fix bogus lazy allocation in ctermid and missing malloc failure check

also clean up, optimize, and simplify the code, removing branches by
simply pre-setting the result string to an empty string, which will be
preserved if other operations fail.

diff --git a/src/unistd/ctermid.c b/src/unistd/ctermid.c
index c238905adae25292756d62dfb6401e66a7c700fd..ffa9b758cb60be3bc2e55c3224d6e3dc3d2e7082 100644 (file)
--- a/src/unistd/ctermid.c
+++ b/src/unistd/ctermid.c
@@ -8,17 +8,14 @@
 
 char *ctermid(char *s)
 {
-       static char *s2;
+       static char s2[L_ctermid];
        int fd;
-       if (!s) {
-               if (!s2) s2 = malloc(L_ctermid);
-               s = s2;
-       }
+       if (!s) s = s2;
+       *s = 0;
        fd = open("/dev/tty", O_WRONLY | O_NOCTTY | O_CLOEXEC);
-       if (fd < 0)
-               return strcpy(s, "");
-       if (ttyname_r(fd, s, L_ctermid))
-               strcpy(s, "");
-       __syscall(SYS_close, fd);
+       if (fd >= 0) {
+               ttyname_r(fd, s, L_ctermid);
+               __syscall(SYS_close, fd);
+       }
        return s;
 }