@matheusbsbs / matheus-bagliano / commits / 4dca1aa650

git-submodule.sh: preserve stdin for the command spawned by foreach

The user-supplied command spawned by 'submodule foreach' loses its connection to the original standard input. Instead, it is connected to the output of a pipe within the git-submodule script. The user-supplied command supplied to 'submodule foreach' is spawned within a while loop which is being piped into. Due to the way shells implement piping output to a while loop, a subshell is created with its standard input attached to the output of the pipe. This results in all of the commands executed within the while loop to have their stdins modified in the same way, including the user-supplied command. This can cause a problem if the command requires reading from stdin or if it changes its behavior based on whether stdin is a tty or not. For example, this problem was noticed when trying to execute the following: git submodule foreach git shortlog --since=two.weeks.ago which printed a message about entering the first submodule and produced no further output and exited with a status of zero. In this case, shortlog detected that it was not connected to a tty, and since no revision was supplied as an argument, it attempted to read the list of revisions from standard input. Instead, it slurped up the list of submodules that was being piped to the enclosing while loop and caused that loop to end early without processing the remaining submodules. Work around this behavior by saving the original standard input file descriptor before the while loop, and restoring it when spawning the user-supplied command. This fixes the tests in t7407. Signed-off-by: Brandon Casey <drafnel@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>

Brandon Casey committed Jun 29, 2011 at 19:34 UTC 4dca1aa6502a46f8d7b6ecc8e7812c5c23ad0923

2 files changed +7 -3

git-submodule.sh

+5 -1

@@ -285,6 +285,10 @@ cmd_foreach()

285

286 toplevel=$(pwd)

287

288 + # dup stdin so that it can be restored when running the external

289 + # command in the subshell (and a recursive call to this function)

290 + exec 3<&0

291 +

292 module_list |

293 while read mode sha1 stage path

294 do

@@ -301,7 +305,7 @@ cmd_foreach()

305 then

306 cmd_foreach "--recursive" "$@"

307 fi

304 - ) ||

308 + ) <&3 3<&- ||

309 die "Stopping at '$path'; script returned non-zero status."

310 fi

311 done

t/t7407-submodule-foreach.sh

+2 -2

@@ -288,7 +288,7 @@ test_expect_success 'use "update --recursive nested1" to checkout all submodules

288 )

289 '

290

291 -test_expect_failure 'command passed to foreach retains notion of stdin' '

291 +test_expect_success 'command passed to foreach retains notion of stdin' '

292 (

293 cd super &&

294 git submodule foreach echo success >../expected &&

@@ -297,7 +297,7 @@ test_expect_failure 'command passed to foreach retains notion of stdin' '

297 test_cmp expected actual

298 '

299

300 -test_expect_failure 'command passed to foreach --recursive retains notion of stdin' '

300 +test_expect_success 'command passed to foreach --recursive retains notion of stdin' '

301 (

302 cd clone2 &&

303 git submodule foreach --recursive echo success >../expected &&