Merge pull request #1916 from libgit2/simplify-examples

Fix examples to make the important stuff more obvious

1 files changed, 184 insertions, 0 deletions

diff --git a/examples/common.c b/examples/common.c
new file mode 100644
index 000000000..5972bc5c7
--- /dev/null
+++ b/examples/common.c
@@ -0,0 +1,184 @@
+/*
+ * Copyright (C) the libgit2 contributors. All rights reserved.
+ *
+ * This file is part of libgit2, distributed under the GNU GPL v2 with
+ * a Linking Exception. For full terms see the included COPYING file.
+ */
+
+#include "common.h"
+
+void check_lg2(int error, const char *message, const char *extra)
+{
+	const git_error *lg2err;
+	const char *lg2msg = "", *lg2spacer = "";
+
+	if (!error)
+		return;
+
+	if ((lg2err = giterr_last()) != NULL && lg2err->message != NULL) {
+		lg2msg = lg2err->message;
+		lg2spacer = " - ";
+	}
+
+	if (extra)
+		fprintf(stderr, "%s '%s' [%d]%s%s\n",
+			message, extra, error, lg2spacer, lg2msg);
+	else
+		fprintf(stderr, "%s [%d]%s%s\n",
+			message, error, lg2spacer, lg2msg);
+
+	exit(1);
+}
+
+void fatal(const char *message, const char *extra)
+{
+	if (extra)
+		fprintf(stderr, "%s %s\n", message, extra);
+	else
+		fprintf(stderr, "%s\n", message);
+
+	exit(1);
+}
+
+size_t is_prefixed(const char *str, const char *pfx)
+{
+	size_t len = strlen(pfx);
+	return strncmp(str, pfx, len) ? 0 : len;
+}
+
+int match_str_arg(
+	const char **out, struct args_info *args, const char *opt)
+{
+	const char *found = args->argv[args->pos];
+	size_t len = is_prefixed(found, opt);
+
+	if (!len)
+		return 0;
+
+	if (!found[len]) {
+		if (args->pos + 1 == args->argc)
+			fatal("expected value following argument", opt);
+		args->pos += 1;
+		*out = args->argv[args->pos];
+		return 1;
+	}
+
+	if (found[len] == '=') {
+		*out = found + len + 1;
+		return 1;
+	}
+
+	return 0;
+}
+
+static const char *match_numeric_arg(struct args_info *args, const char *opt)
+{
+	const char *found = args->argv[args->pos];
+	size_t len = is_prefixed(found, opt);
+
+	if (!len)
+		return NULL;
+
+	if (!found[len]) {
+		if (args->pos + 1 == args->argc)
+			fatal("expected numeric value following argument", opt);
+		args->pos += 1;
+		found = args->argv[args->pos];
+	} else {
+		found = found + len;
+		if (*found == '=')
+			found++;
+	}
+
+	return found;
+}
+
+int match_uint16_arg(
+	uint16_t *out, struct args_info *args, const char *opt)
+{
+	const char *found = match_numeric_arg(args, opt);
+	uint16_t val;
+	char *endptr = NULL;
+
+	if (!found)
+		return 0;
+
+	val = (uint16_t)strtoul(found, &endptr, 0);
+	if (!endptr || *endptr != '\0')
+		fatal("expected number after argument", opt);
+
+	if (out)
+		*out = val;
+	return 1;
+}
+
+static int match_int_internal(
+	int *out, const char *str, int allow_negative, const char *opt)
+{
+	char *endptr = NULL;
+	int	  val = (int)strtol(str, &endptr, 10);
+
+	if (!endptr || *endptr != '\0')
+		fatal("expected number", opt);
+	else if (val < 0 && !allow_negative)
+		fatal("negative values are not allowed", opt);
+
+	if (out)
+		*out = val;
+
+	return 1;
+}
+
+int is_integer(int *out, const char *str, int allow_negative)
+{
+	return match_int_internal(out, str, allow_negative, NULL);
+}
+
+int match_int_arg(
+	int *out, struct args_info *args, const char *opt, int allow_negative)
+{
+	const char *found = match_numeric_arg(args, opt);
+	if (!found)
+		return 0;
+	return match_int_internal(out, found, allow_negative, opt);
+}
+
+int diff_output(
+	const git_diff_delta *d,
+	const git_diff_hunk *h,
+	const git_diff_line *l,
+	void *p)
+{
+	FILE *fp = p;
+
+	(void)d; (void)h;
+
+	if (!fp)
+		fp = stdout;
+
+	if (l->origin == GIT_DIFF_LINE_CONTEXT ||
+		l->origin == GIT_DIFF_LINE_ADDITION ||
+		l->origin == GIT_DIFF_LINE_DELETION)
+		fputc(l->origin, fp);
+
+	fwrite(l->content, 1, l->content_len, fp);
+
+	return 0;
+}
+
+void treeish_to_tree(
+	git_tree **out, git_repository *repo, const char *treeish)
+{
+	git_object *obj = NULL;
+
+	check_lg2(
+		git_revparse_single(&obj, repo, treeish),
+		"looking up object", treeish);
+
+	check_lg2(
+		git_object_peel((git_object **)out, obj, GIT_OBJ_TREE),
+		"resolving object to tree", treeish);
+
+	git_object_free(obj);
+}
+