sch2fig/: support direct reading from git repo (WIP)

sch2fig/Makefile

@@ -12,13 +12,16 @@
 
 NAME = sch2fig
 OBJS = main.o sch-parse.o sch-render.o lib-parse.o lib-render.o \
-       file.o \
+       file.o git-file.o \
        style.o fig.o record.o cro.o diff.o gfx.o dwg.o text.o misc.o
 
 CFLAGS = -g  -Wall -Wextra -Wno-unused-parameter -Wshadow \
 	 -Wmissing-prototypes -Wmissing-declarations \
-	 `pkg-config --cflags cairo`
-LIBS = -lm `pkg-config --libs cairo`
+	 `pkg-config --cflags cairo` \
+	 `pkg-config --cflags libgit2`
+LDLIBS = -lm \
+       `pkg-config --libs cairo` \
+       `pkg-config --libs libgit2`
 
 include ../common/Makefile.c-common
 
@@ -27,7 +30,7 @@ include ../common/Makefile.c-common
 all::		$(NAME)
 
 $(NAME):	$(OBJS)
-		$(CC) -o $(NAME) $(OBJS) $(LIBS)
+		$(CC) -o $(NAME) $(OBJS) $(LDLIBS)
 
 #----- Test sheet -------------------------------------------------------------
 

sch2fig/file.c

@@ -15,24 +15,18 @@
 #include <stdio.h>
 #include <string.h>
 
+#include "util.h"
 #include "main.h"
+#include "git-file.h"
 #include "file.h"
 
 
-void file_read(const char *name, bool (*parse)(void *user, const char *line),
-    void *user)
+static void read_from_file(FILE *file,
+    bool (*parse)(void *user, const char *line), void *user)
 {
-	FILE *file;
 	char buf[1000];
 	char *nl;
 
-	file = fopen(name, "r");
-	if (!file) {
-		perror(name);
-		exit(1);
-	}
-	if (verbose)
-		fprintf(stderr, "reading %s\n", name);
 	while (fgets(buf, sizeof(buf), file)) {
 		nl = strchr(buf, '\n');
 		if (nl)
@@ -40,5 +34,36 @@ void file_read(const char *name, bool (*parse)(void *user, const char *line),
 		if (!parse(user, buf))
 			break;
 	}
-	fclose(file);
+}
+
+
+void file_read(const char *name, bool (*parse)(void *user, const char *line),
+    void *user)
+{
+	FILE *file;
+	char *colon, *tmp;
+
+	file = fopen(name, "r");
+	if (file) {
+		if (verbose)
+			fprintf(stderr, "reading %s\n", name);
+		read_from_file(file, parse, user);
+		fclose(file);
+		return;
+	}
+
+	if (verbose)
+		perror(name);
+
+	colon = strchr(name, ':');
+	if (!colon) {
+		if (!verbose)
+			perror(name);
+		exit(1);
+	}
+
+	tmp = stralloc(name);
+	tmp[colon - name] = 0;
+	git_read(tmp, colon + 1, parse, user);
+	free(tmp);
 }

sch2fig/git-file.c

@@ -0,0 +1,376 @@
+/*
+ * git-file.c - Open and read a file from git
+ *
+ * Written 2016 by Werner Almesberger
+ * Copyright 2016 by Werner Almesberger
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+#define	_GNU_SOURCE	/* for get_current_dir_name */
+#include <stdlib.h>
+#include <stdio.h>
+#include <unistd.h>
+#include <string.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+
+#include <git2.h>
+
+#include "util.h"
+#include "main.h"
+#include "git-file.h"
+
+
+static git_repository *select_repo(const char *path)
+{
+	git_repository *repo = NULL;
+	char *tmp = stralloc(path);
+	char *slash;
+
+	/*
+	 * If we can't find a repo, this may be due to the file or directory
+	 * the path points to not existing in the currently checked-out tree.
+	 * So we trim off elements until we find a repository.
+	 */
+	while (1) {
+		if (!git_repository_open_ext(&repo, *tmp ? tmp : "/",
+		    GIT_REPOSITORY_OPEN_CROSS_FS, NULL))
+			break;
+		slash = strrchr(path, '/');
+		if (!slash)
+			break;
+		*slash = 0;
+	}
+	free(tmp);
+	return repo;
+}
+
+
+static git_tree *pick_revision(git_repository *repo, const char *revision)
+{
+	git_commit *commit;
+	git_object *obj;
+	git_tree *tree;
+
+	if (git_revparse_single(&obj, repo, revision)) {
+		const git_error *e = giterr_last();
+
+		fprintf(stderr, "%s: %s\n",
+		    git_repository_path(repo), e->message);
+		exit(1);
+	}
+
+	if (git_object_type(obj) != GIT_OBJ_COMMIT) {
+		fprintf(stderr, "%s: not a commit\n", revision);
+		exit(1);
+	}
+	commit = (git_commit *) obj;
+
+	if (git_commit_tree(&tree, commit)) {
+		const git_error *e = giterr_last();
+
+		fprintf(stderr, "%s: %s\n", revision, e->message);
+		exit(1);
+	}
+
+	return tree;
+}
+
+
+static char *canonical_path_into_repo(const char *repo_dir, const char *path)
+{
+	struct stat repo_st, path_st;
+	char *tmp, *tmp2, *slash, *tail, *real;
+	char *to;
+	const char *end, *from;
+
+	/* identify inode of repo root */
+
+	if (stat(repo_dir, &repo_st) < 0) {
+		perror(repo_dir);
+		exit(1);
+	}
+	if (!S_ISDIR(repo_st.st_mode)) {
+		fprintf(stderr, "%s: not a directory\n", repo_dir);
+		exit(1);
+	}
+
+	/* convert relative paths to absolute */
+
+	if (*path == '/') {
+		tmp = stralloc(path);
+	} else {
+		char *cwd = get_current_dir_name();
+
+		tmp = alloc_size(strlen(cwd) + 1 + strlen(path) + 1);
+		sprintf(tmp, "%s/%s", cwd, path);
+		free(cwd);
+	}
+
+	/* remove trailing / */
+
+	slash = strrchr(tmp, '/');
+	if (slash && slash != tmp && !slash[1])
+		*slash = 0;
+
+
+	/*
+	 * If path does point to inexistent object, separate into the part that
+	 * is valid on the current system and the tail containing dead things.
+	 */
+	end = tail = strchr(tmp, 0);
+
+	while (1) {
+		if (verbose > 2)
+			fprintf(stderr, "probing \"%s\" tail \"%s\"\n",
+			    tmp, tail);
+		if (stat(tmp, &path_st) == 0)
+			break;
+		if (!tmp[1]) {
+			fprintf(stderr, "%s: cannot resolve\n", path);
+			exit(1);
+		}
+		slash = strrchr(tmp, '/');
+		if (tail != end)
+			tail[-1] = '/';
+		tail = slash + 1;
+		*slash = 0;
+	}
+
+	/* remove . and .. from tail */
+
+	if (verbose > 2)
+		fprintf(stderr, "input tail \"%s\"\n", tail);
+	from = to = tail;
+	while (1) {
+		if (!strncmp(from, "./", 2)) {
+			from += 2;
+			continue;
+		}
+		if (!strcmp(from, "."))
+			break;
+		if (strncmp(from, "../", 3) && strcmp(from, "..")) {
+			while (*from) {
+				*to++ = *from++;
+				if (from[-1] == '/')
+					break;
+			}
+			if (!*from)
+				break;
+		}
+		if (to == tail) {
+			/*
+			 * We have something like this:
+			 * /home/repo/dead/../../foo
+			 */
+			fprintf(stderr, "%s: can't climb out of dead path\n",
+			    path);
+			exit(1);
+		}
+
+		/*
+		 * We have something like
+		 * "foo/" -> ""
+		 * or
+		 * "foo/bar/" -> "foo/"
+		 * where "to" points to the end.
+		 */
+		to--;
+		while (to != tail && to[-1] != '/')
+			to--;
+	}
+	*to = 0;
+	if (verbose > 2)
+		fprintf(stderr, "output tail \"%s\"\n", tail);
+
+	/* resolve all symlinks */
+
+	real = realpath(tmp, NULL);
+	if (verbose > 2)
+		fprintf(stderr, "realpath(\"%s\") = \"%s\"\n", tmp, real);
+
+	/* append tail */
+
+	if (*tail) {
+		tmp2 = alloc_size(strlen(real) + 1 + strlen(tail) + 1);
+		sprintf(tmp2, "%s/%s", real, tail);
+		free(real);
+	} else {
+		tmp2 = real;
+	}
+	free(tmp);
+	tmp = tmp2;
+
+	if (verbose > 1)
+		fprintf(stderr, "full object path \"%s\"\n", tmp);
+
+	/* find which part of out path is inside the repo */
+
+	end = tail = strchr(tmp, 0);
+	while (1) {
+		if (verbose > 2)
+			fprintf(stderr, "trying \"%s\" tail \"%s\"\n",
+			    tmp, tail);
+		/*
+		 * This should never fail, unless someone has been changing
+		 * things while we were searching.
+		 */
+		if (stat(tmp, &path_st) < 0) {
+			perror(tmp);
+			exit(1);
+		}
+
+		if (path_st.st_dev == repo_st.st_dev &&
+		    path_st.st_ino == repo_st.st_ino)
+			break;
+
+		/* another "this cannot happen" problem */
+		if (tail == tmp) {
+			fprintf(stderr,
+			    "divergent paths:\nrepo \"%s\"\nobject \"%s\"\n",
+			    repo_dir, tmp);
+			exit(1);
+		}
+
+		slash = strrchr(tmp, '/');
+		if (tail != end)
+			tail[-1] = '/';
+		tail = slash + 1;
+		*slash = 0;
+	}
+
+	if (verbose > 1)
+		fprintf(stderr, "path in repo \"%s\"\n", tail);
+
+	tmp2 = stralloc(tail);
+	free(tmp);
+	return tmp2;
+}
+
+
+static git_tree_entry *find_file(git_repository *repo, git_tree *tree,
+    const char *path)
+{
+	git_tree_entry *entry;
+	char *repo_path = stralloc(git_repository_path(repo));
+	char *slash, *canon_path;
+	int len;
+
+	/* remove trailing / from repo_path */
+	slash = strrchr(repo_path, '/');
+	if (slash && slash != repo_path && !slash[1])
+		*slash = 0;
+
+	len = strlen(repo_path);
+	if (len >= 5 && !strcmp(repo_path + len - 5, "/.git"))
+		repo_path[len == 5 ? 1 : len - 5] = 0;
+
+	if (verbose > 1)
+		fprintf(stderr, "repo dir \"%s\"\n", repo_path);
+
+	canon_path = canonical_path_into_repo(repo_path, path);
+
+	if (git_tree_entry_bypath(&entry, tree, canon_path)) {
+		const git_error *e = giterr_last();
+
+		fprintf(stderr, "%s: %s\n", path, e->message);
+		exit(1);
+	}
+	free(canon_path);
+
+	return entry;
+}
+
+
+static const void *get_data(git_repository *repo, git_tree_entry *entry,
+    unsigned *size)
+{
+	git_object *obj;
+	git_blob *blob;
+
+	if (git_tree_entry_type(entry) != GIT_OBJ_BLOB) {
+		fprintf(stderr, "entry is not a blob\n");
+		exit(1);
+	}
+	if (git_tree_entry_to_object(&obj, repo, entry)) {
+		const git_error *e = giterr_last();
+
+		fprintf(stderr, "%s\n", e->message);
+		exit(1);
+	}
+
+	blob = (git_blob *) obj;
+	*size = git_blob_rawsize(blob);
+	return git_blob_rawcontent(blob);
+}
+
+
+static bool send_line(const char *s, unsigned len,
+    bool (*parse)(void *user, const char *line), void *user)
+{
+	char *tmp = alloc_size(len + 1);
+	bool res;
+
+	memcpy(tmp, s, len);
+	tmp[len] = 0;
+	res = parse(user, tmp);
+	free(tmp);
+	return res;
+}
+
+
+static void send_data(const char *data, unsigned size,
+    bool (*parse)(void *user, const char *line), void *user)
+{
+	const char *end = data + size;
+	const char *p = data;
+	const char *nl;
+
+	while (p != end) {
+		nl = memchr(p, '\n', end - p);
+		if (!nl) {
+			send_line(p, end - p, parse, user);
+			return;
+		}
+		if (!send_line(p, nl - p + 1, parse, user))
+			return;
+		p = nl + 1;
+	}
+}
+
+
+void git_read(const char *revision, const char *name, 
+    bool (*parse)(void *user, const char *line), void *user)
+{
+	static bool initialized = 0;
+	git_repository *repo;
+	git_tree *tree;
+	git_tree_entry *entry;
+	const void *data;
+	unsigned size;
+
+	if (!initialized) {
+		git_libgit2_init();
+		initialized = 1;
+	}
+
+	repo = select_repo(name);
+	if (!repo) {
+		fprintf(stderr, "%s:%s not found\n", revision, name);
+		exit(1);
+	}
+	if (verbose > 1)
+		fprintf(stderr, "using repository %s\n",
+		    git_repository_path(repo));
+
+	tree = pick_revision(repo, revision);
+	entry = find_file(repo, tree, name);
+	if (verbose)
+		fprintf(stderr, "reading %s:%s\n", revision, name);
+	data = get_data(repo, entry, &size);
+	send_data(data, size, parse, user);
+}

sch2fig/git-file.h

@@ -0,0 +1,22 @@
+/*
+ * git-file.h - Open and read a file from git
+ *
+ * Written 2016 by Werner Almesberger
+ * Copyright 2016 by Werner Almesberger
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+#ifndef GIT_FILE_H
+#define	GIT_FILE_H
+
+#include <stdbool.h>
+
+
+void git_read(const char *revision, const char *name,
+    bool (*parse)(void *user, const char *line), void *user);
+
+#endif /* !GIT_FILE_H */