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Factor start_child out of open_process
* libguile/posix.c (start_child): Factor out from open_process. Based on initial work by Eli Zaretskii.
This commit is contained in:
Andy Wingo
parent
f632d45c69
commit
10ae9cc601
1 changed files with 105 additions and 85 deletions
190
libguile/posix.c
190
libguile/posix.c
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@ -1236,10 +1236,96 @@ SCM_DEFINE (scm_fork, "primitive-fork", 0, 0, 0,
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return scm_from_int (pid);
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}
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#undef FUNC_NAME
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#endif /* HAVE_FORK */
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#ifdef HAVE_FORK
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#define HAVE_START_CHILD 1
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/* Since Guile uses threads, we have to be very careful to avoid calling
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functions that are not async-signal-safe in the child. That's why
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this function is implemented in C. */
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static pid_t
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start_child (const char *exec_file, char **exec_argv,
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int reading, int c2p[2], int writing, int p2c[2],
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int in, int out, int err)
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{
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int pid;
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int max_fd = 1024;
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#if defined (HAVE_GETRLIMIT) && defined (RLIMIT_NOFILE)
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{
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struct rlimit lim = { 0, 0 };
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if (getrlimit (RLIMIT_NOFILE, &lim) == 0)
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max_fd = lim.rlim_cur;
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}
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#endif
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pid = fork ();
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if (pid != 0)
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/* The parent, with either and error (pid == -1), or the PID of the
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child. Return directly in either case. */
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return pid;
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/* The child. */
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if (reading)
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close (c2p[0]);
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if (writing)
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close (p2c[1]);
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/* Close all file descriptors in ports inherited from the parent
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except for in, out, and err. Heavy-handed, but robust. */
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while (max_fd--)
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if (max_fd != in && max_fd != out && max_fd != err)
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close (max_fd);
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/* Ignore errors on these open() calls. */
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if (in == -1)
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in = open ("/dev/null", O_RDONLY);
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if (out == -1)
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out = open ("/dev/null", O_WRONLY);
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if (err == -1)
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err = open ("/dev/null", O_WRONLY);
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if (in > 0)
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{
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if (out == 0)
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do out = dup (out); while (errno == EINTR);
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if (err == 0)
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do err = dup (err); while (errno == EINTR);
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do dup2 (in, 0); while (errno == EINTR);
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close (in);
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}
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if (out > 1)
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{
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if (err == 1)
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do err = dup (err); while (errno == EINTR);
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do dup2 (out, 1); while (errno == EINTR);
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close (out);
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}
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if (err > 2)
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{
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do dup2 (err, 2); while (errno == EINTR);
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close (err);
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}
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execvp (exec_file, exec_argv);
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/* The exec failed! There is nothing sensible to do. */
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if (err > 0)
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{
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char *msg = strerror (errno);
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fprintf (fdopen (err, "a"), "In execvp of %s: %s\n",
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exec_file, msg);
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}
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_exit (EXIT_FAILURE);
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/* Not reached. */
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return -1;
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}
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#endif
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#ifdef HAVE_START_CHILD
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static SCM
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scm_open_process (SCM mode, SCM prog, SCM args)
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#define FUNC_NAME "open-process"
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@ -1252,7 +1338,7 @@ scm_open_process (SCM mode, SCM prog, SCM args)
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int pid;
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char *exec_file;
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char **exec_argv;
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int max_fd = 1024;
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SCM read_port = SCM_BOOL_F, write_port = SCM_BOOL_F;
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exec_file = scm_to_locale_string (prog);
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exec_argv = scm_i_allocate_string_pointers (scm_cons (prog, args));
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@ -1301,15 +1387,8 @@ scm_open_process (SCM mode, SCM prog, SCM args)
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in = SCM_FPORT_FDES (port);
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}
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#if defined (HAVE_GETRLIMIT) && defined (RLIMIT_NOFILE)
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{
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struct rlimit lim = { 0, 0 };
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if (getrlimit (RLIMIT_NOFILE, &lim) == 0)
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max_fd = lim.rlim_cur;
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}
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#endif
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pid = fork ();
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pid = start_child (exec_file, exec_argv, reading, c2p, writing, p2c,
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in, out, err);
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if (pid == -1)
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{
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@ -1329,85 +1408,24 @@ scm_open_process (SCM mode, SCM prog, SCM args)
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SCM_SYSERROR;
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}
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if (pid)
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/* Parent. */
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{
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SCM read_port = SCM_BOOL_F, write_port = SCM_BOOL_F;
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/* There is no sense in catching errors on close(). */
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if (reading)
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{
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close (c2p[1]);
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read_port = scm_fdes_to_port (c2p[0], "r0", sym_read_pipe);
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}
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if (writing)
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{
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close (p2c[0]);
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write_port = scm_fdes_to_port (p2c[1], "w0", sym_write_pipe);
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}
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return scm_values
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(scm_list_3 (read_port, write_port, scm_from_int (pid)));
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}
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/* The child. */
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/* There is no sense in catching errors on close(). */
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if (reading)
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close (c2p[0]);
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{
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close (c2p[1]);
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read_port = scm_fdes_to_port (c2p[0], "r0", sym_read_pipe);
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}
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if (writing)
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close (p2c[1]);
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/* Close all file descriptors in ports inherited from the parent
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except for in, out, and err. Heavy-handed, but robust. */
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while (max_fd--)
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if (max_fd != in && max_fd != out && max_fd != err)
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close (max_fd);
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/* Ignore errors on these open() calls. */
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if (in == -1)
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in = open ("/dev/null", O_RDONLY);
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if (out == -1)
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out = open ("/dev/null", O_WRONLY);
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if (err == -1)
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err = open ("/dev/null", O_WRONLY);
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if (in > 0)
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{
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if (out == 0)
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do out = dup (out); while (errno == EINTR);
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if (err == 0)
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do err = dup (err); while (errno == EINTR);
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do dup2 (in, 0); while (errno == EINTR);
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close (in);
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}
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if (out > 1)
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{
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if (err == 1)
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do err = dup (err); while (errno == EINTR);
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do dup2 (out, 1); while (errno == EINTR);
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close (out);
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}
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if (err > 2)
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{
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do dup2 (err, 2); while (errno == EINTR);
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close (err);
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close (p2c[0]);
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write_port = scm_fdes_to_port (p2c[1], "w0", sym_write_pipe);
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}
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execvp (exec_file, exec_argv);
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/* The exec failed! There is nothing sensible to do. */
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if (err > 0)
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{
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char *msg = strerror (errno);
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fprintf (fdopen (err, "a"), "In execlp of %s: %s\n",
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exec_file, msg);
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}
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_exit (EXIT_FAILURE);
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/* Not reached. */
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return SCM_BOOL_F;
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return scm_values (scm_list_3 (read_port,
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write_port,
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scm_from_int (pid)));
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}
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#undef FUNC_NAME
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#endif /* HAVE_FORK */
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#endif /* HAVE_START_CHILD */
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#ifdef __MINGW32__
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# include "win32-uname.h"
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@ -2215,13 +2233,13 @@ SCM_DEFINE (scm_gethostname, "gethostname", 0, 0, 0,
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#endif /* HAVE_GETHOSTNAME */
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#ifdef HAVE_FORK
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#ifdef HAVE_START_CHILD
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static void
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scm_init_popen (void)
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{
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scm_c_define_gsubr ("open-process", 2, 0, 1, scm_open_process);
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}
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#endif
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#endif /* HAVE_START_CHILD */
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void
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scm_init_posix ()
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@ -2320,11 +2338,13 @@ scm_init_posix ()
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#ifdef HAVE_FORK
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scm_add_feature ("fork");
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#endif /* HAVE_FORK */
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#ifdef HAVE_START_CHILD
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scm_c_register_extension ("libguile-" SCM_EFFECTIVE_VERSION,
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"scm_init_popen",
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(scm_t_extension_init_func) scm_init_popen,
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NULL);
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#endif /* HAVE_FORK */
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#endif /* HAVE_START_CHILD */
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}
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/*
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