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

[Allan McRae]

On 05/11/10 00:20, Dave Reisner wrote:
> 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.

Dan: this sold the patch to me.

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

FYI, comments like this can go below the "---" two lines down.  That way 
they do not get included in the actual git commit.

> 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)) {

Two things here.  The HACKING file says to use if(foo() == 0) rather 
than if(!foo()).  But freopen returns a FILE*.  So we really should be 
checking if that == NULL?   Also, does the FILE* that freopen returns 
need closed here or is that fine as is?  I get slight confused...

> +			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) {