1 files changed, 59 insertions, 0 deletions

diff --git a/subproc.c b/subproc.c
new file mode 100644
index 0000000..ae4991f
--- /dev/null
+++ b/subproc.c
@@ -0,0 +1,59 @@
+#include <stddef.h>
+#include <stdarg.h>
+#include <string.h>
+#include <err.h>
+
+#include <sys/types.h>
+#include <sys/wait.h>
+#include <unistd.h>
+
+#include "subproc.h"
+
+void system_argv_array(char **args)
+{
+    pid_t pid = fork();
+    if (pid < 0)
+        err(1, "fork");
+
+    if (pid == 0) {
+        execvp(args[0], args);
+        warn("execvp");
+        _exit(127);
+    }
+
+    int status;
+    if (waitpid(pid, &status, 0) != pid)
+        err(1, "waitpid");
+    if (!(WIFEXITED(status) && WEXITSTATUS(status) == 0))
+        errx(1, "subcommand failed");
+}
+
+void system_argv(const char *cmd, ...)
+{
+    int nargs, nchars;
+    const char *word;
+    va_list ap;
+
+    va_start(ap, cmd);
+    nargs = 1;                         /* terminating NULL */
+    nchars = 0;
+    for (word = cmd; word; word = va_arg(ap, const char *)) {
+        nargs++;
+        nchars += 1 + strlen(word);
+    }
+    va_end(ap);
+
+    char *args[nargs], chars[nchars];
+    char **argp = args, *charp = chars;
+    va_start(ap, cmd);
+    for (word = cmd; word; word = va_arg(ap, const char *)) {
+        *argp++ = charp;
+        strcpy(charp, word);
+        charp += 1 + strlen(word);
+    }
+    va_end(ap);
+    *argp++ = NULL;
+
+    system_argv_array(args);
+}
+