[src/trunk]: src/lib/libc/gen make popen/pclose thread safe

[cl <cl%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/f92521848b88
branches:  trunk
changeset: 552007:f92521848b88
user:      cl <cl%NetBSD.org@localhost>
date:      Mon Sep 15 22:30:38 2003 +0000

description:
make popen/pclose thread safe

diffstat:

 lib/libc/gen/popen.c |  43 +++++++++++++++++++++++++++++++++++--------
 1 files changed, 35 insertions(+), 8 deletions(-)

diffs (124 lines):

diff -r 2e2cd7c948b9 -r f92521848b88 lib/libc/gen/popen.c
--- a/lib/libc/gen/popen.c      Mon Sep 15 21:03:10 2003 +0000
+++ b/lib/libc/gen/popen.c      Mon Sep 15 22:30:38 2003 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: popen.c,v 1.27 2003/08/07 16:42:55 agc Exp $   */
+/*     $NetBSD: popen.c,v 1.28 2003/09/15 22:30:38 cl Exp $    */
 
 /*
  * Copyright (c) 1988, 1993
@@ -37,7 +37,7 @@
 #if 0
 static char sccsid[] = "@(#)popen.c    8.3 (Berkeley) 5/3/95";
 #else
-__RCSID("$NetBSD: popen.c,v 1.27 2003/08/07 16:42:55 agc Exp $");
+__RCSID("$NetBSD: popen.c,v 1.28 2003/09/15 22:30:38 cl Exp $");
 #endif
 #endif /* LIBC_SCCS and not lint */
 
@@ -68,9 +68,16 @@
 static struct pid {
        struct pid *next;
        FILE *fp;
+#ifdef _REENTRANT
+       int fd;
+#endif
        pid_t pid;
 } *pidlist; 
        
+#ifdef _REENTRANT
+static rwlock_t pidlist_lock = RWLOCK_INITIALIZER;
+#endif
+
 FILE *
 popen(command, type)
        const char *command, *type;
@@ -108,11 +115,13 @@
                return (NULL);
        }
 
+       rwlock_rdlock(&pidlist_lock);
        rwlock_rdlock(&__environ_lock);
        switch (pid = vfork()) {
        case -1:                        /* Error. */
                serrno = errno;
                rwlock_unlock(&__environ_lock);
+               rwlock_unlock(&pidlist_lock);
                free(cur);
                (void)close(pdes[0]);
                (void)close(pdes[1]);
@@ -124,7 +133,11 @@
                   from previous popen() calls that remain open in the 
                   parent process are closed in the new child process. */
                for (old = pidlist; old; old = old->next)
+#ifdef _REENTRANT
+                       close(old->fd); /* don't allow a flush */
+#else
                        close(fileno(old->fp)); /* don't allow a flush */
+#endif
 
                if (*type == 'r') {
                        (void)close(pdes[0]);
@@ -151,9 +164,15 @@
        /* Parent; assume fdopen can't fail. */
        if (*type == 'r') {
                iop = fdopen(pdes[0], type);
+#ifdef _REENTRANT
+               cur->fd = pdes[0];
+#endif
                (void)close(pdes[1]);
        } else {
                iop = fdopen(pdes[1], type);
+#ifdef _REENTRANT
+               cur->fd = pdes[1];
+#endif
                (void)close(pdes[0]);
        }
 
@@ -162,6 +181,7 @@
        cur->pid =  pid;
        cur->next = pidlist;
        pidlist = cur;
+       rwlock_unlock(&pidlist_lock);
 
        return (iop);
 }
@@ -181,25 +201,32 @@
 
        _DIAGASSERT(iop != NULL);
 
+       rwlock_wrlock(&pidlist_lock);
+
        /* Find the appropriate file pointer. */
        for (last = NULL, cur = pidlist; cur; last = cur, cur = cur->next)
                if (cur->fp == iop)
                        break;
-       if (cur == NULL)
+       if (cur == NULL) {
+               rwlock_unlock(&pidlist_lock);
                return (-1);
+       }
 
        (void)fclose(iop);
 
-       do {
-               pid = waitpid(cur->pid, &pstat, 0);
-       } while (pid == -1 && errno == EINTR);
-
        /* Remove the entry from the linked list. */
        if (last == NULL)
                pidlist = cur->next;
        else
                last->next = cur->next;
+
+       rwlock_unlock(&pidlist_lock);
+
+       do {
+               pid = waitpid(cur->pid, &pstat, 0);
+       } while (pid == -1 && errno == EINTR);
+
        free(cur);
-               
+
        return (pid == -1 ? -1 : pstat);
 }