3 files changed, 62 insertions, 0 deletions

diff --git a/cgit.c b/cgit.c
index 2039ab1..779a464 100644
--- a/cgit.c
+++ b/cgit.c
@@ -12,16 +12,31 @@
 #include "configfile.h"
 #include "html.h"
 #include "ui-shared.h"
 #include "ui-stats.h"
 #include "scan-tree.h"
 
 const char *cgit_version = CGIT_VERSION;
 
+struct cgit_filter *new_filter(const char *cmd, int extra_args)
+{
+	struct cgit_filter *f;
+
+	if (!cmd)
+		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;
+}
+
 void config_cb(const char *name, const char *value)
 {
 	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);
diff --git a/cgit.h b/cgit.h
index 8c64efe..d0fff1f 100644
--- a/cgit.h
+++ b/cgit.h
@@ -124,16 +124,25 @@ struct cgit_query {
 	char *url;
 	char *period;
 	int   ofs;
 	int nohead;
 	char *sort;
 	int showmsg;
 };
 
+struct cgit_filter {
+	char *cmd;
+	char **argv;
+	int old_stdout;
+	int pipe_fh[2];
+	int pid;
+	int exitstatus;
+};
+
 struct cgit_config {
 	char *agefile;
 	char *cache_root;
 	char *clone_prefix;
 	char *css;
 	char *favicon;
 	char *footer;
 	char *head_include;
@@ -243,10 +252,13 @@ 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);
+
 
 #endif /* CGIT_H */
diff --git a/shared.c b/shared.c
index cce0af4..288cfa2 100644
--- a/shared.c
+++ b/shared.c
@@ -350,8 +350,43 @@ int cgit_parse_snapshots_mask(const char *str)
 				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);
+}