sftp session cache
diff --git a/src/cmd/sftpcache.c b/src/cmd/sftpcache.c
new file mode 100644
index 0000000..cfe60ab
--- /dev/null
+++ b/src/cmd/sftpcache.c
@@ -0,0 +1,210 @@
+/*
+ * Multiplexor for sftp sessions.
+ * Assumes can parse session with sftp> prompts.
+ * Assumes clients are well-behaved and don't hang up the system.
+ *
+ * Stupid sftp bug: sftp invokes ssh, which always set O_NONBLOCK
+ * on 0, 1, and 2. Ssh inherits sftp's 2, so we can't use the output pipe
+ * on fd 2, since it will get set O_NONBLOCK, sftp won't notice, and
+ * writes will be lost. So instead we use a separate pipe for errors
+ * and consult it after each command. Assume the pipe buffer is
+ * big enough to hold the error output.
+ */
+#include <u.h>
+#include <fcntl.h>
+#include <libc.h>
+#include <bio.h>
+
+#undef pipe
+
+int debug;
+#define dprint if(debug)print
+int sftpfd;
+int sftperr;
+Biobuf bin;
+
+void
+usage(void)
+{
+ fprint(2, "usage: sftpcache system\n");
+ exits("usage");
+}
+
+char*
+Brd(Biobuf *bin)
+{
+ static char buf[1000];
+ int c, tot;
+
+ tot = 0;
+ while((c = Bgetc(bin)) >= 0 && tot<sizeof buf){
+ buf[tot++] = c;
+ if(c == '\n'){
+ buf[tot] = 0;
+ dprint("%s", buf);
+ return buf;
+ }
+ if(c == ' ' && tot == 6 && memcmp(buf, "sftp> ", 5) == 0){
+ buf[tot] = 0;
+ dprint("%s\n", buf);
+ return buf;
+ }
+ }
+ if(tot == sizeof buf)
+ sysfatal("response too long");
+ return nil;
+}
+
+int
+readstr(int fd, char *a, int n)
+{
+ int i;
+
+ for(i=0; i<n; i++){
+ if(read(fd, a+i, 1) != 1)
+ return -1;
+ if(a[i] == '\n'){
+ a[i] = 0;
+ return i;
+ }
+ }
+ return n;
+}
+
+void
+doerrors(int fd)
+{
+ char buf[100];
+ int n;
+
+ while((n = read(sftperr, buf, sizeof buf)) > 0){
+ if(debug)
+ write(1, buf, n);
+ write(fd, buf, n);
+ }
+}
+
+void
+bell(void *x, char *msg)
+{
+ if(strcmp(msg, "sys: child") == 0 || strcmp(msg, "sys: write on closed pipe") == 0)
+ sysfatal("sftp exited");
+ if(strcmp(msg, "alarm") == 0)
+ noted(NCONT);
+ noted(NDFLT);
+}
+
+void
+main(int argc, char **argv)
+{
+ char buf[200], cmd[1000], *q, *s;
+ char dir[100], ndir[100];
+ int p[2], px[2], pe[2], pid, ctl, nctl, fd, n;
+
+ notify(bell);
+ fmtinstall('H', encodefmt);
+
+ ARGBEGIN{
+ case 'D':
+ debug = 1;
+ break;
+ default:
+ usage();
+ }ARGEND
+
+ if(argc != 1)
+ usage();
+
+ if(pipe(p) < 0 || pipe(px) < 0 || pipe(pe) < 0)
+ sysfatal("pipe: %r");
+ pid = fork();
+ if(pid < 0)
+ sysfatal("fork: %r");
+ if(pid == 0){
+ close(p[1]);
+ close(px[0]);
+ close(pe[0]);
+ dup(p[0], 0);
+ dup(px[1], 1);
+ dup(pe[1], 2);
+ if(p[0] > 2)
+ close(p[0]);
+ if(px[1] > 2)
+ close(px[1]);
+ if(pe[1] > 2)
+ close(pe[1]);
+ execl("sftp", "sftp", "-b", "/dev/stdin", argv[0], nil);
+ sysfatal("exec sftp: %r");
+ }
+
+ close(p[0]);
+ close(px[1]);
+ close(pe[1]);
+
+ sftpfd = p[1];
+ sftperr = pe[0];
+ Binit(&bin, px[0], OREAD);
+
+ fcntl(sftperr, F_SETFL, fcntl(sftperr, F_GETFL, 0)|O_NONBLOCK);
+
+ do
+ q = Brd(&bin);
+ while(q && strcmp(q, "sftp> ") != 0);
+ if(q == nil)
+ sysfatal("unexpected eof");
+
+ snprint(buf, sizeof buf, "unix!%s/%s.sftp", getns(), argv[0]);
+ ctl = announce(buf, dir);
+ if(ctl < 0)
+ sysfatal("announce %s: %r", buf);
+
+ pid = fork();
+ if(pid < 0)
+ sysfatal("fork");
+ if(pid != 0)
+ exits(nil);
+
+ for(;;){
+ nctl = listen(dir, ndir);
+ if(nctl < 0)
+ sysfatal("listen %s: %r", buf);
+ fd = accept(ctl, ndir);
+ close(nctl);
+ if(fd < 0)
+ continue;
+ for(;;){
+ // alarm(1000);
+ n = readstr(fd, cmd, sizeof cmd);
+ // alarm(0);
+ if(n <= 0)
+ break;
+ dprint("CMD %s\n", cmd);
+ if(strcmp(cmd, "DONE") == 0)
+ break;
+ fprint(sftpfd, "%s\n", cmd);
+ q = Brd(&bin);
+ if(*q==0 || q[strlen(q)-1] != '\n')
+ sysfatal("unexpected response");
+ q[strlen(q)-1] = 0;
+ if(strcmp(q, cmd) != 0)
+ sysfatal("unexpected response");
+ while((q = Brd(&bin)) != nil){
+ if(strcmp(q, "sftp> ") == 0){
+ doerrors(fd);
+ break;
+ }
+ s = q+strlen(q);
+ while(s > q && (s[-1] == ' ' || s[-1] == '\n' || s[-1] == '\t' || s[-1] == '\r'))
+ s--;
+ *s = 0;
+ fprint(fd, "%s\n", q);
+ }
+ if(q == nil){
+ fprint(fd, "!!! unexpected eof\n");
+ sysfatal("unexpected eof");
+ }
+ }
+ close(fd);
+ }
+}
+
