PATCH: zpty: fix some issues

[Mikael Magnusson <mikachu@xxxxxxxxx>]

checkptycmd would sign extend a 0xff byte to -1, causing the byte to be
dropped, read into an unsigned char instead

the "last despairing effort" code read directly into the int, which
would probably not work on big endian. read into a temporary unsigned
char instead

the FIONREAD path used a totally undeclared variable "val", declare it,
and also initialize pollret to -1 for this path

the USE_CYGWIN_FIX path error message would always report -1 as the fd
it was unable to duplicate, report the original fd instead

initial read before the main loop in ptyread forgot to metafy the byte

avoid calling malloc with 0 length as this may be misinterpreted as oom

don't try to open sfd if opening mfd failed
---
 Src/Modules/zpty.c | 46 +++++++++++++++++++++++++++++++---------------
 1 file changed, 31 insertions(+), 15 deletions(-)

diff --git a/Src/Modules/zpty.c b/Src/Modules/zpty.c
index b766865dd1..d87e327449 100644
--- a/Src/Modules/zpty.c
+++ b/Src/Modules/zpty.c
@@ -292,6 +292,7 @@ get_pty(int master, int *retfd)
 		}
 	    }
 	}
+	return 1; /* don't try to open a slave if we got no master */
     }
     name[5] = 't';
     if ((sfd = open(name, O_RDWR|O_NOCTTY)) >= 0) {
@@ -436,12 +437,15 @@ newptycmd(char *nam, char *pname, char **args, int echo, int nblock)
 	zexit(lastval, ZEXIT_NORMAL);
     }
 #ifndef USE_CYGWIN_FIX
-    master = movefd(master);
-    if (master == -1) {
-	zerrnam(nam, "cannot duplicate fd %d: %e", master, errno);
-	scriptname = oscriptname;
-	ineval = oineval;
-	return 1;
+    {
+	int orig_master = master;
+	master = movefd(master);
+	if (master == -1) {
+	    zerrnam(nam, "cannot duplicate fd %d: %e", orig_master, errno);
+	    scriptname = oscriptname;
+	    ineval = oineval;
+	    return 1;
+	}
     }
 #else
     addmodulefd(master, FDT_INTERNAL);
@@ -529,7 +533,7 @@ deleteallptycmds(void)
 static void
 checkptycmd(Ptycmd cmd)
 {
-    char c;
+    unsigned char c;
     int r;
 
     if (cmd->read != -1 || cmd->fin)
@@ -581,14 +585,19 @@ ptyread(char *nam, Ptycmd cmd, char **args, int noblock, int mustmatch)
 	buf = (char *) zhalloc((blen = 256) + 1);
     }
     if (cmd->read != -1) {
-	buf[used] = (char) cmd->read;
-	buf[used + 1] = '\0';
-	seen = used = 1;
+	int readchar = cmd->read;
 	cmd->read = -1;
+	if (imeta(readchar)) {
+	    buf[used++] = Meta;
+	    buf[used++] = (char) (readchar ^ 32);
+	} else
+	    buf[used++] = (char) readchar;
+	buf[used] = '\0';
+	seen = 1;
     }
     do {
 	if (noblock && cmd->read == -1) {
-	    int pollret;
+	    int pollret = -1;
 	    /*
 	     * Check there is data available.  Borrowed from
 	     * poll_read() in utils.c and simplified.
@@ -604,6 +613,7 @@ ptyread(char *nam, Ptycmd cmd, char **args, int noblock, int mustmatch)
 			 (SELECT_ARG_2_T) &foofd, NULL, NULL, &expire_tv);
 #else
 #ifdef FIONREAD
+	    int val;
 	    if (ioctl(cmd->fd, FIONREAD, (char *) &val) == 0)
 		pollret = (val > 0);
 #endif
@@ -617,9 +627,13 @@ ptyread(char *nam, Ptycmd cmd, char **args, int noblock, int mustmatch)
 		 * character.  cmd->read stores the character read.
 		 */
 		long mode;
+		unsigned char c;
 
-		if (setblock_fd(0, cmd->fd, &mode))
-		    pollret = read(cmd->fd, &cmd->read, 1);
+		if (setblock_fd(0, cmd->fd, &mode)) {
+		    pollret = read(cmd->fd, &c, 1);
+		    if (pollret == 1)
+			cmd->read = (int) c;
+		}
 		if (mode != -1)
 		    fcntl(cmd->fd, F_SETFL, mode);
 	    }
@@ -688,8 +702,10 @@ ptyread(char *nam, Ptycmd cmd, char **args, int noblock, int mustmatch)
 #endif
 #endif
 	) {
-	cmd->old = (char *) zalloc(cmd->olen = used);
-	memcpy(cmd->old, buf, cmd->olen);
+	if (used) {
+	    cmd->old = (char *) zalloc(cmd->olen = used);
+	    memcpy(cmd->old, buf, cmd->olen);
+	}
 	if (prog)
 	    freepatprog(prog);
 
-- 
2.38.1