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authorRich Felker <dalias@aerifal.cx>2011-07-22 00:25:56 -0400
committerRich Felker <dalias@aerifal.cx>2011-07-22 00:25:56 -0400
commitc0fe5b9da9f98b83262717c0090817f1fbb3d8a0 (patch)
treeaf009ffeef44eb430a850edaedb0f544ce3e88d0 /src/misc
parentd40e344f7b311980dfe3c165d8cbecfe04c12bd2 (diff)
downloadmusl-c0fe5b9da9f98b83262717c0090817f1fbb3d8a0.tar.gz
check for fd exhaustion in forkpty
we cannot report failure after forking, so the idea is to ensure prior to fork that fd 0,1,2 exist. this will prevent dup2 from possibly hitting a resource limit and failing in the child process. fcntl rather than dup2 is used prior to forking to avoid race conditions.
Diffstat (limited to 'src/misc')
-rw-r--r--src/misc/forkpty.c17
1 files changed, 15 insertions, 2 deletions
diff --git a/src/misc/forkpty.c b/src/misc/forkpty.c
index 0bbf2de2..07f8d01e 100644
--- a/src/misc/forkpty.c
+++ b/src/misc/forkpty.c
@@ -1,14 +1,25 @@
#include <pty.h>
#include <unistd.h>
#include <sys/ioctl.h>
+#include <fcntl.h>
int forkpty(int *m, char *name, const struct termios *tio, const struct winsize *ws)
{
- int s;
+ int s, t, i, istmp[3]={0};
pid_t pid;
if (openpty(m, &s, name, tio, ws) < 0) return -1;
- pid = fork();
+
+ /* Ensure before forking that we don't exceed fd limit */
+ for (i=0; i<3; i++) {
+ if (fcntl(i, F_GETFL) < 0) {
+ t = fcntl(s, F_DUPFD, i);
+ if (t<0) break;
+ else if (t!=i) close(t);
+ else istmp[i] = 1;
+ }
+ }
+ pid = i==3 ? fork() : -1;
if (!pid) {
close(*m);
setsid();
@@ -19,6 +30,8 @@ int forkpty(int *m, char *name, const struct termios *tio, const struct winsize
if (s>2) close(s);
return 0;
}
+ for (i=0; i<3; i++)
+ if (istmp[i]) close(i);
close(s);
if (pid < 0) close(*m);
return pid;