Add generic filter/plugin infrastructure

The functions cgit_open_filter() and cgit_close_filter() can be used to
execute filters on the output stream from cgit.

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

1 files changed, 35 insertions, 0 deletions

diff --git a/shared.c b/shared.c
index cce0af4..288cfa2 100644
--- a/shared.c
+++ b/shared.c
@@ -102,256 +102,291 @@ char *trim_end(const char *str, char c)
         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);
+}