textselect

pipeto.c (3171B)

---

 #include "arg.h"
 
 #include <errno.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 #include <sys/wait.h>
 #include <unistd.h>
 
 #define USAGE "Usage: %s [-h] [-d delimiter] <inputcmd> {delimiter} <outputcmd>\n"
 
 #define NORETURN  __attribute__((noreturn))
 #define MAX(a, b) ((a) > (b) ? (a) : (b))
 
 
 static char       *argv0     = NULL;
 static const char *delimiter = "+";
 
 static void die(const char *message) {
 	fprintf(stderr, "error: %s: %s\n", message, strerror(errno));
 	exit(EXIT_FAILURE);
 }
 
 static void help(void) {
 	fprintf(stderr,
 	        USAGE "Pipe output of command to another without a shell.\n"
 	              "\n"
 	              "Options:\n"
 	              "  -h              Display this help message and exit\n"
 	              "  -d delimeter    Split commands by demiliter (default: %s)\n"
 	              "\n"
 	              "Examples:\n"
 	              "  pipeto xbps-query -l + wc -l\n"
 	              "  pipeto find -name 'myfile' + xargs rm\n",
 	        argv0, delimiter);
 }
 
 static void usage(int exitcode) {
 	fprintf(stderr, USAGE, argv0);
 	exit(exitcode);
 }
 
 static void runcommand(char **inputcmd, char **outputcmd) {
 	int   pipefd[2];    // pipefd[0] is for reading, pipefd[1] is for writing
 	pid_t pid1, pid2;
 
 	if (pipe(pipefd) == -1) {
 		perror("pipe");
 		exit(EXIT_FAILURE);
 	}
 
 	// First child process to run inputcmd
 	if ((pid1 = fork()) < 0) {
 		perror("fork");
 		exit(EXIT_FAILURE);
 	}
 
 	if (pid1 == 0) {
 		// Child process 1: will exec inputcmd
 		close(pipefd[0]);                  // Close unused read end
 		dup2(pipefd[1], STDOUT_FILENO);    // Redirect stdout to pipe write end
 		close(pipefd[1]);                  // Close write end after dup
 
 		execvp(inputcmd[0], inputcmd);    // Replace child process with inputcmd
 		die("unable to execute input command");
 	}
 
 	// Second child process to run outputcmd
 	if ((pid2 = fork()) < 0) {
 		perror("fork");
 		exit(EXIT_FAILURE);
 	}
 
 	if (pid2 == 0) {
 		// Child process 2: will exec outputcmd
 		close(pipefd[1]);                 // Close unused write end
 		dup2(pipefd[0], STDIN_FILENO);    // Redirect stdin to pipe read end
 		close(pipefd[0]);                 // Close read end after dup
 
 		execvp(outputcmd[0], outputcmd);    // Replace child process with outputcmd
 		die("unable to execute output command");
 	}
 
 	// Parent process
 	close(pipefd[0]);    // Close both ends of the pipe in the parent
 	close(pipefd[1]);
 
 	// Wait for both children to finish
 	waitpid(pid1, NULL, 0);
 	waitpid(pid2, NULL, 0);
 }
 
 int main(int argc, char *argv[]) {
 	argv0 = argv[0];
 	ARGBEGIN
 	switch (OPT) {
 		case 'h':
 			help();
 			exit(0);
 		case 'd':
 			delimiter = EARGF(usage(1));
 			break;
 		default:
 			fprintf(stderr, "error: unknown option '-%c'\n", OPT);
 			usage(1);
 	}
 	ARGEND;
 
 	if (argc == 0) {
 		fprintf(stderr, "error: missing command\n");
 		usage(1);
 	}
 
 	char **outputcmd = NULL;
 
 	for (int i = 0; i < argc; i++) {
 		if (!strcmp(argv[i], delimiter)) {
 			if (outputcmd) {
 				fprintf(stderr, "error: delimiter occured more than once\n");
 				exit(EXIT_FAILURE);
 			}
 			argv[i]   = NULL;
 			outputcmd = &argv[i + 1];
 		}
 	}
 
 	runcommand(argv, outputcmd);
 
 	return 0;
 }