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>

diff --git a/cgit.c b/cgit.c
index 9305d0a873a191e730d622d14067a2eee56003a6..37154e3c2afe9e409bd04f79a6691102cd9d529c 100644 (file)
--- a/cgit.c
+++ b/cgit.c
@@ -148,7 +148,7 @@ void config_cb(const char *name, const char *value)
        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"))
@@ -177,9 +177,9 @@ void config_cb(const char *name, const char *value)
                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"))
@@ -203,7 +203,7 @@ void config_cb(const char *name, const char *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)
@@ -688,7 +688,7 @@ int main(int argc, const char **argv)
        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);
 

diff --git a/cgit.h b/cgit.h
index cd4af7247b7c00dd9562917d2df94472d2e1317e..568e0c088e543846739af1e51c4fcc06fbc82fcc 100644 (file)
--- a/cgit.h
+++ b/cgit.h
@@ -296,4 +296,6 @@ 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 5f4679335e0f063cadc57b79953f2c078cff11a3..76d26dd99e902c0e651c33c9f40dd64428c5f6b7 100644 (file)
--- a/shared.c
+++ b/shared.c
@@ -423,3 +423,74 @@ int readfile(const char *path, char **buf, size_t *size)
        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;
+}