libbb: add a function to make a copy of a region of memory

Introduce a library routine to package the idiom:

    p = xmalloc(b, n);
    memcpy(p, b, n);

and use it where possible.  The example in traceroute used xzalloc
but it didn't need to.

function                                             old     new   delta
xmemdup                                                -      32     +32
last_main                                            834     826      -8
make_device                                         2321    2311     -10
common_traceroute_main                              3698    3685     -13
readtoken1                                          3182    3168     -14
procps_scan                                         1222    1206     -16
forkchild                                            655     638     -17
------------------------------------------------------------------------------
(add/remove: 1/0 grow/shrink: 0/6 up/down: 32/-78)            Total: -46 bytes

Signed-off-by: Ron Yorston <rmy@frippery.org>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

8 files changed, 13 insertions, 17 deletions

diff --git a/include/libbb.h b/include/libbb.h
index f0ac1f50d..54d01b75a 100644
--- a/include/libbb.h
+++ b/include/libbb.h
@@ -673,6 +673,7 @@ uint16_t inet_cksum(uint16_t *addr, int len) FAST_FUNC;
 
 char *xstrdup(const char *s) FAST_FUNC RETURNS_MALLOC;
 char *xstrndup(const char *s, int n) FAST_FUNC RETURNS_MALLOC;
+void *xmemdup(const void *s, int n) FAST_FUNC RETURNS_MALLOC;
 void overlapping_strcpy(char *dst, const char *src) FAST_FUNC;
 char *safe_strncpy(char *dst, const char *src, size_t size) FAST_FUNC;
 char *strncpy_IFNAMSIZ(char *dst, const char *src) FAST_FUNC;
diff --git a/libbb/procps.c b/libbb/procps.c
index 3d335b37b..71ad071e6 100644
--- a/libbb/procps.c
+++ b/libbb/procps.c
@@ -554,8 +554,7 @@ procps_status_t* FAST_FUNC procps_scan(procps_status_t* sp, int flags)
                                 break;
                         if (flags & PSSCAN_ARGVN) {
                                 sp->argv_len = n;
-                                sp->argv0 = xmalloc(n + 1);
-                                memcpy(sp->argv0, buf, n + 1);
+                                sp->argv0 = xmemdup(buf, n + 1);
                                 /* sp->argv0[n] = '\0'; - buf has it */
                         } else {
                                 sp->argv_len = 0;
diff --git a/libbb/xfuncs_printf.c b/libbb/xfuncs_printf.c
index e4ac6a002..73488908d 100644
--- a/libbb/xfuncs_printf.c
+++ b/libbb/xfuncs_printf.c
@@ -112,6 +112,11 @@ char* FAST_FUNC xstrndup(const char *s, int n)
         return memcpy(t, s, n);
 }
 
+void* FAST_FUNC xmemdup(const void *s, int n)
+{
+        return memcpy(xmalloc(n), s, n);
+}
+
 // Die if we can't open a file and return a FILE* to it.
 // Notice we haven't got xfread(), This is for use with fscanf() and friends.
 FILE* FAST_FUNC xfopen(const char *path, const char *mode)
diff --git a/miscutils/last_fancy.c b/miscutils/last_fancy.c
index 8194e31b5..e56e0ba85 100644
--- a/miscutils/last_fancy.c
+++ b/miscutils/last_fancy.c
@@ -233,7 +233,7 @@ int last_main(int argc UNUSED_PARAM, char **argv)
                                 break;
                         }
                         /* add_entry */
-                        llist_add_to(&zlist, memcpy(xmalloc(sizeof(ut)), &ut, sizeof(ut)));
+                        llist_add_to(&zlist, xmemdup(&ut, sizeof(ut)));
                         break;
                 case USER_PROCESS: {
                         int show;
@@ -275,7 +275,7 @@ int last_main(int argc UNUSED_PARAM, char **argv)
                                 show_entry(&ut, state, boot_time);
                         }
                         /* add_entry */
-                        llist_add_to(&zlist, memcpy(xmalloc(sizeof(ut)), &ut, sizeof(ut)));
+                        llist_add_to(&zlist, xmemdup(&ut, sizeof(ut)));
                         break;
                 }
                 }
diff --git a/networking/traceroute.c b/networking/traceroute.c
index 97a7a19e0..12ba614e8 100644
--- a/networking/traceroute.c
+++ b/networking/traceroute.c
@@ -387,15 +387,6 @@ struct globals {
 #define outudp  ((struct udphdr *)(outip + 1))
 
 
-/* libbb candidate? tftp uses this idiom too */
-static len_and_sockaddr* dup_sockaddr(const len_and_sockaddr *lsa)
-{
-        len_and_sockaddr *new_lsa = xzalloc(LSA_LEN_SIZE + lsa->len);
-        memcpy(new_lsa, lsa, LSA_LEN_SIZE + lsa->len);
-        return new_lsa;
-}
-
-
 static int
 wait_for_reply(len_and_sockaddr *from_lsa, struct sockaddr *to, unsigned *timestamp_us, int *left_ms)
 {
@@ -1074,7 +1065,7 @@ common_traceroute_main(int op, char **argv)
                 printf(" from %s", source);
         printf(", %d hops max, %d byte packets\n", max_ttl, packlen);
 
-        from_lsa = dup_sockaddr(dest_lsa);
+        from_lsa = xmemdup(dest_lsa, LSA_LEN_SIZE + dest_lsa->len);
         lastaddr = xzalloc(dest_lsa->len);
         to = xzalloc(dest_lsa->len);
         seq = 0;
diff --git a/networking/udhcp/d6_dhcpc.c b/networking/udhcp/d6_dhcpc.c
index 044f04673..4e9b705b9 100644
--- a/networking/udhcp/d6_dhcpc.c
+++ b/networking/udhcp/d6_dhcpc.c
@@ -118,7 +118,7 @@ static void *d6_copy_option(uint8_t *option, uint8_t *option_end, unsigned code)
         uint8_t *opt = d6_find_option(option, option_end, code);
         if (!opt)
                 return opt;
-        return memcpy(xmalloc(opt[3] + 4), opt, opt[3] + 4);
+        return xmemdup(opt, opt[3] + 4);
 }
 
 static void *d6_store_blob(void *dst, const void *src, unsigned len)
diff --git a/shell/ash.c b/shell/ash.c
index f4779ee2b..f6190c3e2 100644
--- a/shell/ash.c
+++ b/shell/ash.c
@@ -4751,7 +4751,7 @@ forkchild(struct job *jp, union node *n, int mode)
                  * Our solution: ONLY bare $(trap) or `trap` is special.
                  */
                 /* Save trap handler strings for trap builtin to print */
-                trap_ptr = memcpy(xmalloc(sizeof(trap)), trap, sizeof(trap));
+                trap_ptr = xmemdup(trap, sizeof(trap));
                 /* Fall through into clearing traps */
         }
         clear_traps();
diff --git a/util-linux/mdev.c b/util-linux/mdev.c
index ca4b91510..662e8ab38 100644
--- a/util-linux/mdev.c
+++ b/util-linux/mdev.c
@@ -471,7 +471,7 @@ static const struct rule *next_rule(void)
         if (G.parser) {
                 parse_next_rule();
                 if (G.rule_vec) { /* mdev -s */
-                        rule = memcpy(xmalloc(sizeof(G.cur_rule)), &G.cur_rule, sizeof(G.cur_rule));
+                        rule = xmemdup(&G.cur_rule, sizeof(G.cur_rule));
                         G.rule_vec = xrealloc_vector(G.rule_vec, 4, G.rule_idx);
                         G.rule_vec[G.rule_idx++] = rule;
                         dbg3("> G.rule_vec[G.rule_idx:%d]=%p", G.rule_idx, G.rule_vec[G.rule_idx]);