libbb: introduce and use xasprintf_inplace()

function                                             old     new   delta
xasprintf_and_free                                     -      49     +49
watch_main                                           269     282     +13
singlemount                                         1313    1315      +2
append_mount_options                                 157     149      -8
ip_port_str                                          122     112     -10
lsblk_main                                           869     858     -11
add_cmd                                             1178    1167     -11
------------------------------------------------------------------------------
(add/remove: 1/0 grow/shrink: 2/4 up/down: 64/-40)             Total: 24 bytes

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

1 files changed, 16 insertions, 0 deletions

diff --git a/libbb/xfuncs_printf.c b/libbb/xfuncs_printf.c
index 5d26e2bfa..ed10084b3 100644
--- a/libbb/xfuncs_printf.c
+++ b/libbb/xfuncs_printf.c
@@ -349,6 +349,22 @@ char* FAST_FUNC xasprintf(const char *format, ...)
         return string_ptr;
 }
 
+char* FAST_FUNC xasprintf_and_free(char *allocated, const char *format, ...)
+{
+        va_list p;
+        int r;
+        char *string_ptr;
+
+        va_start(p, format);
+        r = vasprintf(&string_ptr, format, p);
+        va_end(p);
+
+        if (r < 0)
+                bb_die_memory_exhausted();
+        free(allocated);
+        return string_ptr;
+}
+
 void FAST_FUNC xsetenv(const char *key, const char *value)
 {
         if (setenv(key, value, 1))