make echo -e "foo\nfoo" | passwd USER work

Suggested by Michael Zhu (linuxsir320 AT gmail.com)

function                                             old     new   delta
bb_ask                                               333     340      +7

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

1 files changed, 21 insertions, 17 deletions

diff --git a/libbb/bb_askpass.c b/libbb/bb_askpass.c
index f9b918cec..bdb756659 100644
--- a/libbb/bb_askpass.c
+++ b/libbb/bb_askpass.c
@@ -30,10 +30,6 @@ char* FAST_FUNC bb_ask(const int fd, int timeout, const char *prompt)
         struct sigaction sa, oldsa;
         struct termios tio, oldtio;
 
-        if (!passwd)
-                passwd = xmalloc(sizeof_passwd);
-        memset(passwd, 0, sizeof_passwd);
-
         tcgetattr(fd, &oldtio);
         tcflush(fd, TCIFLUSH);
         tio = oldtio;
@@ -46,7 +42,7 @@ char* FAST_FUNC bb_ask(const int fd, int timeout, const char *prompt)
 
         memset(&sa, 0, sizeof(sa));
         /* sa.sa_flags = 0; - no SA_RESTART! */
-        /* SIGINT and SIGALRM will interrupt read below */
+        /* SIGINT and SIGALRM will interrupt reads below */
         sa.sa_handler = askpass_timeout;
         sigaction(SIGINT, &sa, &oldsa);
         if (timeout) {
@@ -56,18 +52,26 @@ char* FAST_FUNC bb_ask(const int fd, int timeout, const char *prompt)
 
         fputs(prompt, stdout);
         fflush_all();
-        ret = NULL;
-        /* On timeout or Ctrl-C, read will hopefully be interrupted,
-         * and we return NULL */
-        if (read(fd, passwd, sizeof_passwd - 1) > 0) {
-                ret = passwd;
-                i = 0;
-                /* Last byte is guaranteed to be 0
-                   (read did not overwrite it) */
-                do {
-                        if (passwd[i] == '\r' || passwd[i] == '\n')
-                                passwd[i] = '\0';
-                } while (passwd[i++]);
+
+        if (!passwd)
+                passwd = xmalloc(sizeof_passwd);
+        memset(passwd, 0, sizeof_passwd);
+        ret = passwd;
+        i = 0;
+        while (1) {
+                int r = read(fd, &ret[i], 1);
+                if (r < 0) {
+                        /* read is interrupted by timeout or ^C */
+                        ret = NULL;
+                        break;
+                }
+                if (r == 0 /* EOF */
+                 || ret[i] == '\r' || ret[i] == '\n' /* EOL */
+                 || ++i == sizeof_passwd-1 /* line limit */
+                ) {
+                        ret[i] = '\0';
+                        break;
+                }
         }
 
         if (timeout) {