[arch-projects] [dbscripts] [PATCH 4/8] Use `grep &>/dev/null` instead of `grep -q` when operating on piped stdin.

[Eli Schwartz]

On 03/13/2018 09:52 PM, Luke Shumaker wrote:
> From: Luke Shumaker <lukeshu at parabola.nu>
> 
> `grep -q` may exit as soon as it finds a match; this is a good optimization
> for when the input is a file.  However, if the input is the output of
> another program, then that other program will receive SIGPIPE, and further
> writes will fail.  When this happens, it might (bsdtar does) print a
> message about a "write error" to stderr.  Which is going to confuse and
> alarm the user.
> 
> In one of the cases, this had already been mitigated by wrapping
> bsdtar in "echo "$(bsdtar ...)", as Bash builtin echo doesn't complain
> if it gets SIGPIPE.  However, that means we're storing the entire
> output of bsdtar in memory, which is silly.
> ---
>  db-functions         | 2 +-
>  test/lib/common.bash | 4 ++--
>  2 files changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/db-functions b/db-functions
> index 58b753a..ee390ff 100644
> --- a/db-functions
> +++ b/db-functions
> @@ -303,7 +303,7 @@ check_pkgfile() {
>  
>  	in_array "${pkgarch}" "${ARCHES[@]}" 'any' || return 1
>  
> -	if echo "${pkgfile##*/}" | grep -q "^${pkgname}-${pkgver}-${pkgarch}"; then
> +	if echo "${pkgfile##*/}" | grep "^${pkgname}-${pkgver}-${pkgarch}" &>/dev/null; then

But echo should be fine anyway?

Regardless this could be so much more elegant.

if [[ $pkgfile = $pkgname-$pkgver-$pkgrel-$arch* ]]; then

>  		return 0
>  	else
>  		return 1
> diff --git a/test/lib/common.bash b/test/lib/common.bash
> index 45e4800..ab805dd 100644
> --- a/test/lib/common.bash
> +++ b/test/lib/common.bash
> @@ -215,7 +215,7 @@ checkPackageDB() {
>  
>  				for db in ${DBEXT} ${FILESEXT}; do
>  					[ -r "${FTP_BASE}/${repo}/os/${repoarch}/${repo}${db%.tar.*}" ]
> -					bsdtar -xf "${FTP_BASE}/${repo}/os/${repoarch}/${repo}${db%.tar.*}" -O | grep -q "${pkgfile%${PKGEXT}}"
> +					bsdtar -xf "${FTP_BASE}/${repo}/os/${repoarch}/${repo}${db%.tar.*}" -O | grep "${pkgfile%${PKGEXT}}" &>/dev/null
>  				done
>  			done
>  		done
> @@ -269,7 +269,7 @@ checkRemovedPackageDB() {
>  		for tarch in ${tarches[@]}; do
>  			if [ -r "${FTP_BASE}/${repo}/os/${tarch}/${repo}${db%.tar.*}" ]; then
>  				for pkgname in ${pkgnames[@]}; do
> -					echo "$(bsdtar -xf "${FTP_BASE}/${repo}/os/${tarch}/${repo}${db%.tar.*}" -O)" | grep -qv ${pkgname}
> +					bsdtar -xf "${FTP_BASE}/${repo}/os/${tarch}/${repo}${db%.tar.*}" -O | grep -v ${pkgname} &>/dev/null
>  				done
>  			fi
>  		done
> 


-- 
Eli Schwartz
Bug Wrangler and Trusted User

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