X-Git-Url: https://asedeno.scripts.mit.edu/gitweb/?a=blobdiff_plain;f=unix%2Fuxcons.c;h=abad00db0ef7a065460fd04a1496e9562874b422;hb=2eb952ca31aa13d1f6f429305fbb6f43a9a28c56;hp=eabb7769dddc0a3284018c0efe2a8fa4ed3edd73;hpb=b266d671acee34f9305950bfd87054b3b7fcded6;p=PuTTY.git

diff --git a/unix/uxcons.c b/unix/uxcons.c
index eabb7769..abad00db 100644
--- a/unix/uxcons.c
+++ b/unix/uxcons.c
@@ -7,6 +7,7 @@
 #include <stdlib.h>
 #include <stdarg.h>
 #include <assert.h>
+#include <errno.h>
 
 #include <termios.h>
 #include <unistd.h>
@@ -74,6 +75,38 @@ void timer_change_notify(unsigned long next)
 {
 }
 
+/*
+ * Wrapper around Unix read(2), suitable for use on a file descriptor
+ * that's been set into nonblocking mode. Handles EAGAIN/EWOULDBLOCK
+ * by means of doing a one-fd select and then trying again; all other
+ * errors (including errors from select) are returned to the caller.
+ */
+static int block_and_read(int fd, void *buf, size_t len)
+{
+    int ret;
+
+    while ((ret = read(fd, buf, len)) < 0 && (
+#ifdef EAGAIN
+               (errno == EAGAIN) ||
+#endif
+#ifdef EWOULDBLOCK
+               (errno == EWOULDBLOCK) ||
+#endif
+               0)) {
+
+        fd_set rfds;
+        FD_ZERO(&rfds);
+        FD_SET(fd, &rfds);
+        ret = select(fd+1, &rfds, NULL, NULL, NULL);
+        assert(ret != 0);
+        if (ret < 0)
+            return ret;
+        assert(FD_ISSET(fd, &rfds));
+    }
+
+    return ret;
+}
+
 int verify_ssh_host_key(void *frontend, char *host, int port,
                         const char *keytype, char *keystr, char *fingerprint,
                         void (*callback)(void *ctx, int result), void *ctx)
@@ -163,7 +196,7 @@ int verify_ssh_host_key(void *frontend, char *host, int port,
 	newmode.c_lflag |= ECHO | ISIG | ICANON;
 	tcsetattr(0, TCSANOW, &newmode);
 	line[0] = '\0';
-	if (read(0, line, sizeof(line) - 1) <= 0)
+	if (block_and_read(0, line, sizeof(line) - 1) <= 0)
 	    /* handled below */;
 	tcsetattr(0, TCSANOW, &oldmode);
     }
@@ -216,7 +249,7 @@ int askalg(void *frontend, const char *algtype, const char *algname,
 	newmode.c_lflag |= ECHO | ISIG | ICANON;
 	tcsetattr(0, TCSANOW, &newmode);
 	line[0] = '\0';
-	if (read(0, line, sizeof(line) - 1) <= 0)
+	if (block_and_read(0, line, sizeof(line) - 1) <= 0)
 	    /* handled below */;
 	tcsetattr(0, TCSANOW, &oldmode);
     }
@@ -270,7 +303,7 @@ int askappend(void *frontend, Filename *filename,
 	newmode.c_lflag |= ECHO | ISIG | ICANON;
 	tcsetattr(0, TCSANOW, &newmode);
 	line[0] = '\0';
-	if (read(0, line, sizeof(line) - 1) <= 0)
+	if (block_and_read(0, line, sizeof(line) - 1) <= 0)
 	    /* handled below */;
 	tcsetattr(0, TCSANOW, &oldmode);
     }