Introduce trivial new pager.c helper infrastructure

[git.git] / pager.c

diff --git a/pager.c b/pager.c
new file mode 100644 (file)
index 0000000..1364e15
--- /dev/null
+++ b/pager.c
@@ -0,0 +1,48 @@
+#include "cache.h"
+
+/*
+ * This is split up from the rest of git so that we might do
+ * something different on Windows, for example.
+ */
+
+static void run_pager(void)
+{
+       const char *prog = getenv("PAGER");
+       if (!prog)
+               prog = "less";
+       setenv("LESS", "-S", 0);
+       execlp(prog, prog, NULL);
+}
+
+void setup_pager(void)
+{
+       pid_t pid;
+       int fd[2];
+
+       if (!isatty(1))
+               return;
+       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);
+               close(fd[0]);
+               close(fd[1]);
+               return;
+       }
+
+       /* The original process turns into the PAGER */
+       dup2(fd[0], 0);
+       close(fd[0]);
+       close(fd[1]);
+
+       run_pager();
+       exit(255);
+}