New options: -[io], read/write files from/to stdin/out

Fixes issue #84

README.md

@@ -75,8 +75,10 @@ of small previews is displayed, making it easy to choose an image to open.
     -f           Start in fullscreen mode
     -g GEOMETRY  Set window position and size
                  (see section GEOMETRY SPECIFICATIONS of X(7))
+    -i           Read file list from stdin
     -n NUM       Start at picture NUM
     -N NAME      Set X window resource name to NAME
+    -o           Write file list to stdout when quitting
     -p           Pixelize, i.e. turn off image anti-aliasing
     -q           Be quiet, disable warnings
     -r           Search given directories recursively for images

commands.c

@@ -26,6 +26,7 @@
 
 #include "commands.h"
 #include "image.h"
+#include "options.h"
 #include "thumbs.h"
 #include "util.h"
 #include "config.h"
@@ -57,6 +58,12 @@ const int ss_delays[] = {
 
 bool it_quit(arg_t a)
 {
+	unsigned int i;
+
+	if (options->to_stdout) {
+		for (i = 0; i < filecnt; i++)
+			printf("%s\n", files[i].name);
+	}
 	cleanup();
 	exit(EXIT_SUCCESS);
 }

main.c

@@ -622,7 +622,7 @@ int main(int argc, char **argv)
 		exit(EXIT_SUCCESS);
 	}
 
-	if (options->filecnt == 0) {
+	if (options->filecnt == 0 && !options->from_stdin) {
 		print_usage();
 		exit(EXIT_FAILURE);
 	}
@@ -635,7 +635,6 @@ int main(int argc, char **argv)
 	files = (fileinfo_t*) s_malloc(filecnt * sizeof(fileinfo_t));
 	fileidx = 0;
 
-	/* build file list: */
 	if (options->from_stdin) {
 		filename = NULL;
 		while ((len = get_line(&filename, &n, stdin)) > 0) {
@@ -645,7 +644,8 @@ int main(int argc, char **argv)
 		}
 		if (filename != NULL)
 			free(filename);
-	} else {
+	}
+
 	for (i = 0; i < options->filecnt; i++) {
 		filename = options->filenames[i];
 
@@ -674,7 +674,6 @@ int main(int argc, char **argv)
 				qsort(files + start, fileidx - start, sizeof(fileinfo_t), fncmp);
 		}
 	}
-	}
 
 	if (fileidx == 0) {
 		fprintf(stderr, "sxiv: no valid image file given, aborting\n");

options.c

@@ -33,7 +33,7 @@ const options_t *options = (const options_t*) &_options;
 
 void print_usage(void)
 {
-	printf("usage: sxiv [-bcdFfhpqrstvZ] [-g GEOMETRY] [-n NUM] "
+	printf("usage: sxiv [-bcdFfhiopqrstvZ] [-g GEOMETRY] [-n NUM] "
 	       "[-N name] [-z ZOOM] FILES...\n");
 }
 
@@ -46,6 +46,8 @@ void parse_options(int argc, char **argv)
 {
 	int opt, t;
 
+	_options.from_stdin = false;
+	_options.to_stdout = false;
 	_options.recursive = false;
 	_options.startnum = 0;
 
@@ -63,7 +65,7 @@ void parse_options(int argc, char **argv)
 	_options.thumb_mode = false;
 	_options.clean_cache = false;
 
-	while ((opt = getopt(argc, argv, "bcdFfg:hn:N:pqrstvZz:")) != -1) {
+	while ((opt = getopt(argc, argv, "bcdFfg:hin:N:opqrstvZz:")) != -1) {
 		switch (opt) {
 			case '?':
 				print_usage();
@@ -89,6 +91,9 @@ void parse_options(int argc, char **argv)
 			case 'h':
 				print_usage();
 				exit(EXIT_SUCCESS);
+			case 'i':
+				_options.from_stdin = true;
+				break;
 			case 'n':
 				if (sscanf(optarg, "%d", &t) <= 0 || t < 1) {
 					fprintf(stderr, "sxiv: invalid argument for option -n: %s\n",
@@ -101,6 +106,9 @@ void parse_options(int argc, char **argv)
 			case 'N':
 				_options.res_name = optarg;
 				break;
+			case 'o':
+				_options.to_stdout = true;
+				break;
 			case 'p':
 				_options.aa = false;
 				break;
@@ -137,6 +145,10 @@ void parse_options(int argc, char **argv)
 
 	_options.filenames = argv + optind;
 	_options.filecnt = argc - optind;
-	_options.from_stdin = _options.filecnt == 1 &&
-	                      STREQ(_options.filenames[0], "-");
+
+	if (_options.filecnt == 1 && STREQ(_options.filenames[0], "-")) {
+		_options.filenames++;
+		_options.filecnt--;
+		_options.from_stdin = true;
+	}
 }

options.h

@@ -26,6 +26,7 @@ typedef struct {
 	/* file list: */
 	char **filenames;
 	bool from_stdin;
+	bool to_stdout;
 	bool recursive;
 	int filecnt;
 	int startnum;

sxiv.1

@@ -3,7 +3,7 @@
 sxiv \- Simple X Image Viewer
 .SH SYNOPSIS
 .B sxiv
-.RB [ \-bcdFfhpqrstvZ ]
+.RB [ \-bcdFfhiopqrstvZ ]
 .RB [ \-g
 .IR GEOMETRY ]
 .RB [ \-n
@@ -17,13 +17,6 @@ sxiv \- Simple X Image Viewer
 sxiv is a simple image viewer for X. It only has the most basic features
 required for fast image viewing.
 .P
-sxiv opens all named
-.IR FILE s,
-or reads the names of the files to open from standard input, if only a single
-hyphen\-minus
-.RB ( \- )
-is given.
-.P
 sxiv has two modes of operation: image and thumbnail mode. The default is image
 mode, in which only the current image is shown. In thumbnail mode a grid of 
 small previews is displayed, making it easy to choose an image to open.
@@ -65,6 +58,14 @@ Set the resource name of sxiv's X window to NAME.
 .B \-h
 Print brief usage information to standard output and exit.
 .TP
+.B \-i
+Read names of files to open from standard input.
+.TP
+.B \-o
+Write list of opened files to standard output when quitting. If combined with
+.IR \-i ,
+then sxiv acts as a visual filter/pipe.
+.TP
 .B \-p
 Pixelize images, i.e. turn off anti-aliasing.
 .TP