win32: code shrink copying of argv

There are two places where a copy of an argv array is made with
extra space at the start.  Move this code into a function.

Saves 56-64 bytes.

3 files changed, 19 insertions, 10 deletions

diff --git a/include/mingw.h b/include/mingw.h
index c2c37ba48..6204ded6d 100644
--- a/include/mingw.h
+++ b/include/mingw.h
@@ -526,6 +526,7 @@ int utimes(const char *file_name, const struct timeval times[2]);
 #define is_unc_path(x) (strlen(x) > 4 && is_dir_sep(x[0]) && \
                                                         is_dir_sep(x[1]) && !is_dir_sep(x[2]))
 
+char ** FAST_FUNC grow_argv(char **argv, int n);
 pid_t FAST_FUNC mingw_spawn(char **argv);
 pid_t FAST_FUNC mingw_spawn_detach(char **argv);
 intptr_t FAST_FUNC mingw_spawn_proc(const char **argv);
diff --git a/networking/httpd.c b/networking/httpd.c
index 302d1611d..2b2d14076 100644
--- a/networking/httpd.c
+++ b/networking/httpd.c
@@ -2804,7 +2804,7 @@ static void mini_httpd_win32(int fg, int sock, int argc, char **argv)
 
         argv_copy[0] = (char *)bb_busybox_exec_path;
         argv_copy[1] = (char *)"--busybox";
-        argv_copy[2] = (char *)"httpd";
+        argv_copy[2] = (char *)"-httpd" + 1;    // skip '-'
         argv_copy[3] = (char *)"-I";
         memcpy(&argv_copy[5], &argv[1], argc * sizeof(argv[0]));
 
@@ -2850,14 +2850,12 @@ static void mini_httpd_inetd(void)
 static void mingw_daemonize(char **argv)
 {
         char **new_argv;
-        int argc, fd;
+        int fd;
 
-        argc = string_array_len((char **)argv);
-        new_argv = xmalloc(sizeof(*argv)*(argc+3));
+        new_argv = grow_argv(argv + 1, 3);
         new_argv[0] = (char *)bb_busybox_exec_path;
         new_argv[1] = (char *)"--busybox";
-        new_argv[2] = (char *)"-httpd";
-        memcpy(&new_argv[3], &argv[1], sizeof(*argv)*argc);
+        new_argv[2] = (char *)"-httpd"; // '-' marks the daemonised process
 
         fd = xopen(bb_dev_null, O_RDWR);
         xdup2(fd, 0);
diff --git a/win32/process.c b/win32/process.c
index 5c818a3c0..e93efa103 100644
--- a/win32/process.c
+++ b/win32/process.c
@@ -259,6 +259,19 @@ mingw_spawn_applet(int mode,
 }
 #endif
 
+/* Make a copy of an argv array with n extra slots at the start */
+char ** FAST_FUNC
+grow_argv(char **argv, int n)
+{
+        char **new_argv;
+        int argc;
+
+        argc = string_array_len(argv) + 1;
+        new_argv = xmalloc(sizeof(*argv) * (argc + n));
+        memcpy(new_argv + n, argv, sizeof(*argv) * argc);
+        return new_argv;
+}
+
 static intptr_t
 mingw_spawn_interpreter(int mode, const char *prog, char *const *argv,
                         char *const *envp, int level)
@@ -267,7 +280,6 @@ mingw_spawn_interpreter(int mode, const char *prog, char *const *argv,
         int nopts;
         interp_t interp;
         char **new_argv;
-        int argc;
         char *path = NULL;
 
         if (!parse_interpreter(prog, &interp))
@@ -279,11 +291,9 @@ mingw_spawn_interpreter(int mode, const char *prog, char *const *argv,
         }
 
         nopts = interp.opts != NULL;
-        argc = string_array_len((char **)argv);
-        new_argv = xmalloc(sizeof(*argv)*(argc+nopts+2));
+        new_argv = grow_argv((char **)(argv + 1), nopts + 2);
         new_argv[1] = interp.opts;
         new_argv[nopts+1] = (char *)prog; /* pass absolute path */
-        memcpy(new_argv+nopts+2, argv+1, sizeof(*argv)*argc);
 
 #if ENABLE_FEATURE_PREFER_APPLETS && NUM_APPLETS > 1
         if (unix_path(interp.path) && find_applet_by_name(interp.name) >= 0) {