xstrcpy() aborts on argument too long

Which may be dumb, but it's better than bluntly truncating a string

1 files changed, 20 insertions, 24 deletions

diff --git a/support.c b/support.c
index 7ee2dad..fe084cf 100644
--- a/support.c
+++ b/support.c
@@ -37,10 +37,22 @@ char tac_service[64];
 char tac_protocol[64];
 char tac_prompt[64];
 
+void _pam_log(int err, const char *format,...) {
+    char msg[256];
+    va_list args;
+
+    va_start(args, format);
+    vsnprintf(msg, sizeof(msg), format, args);
+    openlog("PAM-tacplus", LOG_PID, LOG_AUTH);
+    syslog(err, "%s", msg);
+    va_end(args);
+    closelog();
+}
+
 /*
-    safe string copy, like strlcpy() really
+    safe string copy that aborts when destination buffer is too small
 */
-size_t xstrcpy(char *dst, const char *src, size_t dst_size) {
+char *xstrcpy(char *dst, const char *src, size_t dst_size) {
     if (dst == NULL)
         _pam_log(LOG_ERR, "xstrcpy(): dst == NULL");
 
@@ -48,30 +60,14 @@ size_t xstrcpy(char *dst, const char *src, size_t dst_size) {
         _pam_log(LOG_ERR, "xstrcpy(): src == NULL");
 
     if (!dst_size)
-        return 0;
-
-    size_t s_len = strlen(src);
+        return NULL;
 
-    size_t n = s_len;
-    if (n >= dst_size)
-        n = dst_size - 1;
+    if (strlen(src) >= dst_size) {
+        _pam_log(LOG_ERR, "xstrcpy(): argument too long, aborting");
+		abort();
+	}
 
-    strncpy(dst, src, n);
-    dst[n] = 0;
-
-    return n;
-}
-
-void _pam_log(int err, const char *format,...) {
-    char msg[256];
-    va_list args;
-
-    va_start(args, format);
-    vsnprintf(msg, sizeof(msg), format, args);
-    openlog("PAM-tacplus", LOG_PID, LOG_AUTH);
-    syslog(err, "%s", msg);
-    va_end(args);
-    closelog();
+    return strcpy(dst, src);
 }
 
 char *_pam_get_user(pam_handle_t *pamh) {