X-Git-Url: http://git.ozlabs.org/?a=blobdiff_plain;f=ccan%2Fpipecmd%2Fpipecmd.c;fp=ccan%2Fpipecmd%2Fpipecmd.c;h=352677fac1c216240eb38252216f72584793221c;hb=66de67ea48009a086f940288eacf9928515f3aec;hp=0000000000000000000000000000000000000000;hpb=4a439212da1b6d88cc370e2a2ee3dbeb8e2081c5;p=ccan

diff --git a/ccan/pipecmd/pipecmd.c b/ccan/pipecmd/pipecmd.c
new file mode 100644
index 00000000..352677fa
--- /dev/null
+++ b/ccan/pipecmd/pipecmd.c
@@ -0,0 +1,130 @@
+/* CC0 license (public domain) - see LICENSE file for details */
+#include <ccan/pipecmd/pipecmd.h>
+#include <ccan/noerr/noerr.h>
+#include <stdlib.h>
+#include <errno.h>
+#include <unistd.h>
+#include <fcntl.h>
+
+static char **gather_args(const char *arg0, va_list ap)
+{
+	size_t n = 1;
+	char **arr = calloc(sizeof(char *), n + 1);
+
+	if (!arr)
+		return NULL;
+	arr[0] = (char *)arg0;
+
+	while ((arr[n++] = va_arg(ap, char *)) != NULL) {
+		arr = realloc(arr, sizeof(char *) * (n + 1));
+		if (!arr)
+			return NULL;
+	}
+	return arr;
+}
+
+pid_t pipecmdv(int *fd_fromchild, int *fd_tochild, const char *cmd, va_list ap)
+{
+	int tochild[2], fromchild[2], execfail[2];
+	pid_t childpid;
+	int err;
+
+	if (fd_tochild) {
+		if (pipe(tochild) != 0)
+			goto fail;
+	} else {
+		tochild[0] = open("/dev/null", O_RDONLY);
+		if (tochild[0] < 0)
+			goto fail;
+	}
+	if (fd_fromchild) {
+		if (pipe(fromchild) != 0)
+			goto close_tochild_fail;
+	} else {
+		fromchild[1] = open("/dev/null", O_WRONLY);
+		if (fromchild[1] < 0)
+			goto close_tochild_fail;
+	}
+	if (pipe(execfail) != 0)
+		goto close_fromchild_fail;
+
+	if (fcntl(execfail[1], F_SETFD, fcntl(execfail[1], F_GETFD)
+		  | FD_CLOEXEC) < 0)
+		goto close_execfail_fail;
+
+	childpid = fork();
+	if (childpid < 0)
+		goto close_execfail_fail;
+
+	if (childpid == 0) {
+		char **args = gather_args(cmd, ap);
+
+		if (fd_tochild)
+			close(tochild[1]);
+		if (fd_fromchild)
+			close(fromchild[0]);
+		close(execfail[0]);
+
+		// Child runs command.
+		if (!args)
+			err = ENOMEM;
+		else {
+			if (tochild[0] != STDIN_FILENO) {
+				if (dup2(tochild[0], STDIN_FILENO) == -1)
+					goto child_errno_fail;
+				close(tochild[0]);
+			}
+			if (fromchild[1] != STDOUT_FILENO) {
+				if (dup2(fromchild[1], STDOUT_FILENO) == -1)
+					goto child_errno_fail;
+				close(fromchild[1]);
+			}
+			execvp(cmd, args);
+		child_errno_fail:
+			err = errno;
+		}
+		write(execfail[1], &err, sizeof(err));
+		exit(127);
+	}
+
+	close(tochild[0]);
+	close(fromchild[1]);
+	close(execfail[1]);
+	/* Child will close this without writing on successful exec. */
+	if (read(execfail[0], &err, sizeof(err)) == sizeof(err)) {
+		waitpid(childpid, NULL, 0);
+		errno = err;
+		return -1;
+	}
+	if (fd_tochild)
+		*fd_tochild = tochild[1];
+	if (fd_fromchild)
+		*fd_fromchild = fromchild[0];
+	return childpid;
+
+close_execfail_fail:
+	close_noerr(execfail[0]);
+	close_noerr(execfail[1]);
+close_fromchild_fail:
+	if (fd_fromchild)
+		close_noerr(fromchild[0]);
+	close_noerr(fromchild[1]);
+close_tochild_fail:
+	close_noerr(tochild[0]);
+	if (fd_tochild)
+		close_noerr(tochild[1]);
+fail:
+	return -1;
+}
+
+pid_t pipecmd(int *fd_fromchild, int *fd_tochild, const char *cmd, ...)
+{
+	pid_t childpid;
+
+	va_list ap;
+	va_start(ap, cmd);
+	childpid = pipecmdv(fd_fromchild, fd_tochild, cmd, ap);
+	va_end(ap);
+
+	return childpid;
+}