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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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6
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 */
// FIXME: error check?
transformer(src_fd, fd_pipe[1]);
close(fd_pipe[1]); /* Send EOF */
close(src_fd);
if (ENABLE_FEATURE_CLEAN_UP) {
close(fd_pipe[1]); /* Send EOF */
close(src_fd);
}
exit(0);
/* notreached */
}

82
archival/tar.c
View File

@ -106,7 +106,7 @@ enum TarFileType {
typedef enum TarFileType TarFileType;
/* Might be faster (and bigger) if the dev/ino were stored in numeric order;) */
static void addHardLinkInfo(HardLinkInfo ** hlInfoHeadPtr,
static void addHardLinkInfo(HardLinkInfo **hlInfoHeadPtr,
struct stat *statbuf,
const char *fileName)
{
@ -122,7 +122,7 @@ static void addHardLinkInfo(HardLinkInfo ** hlInfoHeadPtr,
strcpy(hlInfo->name, fileName);
}
static void freeHardLinkInfo(HardLinkInfo ** hlInfoHeadPtr)
static void freeHardLinkInfo(HardLinkInfo **hlInfoHeadPtr)
{
HardLinkInfo *hlInfo;
HardLinkInfo *hlInfoNext;
@ -139,7 +139,7 @@ static void freeHardLinkInfo(HardLinkInfo ** hlInfoHeadPtr)
}
/* Might be faster (and bigger) if the dev/ino were stored in numeric order;) */
static HardLinkInfo *findHardLinkInfo(HardLinkInfo * hlInfo, struct stat *statbuf)
static HardLinkInfo *findHardLinkInfo(HardLinkInfo *hlInfo, struct stat *statbuf)
{
while (hlInfo) {
if ((statbuf->st_ino == hlInfo->ino) && (statbuf->st_dev == hlInfo->dev))
@ -504,13 +504,21 @@ static int writeTarFile(const int tar_fd, const int verboseFlag,
bb_perror_msg_and_die("cannot stat tar file");
if ((ENABLE_FEATURE_TAR_GZIP || ENABLE_FEATURE_TAR_BZIP2) && gzip) {
int gzipDataPipe[2] = { -1, -1 };
int gzipStatusPipe[2] = { -1, -1 };
// On Linux, vfork never unpauses parent early, although standard
// allows for that. Do we want to waste bytes checking for it?
#define WAIT_FOR_CHILD 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";
xpipe(gzipDataPipe);
xpipe(gzipStatusPipe);
xpipe(&gzipDataPipe.rd);
#if WAIT_FOR_CHILD
xpipe(&gzipStatusPipe.rd);
#endif
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
gzipPid = vfork();
if (gzipPid < 0)
bb_perror_msg_and_die("vfork gzip");
if (gzipPid == 0) {
dup2(gzipDataPipe[0], 0);
close(gzipDataPipe[1]);
dup2(tbInfo.tarFd, 1);
close(gzipStatusPipe[0]);
fcntl(gzipStatusPipe[1], F_SETFD, FD_CLOEXEC); /* close on exec shows success */
/* child */
xmove_fd(tbInfo.tarFd, 1);
xmove_fd(gzipDataPipe.rd, 0);
close(gzipDataPipe.wr);
#if WAIT_FOR_CHILD
close(gzipStatusPipe.rd);
fcntl(gzipStatusPipe.wr, F_SETFD, FD_CLOEXEC);
#endif
/* exec gzip/bzip2 program/applet */
BB_EXECLP(zip_exec, zip_exec, "-f", NULL);
vfork_exec_errno = errno;
_exit(1);
}
close(gzipStatusPipe[1]);
exit(-1);
} else if (gzipPid > 0) {
close(gzipDataPipe[0]);
close(gzipStatusPipe[1]);
/* parent */
xmove_fd(gzipDataPipe.wr, tbInfo.tarFd);
close(gzipDataPipe.rd);
#if WAIT_FOR_CHILD
close(gzipStatusPipe.wr);
while (1) {
char buf;
int n;
while (1) {
char buf;
/* 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 */
int n = full_read(gzipStatusPipe[0], &buf, 1);
if (n == 0 && vfork_exec_errno != 0) {
errno = vfork_exec_errno;
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");
}
close(gzipStatusPipe.rd);
#endif
if (vfork_exec_errno) {
errno = vfork_exec_errno;
bb_perror_msg_and_die("cannot exec %s", zip_exec);
}
}
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);
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
int bb_execvp(const char *file, char *const argv[]);
#define BB_EXECVP(prog,cmd) bb_execvp(prog,cmd)