1 files changed, 122 insertions, 0 deletions
diff --git a/pager.c b/pager.c
new file mode 100644
index 0000000000..6b5c9e44b4
--- /dev/null
+++ b/pager.c
@@ -0,0 +1,122 @@
+#include "cache.h"
+
+/*
+ * This is split up from the rest of git so that we can do
+ * something different on Windows.
+ */
+
+static int spawned_pager;
+
+#ifndef __MINGW32__
+static void run_pager(const char *pager)
+{
+	/*
+	 * Work around bug in "less" by not starting it until we
+	 * have real input
+	 */
+	fd_set in;
+
+	FD_ZERO(&in);
+	FD_SET(0, &in);
+	select(1, &in, NULL, &in, NULL);
+
+	execlp(pager, pager, NULL);
+	execl("/bin/sh", "sh", "-c", pager, NULL);
+}
+#else
+#include "run-command.h"
+
+static const char *pager_argv[] = { "sh", "-c", NULL, NULL };
+static struct child_process pager_process = {
+	.argv = pager_argv,
+	.in = -1
+};
+static void wait_for_pager(void)
+{
+	fflush(stdout);
+	fflush(stderr);
+	/* signal EOF to pager */
+	close(1);
+	close(2);
+	finish_command(&pager_process);
+}
+#endif
+
+void setup_pager(void)
+{
+#ifndef __MINGW32__
+	pid_t pid;
+	int fd[2];
+#endif
+	const char *pager = getenv("GIT_PAGER");
+
+	if (!isatty(1))
+		return;
+	if (!pager) {
+		if (!pager_program)
+			git_config(git_default_config, NULL);
+		pager = pager_program;
+	}
+	if (!pager)
+		pager = getenv("PAGER");
+	if (!pager)
+		pager = "less";
+	else if (!*pager || !strcmp(pager, "cat"))
+		return;
+
+	spawned_pager = 1; /* means we are emitting to terminal */
+
+#ifndef __MINGW32__
+	if (pipe(fd) < 0)
+		return;
+	pid = fork();
+	if (pid < 0) {
+		close(fd[0]);
+		close(fd[1]);
+		return;
+	}
+
+	/* return in the child */
+	if (!pid) {
+		dup2(fd[1], 1);
+		dup2(fd[1], 2);
+		close(fd[0]);
+		close(fd[1]);
+		return;
+	}
+
+	/* The original process turns into the PAGER */
+	dup2(fd[0], 0);
+	close(fd[0]);
+	close(fd[1]);
+
+	setenv("LESS", "FRSX", 0);
+	run_pager(pager);
+	die("unable to execute pager '%s'", pager);
+	exit(255);
+#else
+	/* spawn the pager */
+	pager_argv[2] = pager;
+	if (start_command(&pager_process))
+		return;
+
+	/* original process continues, but writes to the pipe */
+	dup2(pager_process.in, 1);
+	dup2(pager_process.in, 2);
+	close(pager_process.in);
+
+	/* this makes sure that the parent terminates after the pager */
+	atexit(wait_for_pager);
+#endif
+}
+
+int pager_in_use(void)
+{
+	const char *env;
+
+	if (spawned_pager)
+		return 1;
+
+	env = getenv("GIT_PAGER_IN_USE");
+	return env ? git_config_bool("GIT_PAGER_IN_USE", env) : 0;
+}