From 5a867317bb1cbf36d396d9cdb552212607dcc2b1 Mon Sep 17 00:00:00 2001 From: Denis Vlasenko Date: Thu, 24 Jul 2008 19:46:38 +0000 Subject: [PATCH] ash: fix a bug where redirection fds were not closed afterwards. optimize close+fcntl(DUPFD) into dup2. add testsuites. function old new delta copyfd 47 68 +21 argstr 1311 1298 -13 popredir 148 131 -17 redirect 1139 1107 -32 ------------------------------------------------------------------------------ (add/remove: 0/0 grow/shrink: 1/3 up/down: 21/-62) Total: -41 bytes --- shell/ash.c | 74 +++++++++++++-------------- shell/ash_test/ash-redir/redir2.right | 1 + shell/ash_test/ash-redir/redir2.tests | 5 ++ shell/ash_test/ash-redir/redir3.right | 3 ++ shell/ash_test/ash-redir/redir3.tests | 5 ++ shell/ash_test/run-all | 4 +- 6 files changed, 53 insertions(+), 39 deletions(-) create mode 100644 shell/ash_test/ash-redir/redir2.right create mode 100755 shell/ash_test/ash-redir/redir2.tests create mode 100644 shell/ash_test/ash-redir/redir3.right create mode 100755 shell/ash_test/ash-redir/redir3.tests diff --git a/shell/ash.c b/shell/ash.c index 22575ffbc..ec3bd0927 100644 --- a/shell/ash.c +++ b/shell/ash.c @@ -4846,12 +4846,21 @@ openredirect(union node *redir) * if the source file descriptor is closed, EMPTY if there are no unused * file descriptors left. */ +/* 0x800..00: bit to set in "to" to request dup2 instead of fcntl(F_DUPFD). + * old code was doing close(to) prior to copyfd() to achieve the same */ +#define COPYFD_EXACT ((int)~INT_MAX) static int copyfd(int from, int to) { int newfd; - newfd = fcntl(from, F_DUPFD, to); + if (to & COPYFD_EXACT) { + to &= ~COPYFD_EXACT; + /*if (from != to)*/ + newfd = dup2(from, to); + } else { + newfd = fcntl(from, F_DUPFD, to); + } if (newfd < 0) { if (errno == EMFILE) return EMPTY; @@ -4947,11 +4956,7 @@ redirect(union node *redir, int flags) /* Descriptor wasn't open before redirect. * Mark it for close in the future */ if (need_to_remember(sv, fd)) { - if (fd == 2) - copied_fd2 = CLOSED; /// do we need this? - sv->two_fd[sv_pos].orig = fd; - sv->two_fd[sv_pos].copy = CLOSED; - sv_pos++; + goto remember_to_close; } continue; } @@ -4959,6 +4964,10 @@ redirect(union node *redir, int flags) if (need_to_remember(sv, fd)) { /* Copy old descriptor */ i = fcntl(fd, F_DUPFD, 10); +/* You'd expect copy to be CLOEXECed. Currently these extra "saved" fds + * are closed in popredir() in the child, preventing them from leaking + * into child. (popredir() also cleans up the mess in case of failures) + */ if (i == -1) { i = errno; if (i != EBADF) { @@ -4969,31 +4978,25 @@ redirect(union node *redir, int flags) ash_msg_and_raise_error("%d: %m", fd); /* NOTREACHED */ } - /* EBADF: it is not open - ok */ - } else { - /* fd is open, save its copy */ -/* You'd expect copy to be CLOEXECed. Currently these extra "saved" fds - * are closed in popredir() in the child, preventing them from leaking - * into child. (popredir() also cleans up the mess in case of failures) - */ - if (fd == 2) - copied_fd2 = i; - sv->two_fd[sv_pos].orig = fd; - sv->two_fd[sv_pos].copy = i; - sv_pos++; - close(fd); - } - } else { - close(fd); + /* EBADF: it is not open - good, remember to close it */ + remember_to_close: + i = CLOSED; + } /* else: fd is open, save its copy */ + if (fd == 2) + copied_fd2 = i; + sv->two_fd[sv_pos].orig = fd; + sv->two_fd[sv_pos].copy = i; + sv_pos++; } - /* At this point fd is closed */ if (newfd < 0) { /* NTOFD/NFROMFD: copy redir->ndup.dupfd to fd */ - if (redir->ndup.dupfd >= 0) { /* if not ">&-" */ - copyfd(redir->ndup.dupfd, fd); + if (redir->ndup.dupfd < 0) { /* "NN>&-" */ + close(fd); + } else { + copyfd(redir->ndup.dupfd, fd | COPYFD_EXACT); } - } else { /* move newfd to fd */ - copyfd(newfd, fd); + } else if (fd != newfd) { /* move newfd to fd */ + copyfd(newfd, fd | COPYFD_EXACT); close(newfd); } } while ((redir = redir->nfile.next) != NULL); @@ -5025,8 +5028,8 @@ popredir(int drop) } if (rp->two_fd[i].copy != EMPTY) { if (!drop) { - close(fd); - copyfd(rp->two_fd[i].copy, fd); + /*close(fd);*/ + copyfd(rp->two_fd[i].copy, fd | COPYFD_EXACT); } close(rp->two_fd[i].copy); } @@ -5064,7 +5067,8 @@ redirectsafe(union node *redir, int flags) struct jmploc jmploc; SAVE_INT(saveint); - err = setjmp(jmploc.loc) * 2; + /* "echo 9>/dev/null; echo >&9; echo result: $?" - result should be 1, not 2! */ + err = setjmp(jmploc.loc); // huh?? was = setjmp(jmploc.loc) * 2; if (!err) { exception_handler = &jmploc; redirect(redir, flags); @@ -5443,8 +5447,8 @@ evalbackcmd(union node *n, struct backcmd *result) FORCE_INT_ON; close(pip[0]); if (pip[1] != 1) { - close(1); - copyfd(pip[1], 1); + /*close(1);*/ + copyfd(pip[1], 1 | COPYFD_EXACT); close(pip[1]); } eflag = 0; @@ -10691,11 +10695,7 @@ readtoken1(int firstc, int syntax, char *eofmark, int striptabs) len = out - (char *)stackblock(); out = stackblock(); if (eofmark == NULL) { - if ((c == '>' || c == '<') - && quotef == 0 - // && len <= 2 // THIS LIMITS fd to 1 char: N>file, but no NN>file! - // && (*out == '\0' || isdigit(*out)) - ) { + if ((c == '>' || c == '<') && quotef == 0) { int maxlen = 9 + 1; /* max 9 digit fd#: 999999999 */ char *np = out; while (--maxlen && isdigit(*np)) diff --git a/shell/ash_test/ash-redir/redir2.right b/shell/ash_test/ash-redir/redir2.right new file mode 100644 index 000000000..d86bac9de --- /dev/null +++ b/shell/ash_test/ash-redir/redir2.right @@ -0,0 +1 @@ +OK diff --git a/shell/ash_test/ash-redir/redir2.tests b/shell/ash_test/ash-redir/redir2.tests new file mode 100755 index 000000000..61ccea30c --- /dev/null +++ b/shell/ash_test/ash-redir/redir2.tests @@ -0,0 +1,5 @@ +# ash once couldn't redirect above fd#9 +exec 1>/dev/null +(echo LOST1 >&22) 22>&1 +(echo LOST2 >&22) 22>&1 +(echo OK >&22) 22>&2 diff --git a/shell/ash_test/ash-redir/redir3.right b/shell/ash_test/ash-redir/redir3.right new file mode 100644 index 000000000..fd641a8ea --- /dev/null +++ b/shell/ash_test/ash-redir/redir3.right @@ -0,0 +1,3 @@ +TEST +./redir3.tests: line 4: 9: Bad file descriptor +Output to fd#9: 1 diff --git a/shell/ash_test/ash-redir/redir3.tests b/shell/ash_test/ash-redir/redir3.tests new file mode 100755 index 000000000..f50a7674c --- /dev/null +++ b/shell/ash_test/ash-redir/redir3.tests @@ -0,0 +1,5 @@ +# redirects to closed descriptors should not leave these descriptors" +# open afterwards +echo TEST 9>/dev/null +echo MUST ERROR OUT >&9 +echo "Output to fd#9: $?" diff --git a/shell/ash_test/run-all b/shell/ash_test/run-all index b0a6d1088..4d0f39a41 100755 --- a/shell/ash_test/run-all +++ b/shell/ash_test/run-all @@ -3,8 +3,8 @@ TOPDIR=$PWD test -x ash || { - echo "No ./ash?! Perhaps you want to run 'ln -s ../../busybox ash'" - exit + echo "No ./ash - creating a link to ../../busybox" + ln -s ../../busybox ash } test -x printenv || gcc -O2 -o printenv printenv.c || exit $? test -x recho || gcc -O2 -o recho recho.c || exit $? -- 2.25.1