt--;
+                        }
+                        p++;
+                        txt++;
+                        continue;
+                }
+                if (*txt == '$') {
+                        start = p;
+                        txt++;
+                        continue;
+                }
+                p++;
+                txt++;
+        }
+        *p = '\0';
+        if (start && p - start > 0) {
+                len = result + EXPBUFSIZE - start - 1;
+                p = expand_macro(start, len);
+                *p = '\0';
+        }
+        return result;
+}