filter: basic write hooking infrastructure

Filters can now call hook_write and unhook_write if they want to
redirect writing to stdout to a different function. This saves us from
potential file descriptor pipes and other less efficient mechanisms.

We do this instead of replacing the call in html_raw because some places
stdlib's printf functions are used (ui-patch or within git itself),
which has its own internal buffering, which makes it difficult to
interlace our function calls. So, we dlsym libc's write and then
override it in the link stage.

While we're at it, we move considerations of argument count into the
generic new filter handler.

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>

1 files changed, 2 insertions, 1 deletions

diff --git a/cgit.h b/cgit.h
index 893c38f..519d2af 100644
--- a/cgit.h
+++ b/cgit.h
@@ -61,13 +61,13 @@ struct cgit_filter {
         int (*close)(struct cgit_filter *);
         void (*fprintf)(struct cgit_filter *, FILE *, const char *prefix);
         void (*cleanup)(struct cgit_filter *);
+        int argument_count;
 };
 
 struct cgit_exec_filter {
         struct cgit_filter base;
         char *cmd;
         char **argv;
-        int extra_args;
         int old_stdout;
         int pipe_fh[2];
         int pid;
@@ -357,6 +357,7 @@ extern void cgit_fprintf_filter(struct cgit_filter *filter, FILE *f, const char
 extern void cgit_exec_filter_init(struct cgit_exec_filter *filter, char *cmd, char **argv);
 extern struct cgit_filter *cgit_new_filter(const char *cmd, filter_type filtertype);
 extern void cgit_cleanup_filters(void);
+extern void cgit_init_filters(void);
 
 extern void cgit_prepare_repo_env(struct cgit_repo * repo);