sim/posix: Add the host_system interface used to execute the host command

Encapsulate the host system/popen interface to host_system.

Signed-off-by: liqinhui <liqinhui@xiaomi.com>

arch/sim/src/nuttx-names.in

@@ -143,6 +143,7 @@ NXSYMBOLS(strlen)
 NXSYMBOLS(strtol)
 NXSYMBOLS(sysconf)
 NXSYMBOLS(syslog)
+NXSYMBOLS(system)
 NXSYMBOLS(tcgetattr)
 NXSYMBOLS(tcsetattr)
 NXSYMBOLS(unlink)

arch/sim/src/sim/posix/sim_hostmisc.c

@@ -29,6 +29,7 @@
 #include <stdlib.h>
 #include <string.h>
 #include <unistd.h>
+#include <stdarg.h>
 #include <sys/wait.h>
 #include <sys/types.h>
 
@@ -108,6 +109,61 @@ int host_backtrace(void** array, int size)
 #endif
 }
 
+/****************************************************************************
+ * Name: host_system
+ *
+ * Description:
+ *   Execute the command and get the result.
+ *
+ * Input Parameters:
+ *   buf - return massage, which return info will be stored
+ *   len - buf length
+ *   fmt - the format of parameters
+ *   ... - variable parameters.
+ *
+ * Returned Value:
+ *   A nonnegative integer is returned on success.  Otherwise,
+ *   a negated errno value is returned to indicate the nature of the failure.
+ ****************************************************************************/
+
+int host_system(char *buf, size_t len, const char *fmt, ...)
+{
+  FILE *fp;
+  int ret;
+  uint64_t flags;
+  char cmd[512];
+  va_list vars;
+
+  va_start(vars, fmt);
+  ret = vsnprintf(cmd, sizeof(cmd), fmt, vars);
+  va_end(vars);
+  if (ret <= 0 || ret > sizeof(cmd))
+    {
+      return ret < 0 ? -errno : -EINVAL;
+    }
+
+  if (buf == NULL)
+    {
+      ret = system(cmd);
+    }
+  else
+    {
+      flags = up_irq_save();
+      fp = popen(cmd, "r");
+      if (fp == NULL)
+        {
+          up_irq_restore(flags);
+          return -errno;
+        }
+
+      ret = fread(buf, sizeof(char), len, fp);
+      pclose(fp);
+      up_irq_restore(flags);
+    }
+
+  return ret < 0 ? -errno : ret;
+}
+
 /****************************************************************************
  * Name: host_init_cwd
  ****************************************************************************/

arch/sim/src/sim/sim_internal.h

@@ -163,6 +163,7 @@ void *sim_doirq(int irq, void *regs);
 
 void host_abort(int status);
 int  host_backtrace(void** array, int size);
+int  host_system(char *buf, size_t len, const char *fmt, ...);
 
 #ifdef CONFIG_SIM_IMAGEPATH_AS_CWD
 void host_init_cwd(void);