1 files changed, 75 insertions, 0 deletions
diff --git a/gitenv.c b/gitenv.c
new file mode 100644
index 0000000000..ab9396f969
--- /dev/null
+++ b/gitenv.c
@@ -0,0 +1,75 @@
+/*
+ * Copyright (C) 2005 Junio C Hamano
+ */
+#include "cache.h"
+
+/*
+ * This array must be sorted by its canonical name, because
+ * we do look-up by binary search.
+ */
+static struct backward_compatible_env {
+	const char *canonical;
+	const char *old;
+} bc_name[] = {
+	{ "GIT_ALTERNATE_OBJECT_DIRECTORIES", "SHA1_FILE_DIRECTORIES" },
+	{ "GIT_AUTHOR_DATE", "AUTHOR_DATE" },
+	{ "GIT_AUTHOR_EMAIL", "AUTHOR_EMAIL" },
+	{ "GIT_AUTHOR_NAME", "AUTHOR_NAME" }, 
+	{ "GIT_COMMITTER_EMAIL", "COMMIT_AUTHOR_EMAIL" },
+	{ "GIT_COMMITTER_NAME", "COMMIT_AUTHOR_NAME" },
+	{ "GIT_OBJECT_DIRECTORY", "SHA1_FILE_DIRECTORY" },
+};
+
+static void warn_old_environment(int pos)
+{
+	int i;
+	static int warned = 0;
+	if (warned)
+		return;
+
+	warned = 1;
+	fprintf(stderr,
+		"warning: Attempting to use %s\n",
+		bc_name[pos].old);
+	fprintf(stderr,
+		"warning: GIT environment variables have been renamed.\n"
+		"warning: Please adjust your scripts and environment.\n");
+	for (i = 0; i < sizeof(bc_name) / sizeof(bc_name[0]); i++) {
+		/* warning is needed only when old name is there and
+		 * new name is not.
+		 */
+		if (!getenv(bc_name[i].canonical) && getenv(bc_name[i].old))
+			fprintf(stderr, "warning: old %s => new %s\n",
+				bc_name[i].old, bc_name[i].canonical);
+	}
+}
+
+char *gitenv_bc(const char *e)
+{
+	int first, last;
+	char *val = getenv(e);
+	if (val)
+		die("gitenv_bc called on existing %s; fix the caller.", e);
+
+	first = 0;
+	last = sizeof(bc_name) / sizeof(bc_name[0]);
+	while (last > first) {
+		int next = (last + first) >> 1;
+		int cmp = strcmp(e, bc_name[next].canonical);
+		if (!cmp) {
+			val = getenv(bc_name[next].old);
+			/* If the user has only old name, warn.
+			 * otherwise stay silent.
+			 */
+			if (val)
+				warn_old_environment(next);
+			return val;
+		}
+		if (cmp < 0) {
+			last = next;
+			continue;
+		}
+		first = next+1;
+	}
+	return NULL;
+}