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	dd: Use sigaction(2) to obviate select(2) - ubase - suckless linux base utils
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	---
	commit 55795531f03ccb5a41cf80fd564b862c103252cc
	parent fae9ca81a2eaf3534299b7ca3033b1e6605f9ab2
	Author: Eric Pruitt <[email protected]>
	Date: Tue, 10 Oct 2017 16:27:27 +0100

	dd: Use sigaction(2) to obviate select(2)

	By setting the SIGINT handler with sigaction(2), automatic retries of
	the splice(2) syscall can be disabled by not setting SA_RESTART. This
	makes it possible to use Ctrl+C even if the "if" operand refers to the
	controlling terminal. The SIGINT message has also been moved outside
	the signal handler since fprintf(3) is not an async-signal-safe
	function.

	Diffstat:
	M dd.c \| 61 ++++++++++++++++-------------…

	1 file changed, 32 insertions(+), 29 deletions(-)
	---
	diff --git a/dd.c b/dd.c
	@@ -8,7 +8,6 @@
	*/
	#include <sys/ioctl.h>
	#include <sys/mount.h>
	-#include <sys/select.h>
	#include <sys/stat.h>
	#include <sys/time.h>
	#include <sys/types.h>
	@@ -38,6 +37,15 @@ struct dd_config {

	static int sigint = 0;

	+static void
	+sig_int(int unused_1, siginfo_t unused_2, void unused_3)
	+{
	+ (void) unused_1;
	+ (void) unused_2;
	+ (void) unused_3;
	+ sigint = 1;
	+}
	+
	static int
	prepare_copy(struct dd_config ddc, int ifd, int *ofd)
	{
	@@ -147,7 +155,6 @@ copy_splice(struct dd_config *ddc)
	int ifd, ofd, p[2] = {-1, -1};
	ssize_t r = 0;
	size_t n = 0;
	- fd_set rfd, wfd;

	if (prepare_copy(ddc, &ifd, &ofd) < 0)
	return -1;
	@@ -165,27 +172,24 @@ copy_splice(struct dd_config *ddc)
	#endif
	n = ddc->bs;
	for (;ddc->b_out != ddc->count && !sigint;) {
	- FD_ZERO(&rfd);
	- FD_ZERO(&wfd);
	- FD_SET(ifd, &rfd);
	- FD_SET(ofd, &wfd);
	- r = select(ifd > ofd ? ifd + 1 : ofd + 1, &rfd, &wfd, NULL, NU…
	if (r < 0)
	break;
	- if (FD_ISSET(ifd, &rfd) == 1 && FD_ISSET(ofd, &wfd) == 1) {
	- if (n > ddc->count - ddc->b_out)
	- n = ddc->count - ddc->b_out;
	- r = splice(ifd, NULL, p[1], NULL, n, SPLICE_F_MORE);
	- if (r <= 0)
	- break;
	- ++ddc->rec_in;
	- r = splice(p[0], NULL, ofd, NULL, r, SPLICE_F_MORE);
	- if (r <= 0)
	- break;
	- ddc->b_out += r;
	- ++ddc->rec_out;
	- }
	+ if (n > ddc->count - ddc->b_out)
	+ n = ddc->count - ddc->b_out;
	+ r = splice(ifd, NULL, p[1], NULL, n, SPLICE_F_MORE);
	+ if (r <= 0)
	+ break;
	+ ++ddc->rec_in;
	+ r = splice(p[0], NULL, ofd, NULL, r, SPLICE_F_MORE);
	+ if (r <= 0)
	+ break;
	+ ddc->b_out += r;
	+ ++ddc->rec_out;
	}
	+
	+ if (sigint)
	+ fprintf(stderr, "SIGINT! Aborting ...\n");
	+
	close(ifd);
	close(ofd);
	close(p[0]);
	@@ -227,14 +231,6 @@ print_stat(const struct dd_config *ddc)
	}

	static void
	-sig_int(int unused)
	-{
	- (void) unused;
	- fprintf(stderr, "SIGINT! Aborting ...\n");
	- sigint = 1;
	-}
	-
	-static void
	usage(void)
	{
	eprintf("usage: %s [-h] [if=infile] [of=outfile] [bs[=N]] [seek=N] "
	@@ -248,6 +244,7 @@ main(int argc, char *argv[])
	int i = 0;
	char buf[1024];
	struct dd_config config;
	+ struct sigaction sa;

	argv0 = argv[0];
	memset(&config, 0, sizeof(config));
	@@ -286,7 +283,13 @@ main(int argc, char *argv[])
	}

	signal(SIGPIPE, SIG_IGN);
	- signal(SIGINT, sig_int);
	+
	+ sa.sa_flags = SA_SIGINFO;
	+ sigemptyset(&sa.sa_mask);
	+ sa.sa_sigaction = sig_int;
	+
	+ if (sigaction(SIGINT, &sa, NULL) == -1)
	+ weprintf("sigaction");

	if (copy(&config) < 0)
	weprintf("copy:");