Fix wc -c optimization.

Check the fstat(2) return value rather than read uninitialized memory if
it failed, and add a special case for files that claim to be zero-length
but aren't (as is common in /proc on Linux).

diff --git a/toys/posix/wc.c b/toys/posix/wc.c
index 62d1f7a..e7afc81 100644 (file)
--- a/toys/posix/wc.c
+++ b/toys/posix/wc.c
@@ -53,8 +53,8 @@ static void do_wc(int fd, char *name)
   if (toys.optflags == FLAG_c) {
     struct stat st;
 
-    fstat(fd, &st);
-    if (S_ISREG(st.st_mode)) {
+    // On Linux, files in /proc often report their size as 0.
+    if (!fstat(fd, &st) && S_ISREG(st.st_mode) && st.st_size > 0) {
       lengths[2] = st.st_size;
       goto show;
     }