fix errno value for getcwd when size argument is zero

based on patch by Michael Forney. at the same time, I've changed the
if branch to be more clear, avoiding the comma operator.

the underlying issue is that Linux always returns ERANGE when size is
too short, even when it's zero, rather than returning EINVAL for the
special case of zero as required by POSIX.

diff --git a/src/unistd/getcwd.c b/src/unistd/getcwd.c
index 2e540cd41daef91efd37c7656f8f9274d4447ed6..a7b925d2dbee5a99f5ec61b77b5870ae3a839143 100644 (file)
--- a/src/unistd/getcwd.c
+++ b/src/unistd/getcwd.c
@@ -7,7 +7,13 @@
 char *getcwd(char *buf, size_t size)
 {
        char tmp[PATH_MAX];
-       if (!buf) buf = tmp, size = PATH_MAX;
+       if (!buf) {
+               buf = tmp;
+               size = PATH_MAX;
+       } else if (!size) {
+               errno = EINVAL;
+               return 0;
+       }
        if (syscall(SYS_getcwd, buf, size) < 0) return 0;
        return buf == tmp ? strdup(buf) : buf;
 }