setpwnam: use getline instead of fgets

Handling long lines takes already a lot of code and if a line starts
with a NUL character, an out of boundary read occurs.

Just use getline.

Signed-off-by: Tobias Stoeckmann <tobias@stoeckmann.org>

diff --git a/login-utils/setpwnam.c b/login-utils/setpwnam.c
index f95a7726d24126907ead5701ebe811c8f5124ba1..55fb174d0d0a4aef439b9d4e0621bcf5e73ac95d 100644 (file)
--- a/login-utils/setpwnam.c
+++ b/login-utils/setpwnam.c
@@ -77,8 +77,7 @@ int setpwnam(struct passwd *pwd, const char *prefix)
        int save_errno, rc;
        uint8_t found = 0, locked = 0;
        size_t namelen;
-       size_t contlen;
-       size_t buflen = 256;
+       size_t buflen = 0;
        char *linebuf = NULL;
        char *tmpname = NULL;
 
@@ -100,33 +99,11 @@ int setpwnam(struct passwd *pwd, const char *prefix)
                goto fail;
 
        namelen = strlen(pwd->pw_name);
-       if (namelen > buflen)
-               buflen += namelen;
-       linebuf = malloc(buflen);
-       if (!linebuf)
-               goto fail;
 
        /* parse the passwd file */
        /* Do you wonder why I don't use getpwent? Read comments at top of
         * file */
-       while (fgets(linebuf, buflen, pwf) != NULL) {
-               contlen = strlen(linebuf);
-               while (linebuf[contlen - 1] != '\n' && !feof(pwf)) {
-                       char *tmp;
-                       /* Extend input buffer if it failed getting the whole line,
-                        * so now we double the buffer size */
-                       buflen *= 2;
-                       tmp = realloc(linebuf, buflen);
-                       if (tmp == NULL)
-                               goto fail;
-                       linebuf = tmp;
-                       /* And fill the rest of the buffer */
-                       if (fgets(&linebuf[contlen], buflen / 2, pwf) == NULL)
-                               break;
-                       contlen = strlen(linebuf);
-                       /* That was a lot of work for nothing. Gimme perl! */
-               }
-
+       while (getline(&linebuf, &buflen, pwf) != -1) {
                /* Is this the username we were sent to change? */
                if (!found &&
                    strncmp(linebuf, pwd->pw_name, namelen) == 0 &&