From 6e997d497c90562bfc1a1759142439b347a9e27a Mon Sep 17 00:00:00 2001
From: Aki <please@ignore.pl>
Date: Wed, 6 Jul 2022 22:06:42 +0200
Subject: Implemented a naive printer for commits that change cwd/PKGBUILD

---
 .gitignore |   2 +
 Makefile   |   9 +++++
 pkgrel.c   | 132 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 143 insertions(+)
 create mode 100644 .gitignore
 create mode 100644 Makefile
 create mode 100644 pkgrel.c

diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..ad2ddb2
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,2 @@
+*.o
+pkgrel
diff --git a/Makefile b/Makefile
new file mode 100644
index 0000000..17249eb
--- /dev/null
+++ b/Makefile
@@ -0,0 +1,9 @@
+CFLAGS=`pkg-config --cflags libgit2 libpcre2-8`
+LDLIBS=`pkg-config --libs libgit2 libpcre2-8`
+
+all: pkgrel
+
+clean:
+	rm -f *.o pkgrel
+
+.PHONY: all clean
diff --git a/pkgrel.c b/pkgrel.c
new file mode 100644
index 0000000..a803c39
--- /dev/null
+++ b/pkgrel.c
@@ -0,0 +1,132 @@
+#define PCRE2_CODE_UNIT_WIDTH 8
+
+#include <errno.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+#include <git2.h>
+#include <pcre2.h>
+
+
+size_t
+min(const size_t lhs, const size_t rhs)
+{
+	return lhs > rhs ? rhs : lhs;
+}
+
+
+char*
+relative_path_in_current_dir(git_repository* repo, const char* filename)
+{
+	const long maximum = pathconf(".", _PC_PATH_MAX);
+	size_t len = 0 > maximum ? 1024 : maximum;
+	char* buf = NULL;
+	char* cwd = NULL;
+	for (; NULL == cwd && 1024 * 50 > len; len *= 2) {
+		if (NULL == (cwd = realloc(buf, len))) {
+			if (NULL != buf)
+				free(buf);
+			return NULL;
+		}
+		buf = cwd;
+		cwd = getcwd(buf, len);
+		if (NULL == cwd && ERANGE != errno) {
+			free(buf);
+			return NULL;
+		}
+	}
+	const char* workdir = git_repository_workdir(repo);
+	const size_t prefix = min(strlen(cwd), strlen(workdir));
+	if (0 != strncmp(cwd, workdir, prefix)) {
+		free(cwd);
+		return NULL;
+	}
+	const size_t relative = strlen(cwd + prefix);
+	if (NULL == (buf = malloc(relative + strlen(filename) + 2))) {
+		free(cwd);
+		return NULL;
+	}
+	strcpy(buf, cwd + prefix);
+	if (0 < relative)
+		strcat(buf, "/");
+	strcat(buf, filename);
+	free(cwd);
+	return buf;
+}
+
+
+void
+gerror(void)
+{
+	const git_error* err = git_error_last();
+	dprintf(2, "%s\n", err->message);
+}
+
+
+int
+main(int argc, char* argv[])
+{
+	git_libgit2_init();
+	git_repository* repo = NULL;
+	int err = git_repository_open_ext(&repo, NULL, GIT_REPOSITORY_OPEN_FROM_ENV, NULL);
+	if (0 > err) {
+		gerror();
+		return 1;
+	}
+	git_diff_options diffopts = GIT_DIFF_OPTIONS_INIT;
+	diffopts.pathspec.strings = (char*[]){relative_path_in_current_dir(repo, "PKGBUILD")};
+	diffopts.pathspec.count = 1;
+	git_pathspec* pathspec = NULL;
+	err = git_pathspec_new(&pathspec, &diffopts.pathspec);
+	if (0 > err) {
+		gerror();
+		return 1;
+	}
+	git_revwalk* walker = NULL;
+	err = git_revwalk_new(&walker, repo);
+	if (0 > err) {
+		gerror();
+		return 1;
+	}
+	err = git_revwalk_push_head(walker);
+	if (0 > err) {
+		gerror();
+		return 1;
+	}
+	git_oid oid;
+	git_tree* earlier = NULL;
+	git_tree* later = NULL;
+	while (0 == git_revwalk_next(&oid, walker)) {
+		git_commit* commit;
+		err = git_commit_lookup(&commit, repo, &oid);
+		if (0 > err) {
+			gerror();
+			return 1;
+		}
+		if (NULL != earlier)
+			git_tree_free(earlier);
+		earlier = later;
+		err = git_commit_tree(&later, commit);
+		if (0 > err) {
+			gerror();
+			return 1;
+		}
+		const int matched = 0 == git_pathspec_match_tree(NULL, later, GIT_PATHSPEC_NO_MATCH_ERROR, pathspec);
+		if (matched) {
+			char buf[GIT_OID_HEXSZ + 1];
+			git_oid_tostr(buf, sizeof(buf), git_commit_id(commit));
+			puts(buf);
+		}
+		git_commit_free(commit);
+	}
+	if (NULL != earlier)
+		git_tree_free(earlier);
+	if (NULL != later)
+		git_tree_free(later);
+	git_revwalk_free(walker);
+	git_pathspec_free(pathspec);
+	free(diffopts.pathspec.strings[0]);
+	git_repository_free(repo);
+}
-- 
cgit v1.1