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tar: conditionally don't wait for vforked child to exec, as it always

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works right on Linux, and anyway mayresult only on less-than-clear error
message only, it will not cause tar to misbehave.

function                                             old     new   delta
open_transformer                                      98      80     -18
writeTarFile                                         714     547    -167
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 0/2 up/down: 0/-185)           Total: -185 bytes
   text    data     bss     dec     hex filename
 770651    1051   10764  782466   bf082 busybox_old
 770463    1051   10764  782278   befc6 busybox_unstripped
This commit is contained in:
Denis Vlasenko 2007-09-04 19:33:22 +00:00
parent f0000653e9
commit 7e0fbf9c26
3 changed files with 54 additions and 37 deletions
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2
archival/libunarchive/open_transformer.c
View File

@ -25,8 +25,10 @@ int open_transformer(int src_fd,
close(fd_pipe[0]); /* We don't wan't to read from the parent */ close(fd_pipe[0]); /* We don't wan't to read from the parent */
// FIXME: error check? // FIXME: error check?
transformer(src_fd, fd_pipe[1]); transformer(src_fd, fd_pipe[1]);
if (ENABLE_FEATURE_CLEAN_UP) {
close(fd_pipe[1]); /* Send EOF */ close(fd_pipe[1]); /* Send EOF */
close(src_fd); close(src_fd);
}
exit(0); exit(0);
/* notreached */ /* notreached */
} }

66
archival/tar.c
View File

@ -504,13 +504,21 @@ static int writeTarFile(const int tar_fd, const int verboseFlag,
bb_perror_msg_and_die("cannot stat tar file"); bb_perror_msg_and_die("cannot stat tar file");
if ((ENABLE_FEATURE_TAR_GZIP || ENABLE_FEATURE_TAR_BZIP2) && gzip) { if ((ENABLE_FEATURE_TAR_GZIP || ENABLE_FEATURE_TAR_BZIP2) && gzip) {
int gzipDataPipe[2] = { -1, -1 }; // On Linux, vfork never unpauses parent early, although standard
int gzipStatusPipe[2] = { -1, -1 }; // allows for that. Do we want to waste bytes checking for it?
#define WAIT_FOR_CHILD 0
volatile int vfork_exec_errno = 0; volatile int vfork_exec_errno = 0;
#if WAIT_FOR_CHILD
struct { int rd; int wr; } gzipStatusPipe;
#endif
struct { int rd; int wr; } gzipDataPipe;
const char *zip_exec = (gzip == 1) ? "gzip" : "bzip2"; const char *zip_exec = (gzip == 1) ? "gzip" : "bzip2";
xpipe(gzipDataPipe); xpipe(&gzipDataPipe.rd);
xpipe(gzipStatusPipe); #if WAIT_FOR_CHILD
xpipe(&gzipStatusPipe.rd);
#endif
signal(SIGPIPE, SIG_IGN); /* we only want EPIPE on errors */ signal(SIGPIPE, SIG_IGN); /* we only want EPIPE on errors */
@ -522,41 +530,45 @@ static int writeTarFile(const int tar_fd, const int verboseFlag,
#endif #endif
gzipPid = vfork(); gzipPid = vfork();
if (gzipPid < 0)
bb_perror_msg_and_die("vfork gzip");
if (gzipPid == 0) { if (gzipPid == 0) {
dup2(gzipDataPipe[0], 0); /* child */
close(gzipDataPipe[1]); xmove_fd(tbInfo.tarFd, 1);
xmove_fd(gzipDataPipe.rd, 0);
dup2(tbInfo.tarFd, 1); close(gzipDataPipe.wr);
#if WAIT_FOR_CHILD
close(gzipStatusPipe[0]); close(gzipStatusPipe.rd);
fcntl(gzipStatusPipe[1], F_SETFD, FD_CLOEXEC); /* close on exec shows success */ fcntl(gzipStatusPipe.wr, F_SETFD, FD_CLOEXEC);
#endif
/* exec gzip/bzip2 program/applet */
BB_EXECLP(zip_exec, zip_exec, "-f", NULL); BB_EXECLP(zip_exec, zip_exec, "-f", NULL);
vfork_exec_errno = errno; vfork_exec_errno = errno;
_exit(1);
}
close(gzipStatusPipe[1]); /* parent */
exit(-1); xmove_fd(gzipDataPipe.wr, tbInfo.tarFd);
} else if (gzipPid > 0) { close(gzipDataPipe.rd);
close(gzipDataPipe[0]); #if WAIT_FOR_CHILD
close(gzipStatusPipe[1]); close(gzipStatusPipe.wr);
while (1) { while (1) {
char buf; char buf;
int n;
int n = full_read(gzipStatusPipe[0], &buf, 1); /* Wait until child execs (or fails to) */
n = full_read(gzipStatusPipe.rd, &buf, 1);
if ((n < 0) && (/*errno == EAGAIN ||*/ errno == EINTR))
continue; /* try it again */
if (n == 0 && vfork_exec_errno != 0) { }
close(gzipStatusPipe.rd);
#endif
if (vfork_exec_errno) {
errno = vfork_exec_errno; errno = vfork_exec_errno;
bb_perror_msg_and_die("cannot exec %s", zip_exec); bb_perror_msg_and_die("cannot exec %s", zip_exec);
} else if ((n < 0) && (errno == EAGAIN || errno == EINTR))
continue; /* try it again */
break;
} }
close(gzipStatusPipe[0]);
tbInfo.tarFd = gzipDataPipe[1];
} else bb_perror_msg_and_die("vfork gzip");
} }
tbInfo.excludeList = exclude; tbInfo.excludeList = exclude;

3
include/libbb.h
View File

@ -512,6 +512,9 @@ int execable_file(const char *name);
char *find_execable(const char *filename); char *find_execable(const char *filename);
int exists_execable(const char *filename); int exists_execable(const char *filename);
/* BB_EXECxx always execs (it's not doing NOFORK/NOEXEC stuff),
* but it may exec busybox and call applet instead of searching PATH.
*/
#if ENABLE_FEATURE_PREFER_APPLETS #if ENABLE_FEATURE_PREFER_APPLETS
int bb_execvp(const char *file, char *const argv[]); int bb_execvp(const char *file, char *const argv[]);
#define BB_EXECVP(prog,cmd) bb_execvp(prog,cmd) #define BB_EXECVP(prog,cmd) bb_execvp(prog,cmd)