# [PATCH] Documentation/install-webdoc.sh: quote a potentially unsafe shell expansion 3 messages from 2016-12-01 to 2016-12-02. Participants: Austin English, Junio C Hamano. Thread: https://gitlist.dev/t/44580 ## Austin English, 2016-12-01 01:22 Subject: [PATCH] Documentation/install-webdoc.sh: quote a potentially unsafe shell expansion Message-ID: URL: https://gitlist.dev/e/CACC5Q1eFM_G4wKopkbxabLEu8%2Bnbt66wF1jKSoTuL1vnS5Tb4Q%40mail.gmail.com ``` Found via shellcheck In Documentation/install-webdoc.sh line 21: mkdir -p $(dirname "$T/$h") ^-- SC2046: Quote this to prevent word splitting. -- -Austin GPG: 14FB D7EA A041 937B From 1050538f252d22311185065ab8837c71b17003fb Mon Sep 17 00:00:00 2001 From: Austin English Date: Wed, 30 Nov 2016 19:21:25 -0600 Subject: [PATCH] Documentation/install-webdoc.sh: quote a potentially unsafe shell expansion Signed-off-by: Austin English --- Documentation/install-webdoc.sh | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/Documentation/install-webdoc.sh b/Documentation/install-webdoc.sh index ed8b4ff..5fb2dc5 100755 --- a/Documentation/install-webdoc.sh +++ b/Documentation/install-webdoc.sh @@ -18,7 +18,7 @@ do else echo >&2 "# install $h $T/$h" rm -f "$T/$h" - mkdir -p $(dirname "$T/$h") + mkdir -p "$(dirname "$T/$h")" cp "$h" "$T/$h" fi done -- 2.7.3 ``` ## Junio C Hamano, 2016-12-01 20:42 Subject: Re: [PATCH] Documentation/install-webdoc.sh: quote a potentially unsafe shell expansion Message-ID: URL: https://gitlist.dev/e/xmqqfum78jq0.fsf%40gitster.mtv.corp.google.com In-Reply-To: ``` Austin English writes: > diff --git a/Documentation/install-webdoc.sh b/Documentation/install-webdoc.sh > index ed8b4ff..5fb2dc5 100755 > --- a/Documentation/install-webdoc.sh > +++ b/Documentation/install-webdoc.sh > @@ -18,7 +18,7 @@ do > else > echo >&2 "# install $h $T/$h" > rm -f "$T/$h" > - mkdir -p $(dirname "$T/$h") > + mkdir -p "$(dirname "$T/$h")" > cp "$h" "$T/$h" > fi > done We know $h is safe without quoting (see what the for loop iterates over a list and binding each element of it to this variable), but T is the parameter given to this script, which comes from these install-html: html '$(SHELL_PATH_SQ)' ./install-webdoc.sh $(DESTDIR)$(htmldir) install-webdoc : html '$(SHELL_PATH_SQ)' ./install-webdoc.sh $(WEBDOC_DEST) in the Makefile. So quoting the result of $(dirname "$T/$h") is just as necessary as quoting the argument given to this dirname. But I do not think it is sufficient, if we are truly worried about people who specify a path that contains IFS whitespace in DESTDIR, WEBDOC_DEST, htmldir and other *dir variables used in the Makefile. The references to these variables, when they are mentioned on the command lines of Makefile actions, all need to be quoted. The remainder of the Makefile tells me that we decided that we are not worried about those people at all. So while I could take your patch as-is, I am not sure how much value it adds to the overall callchain that would reach the location that is updated by the patch. If you run make DESTDIR="/tmp/My Temporary Place" install it would still not do the right thing even with your patch, I would suspect. Thanks. ``` ## Austin English, 2016-12-02 01:40 Subject: Re: [PATCH] Documentation/install-webdoc.sh: quote a potentially unsafe shell expansion Message-ID: URL: https://gitlist.dev/e/CACC5Q1dfbDcDdFNmbsM63nkLWzbE6WXxLrTLZm5YTRTbVtgoOQ%40mail.gmail.com In-Reply-To: ``` On Thu, Dec 1, 2016 at 2:42 PM, Junio C Hamano wrote: > Austin English writes: > >> diff --git a/Documentation/install-webdoc.sh b/Documentation/install-webdoc.sh >> index ed8b4ff..5fb2dc5 100755 >> --- a/Documentation/install-webdoc.sh >> +++ b/Documentation/install-webdoc.sh >> @@ -18,7 +18,7 @@ do >> else >> echo >&2 "# install $h $T/$h" >> rm -f "$T/$h" >> - mkdir -p $(dirname "$T/$h") >> + mkdir -p "$(dirname "$T/$h")" >> cp "$h" "$T/$h" >> fi >> done > > We know $h is safe without quoting (see what the for loop iterates > over a list and binding each element of it to this variable), but T > is the parameter given to this script, which comes from these > > install-html: html > '$(SHELL_PATH_SQ)' ./install-webdoc.sh $(DESTDIR)$(htmldir) > > install-webdoc : html > '$(SHELL_PATH_SQ)' ./install-webdoc.sh $(WEBDOC_DEST) > > in the Makefile. So quoting the result of $(dirname "$T/$h") is > just as necessary as quoting the argument given to this dirname. > > But I do not think it is sufficient, if we are truly worried about > people who specify a path that contains IFS whitespace in DESTDIR, > WEBDOC_DEST, htmldir and other *dir variables used in the Makefile. > The references to these variables, when they are mentioned on the > command lines of Makefile actions, all need to be quoted. The > remainder of the Makefile tells me that we decided that we are not > worried about those people at all. > > So while I could take your patch as-is, I am not sure how much value > it adds to the overall callchain that would reach the location that > is updated by the patch. If you run > > make DESTDIR="/tmp/My Temporary Place" install > > it would still not do the right thing even with your patch, I would > suspect. > > Thanks. Hi Junio, Thanks for reply and reviewing. Your concerns are totally valid. Some context for the change. I wrote a wrapper script for checkbashisms/shellcheck that I use in my project. I decided to run it on other projects I have checked out, out of curiosity, and looked at some of the results. This was the only one in git, so I thought it was worth fixing. I did not test the full pipeline. I'll look again and send a follow up patch soon. -- -Austin GPG: 14FB D7EA A041 937B ```