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tar: make source code a bit more terse, no logic changes

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Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
This commit is contained in:
Denys Vlasenko 2018-08-04 17:48:59 +02:00
parent 3f2e963768
commit 45d68c3749
1 changed files with 25 additions and 32 deletions
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41
archival/tar.c
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@ -596,34 +596,30 @@ static int FAST_FUNC writeFileToTarball(const char *fileName, struct stat *statb
/* Don't inline: vfork scares gcc and pessimizes code */ /* Don't inline: vfork scares gcc and pessimizes code */
static void NOINLINE vfork_compressor(int tar_fd, const char *gzip) static void NOINLINE vfork_compressor(int tar_fd, const char *gzip)
{ {
pid_t gzipPid;
// On Linux, vfork never unpauses parent early, although standard // On Linux, vfork never unpauses parent early, although standard
// allows for that. Do we want to waste bytes checking for it? // allows for that. Do we want to waste bytes checking for it?
# define WAIT_FOR_CHILD 0 # define WAIT_FOR_CHILD 0
volatile int vfork_exec_errno = 0; volatile int vfork_exec_errno = 0;
struct fd_pair gzipDataPipe; struct fd_pair data;
# if WAIT_FOR_CHILD # if WAIT_FOR_CHILD
struct fd_pair gzipStatusPipe; struct fd_pair status;
xpiped_pair(gzipStatusPipe); xpiped_pair(status);
# endif # endif
xpiped_pair(gzipDataPipe); xpiped_pair(data);
signal(SIGPIPE, SIG_IGN); /* we only want EPIPE on errors */ signal(SIGPIPE, SIG_IGN); /* we only want EPIPE on errors */
gzipPid = xvfork(); if (xvfork() == 0) {
if (gzipPid == 0) {
/* child */ /* child */
/* NB: close _first_, then move fds! */ /* NB: close _first_, then move fds! */
close(gzipDataPipe.wr); close(data.wr);
# if WAIT_FOR_CHILD # if WAIT_FOR_CHILD
close(gzipStatusPipe.rd); close(status.rd);
/* gzipStatusPipe.wr will close only on exec - /* status.wr will close only on exec -
* parent waits for this close to happen */ * parent waits for this close to happen */
fcntl(gzipStatusPipe.wr, F_SETFD, FD_CLOEXEC); fcntl(status.wr, F_SETFD, FD_CLOEXEC);
# endif # endif
xmove_fd(gzipDataPipe.rd, 0); xmove_fd(data.rd, 0);
xmove_fd(tar_fd, 1); xmove_fd(tar_fd, 1);
/* exec gzip/bzip2 program/applet */ /* exec gzip/bzip2 program/applet */
BB_EXECLP(gzip, gzip, "-f", (char *)0); BB_EXECLP(gzip, gzip, "-f", (char *)0);
@ -632,20 +628,18 @@ static void NOINLINE vfork_compressor(int tar_fd, const char *gzip)
} }
/* parent */ /* parent */
xmove_fd(gzipDataPipe.wr, tar_fd); xmove_fd(data.wr, tar_fd);
close(gzipDataPipe.rd); close(data.rd);
# if WAIT_FOR_CHILD # if WAIT_FOR_CHILD
close(gzipStatusPipe.wr); close(status.wr);
while (1) { while (1) {
char buf;
int n;
/* Wait until child execs (or fails to) */ /* Wait until child execs (or fails to) */
n = full_read(gzipStatusPipe.rd, &buf, 1); char buf;
int n = full_read(status.rd, &buf, 1);
if (n < 0 /* && errno == EAGAIN */) if (n < 0 /* && errno == EAGAIN */)
continue; /* try it again */ continue; /* try it again */
} }
close(gzipStatusPipe.rd); close(status.rd);
# endif # endif
if (vfork_exec_errno) { if (vfork_exec_errno) {
errno = vfork_exec_errno; errno = vfork_exec_errno;
@ -1155,7 +1149,7 @@ int tar_main(int argc UNUSED_PARAM, char **argv)
if (LONE_DASH(tar_filename)) { if (LONE_DASH(tar_filename)) {
tar_handle->src_fd = tar_fd; tar_handle->src_fd = tar_fd;
tar_handle->seek = seek_by_read; tar_handle->seek = seek_by_read;
} else { } else
if (ENABLE_FEATURE_TAR_AUTODETECT if (ENABLE_FEATURE_TAR_AUTODETECT
&& flags == O_RDONLY && flags == O_RDONLY
&& !(opt & OPT_ANY_COMPRESS) && !(opt & OPT_ANY_COMPRESS)
@ -1167,7 +1161,6 @@ int tar_main(int argc UNUSED_PARAM, char **argv)
tar_handle->src_fd = xopen(tar_filename, flags); tar_handle->src_fd = xopen(tar_filename, flags);
} }
} }
}
if (base_dir) if (base_dir)
xchdir(base_dir); xchdir(base_dir);