037759bb4
Denys Vlasenko
2018-08-04
Subject
tar: handle the case when opened created tarball happens to have fd#0
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Architecture & Compiler Flags
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Build Log
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Commit Diff GitHub →
archival/tar.c+18 -6
| @@ -611,6 +611,7 @@ static void NOINLINE vfork_compressor(int tar_fd, const char *gzip) | |
| if (xvfork() == 0) { | |
| /* child */ | |
| + | int tfd; |
| /* NB: close _first_, then move fds! */ | |
| close(data.wr); | |
| # if WAIT_FOR_CHILD | |
| @@ -619,8 +620,23 @@ static void NOINLINE vfork_compressor(int tar_fd, const char *gzip) | |
| * parent waits for this close to happen */ | |
| fcntl(status.wr, F_SETFD, FD_CLOEXEC); | |
| # endif | |
| + | /* copy it: parent's tar_fd variable must not change */ |
| + | tfd = tar_fd; |
| + | if (tfd == 0) { |
| + | /* Output tar fd may be zero. |
| + | * xmove_fd(data.rd, 0) would destroy it. |
| + | * Reproducer: |
| + | * exec 0>&- |
| + | * exec 1>&- |
| + | * tar czf Z.tar.gz FILE |
| + | * Swapping move_fd's order wouldn't work: |
| + | * data.rd is 1 and _it_ would be destroyed. |
| + | */ |
| + | xmove_fd(tfd, 3); |
| + | tfd = 3; |
| + | } |
| xmove_fd(data.rd, 0); | |
| - | xmove_fd(tar_fd, 1); |
| + | xmove_fd(tfd, 1); |
| /* exec gzip/bzip2 program/applet */ | |
| BB_EXECLP(gzip, gzip, "-f", (char *)0); | |
| vfork_exec_errno = errno; | |
| @@ -715,11 +731,7 @@ static NOINLINE int writeTarFile( | |
| return errorFlag; | |
| } | |
| - | #else /* !FEATURE_TAR_CREATE */ |
| - | |
| - | # define writeTarFile(...) 0 |
| - | |
| - | #endif |
| + | #endif /* FEATURE_TAR_CREATE */ |
| #if ENABLE_FEATURE_TAR_FROM | |
| static llist_t *append_file_list_to_list(llist_t *list) | |