cftw.c: Check errors from readdir(3)

According to POSIX.1-2017, applications are advised to assign errno(3)
to 0 before a call to readdir(3), and compare errno(3) after the call to
check for errors.

1 files changed, 12 insertions, 2 deletions

diff --git a/cftw.c b/cftw.c
index d11cb87..2990888 100644
--- a/cftw.c
+++ b/cftw.c
@@ -14,7 +14,6 @@ int cftw(const char *const dirpath, int (*const fn)(const char *,
 {
     int ret = -1;
     DIR *const d = opendir(dirpath);
-    struct dirent *de;
 
     if (!d)
     {
@@ -22,8 +21,19 @@ int cftw(const char *const dirpath, int (*const fn)(const char *,
         goto end;
     }
 
-    while ((de = readdir(d)))
+    for (;;)
     {
+        errno = 0;
+        struct dirent *const de = readdir(d);
+
+        if (errno)
+        {
+            fprintf(stderr, "%s: readdir(3): %s\n", __func__, strerror(errno));
+            goto end;
+        }
+        else if (!de)
+            break;
+
         const char *const path = de->d_name;
 
         if (!strcmp(path, ".") || !strcmp(path, ".."))