utils-std

env.c (4332B)

// utils-std: Collection of commonly available Unix tools
// SPDX-FileCopyrightText: 2017 Haelwenn (lanodan) Monnier <contact+utils@hacktivis.me>
// SPDX-License-Identifier: MPL-2.0
#define _POSIX_C_SOURCE 200809L
#define _XOPEN_SOURCE 800 // wordexp
#include "../config.h" // HAS_*
#include "../libutils/getopt_nolong.h"
#include <assert.h>  // assert
#include <errno.h>   // errno
#include <stdbool.h> // bool, true, false
#include <stdio.h>   // puts, fprintf
#include <stdlib.h>  // putenv
#include <string.h>  // strchr, strerror
#include <unistd.h>  // getopt, opt*
#ifdef HAS_WORDEXP
#include <wordexp.h>
#endif
#ifdef HAS_GETOPT_LONG
#include <getopt.h>
#endif
const char *argv0 = "env";
extern char **environ;
char *envclear[1];
static int
do_export(void)
{
	int i = 0;
	for(; environ[i] != NULL; i++)
	{
		if(puts(environ[i]) < 0)
		{
			fprintf(stderr, "env: error: Failed writing environ: %s\n", strerror(errno));
			return 1;
		}
	}
	return 0;
}
static void
usage(void)
{
	fprintf(stderr,
	        "Usage: env [-i] [-C dir] [-u key] [key=value ...] [command [args]]\n"
	        "       env [-i] [-C dir] [-u key] [key=value ...] -S command_string\n");
}
int
main(int argc, char *argv[])
{
	const char *newdir = NULL;
	bool flag_i = false;
#ifdef HAS_WORDEXP
	bool flag_S = false;
	wordexp_t opt_S;
#define OPTARGS ":C:iu:S:"
#else
#define OPTARGS ":C:iu:"
#endif
#ifdef HAS_GETOPT_LONG
	// Strictly for GNUisms compatibility so no long-only options
	// clang-format off
	static struct option opts[] = {
		{"ignore-environment", no_argument, NULL, 'i'},
		{"unset", required_argument, NULL, 'u'},
		{"chdir", required_argument, NULL, 'C'},
#ifdef HAS_WORDEXP
		{"split-string", required_argument, NULL, 'S'},
#endif
		{0, 0, 0, 0},
	};
	// clang-format on
	// Need + as first character to get POSIX-style option parsing
	for(int c = -1; (c = getopt_long(argc, argv, "+" OPTARGS, opts, NULL)) != -1;)
#else
	for(int c = -1; (c = getopt_nolong(argc, argv, OPTARGS)) != -1;)
#endif
	{
		switch(c)
		{
		case 'C':
			newdir = optarg;
			break;
		case 'i':
			flag_i = true;
			break;
		case 'u':
			unsetenv(optarg);
			break;
#ifdef HAS_WORDEXP
		case 'S':
			flag_S = true;
			int ret = wordexp(optarg, &opt_S, WRDE_NOCMD);
			switch(ret)
			{
			case 0:
				break;
			case WRDE_BADCHAR:
				fputs("env: error: wordexpr returned WRDE_BADCHAR\n", stderr);
				return 1;
			case WRDE_BADVAL:
				fputs("env: error: Undefined shell variable (WRDE_BADVAL)\n", stderr);
				return 1;
			case WRDE_CMDSUB:
				fputs("env: error: Command substitution forbidden (WRDE_CMDSUB)\n", stderr);
				return 1;
			case WRDE_NOSPACE:
				fputs("env: error: Out of memory (WRDE_NOSPACE)\n", stderr);
				return 1;
			case WRDE_SYNTAX:
				fputs("env: error: Syntax Error (WRDE_SYNTAX)\n", stderr);
				return 1;
			default:
				fprintf(stderr, "env: error: Unknown error %d from wordexp\n", ret);
				return 1;
			}
			break;
#endif
		case ':':
			fprintf(stderr, "env: error: Missing operand for option: '-%c'\n", optopt);
			usage();
			return 1;
		case '?':
			GETOPT_UNKNOWN_OPT
			usage();
			return 1;
		default:
			assert(false);
		}
	}
	argc -= optind;
	argv += optind;
	if(flag_i)
	{
		environ = envclear;
		envclear[0] = NULL;
	}
	for(; argv[0]; argv++, argc--)
	{
		char *sep = strchr(argv[0], '=');
		if(sep == NULL)
		{
			break;
		}
		*sep = 0;
		sep++;
		if(setenv(argv[0], sep, 1))
		{
			fprintf(stderr,
			        "env: error: Failed setting environment variable '%s' to '%s': %s\n",
			        argv[0],
			        sep,
			        strerror(errno));
			return 1;
		}
	}
	if(newdir && chdir(newdir) != 0)
	{
		fprintf(stderr,
		        "env: error: Failed changing workding directory into '%s': %s\n",
		        newdir,
		        strerror(errno));
		return 1;
	}
#ifdef HAS_WORDEXP
	if(flag_S)
	{
		errno = 0;
		if(execvp(opt_S.we_wordv[0], opt_S.we_wordv) < 0)
		{
			fprintf(
			    stderr, "env: error: Failed executing '%s': %s\n", opt_S.we_wordv[0], strerror(errno));
			return (errno == ENOENT) ? 127 : 126;
		}
		assert(false);
	}
#endif
	if(argc < 1)
	{
		return do_export();
	}
	assert(argv[0]);
	errno = 0;
	if(execvp(argv[0], argv) < 0)
	{
		fprintf(stderr, "env: error: Failed executing '%s': %s\n", argv[0], strerror(errno));
		return (errno == ENOENT) ? 127 : 126;
	}
	assert(false);
}