--- /dev/null
+../../licenses/CC0
\ No newline at end of file
--- /dev/null
+#include "config.h"
+#include <stdio.h>
+#include <string.h>
+
+/**
+ * pipecmd - code to fork and run a command in a pipe.
+ *
+ * This code is a classic example of how to run a command in a child, while
+ * handling the case where the exec fails.
+ *
+ * License: CC0 (Public domain)
+ * Author: Rusty Russell <rusty@rustcorp.com.au>
+ *
+ * Example:
+ * // Outputs HELLO WORLD
+ * #include <ccan/pipecmd/pipecmd.h>
+ * #include <ccan/err/err.h>
+ * #include <sys/types.h>
+ * #include <sys/wait.h>
+ * #include <unistd.h>
+ * #include <ctype.h>
+ *
+ * // Runs ourselves with an argument, upcases output.
+ * int main(int argc, char **argv)
+ * {
+ * pid_t child;
+ * int outputfd, i, status;
+ * char input[12];
+ *
+ * if (argc == 2) {
+ * write(STDOUT_FILENO, "hello world\n", 12);
+ * exit(0);
+ * }
+ * child = pipecmd(&outputfd, NULL, argv[0], "ignoredarg", NULL);
+ * if (child < 0)
+ * err(1, "Creating child");
+ * if (read(outputfd, input, sizeof(input)) != sizeof(input))
+ * err(1, "Reading input");
+ * if (waitpid(child, &status, 0) != child)
+ * err(1, "Waiting for child");
+ * for (i = 0; i < sizeof(input); i++)
+ * printf("%c", toupper(input[i]));
+ * exit(0);
+ * }
+ */
+int main(int argc, char *argv[])
+{
+ /* Expect exactly one argument */
+ if (argc != 2)
+ return 1;
+
+ if (strcmp(argv[1], "depends") == 0) {
+ printf("ccan/noerr\n");
+ return 0;
+ }
+
+ return 1;
+}
--- /dev/null
+/* 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;
+}
--- /dev/null
+/* CC0 license (public domain) - see LICENSE file for details */
+#ifndef CCAN_PIPECMD_H
+#define CCAN_PIPECMD_H
+#include "config.h"
+#include <sys/types.h>
+#include <sys/wait.h>
+#include <stdarg.h>
+
+/**
+ * pipecmd - run a command, optionally connect pipes.
+ * @infd: input fd to write to child (if non-NULL)
+ * @outfd: output fd to read from child (if non-NULL)
+ * @cmd...: NULL-terminate list of command and arguments.
+ *
+ * If @infd is NULL, the child's input is (read-only) /dev/null.
+ * If @outfd is NULL, the child's output is (write-only) /dev/null.
+ *
+ * The return value is the pid of the child, or -1.
+ */
+pid_t pipecmd(int *infd, int *outfd, const char *cmd, ...);
+
+/**
+ * pipecmdv - run a command, optionally connect pipes (stdarg version)
+ * @infd: input fd to write to child (if non-NULL)
+ * @outfd: output fd to read from child (if non-NULL)
+ * @cmd: command to run.
+ * @ap: argument list for arguments.
+ */
+pid_t pipecmdv(int *infd, int *outfd, const char *cmd, va_list ap);
+#endif /* CCAN_PIPECMD_H */
--- /dev/null
+#include <ccan/pipecmd/pipecmd.h>
+/* Include the C files directly. */
+#include <ccan/pipecmd/pipecmd.c>
+#include <ccan/tap/tap.h>
+#include <string.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+
+int main(int argc, char *argv[])
+{
+ pid_t child;
+ int infd, outfd, status;
+ char buf[5] = "test";
+
+ /* We call ourselves, to test pipe. */
+ if (argc == 2) {
+ if (strcmp(argv[1], "out") == 0) {
+ if (write(STDOUT_FILENO, buf, sizeof(buf)) != sizeof(buf))
+ exit(1);
+ } else if (strcmp(argv[1], "in") == 0) {
+ if (read(STDIN_FILENO, buf, sizeof(buf)) != sizeof(buf))
+ exit(1);
+ if (memcmp(buf, "test", sizeof(buf)) != 0)
+ exit(1);
+ } else if (strcmp(argv[1], "inout") == 0) {
+ if (read(STDIN_FILENO, buf, sizeof(buf)) != sizeof(buf))
+ exit(1);
+ buf[0]++;
+ if (write(STDOUT_FILENO, buf, sizeof(buf)) != sizeof(buf))
+ exit(1);
+ } else
+ abort();
+ exit(0);
+ }
+
+ /* This is how many tests you plan to run */
+ plan_tests(26);
+ child = pipecmd(&outfd, &infd, argv[0], "inout", NULL);
+ if (!ok1(child > 0))
+ exit(1);
+ ok1(write(infd, buf, sizeof(buf)) == sizeof(buf));
+ ok1(read(outfd, buf, sizeof(buf)) == sizeof(buf));
+ buf[0]--;
+ ok1(memcmp(buf, "test", sizeof(buf)) == 0);
+ ok1(waitpid(child, &status, 0) == child);
+ ok1(WIFEXITED(status));
+ ok1(WEXITSTATUS(status) == 0);
+
+ child = pipecmd(NULL, &infd, argv[0], "in", NULL);
+ if (!ok1(child > 0))
+ exit(1);
+ ok1(write(infd, buf, sizeof(buf)) == sizeof(buf));
+ ok1(waitpid(child, &status, 0) == child);
+ ok1(WIFEXITED(status));
+ ok1(WEXITSTATUS(status) == 0);
+
+ child = pipecmd(&outfd, NULL, argv[0], "out", NULL);
+ if (!ok1(child > 0))
+ exit(1);
+ ok1(read(outfd, buf, sizeof(buf)) == sizeof(buf));
+ ok1(memcmp(buf, "test", sizeof(buf)) == 0);
+ ok1(waitpid(child, &status, 0) == child);
+ ok1(WIFEXITED(status));
+ ok1(WEXITSTATUS(status) == 0);
+
+ // Writing to /dev/null should be fine.
+ child = pipecmd(NULL, NULL, argv[0], "out", NULL);
+ if (!ok1(child > 0))
+ exit(1);
+ ok1(waitpid(child, &status, 0) == child);
+ ok1(WIFEXITED(status));
+ ok1(WEXITSTATUS(status) == 0);
+
+ // Reading should fail.
+ child = pipecmd(NULL, NULL, argv[0], "in", NULL);
+ if (!ok1(child > 0))
+ exit(1);
+ ok1(waitpid(child, &status, 0) == child);
+ ok1(WIFEXITED(status));
+ ok1(WEXITSTATUS(status) == 1);
+
+ /* This exits depending on whether all tests passed */
+ return exit_status();
+}
projects / ccan / commitdiff