Blame src/helper/slbt_dump_machine.c

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/*******************************************************************/
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/*  slibtool: a skinny libtool implementation, written in C        */
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/*  Copyright (C) 2016--2018  Z. Gilboa                            */
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/*  Released under the Standard MIT License; see COPYING.SLIBTOOL. */
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/*******************************************************************/
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#include <stdio.h>
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#include <limits.h>
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#include <unistd.h>
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#include <fcntl.h>
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#include <string.h>
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#include <stdlib.h>
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#include <stdbool.h>
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#include <sys/wait.h>
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#include <slibtool/slibtool.h>
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#include "slibtool_spawn_impl.h"
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static void slbt_dump_machine_child(
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	char *	program,
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	int	fd[2])
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{
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	char *	compiler;
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	char *	argv[3];
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	close(fd[0]);
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	if ((compiler = strrchr(program,'/')))
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		compiler++;
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	else
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		compiler = program;
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	argv[0] = compiler;
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	argv[1] = "-dumpmachine";
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	argv[2] = 0;
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	if ((fd[0] = openat(AT_FDCWD,"/dev/null",O_RDONLY,0)) >= 0)
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		if (dup2(fd[0],0) == 0)
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			if (dup2(fd[1],1) == 1)
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				execvp(program,argv);
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	_exit(EXIT_FAILURE);
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}
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int slbt_dump_machine(
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	const char *	compiler,
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	char *		machine,
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	size_t		buflen)
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{
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	ssize_t	ret;
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	pid_t	pid;
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	pid_t	rpid;
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	int	code;
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	int	fd[2];
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	char *	mark;
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	char	program[PATH_MAX];
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	/* setup */
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	if (!machine || !buflen || !--buflen) {
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		errno = EINVAL;
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		return -1;
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	}
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	if ((size_t)snprintf(program,sizeof(program),"%s",
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			compiler) >= sizeof(program))
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		return -1;
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	/* fork */
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	if (pipe(fd))
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		return -1;
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	if ((pid = fork()) < 0) {
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		close(fd[0]);
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		close(fd[1]);
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		return -1;
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	}
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	/* child */
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	if (pid == 0)
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		slbt_dump_machine_child(
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			program,
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			fd);
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	/* parent */
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	close(fd[1]);
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	mark = machine;
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	for (; buflen; ) {
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		ret = read(fd[0],mark,buflen);
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		while ((ret < 0) && (errno == EINTR))
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			ret = read(fd[0],mark,buflen);
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		if (ret > 0) {
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			buflen -= ret;
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			mark   += ret;
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		} else if (ret == 0) {
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			close(fd[0]);
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			buflen = 0;
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		} else {
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			close(fd[0]);
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			return -1;
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		}
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	}
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	/* execve verification */
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	rpid = waitpid(
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		pid,
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		&code,
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		0);
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	if ((rpid != pid) || code) {
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		errno = ESTALE;
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		return -1;
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	}
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	/* newline verification */
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	if ((mark == machine) || (*--mark != '\n')) {
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		errno = ERANGE;
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		return -1;
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	}
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	*mark = 0;
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	/* portbld <--> unknown synonym? */
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	if ((mark = strstr(machine,"-portbld-")))
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		memcpy(mark,"-unknown",8);
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	/* all done */
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	return 0;
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}