hush: fix a case when redirect to a closed fd #1 is not restoring (closing) it

[oweals/busybox.git] / shell / hush.c

diff --git a/shell/hush.c b/shell/hush.c
index 170d5f33b54ba53e991c4941f2e037e095e15b65..20b092398fa220a4445855e2d314bab7a216347e 100644 (file)
--- a/shell/hush.c
+++ b/shell/hush.c
@@ -2662,9 +2662,8 @@ static void o_delchr(o_string *o)
 static void o_addblock(o_string *o, const char *str, int len)
 {
        o_grow_by(o, len);
-       memcpy(&o->data[o->length], str, len);
+       ((char*)mempcpy(&o->data[o->length], str, len))[0] = '\0';
        o->length += len;
-       o->data[o->length] = '\0';
 }
 
 static void o_addstr(o_string *o, const char *str)
@@ -5519,17 +5518,15 @@ static char *replace_pattern(char *val, const char *pattern, const char *repl, c
                        break;
 
                result = xrealloc(result, res_len + (s - val) + repl_len + 1);
-               memcpy(result + res_len, val, s - val);
-               res_len += s - val;
-               strcpy(result + res_len, repl);
-               res_len += repl_len;
+               strcpy(mempcpy(result + res_len, val, s - val), repl);
+               res_len += (s - val) + repl_len;
                debug_printf_varexp("val:'%s' s:'%s' result:'%s'\n", val, s, result);
 
                val = s + size;
                if (exp_op == '/')
                        break;
        }
-       if (val[0] && result) {
+       if (*val && result) {
                result = xrealloc(result, res_len + strlen(val) + 1);
                strcpy(result + res_len, val);
                debug_printf_varexp("val:'%s' result:'%s'\n", val, result);
@@ -6646,8 +6643,18 @@ struct squirrel {
        /* moved_to = -1: fd was opened by redirect; close orig_fd after redir */
 };
 
+static struct squirrel *append_squirrel(struct squirrel *sq, int i, int orig, int moved)
+{
+       sq = xrealloc(sq, (i + 2) * sizeof(sq[0]));
+       sq[i].orig_fd = orig;
+       sq[i].moved_to = moved;
+       sq[i+1].orig_fd = -1; /* end marker */
+       return sq;
+}
+
 static struct squirrel *add_squirrel(struct squirrel *sq, int fd, int avoid_fd)
 {
+       int moved_to;
        int i = 0;
 
        if (sq) while (sq[i].orig_fd >= 0) {
@@ -6667,15 +6674,12 @@ static struct squirrel *add_squirrel(struct squirrel *sq, int fd, int avoid_fd)
                i++;
        }
 
-       sq = xrealloc(sq, (i + 2) * sizeof(sq[0]));
-       sq[i].orig_fd = fd;
        /* If this fd is open, we move and remember it; if it's closed, moved_to = -1 */
-       sq[i].moved_to = fcntl_F_DUPFD(fd, avoid_fd);
-       debug_printf_redir("redirect_fd %d: previous fd is moved to %d (-1 if it was closed)\n", fd, sq[i].moved_to);
-       if (sq[i].moved_to < 0 && errno != EBADF)
+       moved_to = fcntl_F_DUPFD(fd, avoid_fd);
+       debug_printf_redir("redirect_fd %d: previous fd is moved to %d (-1 if it was closed)\n", fd, moved_to);
+       if (moved_to < 0 && errno != EBADF)
                xfunc_die();
-       sq[i+1].orig_fd = -1; /* end marker */
-       return sq;
+       return append_squirrel(sq, i, fd, moved_to);
 }
 
 /* fd: redirect wants this fd to be used (e.g. 3>file).
@@ -6781,6 +6785,19 @@ static int setup_redirects(struct command *prog, struct squirrel **sqp)
                                 */
                                return 1;
                        }
+                       if (openfd == redir->rd_fd && sqp) {
+                               /* open() gave us precisely the fd we wanted.
+                                * This means that this fd was not busy
+                                * (not opened to anywhere).
+                                * Remember to close it on restore:
+                                */
+                               struct squirrel *sq = *sqp;
+                               int i = 0;
+                               if (sq) while (sq[i].orig_fd >= 0)
+                                       i++;
+                               *sqp = append_squirrel(sq, i, openfd, -1); /* -1 = "it was closed" */
+                               debug_printf_redir("redir to previously closed fd %d\n", openfd);
+                       }
                } else {
                        /* "rd_fd<*>rd_dup" or "rd_fd<*>-" cases */
                        openfd = redir->rd_dup;