diff options
| -rw-r--r-- | libguile/posix.c | 47 |
1 files changed, 38 insertions, 9 deletions
diff --git a/libguile/posix.c b/libguile/posix.c index 7ede7b756..a40ddb978 100644 --- a/libguile/posix.c +++ b/libguile/posix.c @@ -1243,6 +1243,36 @@ SCM_DEFINE (scm_fork, "primitive-fork", 0, 0, 0, #endif /* HAVE_FORK */ #ifdef HAVE_FORK +/* 'renumber_file_descriptor' is a helper function for 'start_child' + below, and is specialized for that particular environment where it + doesn't make sense to report errors via exceptions. It uses dup(2) + to duplicate the file descriptor FD, closes the original FD, and + returns the new descriptor. If dup(2) fails, print an error message + to ERR and abort. */ +static int +renumber_file_descriptor (int fd, int err) +{ + int new_fd; + + do + new_fd = dup (fd); + while (new_fd == -1 && errno == EINTR); + + if (new_fd == -1) + { + /* At this point we are in the child process before exec. We + cannot safely raise an exception in this environment. */ + char *msg = strerror (errno); + fprintf (fdopen (err, "a"), "start_child: dup failed: %s\n", msg); + _exit (127); /* Use exit status 127, as with other exec errors. */ + } + + close (fd); + return new_fd; +} +#endif /* HAVE_FORK */ + +#ifdef HAVE_FORK #define HAVE_START_CHILD 1 /* Since Guile uses threads, we have to be very careful to avoid calling functions that are not async-signal-safe in the child. That's why @@ -1293,16 +1323,16 @@ start_child (const char *exec_file, char **exec_argv, if (in > 0) { if (out == 0) - do out = dup (out); while (errno == EINTR); + out = renumber_file_descriptor (out, err); if (err == 0) - do err = dup (err); while (errno == EINTR); + err = renumber_file_descriptor (err, err); do dup2 (in, 0); while (errno == EINTR); close (in); } if (out > 1) { if (err == 1) - do err = dup (err); while (errno == EINTR); + err = renumber_file_descriptor (err, err); do dup2 (out, 1); while (errno == EINTR); close (out); } @@ -1315,12 +1345,11 @@ start_child (const char *exec_file, char **exec_argv, execvp (exec_file, exec_argv); /* The exec failed! There is nothing sensible to do. */ - if (err > 0) - { - char *msg = strerror (errno); - fprintf (fdopen (err, "a"), "In execvp of %s: %s\n", - exec_file, msg); - } + { + char *msg = strerror (errno); + fprintf (fdopen (2, "a"), "In execvp of %s: %s\n", + exec_file, msg); + } /* Use exit status 127, like shells in this case, as per POSIX <http://pubs.opengroup.org/onlinepubs/007904875/utilities/xcu_chap02.html#tag_02_09_01_01>. */ |