[pacman-dev] [PATCH] Support reading package args from stdin

[Dave Reisner]

Only occurs if no arguments were provided directly. Arguments can be
separated by any amount of valid whitespace. This allows for piping into
pacman from other programs or from itself, e.g.:

  pacman -Qdtq | pacman -Rs

This is better than using xargs, as xargs will not reconnect stdin to
the terminal. The above operation performed using xargs would require
the --noconfirm flag to be passed to pacman.

Revised from the original 7/24 submission at Allan's request to check
the return value of freopen().

Signed-off-by: Dave Reisner <d at falconindy.com>
---
 src/pacman/pacman.c |   27 +++++++++++++++++++++++++++
 1 files changed, 27 insertions(+), 0 deletions(-)

diff --git a/src/pacman/pacman.c b/src/pacman/pacman.c
index 15abecc..6f40a97 100644
--- a/src/pacman/pacman.c
+++ b/src/pacman/pacman.c
@@ -26,6 +26,7 @@
 #define PACKAGE_VERSION GIT_VERSION
 #endif
 
+#include <ctype.h> /* isspace */
 #include <stdlib.h> /* atoi */
 #include <stdio.h>
 #include <limits.h>
@@ -1305,6 +1306,32 @@ int main(int argc, char *argv[])
 		cleanup(ret);
 	}
 
+	/* read package arguments from stdin if we have none yet */
+	if(!pm_targets && !isatty(0)) {
+		char line[BUFSIZ];
+		int i = 0;
+		while((line[i] = fgetc(stdin)) != EOF) {
+			if(isspace(line[i])) {
+				line[i] = 0;
+				/* avoid adding zero length arg when multiple spaces separate args */
+				if(i > 0) {
+					pm_targets = alpm_list_add(pm_targets, strdup(line));
+					i = 0;
+				}
+			} else {
+				++i;
+			}
+		}
+		/* end of stream -- check for data still in line buffer */
+		if(i > 0) {
+			pm_targets = alpm_list_add(pm_targets, strdup(line));
+		}
+		if (!freopen(ctermid(NULL), "r", stdin)) {
+			pm_printf(PM_LOG_ERROR, _("failed to reopen stdin for reading: (%s)\n"),
+					strerror(errno));
+		}
+	}
+
 	/* parse the config file */
 	ret = parseconfig(config->configfile);
 	if(ret != 0) {
-- 
1.7.3.2