agetty: use a generic function for strings concatenation

Signed-off-by: Karel Zak <kzak@redhat.com>

diff --git a/term-utils/agetty.c b/term-utils/agetty.c
index 468aa5e8a8b76e150eabeead70d439c3f151a340..4a90dad943138957fdc1bad1470b8bdeb6167142 100644 (file)
--- a/term-utils/agetty.c
+++ b/term-utils/agetty.c
@@ -254,6 +254,7 @@ static void log_err(const char *, ...) __attribute__((__noreturn__))
                               __attribute__((__format__(printf, 1, 2)));
 static void log_warn (const char *, ...)
                                __attribute__((__format__(printf, 1, 2)));
+static ssize_t append(char *dest, size_t len, const char  *sep, const char *src);
 static void checkname (const char* nm);
 static void replacename (char** arr, const char* nm);
 static void mkarray (char** arr, char* str);
@@ -402,9 +403,9 @@ int main(int argc, char **argv)
        sigaction(SIGQUIT, &sa_quit, NULL);
        sigaction(SIGINT, &sa_int, NULL);
 
-       strncpy(logcmd, options.login, NAME_MAX);
-       strncat(logcmd, " ", NAME_MAX - strlen(logcmd));
-       strncat(logcmd, options.logopt, NAME_MAX - strlen(logcmd));
+       *logcmd = '\0';
+       append(logcmd, sizeof(logcmd), NULL, options.login);
+       append(logcmd, sizeof(logcmd), " ", options.logopt);
 
        checkname(logname);
        mkarray(logarr, logcmd);
@@ -1187,54 +1188,30 @@ static void do_prompt(struct options *op, struct termios *tp)
        }
 #ifdef KDGKBLED
        if (op->autolog == (char*)0 && (op->flags & F_VCONSOLE)) {
-               int kb = 0, nl = 0;
-               struct stat st;
-               if (stat("/var/run/numlock-on", &st) == 0)
-                       nl = 1;
+               int kb = 0;
+
                if (ioctl(STDIN_FILENO, KDGKBLED, &kb) == 0) {
-                       const char *hint = _("Hint: ");
-                       char warn[256];
-                       off_t space = sizeof(warn) - 1, off = 0;
-
-                       if (nl && (kb & 0x02) == 0) {
-                               const char *msg = _("Num Lock off");
-                               const size_t len = strlen(msg);
-                               strncpy(&warn[0], msg, space);
-                               space -= len;
-                               off += len;
-                       } else if (nl == 0 && (kb & 2) && (kb & 0x20) == 0) {
-                               const char *msg = _("Num Lock on");
-                               const size_t len = strlen(msg);
-                               strncpy(&warn[0], msg, space);
-                               space -= len;
-                               off += len;
-                       }
-                       if ((kb & 0x04) && (kb & 0x40) == 0) {
-                               const char *msg = _("Caps Lock on");
-                               const size_t len = strlen(msg);
-                               if (off) {
-                                       strncpy(&warn[off], ", ", space);
-                                       space -= 2;
-                                       off += 2;
-                               }
-                               strncpy(&warn[off], msg, space);
-                               space -= len;
-                               off += len;
-                       }
-                       if ((kb & 0x01) && (kb & 0x10) == 0) {
-                               const char *msg = _("Scroll Lock on");
-                               const size_t len = strlen(msg);
-                               if (off) {
-                                       strncpy(&warn[off], ", ", space);
-                                       space -= 2;
-                                       off += 2;
-                               }
-                               strncpy(&warn[off], msg, space);
-                               space -= len;
-                               off += len;
-                       }
-                       if (off)
-                               printf ("%s%s\n\n", hint, warn);
+                       char hint[256] = { '\0' };
+                       int nl = 0;
+                       struct stat st;
+
+                       if (stat("/var/run/numlock-on", &st) == 0)
+                               nl = 1;
+
+                       if (nl && (kb & 0x02) == 0)
+                               append(hint, sizeof(hint), NULL, _("Num Lock off"));
+
+                       else if (nl == 0 && (kb & 2) && (kb & 0x20) == 0)
+                               append(hint, sizeof(hint), NULL, _("Num Lock on"));
+
+                       if ((kb & 0x04) && (kb & 0x40) == 0)
+                               append(hint, sizeof(hint), ", ", _("Caps Lock on"));
+
+                       if ((kb & 0x01) && (kb & 0x10) == 0)
+                               append(hint, sizeof(hint), ", ",  _("Scroll Lock on"));
+
+                       if (*hint)
+                               printf(_("Hint: %s\n\n"), hint);
                }
        }
 #endif /* KDGKBLED */
@@ -1798,6 +1775,39 @@ static void init_special_char(char* arg, struct options *op)
        *q = '\0';
 }
 
+/*
+ * Appends @str to @dest and if @dest is not empty then use use @sep as a
+ * separator. The maximal final length of the @dest is @len.
+ *
+ * Returns the final @dest length or -1 in case of error.
+ */
+static ssize_t append(char *dest, size_t len, const char  *sep, const char *src)
+{
+       size_t dsz = 0, ssz = 0, sz;
+       char *p;
+
+       if (!dest || !len || !src)
+               return -1;
+
+       if (*dest)
+               dsz = strlen(dest);
+       if (dsz && sep)
+               ssz = strlen(sep);
+       sz = strlen(src);
+
+       if (dsz + ssz + sz + 1 > len)
+               return -1;
+
+       p = dest + dsz;
+       if (ssz) {
+               memcpy(p, sep, ssz);
+               p += ssz;
+       }
+       memcpy(p, src, sz);
+       *(p + sz) = '\0';
+
+       return dsz + ssz + sz;
+}
 /*
  * Do not allow the user to pass an option as a user name
  * To be more safe: Use `--' to make sure the rest is