#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <signal.h>
#include <stdio.h>


char *defmanpath = "/usr/local/share/man:/usr/share/man:/usr/man";

void
adios(char *str)
{
	perror(str);
	exit(1);
}

/*
** Function does not return if the page is there.
*/
int
display(char *path, int sec, char *name)
{
	char buf[BUFSIZ];
	struct stat sb;
	char *catprog;
	int pd1[2], pd2[2], pd3[2];
	pid_t pid;

	snprintf(buf, sizeof buf, "%s/man%d/%s.%d", path, sec, name, sec);
	if (stat(buf, &sb) != -1) {
		catprog = "cat";
		goto displ;
	}
	snprintf(buf, sizeof buf, "%s/man%d/%s.%d.gz", path, sec, name, sec);
	if (stat(buf, &sb) != -1) {
		catprog = "zcat";
		goto displ;
	}
	return 0;

displ:
	/* Have zombies burried automatically */
	signal(SIGCHLD, SIG_IGN);

	if (pipe(pd1) == -1) {
		adios("pipe");
	}
	if ((pid = fork()) == -1) {
		adios("fork");
	} else if (!pid) {
		/* child */
		close(1); dup(pd1[1]); close(pd1[1]);
		close(pd1[0]);
		execlp(catprog, catprog, buf, NULL);
		adios("exec");
	}
	/* parent */
	close(pd1[1]);

	if (pipe(pd2) == -1) {
		adios("pipe");
	}
	if ((pid = fork()) == -1) {
		adios("fork");
	} else if (!pid) {
		/* child */
		close(0); dup(pd1[0]); close(pd1[0]);
		close(1); dup(pd2[1]); close(pd2[1]);
		close(pd2[0]);
		execlp("nroff", "nroff", "-Tlp", "-man", NULL);
		adios("exec");
	}
	/* parent */
	close(pd2[1]);

	if (pipe(pd3) == -1) {
		adios("pipe");
	}
	if ((pid = fork()) == -1) {
		adios("fork");
	} else if (!pid) {
		/* child */
		close(0); dup(pd2[0]); close(pd2[0]);
		close(1); dup(pd3[1]); close(pd3[1]);
		close(pd3[0]);
		execlp("col", "col", "-x", NULL);
		adios("exec");
	}
	/* parent */
	close(pd3[1]);

	/* parent */
	close(0); dup(pd3[0]); close(pd3[0]);
	execlp("less", "less", "-is", NULL);
	adios("exec");
	return 0;
}


int
main(int argc, char *argv[])
{
	int sec;
	char *name, *manpath, *str, *tok;

	if (argc != 3) {
		fprintf(stderr, "Usage: %s SECTION NAME\n", argv[0]);
		exit(1);
	}
	sec = atoi(argv[1]);
	name = argv[2];

	if (!(manpath = getenv("MANPATH"))) {
		manpath = defmanpath;
	}
	if (!(manpath = strdup(manpath))) {
		adios("strdup");
	}

	for (str=manpath; ; str=NULL) {
		if (!(tok = strtok(str, ":"))) {
			break;
		}
		display(tok, sec, name);  /* return only on failure */
	}

	fprintf(stderr, "No man page  for `%s' in section %d\n", name, sec);
	return 1;
}