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[libiberty] Use pipe inside pex_run 

https://gcc.gnu.org/ml/gcc-patches/2018-10/msg00039.html
	* configure.ac (checkfuncs): Add pipe2.
	* config.in, configure: Rebuilt.
	* pex-unix.c (pex_unix_exec_child): Comminicate errors from child
	to parent with a pipe, when possible.

From-SVN: r264769
This commit is contained in:
Nathan Sidwell 2018-10-01 18:46:51 +00:00 committed by Nathan Sidwell
parent 2649038cea
commit df1346b423
5 changed files with 113 additions and 49 deletions
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7
libiberty/ChangeLog
View File

@ -1,3 +1,10 @@
2018-10-01 Nathan Sidwell <nathan@acm.org>
* configure.ac (checkfuncs): Add pipe2.
* config.in, configure: Rebuilt.
* pex-unix.c (pex_unix_exec_child): Comminicate errors from child
to parent with a pipe, when possible.
2018-08-23 Nathan Sidwell <nathan@acm.org>
Martin Liska <mliska@suse.cz>

3
libiberty/config.in
View File

@ -195,6 +195,9 @@
/* Define to 1 if you have the `on_exit' function. */
#undef HAVE_ON_EXIT
/* Define to 1 if you have the `pipe2' function. */
#undef HAVE_PIPE2
/* Define to 1 if you have the <process.h> header file. */
#undef HAVE_PROCESS_H

4
libiberty/configure vendored
View File

@ -5727,7 +5727,7 @@ funcs="$funcs setproctitle"
vars="sys_errlist sys_nerr sys_siglist"
checkfuncs="__fsetlocking canonicalize_file_name dup3 getrlimit getrusage \
getsysinfo gettimeofday on_exit psignal pstat_getdynamic pstat_getstatic \
getsysinfo gettimeofday on_exit pipe2 psignal pstat_getdynamic pstat_getstatic \
realpath setrlimit sbrk spawnve spawnvpe strerror strsignal sysconf sysctl \
sysmp table times wait3 wait4"
@ -5743,7 +5743,7 @@ if test "x" = "y"; then
index insque \
memchr memcmp memcpy memmem memmove memset mkstemps \
on_exit \
psignal pstat_getdynamic pstat_getstatic putenv \
pipe2 psignal pstat_getdynamic pstat_getstatic putenv \
random realpath rename rindex \
sbrk setenv setproctitle setrlimit sigsetmask snprintf spawnve spawnvpe \
stpcpy stpncpy strcasecmp strchr strdup \

4
libiberty/configure.ac
View File

@ -391,7 +391,7 @@ funcs="$funcs setproctitle"
vars="sys_errlist sys_nerr sys_siglist"
checkfuncs="__fsetlocking canonicalize_file_name dup3 getrlimit getrusage \
getsysinfo gettimeofday on_exit psignal pstat_getdynamic pstat_getstatic \
getsysinfo gettimeofday on_exit pipe2 psignal pstat_getdynamic pstat_getstatic \
realpath setrlimit sbrk spawnve spawnvpe strerror strsignal sysconf sysctl \
sysmp table times wait3 wait4"
@ -407,7 +407,7 @@ if test "x" = "y"; then
index insque \
memchr memcmp memcpy memmem memmove memset mkstemps \
on_exit \
psignal pstat_getdynamic pstat_getstatic putenv \
pipe2 psignal pstat_getdynamic pstat_getstatic putenv \
random realpath rename rindex \
sbrk setenv setproctitle setrlimit sigsetmask snprintf spawnve spawnvpe \
stpcpy stpncpy strcasecmp strchr strdup \

144
libiberty/pex-unix.c
View File

@ -569,6 +569,38 @@ pex_unix_exec_child (struct pex_obj *obj, int flags, const char *executable,
int toclose, const char **errmsg, int *err)
{
pid_t pid = -1;
/* Tuple to communicate error from child to parent. We can safely
transfer string literal pointers as both run with identical
address mappings. */
struct fn_err
{
const char *fn;
int err;
};
volatile int do_pipe = 0;
volatile int pipes[2]; /* [0]:reader,[1]:writer. */
#ifdef O_CLOEXEC
do_pipe = 1;
#endif
if (do_pipe)
{
#ifdef HAVE_PIPE2
if (pipe2 ((int *)pipes, O_CLOEXEC))
do_pipe = 0;
#else
if (pipe ((int *)pipes))
do_pipe = 0;
else
{
if (fcntl (pipes[1], F_SETFD, FD_CLOEXEC) == -1)
{
close (pipes[0]);
close (pipes[1]);
do_pipe = 0;
}
}
#endif
}
/* We declare these to be volatile to avoid warnings from gcc about
them being clobbered by vfork. */
@ -579,8 +611,9 @@ pex_unix_exec_child (struct pex_obj *obj, int flags, const char *executable,
This clobbers the parent's environ so we need to restore it.
It would be nice to use one of the exec* functions that takes an
environment as a parameter, but that may have portability
issues. */
char **save_environ = environ;
issues. It is marked volatile so the child doesn't consider it a
dead variable and therefore clobber where ever it is stored. */
char **volatile save_environ = environ;
for (retries = 0; retries < 4; ++retries)
{
@ -594,6 +627,11 @@ pex_unix_exec_child (struct pex_obj *obj, int flags, const char *executable,
switch (pid)
{
case -1:
if (do_pipe)
{
close (pipes[0]);
close (pipes[1]);
}
*err = errno;
*errmsg = VFORK_STRING;
return (pid_t) -1;
@ -601,40 +639,43 @@ pex_unix_exec_child (struct pex_obj *obj, int flags, const char *executable,
case 0:
/* Child process. */
{
const char *bad_fn = NULL;
struct fn_err failed;
failed.fn = NULL;
if (!bad_fn && in != STDIN_FILE_NO)
if (do_pipe)
close (pipes[0]);
if (!failed.fn && in != STDIN_FILE_NO)
{
if (dup2 (in, STDIN_FILE_NO) < 0)
bad_fn = "dup2";
failed.fn = "dup2", failed.err = errno;
else if (close (in) < 0)
bad_fn = "close";
failed.fn = "close", failed.err = errno;
}
if (!bad_fn && out != STDOUT_FILE_NO)
if (!failed.fn && out != STDOUT_FILE_NO)
{
if (dup2 (out, STDOUT_FILE_NO) < 0)
bad_fn = "dup2";
failed.fn = "dup2", failed.err = errno;
else if (close (out) < 0)
bad_fn = "close";
failed.fn = "close", failed.err = errno;
}
if (!bad_fn && errdes != STDERR_FILE_NO)
if (!failed.fn && errdes != STDERR_FILE_NO)
{
if (dup2 (errdes, STDERR_FILE_NO) < 0)
bad_fn = "dup2";
failed.fn = "dup2", failed.err = errno;
else if (close (errdes) < 0)
bad_fn = "close";
failed.fn = "close", failed.err = errno;
}
if (!bad_fn && toclose >= 0)
if (!failed.fn && toclose >= 0)
{
if (close (toclose) < 0)
bad_fn = "close";
failed.fn = "close", failed.err = errno;
}
if (!bad_fn && (flags & PEX_STDERR_TO_STDOUT) != 0)
if (!failed.fn && (flags & PEX_STDERR_TO_STDOUT) != 0)
{
if (dup2 (STDOUT_FILE_NO, STDERR_FILE_NO) < 0)
bad_fn = "dup2";
failed.fn = "dup2", failed.err = errno;
}
if (!bad_fn)
if (!failed.fn)
{
if (env)
/* NOTE: In a standard vfork implementation this clobbers
@ -644,30 +685,35 @@ pex_unix_exec_child (struct pex_obj *obj, int flags, const char *executable,
if ((flags & PEX_SEARCH) != 0)
{
execvp (executable, to_ptr32 (argv));
bad_fn = "execvp";
failed.fn = "execvp", failed.err = errno;
}
else
{
execv (executable, to_ptr32 (argv));
bad_fn = "execv";
failed.fn = "execv", failed.err = errno;
}
}
/* Something failed, report an error. We don't use stdio
routines, because we might be here due to a vfork call. */
ssize_t retval = 0;
int eno = errno;
if (!do_pipe
|| write (pipes[1], &failed, sizeof (failed)) != sizeof (failed))
{
/* The parent will not see our scream above, so write to
stdout. */
#define writeerr(s) (retval |= write (STDERR_FILE_NO, s, strlen (s)))
writeerr (obj->pname);
writeerr (": error trying to exec '");
writeerr (executable);
writeerr ("': ");
writeerr (bad_fn);
writeerr (": ");
writeerr (xstrerror (eno));
writeerr ("\n");
writeerr (obj->pname);
writeerr (": error trying to exec '");
writeerr (executable);
writeerr ("': ");
writeerr (failed.fn);
writeerr (": ");
writeerr (xstrerror (failed.err));
writeerr ("\n");
#undef writeerr
}
/* Exit with -2 if the error output failed, too. */
_exit (retval < 0 ? -2 : -1);
@ -678,8 +724,6 @@ pex_unix_exec_child (struct pex_obj *obj, int flags, const char *executable,
default:
/* Parent process. */
{
const char *bad_fn = NULL;
/* Restore environ. Note that the parent either doesn't run
until the child execs/exits (standard vfork behaviour), or
if it does run then vfork is behaving more like fork. In
@ -687,24 +731,34 @@ pex_unix_exec_child (struct pex_obj *obj, int flags, const char *executable,
copy of environ. */
environ = save_environ;
if (!bad_fn && in != STDIN_FILE_NO)
if (close (in) < 0)
bad_fn = "close";
if (!bad_fn && out != STDOUT_FILE_NO)
if (close (out) < 0)
bad_fn = "close";
if (!bad_fn && errdes != STDERR_FILE_NO)
if (close (errdes) < 0)
bad_fn = "close";
if (bad_fn)
struct fn_err failed;
failed.fn = NULL;
if (do_pipe)
{
*err = errno;
*errmsg = bad_fn;
close (pipes[1]);
ssize_t len = read (pipes[0], &failed, sizeof (failed));
if (len < 0)
failed.fn = NULL;
close (pipes[0]);
}
if (!failed.fn && in != STDIN_FILE_NO)
if (close (in) < 0)
failed.fn = "close", failed.err = errno;
if (!failed.fn && out != STDOUT_FILE_NO)
if (close (out) < 0)
failed.fn = "close", failed.err = errno;
if (!failed.fn && errdes != STDERR_FILE_NO)
if (close (errdes) < 0)
failed.fn = "close", failed.err = errno;
if (failed.fn)
{
*err = failed.err;
*errmsg = failed.fn;
return (pid_t) -1;
}
}
return pid;
}
}