Adding upstream version 2.38.1.upstream/2.38.1upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 317 insertions, 0 deletions

diff --git a/lib/pager.c b/lib/pager.c
new file mode 100644
index 0000000..747521e
--- /dev/null
+++ b/lib/pager.c
@@ -0,0 +1,317 @@
+/*
+ * Based on linux-perf/git scm
+ *
+ * Some modifications and simplifications for util-linux
+ * by Davidlohr Bueso <dave@xxxxxxx> - March 2012.
+ */
+
+#include <unistd.h>
+#include <stdlib.h>
+#include <string.h>
+#include <err.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <sys/wait.h>
+#include <signal.h>
+
+#include "c.h"
+#include "xalloc.h"
+#include "nls.h"
+#include "ttyutils.h"
+#include "pager.h"
+
+#define NULL_DEVICE	"/dev/null"
+
+static const char *pager_argv[] = { "sh", "-c", NULL, NULL };
+
+struct child_process {
+	const char **argv;
+	pid_t pid;
+	int in;
+	int out;
+	int err;
+
+	int org_err;
+	int org_out;
+	struct sigaction orig_sigint;
+	struct sigaction orig_sighup;
+	struct sigaction orig_sigterm;
+	struct sigaction orig_sigquit;
+	struct sigaction orig_sigpipe;
+
+	unsigned no_stdin:1;
+	void (*preexec_cb)(void);
+};
+static struct child_process pager_process;
+
+static inline void close_pair(int fd[2])
+{
+	close(fd[0]);
+	close(fd[1]);
+}
+
+static int start_command(struct child_process *cmd)
+{
+	int need_in;
+	int fdin[2];
+
+	/*
+	 * In case of errors we must keep the promise to close FDs
+	 * that have been passed in via ->in and ->out.
+	 */
+	need_in = !cmd->no_stdin && cmd->in < 0;
+	if (need_in) {
+		if (pipe(fdin) < 0) {
+			if (cmd->out > 0)
+				close(cmd->out);
+			return -1;
+		}
+		cmd->in = fdin[1];
+	}
+
+	fflush(NULL);
+	cmd->pid = fork();
+	if (!cmd->pid) {
+		if (need_in) {
+			dup2(fdin[0], STDIN_FILENO);
+			close_pair(fdin);
+		} else if (cmd->in > 0) {
+			dup2(cmd->in, STDIN_FILENO);
+			close(cmd->in);
+		}
+
+		cmd->preexec_cb();
+		execvp(cmd->argv[0], (char *const*) cmd->argv);
+		errexec(cmd->argv[0]);
+	}
+
+	if (cmd->pid < 0) {
+		if (need_in)
+			close_pair(fdin);
+		else if (0 <= cmd->in)
+			close(cmd->in);
+		return -1;
+	}
+
+	if (need_in)
+		close(fdin[0]);
+	else if (0 <= cmd->in)
+		close(cmd->in);
+	return 0;
+}
+
+static int wait_or_whine(pid_t pid)
+{
+	for (;;) {
+		int status, code;
+		pid_t waiting = waitpid(pid, &status, 0);
+
+		if (waiting < 0) {
+			if (errno == EINTR)
+				continue;
+			err(EXIT_FAILURE, _("waitpid failed (%s)"), strerror(errno));
+		}
+		if (waiting != pid)
+			return -1;
+		if (WIFSIGNALED(status))
+			return -1;
+
+		if (!WIFEXITED(status))
+			return -1;
+		code = WEXITSTATUS(status);
+		switch (code) {
+		case 127:
+			return -1;
+		case 0:
+			return 0;
+		default:
+			return -1;
+		}
+	}
+}
+
+static int finish_command(struct child_process *cmd)
+{
+	return wait_or_whine(cmd->pid);
+}
+
+static void pager_preexec(void)
+{
+	/*
+	 * Work around bug in "less" by not starting it until we
+	 * have real input
+	 */
+	fd_set in, ex;
+
+	FD_ZERO(&in);
+	FD_SET(STDIN_FILENO, &in);
+	ex = in;
+
+	select(STDIN_FILENO + 1, &in, NULL, &ex, NULL);
+
+	if (setenv("LESS", "FRSX", 0) != 0)
+		warn(_("failed to set the %s environment variable"), "LESS");
+}
+
+static void wait_for_pager(void)
+{
+	if (pager_process.pid == 0)
+		return;
+
+	fflush(stdout);
+	fflush(stderr);
+	/* signal EOF to pager */
+	close(STDOUT_FILENO);
+	close(STDERR_FILENO);
+	finish_command(&pager_process);
+}
+
+static void wait_for_pager_signal(int signo)
+{
+	wait_for_pager();
+	raise(signo);
+}
+
+static int has_command(const char *cmd)
+{
+	const char *path;
+	char *p, *s;
+	int rc = 0;
+
+	if (!cmd)
+		goto done;
+	if (*cmd == '/') {
+		rc = access(cmd, X_OK) == 0;
+		goto done;
+	}
+
+	path = getenv("PATH");
+	if (!path)
+		goto done;
+	p = xstrdup(path);
+	if (!p)
+		goto done;
+
+	for(s = strtok(p, ":"); s; s = strtok(NULL, ":")) {
+		int fd = open(s, O_RDONLY|O_CLOEXEC);
+		if (fd < 0)
+			continue;
+		rc = faccessat(fd, cmd, X_OK, 0) == 0;
+		close(fd);
+		if (rc)
+			break;
+	}
+	free(p);
+done:
+	/*fprintf(stderr, "has PAGER %s rc=%d\n", cmd, rc);*/
+	return rc;
+}
+
+static void __setup_pager(void)
+{
+	const char *pager = getenv("PAGER");
+	struct sigaction sa;
+
+	if (!isatty(STDOUT_FILENO))
+		return;
+
+	if (!pager)
+		pager = "less";
+	else if (!*pager || !strcmp(pager, "cat"))
+		return;
+
+	if (!has_command(pager))
+		return;
+
+	/* spawn the pager */
+	pager_argv[2] = pager;
+	pager_process.argv = pager_argv;
+	pager_process.in = -1;
+	pager_process.preexec_cb = pager_preexec;
+
+	if (start_command(&pager_process))
+		return;
+
+	/* original process continues, but writes to the pipe */
+	dup2(pager_process.in, STDOUT_FILENO);
+	if (isatty(STDERR_FILENO))
+		dup2(pager_process.in, STDERR_FILENO);
+	close(pager_process.in);
+
+	memset(&sa, 0, sizeof(sa));
+	sa.sa_handler = wait_for_pager_signal;
+
+	/* this makes sure that the parent terminates after the pager */
+	sigaction(SIGINT,  &sa, &pager_process.orig_sigint);
+	sigaction(SIGHUP,  &sa, &pager_process.orig_sighup);
+	sigaction(SIGTERM, &sa, &pager_process.orig_sigterm);
+	sigaction(SIGQUIT, &sa, &pager_process.orig_sigquit);
+	sigaction(SIGPIPE, &sa, &pager_process.orig_sigpipe);
+}
+
+/* Setup pager and redirects output to the $PAGER. The pager is closed at exit.
+ */
+void pager_redirect(void)
+{
+	if (pager_process.pid)
+		return;		/* already running */
+
+	__setup_pager();
+
+	atexit(wait_for_pager);
+}
+
+/* Setup pager and redirect output, the pager may be closed by pager_close().
+ */
+void pager_open(void)
+{
+	if (pager_process.pid)
+		return;		/* already running */
+
+	pager_process.org_out = dup(STDOUT_FILENO);
+	pager_process.org_err = dup(STDERR_FILENO);
+
+	__setup_pager();
+}
+
+/* Close pager and restore original std{out,err}.
+ */
+void pager_close(void)
+{
+	if (pager_process.pid == 0)
+		return;
+
+	wait_for_pager();
+
+	/* restore original output */
+	dup2(pager_process.org_out, STDOUT_FILENO);
+	dup2(pager_process.org_err, STDERR_FILENO);
+
+	close(pager_process.org_out);
+	close(pager_process.org_err);
+
+	/* restore original segnals setting */
+	sigaction(SIGINT,  &pager_process.orig_sigint, NULL);
+	sigaction(SIGHUP,  &pager_process.orig_sighup, NULL);
+	sigaction(SIGTERM, &pager_process.orig_sigterm, NULL);
+	sigaction(SIGQUIT, &pager_process.orig_sigquit, NULL);
+	sigaction(SIGPIPE, &pager_process.orig_sigpipe, NULL);
+
+	memset(&pager_process, 0, sizeof(pager_process));
+}
+
+#ifdef TEST_PROGRAM_PAGER
+
+#define MAX 255
+
+int main(int argc __attribute__ ((__unused__)),
+	 char *argv[] __attribute__ ((__unused__)))
+{
+	int i;
+
+	pager_redirect();
+	for (i = 0; i < MAX; i++)
+		printf("%d\n", i);
+	return EXIT_SUCCESS;
+}
+#endif /* TEST_PROGRAM_PAGER */