diff options
Diffstat (limited to 'lib/spawn-pipe.c')
| -rw-r--r-- | lib/spawn-pipe.c | 672 |
1 files changed, 672 insertions, 0 deletions
diff --git a/lib/spawn-pipe.c b/lib/spawn-pipe.c new file mode 100644 index 0000000..d2d21e6 --- /dev/null +++ b/lib/spawn-pipe.c @@ -0,0 +1,672 @@ +/* Creation of subprocesses, communicating via pipes. + Copyright (C) 2001-2004, 2006-2023 Free Software Foundation, Inc. + Written by Bruno Haible <haible@clisp.cons.org>, 2001. + + This program is free software: you can redistribute it and/or modify + it under the terms of the GNU General Public License as published by + the Free Software Foundation, either version 3 of the License, or + (at your option) any later version. + + This program is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + GNU General Public License for more details. + + You should have received a copy of the GNU General Public License + along with this program. If not, see <https://www.gnu.org/licenses/>. */ + + +/* Tell clang not to warn about the 'child' variable, below. */ +#if defined __clang__ +# pragma clang diagnostic ignored "-Wconditional-uninitialized" +#endif + +#include <config.h> + +/* Specification. */ +#include "spawn-pipe.h" + +#include <errno.h> +#include <fcntl.h> +#include <stdlib.h> +#include <signal.h> +#include <unistd.h> + +#include "canonicalize.h" +#include "error.h" +#include "fatal-signal.h" +#include "filename.h" +#include "findprog.h" +#include "unistd-safer.h" +#include "wait-process.h" +#include "xalloc.h" +#include "gettext.h" + +#define _(str) gettext (str) + + +/* Choice of implementation for native Windows. + - Define to 0 to use the posix_spawn facility (modules 'posix_spawn' and + 'posix_spawnp'), that is based on the module 'windows-spawn'. + - Define to 1 to use the older code, that uses the module 'windows-spawn' + directly. + You can set this macro from a Makefile or at configure time, from the + CPPFLAGS. */ +#ifndef SPAWN_PIPE_IMPL_AVOID_POSIX_SPAWN +# define SPAWN_PIPE_IMPL_AVOID_POSIX_SPAWN 0 +#endif + + +#if (defined _WIN32 && !defined __CYGWIN__) && SPAWN_PIPE_IMPL_AVOID_POSIX_SPAWN + +/* Native Windows API. */ +# if GNULIB_MSVC_NOTHROW +# include "msvc-nothrow.h" +# else +# include <io.h> +# endif +# include <process.h> +# include "windows-spawn.h" + +#elif defined __KLIBC__ + +/* OS/2 kLIBC API. */ +# include <process.h> +# include "os2-spawn.h" + +#else + +/* Unix API. */ +# include <spawn.h> + +#endif + + +#ifdef EINTR + +/* EINTR handling for close(). + These functions can return -1/EINTR even though we don't have any + signal handlers set up, namely when we get interrupted via SIGSTOP. */ + +static int +nonintr_close (int fd) +{ + int retval; + + do + retval = close (fd); + while (retval < 0 && errno == EINTR); + + return retval; +} +#undef close /* avoid warning related to gnulib module unistd */ +#define close nonintr_close + +#if (defined _WIN32 && !defined __CYGWIN__) && SPAWN_PIPE_IMPL_AVOID_POSIX_SPAWN +static int +nonintr_open (const char *pathname, int oflag, mode_t mode) +{ + int retval; + + do + retval = open (pathname, oflag, mode); + while (retval < 0 && errno == EINTR); + + return retval; +} +# undef open /* avoid warning on VMS */ +# define open nonintr_open +#endif + +#endif + + +/* Open a pipe connected to a child process. + * + * write system read + * parent -> fd[1] -> STDIN_FILENO -> child if pipe_stdin + * parent <- fd[0] <- STDOUT_FILENO <- child if pipe_stdout + * read system write + * + * At least one of pipe_stdin, pipe_stdout must be true. + * pipe_stdin and prog_stdin together determine the child's standard input. + * pipe_stdout and prog_stdout together determine the child's standard output. + * If pipe_stdin is true, prog_stdin is ignored. + * If pipe_stdout is true, prog_stdout is ignored. + */ +static pid_t +create_pipe (const char *progname, + const char *prog_path, + const char * const *prog_argv, + const char *directory, + bool pipe_stdin, bool pipe_stdout, + const char *prog_stdin, const char *prog_stdout, + bool null_stderr, + bool slave_process, bool exit_on_error, + int fd[2]) +{ + int saved_errno; + char *prog_path_to_free = NULL; + + if (directory != NULL) + { + /* If a change of directory is requested, make sure PROG_PATH is absolute + before we do so. This is needed because + - posix_spawn and posix_spawnp are required to resolve a relative + PROG_PATH *after* changing the directory. See + <https://www.austingroupbugs.net/view.php?id=1208>: + "if this pathname does not start with a <slash> it shall be + interpreted relative to the working directory of the child + process _after_ all file_actions have been performed." + But this would be a surprising application behaviour, possibly + even security relevant. + - For the Windows CreateProcess() function, it is unspecified whether + a relative file name is interpreted to the parent's current + directory or to the specified directory. See + <https://docs.microsoft.com/en-us/windows/win32/api/processthreadsapi/nf-processthreadsapi-createprocessa> */ + if (! IS_ABSOLUTE_FILE_NAME (prog_path)) + { + const char *resolved_prog = + find_in_given_path (prog_path, getenv ("PATH"), NULL, false); + if (resolved_prog == NULL) + goto fail_with_errno; + if (resolved_prog != prog_path) + prog_path_to_free = (char *) resolved_prog; + prog_path = resolved_prog; + + if (! IS_ABSOLUTE_FILE_NAME (prog_path)) + { + char *absolute_prog = + canonicalize_filename_mode (prog_path, CAN_MISSING | CAN_NOLINKS); + if (absolute_prog == NULL) + { + free (prog_path_to_free); + goto fail_with_errno; + } + free (prog_path_to_free); + prog_path_to_free = absolute_prog; + prog_path = absolute_prog; + + if (! IS_ABSOLUTE_FILE_NAME (prog_path)) + abort (); + } + } + } + + int ifd[2]; + int ofd[2]; + + /* It is important to create the file descriptors with the close-on-exec bit + set. + * In the child process that we are about to create here, the file + descriptors ofd[0] -> STDIN_FILENO and ifd[1] -> STDOUT_FILENO will be + preserved across exec, because each dup2 call scheduled by + posix_spawn_file_actions_adddup2 creates a file descriptor with the + close-on-exec bit clear. Similarly on native Windows, where we use + explicit DuplicateHandle calls, and on kLIBC, where we use explicit dup2 + calls. + * In the parent process, we close ofd[0] and ifd[1]; so, ofd[1] and ofd[0] + are still open. But if the parent process spawns another child process + later, if ofd[1] and ofd[0] were inherited by that child process, the + "end of input" / "end of output" detection would not work any more. The + parent or the child process would block, as long as that other child + process is running. */ + if (pipe_stdout) + if (pipe2_safer (ifd, O_BINARY | O_CLOEXEC) < 0) + error (EXIT_FAILURE, errno, _("cannot create pipe")); + if (pipe_stdin) + if (pipe2_safer (ofd, O_BINARY | O_CLOEXEC) < 0) + error (EXIT_FAILURE, errno, _("cannot create pipe")); +/* Data flow diagram: + * + * write system read + * parent -> ofd[1] -> ofd[0] -> child if pipe_stdin + * parent <- ifd[0] <- ifd[1] <- child if pipe_stdout + * read system write + * + */ + +#if ((defined _WIN32 && !defined __CYGWIN__) && SPAWN_PIPE_IMPL_AVOID_POSIX_SPAWN) || defined __KLIBC__ + + /* Native Windows API. + This uses _pipe(), dup2(), and _spawnv(). It could also be implemented + using the low-level functions CreatePipe(), DuplicateHandle(), + CreateProcess() and _open_osfhandle(); see the GNU make and GNU clisp + and cvs source code. */ + char *argv_mem_to_free; + int child; + int nulloutfd; + int stdinfd; + int stdoutfd; + + const char **argv = prepare_spawn (prog_argv, &argv_mem_to_free); + if (argv == NULL) + xalloc_die (); + + child = -1; + +# if (defined _WIN32 && !defined __CYGWIN__) && SPAWN_PIPE_IMPL_AVOID_POSIX_SPAWN + bool must_close_ifd1 = pipe_stdout; + bool must_close_ofd0 = pipe_stdin; + + /* Create standard file handles of child process. */ + HANDLE stdin_handle = INVALID_HANDLE_VALUE; + HANDLE stdout_handle = INVALID_HANDLE_VALUE; + nulloutfd = -1; + stdinfd = -1; + stdoutfd = -1; + if ((!null_stderr + || (nulloutfd = open ("NUL", O_RDWR, 0)) >= 0) + && (pipe_stdin + || prog_stdin == NULL + || (stdinfd = open (prog_stdin, O_RDONLY, 0)) >= 0) + && (pipe_stdout + || prog_stdout == NULL + || (stdoutfd = open (prog_stdout, O_WRONLY, 0)) >= 0)) + /* The child process doesn't inherit ifd[0], ifd[1], ofd[0], ofd[1], + but it inherits the three STD*_FILENO for which we pass the handles. */ + /* Pass the environment explicitly. This is needed if the program has + modified the environment using putenv() or [un]setenv(). On Windows, + processes have two environments, one in the "environment block" of the + process and managed through SetEnvironmentVariable(), and one inside the + process, in the location retrieved by the 'environ' macro. If we were + to pass NULL, the child process would inherit a copy of the environment + block - ignoring the effects of putenv() and [un]setenv(). */ + { + stdin_handle = + (HANDLE) _get_osfhandle (pipe_stdin ? ofd[0] : + prog_stdin == NULL ? STDIN_FILENO : stdinfd); + if (pipe_stdin) + { + HANDLE curr_process = GetCurrentProcess (); + HANDLE duplicate; + if (!DuplicateHandle (curr_process, stdin_handle, + curr_process, &duplicate, + 0, TRUE, DUPLICATE_SAME_ACCESS)) + { + errno = EBADF; /* arbitrary */ + goto failed; + } + must_close_ofd0 = false; + close (ofd[0]); /* implies CloseHandle (stdin_handle); */ + stdin_handle = duplicate; + } + stdout_handle = + (HANDLE) _get_osfhandle (pipe_stdout ? ifd[1] : + prog_stdout == NULL ? STDOUT_FILENO : stdoutfd); + if (pipe_stdout) + { + HANDLE curr_process = GetCurrentProcess (); + HANDLE duplicate; + if (!DuplicateHandle (curr_process, stdout_handle, + curr_process, &duplicate, + 0, TRUE, DUPLICATE_SAME_ACCESS)) + { + errno = EBADF; /* arbitrary */ + goto failed; + } + must_close_ifd1 = false; + close (ifd[1]); /* implies CloseHandle (stdout_handle); */ + stdout_handle = duplicate; + } + HANDLE stderr_handle = + (HANDLE) _get_osfhandle (null_stderr ? nulloutfd : STDERR_FILENO); + + child = spawnpvech (P_NOWAIT, prog_path, argv + 1, + (const char * const *) environ, directory, + stdin_handle, stdout_handle, stderr_handle); +# if 0 /* Executing arbitrary files as shell scripts is unsecure. */ + if (child == -1 && errno == ENOEXEC) + { + /* prog is not a native executable. Try to execute it as a + shell script. Note that prepare_spawn() has already prepended + a hidden element "sh.exe" to argv. */ + argv[1] = prog_path; + child = spawnpvech (P_NOWAIT, argv[0], argv, + (const char * const *) environ, directory, + stdin_handle, stdout_handle, stderr_handle); + } +# endif + } + failed: + if (child == -1) + saved_errno = errno; + if (stdinfd >= 0) + close (stdinfd); + if (stdoutfd >= 0) + close (stdoutfd); + if (nulloutfd >= 0) + close (nulloutfd); + + if (pipe_stdin) + { + if (must_close_ofd0) + close (ofd[0]); + else + if (stdin_handle != INVALID_HANDLE_VALUE) + CloseHandle (stdin_handle); + } + if (pipe_stdout) + { + if (must_close_ifd1) + close (ifd[1]); + else + if (stdout_handle != INVALID_HANDLE_VALUE) + CloseHandle (stdout_handle); + } + +# else /* __KLIBC__ */ + if (!(directory == NULL || strcmp (directory, ".") == 0)) + { + /* A directory argument is not supported in this implementation. */ + saved_errno = EINVAL; + goto fail_with_saved_errno; + } + + int orig_stdin; + int orig_stdout; + int orig_stderr; + + /* Save standard file handles of parent process. */ + if (pipe_stdin || prog_stdin != NULL) + orig_stdin = dup_safer_noinherit (STDIN_FILENO); + if (pipe_stdout || prog_stdout != NULL) + orig_stdout = dup_safer_noinherit (STDOUT_FILENO); + if (null_stderr) + orig_stderr = dup_safer_noinherit (STDERR_FILENO); + + /* Create standard file handles of child process. */ + nulloutfd = -1; + stdinfd = -1; + stdoutfd = -1; + if ((!pipe_stdin || dup2 (ofd[0], STDIN_FILENO) >= 0) + && (!pipe_stdout || dup2 (ifd[1], STDOUT_FILENO) >= 0) + && (!null_stderr + || ((nulloutfd = open ("NUL", O_RDWR, 0)) >= 0 + && (nulloutfd == STDERR_FILENO + || (dup2 (nulloutfd, STDERR_FILENO) >= 0 + && close (nulloutfd) >= 0)))) + && (pipe_stdin + || prog_stdin == NULL + || ((stdinfd = open (prog_stdin, O_RDONLY, 0)) >= 0 + && (stdinfd == STDIN_FILENO + || (dup2 (stdinfd, STDIN_FILENO) >= 0 + && close (stdinfd) >= 0)))) + && (pipe_stdout + || prog_stdout == NULL + || ((stdoutfd = open (prog_stdout, O_WRONLY, 0)) >= 0 + && (stdoutfd == STDOUT_FILENO + || (dup2 (stdoutfd, STDOUT_FILENO) >= 0 + && close (stdoutfd) >= 0))))) + /* The child process doesn't inherit ifd[0], ifd[1], ofd[0], ofd[1], + but it inherits all open()ed or dup2()ed file handles (which is what + we want in the case of STD*_FILENO). */ + { + child = _spawnvpe (P_NOWAIT, prog_path, argv + 1, + (const char **) environ); +# if 0 /* Executing arbitrary files as shell scripts is unsecure. */ + if (child == -1 && errno == ENOEXEC) + { + /* prog is not a native executable. Try to execute it as a + shell script. Note that prepare_spawn() has already prepended + a hidden element "sh.exe" to argv. */ + child = _spawnvpe (P_NOWAIT, argv[0], argv, + (const char **) environ); + } +# endif + } + if (child == -1) + saved_errno = errno; + if (stdinfd >= 0) + close (stdinfd); + if (stdoutfd >= 0) + close (stdoutfd); + if (nulloutfd >= 0) + close (nulloutfd); + + /* Restore standard file handles of parent process. */ + if (null_stderr) + undup_safer_noinherit (orig_stderr, STDERR_FILENO); + if (pipe_stdout || prog_stdout != NULL) + undup_safer_noinherit (orig_stdout, STDOUT_FILENO); + if (pipe_stdin || prog_stdin != NULL) + undup_safer_noinherit (orig_stdin, STDIN_FILENO); + + if (pipe_stdin) + close (ofd[0]); + if (pipe_stdout) + close (ifd[1]); +# endif + + free (argv); + free (argv_mem_to_free); + free (prog_path_to_free); + + if (child == -1) + { + if (pipe_stdout) + close (ifd[0]); + if (pipe_stdin) + close (ofd[1]); + goto fail_with_saved_errno; + } + + if (pipe_stdout) + fd[0] = ifd[0]; + if (pipe_stdin) + fd[1] = ofd[1]; + return child; + +#else + + /* Unix API. */ + sigset_t blocked_signals; + posix_spawn_file_actions_t actions; + bool actions_allocated; + posix_spawnattr_t attrs; + bool attrs_allocated; + int err; + pid_t child; + + if (slave_process) + { + sigprocmask (SIG_SETMASK, NULL, &blocked_signals); + block_fatal_signals (); + } + actions_allocated = false; + attrs_allocated = false; + if ((err = posix_spawn_file_actions_init (&actions)) != 0 + || (actions_allocated = true, + (pipe_stdin + && (err = posix_spawn_file_actions_adddup2 (&actions, + ofd[0], STDIN_FILENO)) + != 0) + || (pipe_stdout + && (err = posix_spawn_file_actions_adddup2 (&actions, + ifd[1], STDOUT_FILENO)) + != 0) + || (pipe_stdin + && (err = posix_spawn_file_actions_addclose (&actions, ofd[0])) + != 0) + || (pipe_stdout + && (err = posix_spawn_file_actions_addclose (&actions, ifd[1])) + != 0) + || (pipe_stdin + && (err = posix_spawn_file_actions_addclose (&actions, ofd[1])) + != 0) + || (pipe_stdout + && (err = posix_spawn_file_actions_addclose (&actions, ifd[0])) + != 0) + || (null_stderr + && (err = posix_spawn_file_actions_addopen (&actions, + STDERR_FILENO, + "/dev/null", O_RDWR, + 0)) + != 0) + || (!pipe_stdin + && prog_stdin != NULL + && (err = posix_spawn_file_actions_addopen (&actions, + STDIN_FILENO, + prog_stdin, O_RDONLY, + 0)) + != 0) + || (!pipe_stdout + && prog_stdout != NULL + && (err = posix_spawn_file_actions_addopen (&actions, + STDOUT_FILENO, + prog_stdout, O_WRONLY, + 0)) + != 0) + || (directory != NULL + && (err = posix_spawn_file_actions_addchdir (&actions, + directory))) + || (slave_process + && ((err = posix_spawnattr_init (&attrs)) != 0 + || (attrs_allocated = true, +# if defined _WIN32 && !defined __CYGWIN__ + (err = posix_spawnattr_setpgroup (&attrs, 0)) != 0 + || (err = posix_spawnattr_setflags (&attrs, + POSIX_SPAWN_SETPGROUP)) + != 0 +# else + (err = posix_spawnattr_setsigmask (&attrs, + &blocked_signals)) + != 0 + || (err = posix_spawnattr_setflags (&attrs, + POSIX_SPAWN_SETSIGMASK)) + != 0 +# endif + ) ) ) + || (err = (directory != NULL + ? posix_spawn (&child, prog_path, &actions, + attrs_allocated ? &attrs : NULL, + (char * const *) prog_argv, environ) + : posix_spawnp (&child, prog_path, &actions, + attrs_allocated ? &attrs : NULL, + (char * const *) prog_argv, environ))) + != 0)) + { + if (actions_allocated) + posix_spawn_file_actions_destroy (&actions); + if (attrs_allocated) + posix_spawnattr_destroy (&attrs); + if (slave_process) + unblock_fatal_signals (); + if (pipe_stdout) + { + close (ifd[0]); + close (ifd[1]); + } + if (pipe_stdin) + { + close (ofd[0]); + close (ofd[1]); + } + free (prog_path_to_free); + saved_errno = err; + goto fail_with_saved_errno; + } + posix_spawn_file_actions_destroy (&actions); + if (attrs_allocated) + posix_spawnattr_destroy (&attrs); + if (slave_process) + { + register_slave_subprocess (child); + unblock_fatal_signals (); + } + if (pipe_stdin) + close (ofd[0]); + if (pipe_stdout) + close (ifd[1]); + free (prog_path_to_free); + + if (pipe_stdout) + fd[0] = ifd[0]; + if (pipe_stdin) + fd[1] = ofd[1]; + return child; + +#endif + + fail_with_errno: + saved_errno = errno; + fail_with_saved_errno: + if (exit_on_error || !null_stderr) + error (exit_on_error ? EXIT_FAILURE : 0, saved_errno, + _("%s subprocess failed"), progname); + errno = saved_errno; + return -1; +} + +/* Open a bidirectional pipe. + * + * write system read + * parent -> fd[1] -> STDIN_FILENO -> child + * parent <- fd[0] <- STDOUT_FILENO <- child + * read system write + * + */ +pid_t +create_pipe_bidi (const char *progname, + const char *prog_path, const char * const *prog_argv, + const char *directory, + bool null_stderr, + bool slave_process, bool exit_on_error, + int fd[2]) +{ + pid_t result = create_pipe (progname, prog_path, prog_argv, directory, + true, true, NULL, NULL, + null_stderr, slave_process, exit_on_error, + fd); + return result; +} + +/* Open a pipe for input from a child process. + * The child's stdin comes from a file. + * + * read system write + * parent <- fd[0] <- STDOUT_FILENO <- child + * + */ +pid_t +create_pipe_in (const char *progname, + const char *prog_path, const char * const *prog_argv, + const char *directory, + const char *prog_stdin, bool null_stderr, + bool slave_process, bool exit_on_error, + int fd[1]) +{ + int iofd[2]; + pid_t result = create_pipe (progname, prog_path, prog_argv, directory, + false, true, prog_stdin, NULL, + null_stderr, slave_process, exit_on_error, + iofd); + if (result != -1) + fd[0] = iofd[0]; + return result; +} + +/* Open a pipe for output to a child process. + * The child's stdout goes to a file. + * + * write system read + * parent -> fd[0] -> STDIN_FILENO -> child + * + */ +pid_t +create_pipe_out (const char *progname, + const char *prog_path, const char * const *prog_argv, + const char *directory, + const char *prog_stdout, bool null_stderr, + bool slave_process, bool exit_on_error, + int fd[1]) +{ + int iofd[2]; + pid_t result = create_pipe (progname, prog_path, prog_argv, directory, + true, false, NULL, prog_stdout, + null_stderr, slave_process, exit_on_error, + iofd); + if (result != -1) + fd[0] = iofd[1]; + return result; +} |