coreutils

// chmod.c, version 1.0.2

// OMKOV coreutils implementation of POSIX chmod

// Copyright (C) 2020, Jakob Wakeling

// MIT Licence

/*

	TODO Don't recursively change symlink permissions

	TODO Handle copying permission

*/

#include "util/error.h"

#include "util/mode.h"

#include "util/optget.h"

#include <dirent.h>

#include <sys/stat.h>

#include <unistd.h>

#include <errno.h>

#include <stdbool.h>

#include <stdio.h>

#include <stdlib.h>

#include <string.h>

#define VERSION "1.0.2"

static struct lop lops[] = {

	{ "help",    ARG_NUL, 256 },

	{ "version", ARG_NUL, 257 },

	{ NULL, 0, 0 }

};

static bool Rflag;

static mode_t mask;

static inline int   setmode(const char *path, chmod_t *m);

static inline char *mkpath(const char *path, const char *file);

static void hlp(void);

static void ver(void);

int main(int ac, char *av[]) { A0 = av[0];

	struct opt opt = OPTGET_INIT; opt.str = "R"; opt.lops = lops;

	for (int o; (o = optget(&opt, av, 1)) != -1;) switch (o) {

	case 'R': { Rflag = true; break; }

	case 256: { hlp(); return 0; }

	case 257: { ver(); return 0; }

	default: { return 1; }

	}

	if (opt.ind >= ac - 1) { error(1, "missing operand"); }

	mask = umask(0); chmod_t *m = strmode(av[opt.ind]);

	if (!m) { error(1, "%s: invalid mode", av[opt.ind]); }

	for (char **p = &av[opt.ind + 1]; *p; ++p) {

		if (setmode(*p, m)) { warn("%s: %s", *p, serr()); warned = true; }

	}

	free(m); return warned;

}

/* Set the mode of the specified file */

static inline int setmode(const char *path, chmod_t *m) {

	struct stat st; register bool ln = false;

	// Get current permissions of file

	if (lstat(path, &st)) { return 1; };

	if (S_ISLNK(st.st_mode)) { if (stat(path, &st)) { return 1; } ln = true; }

	mode_t mode = st.st_mode;

	// Handle each chmod_t

	for (int i = 0;; ++i) switch (m[i].flag) {

	case MF_NORM: case MF_XIFX: {

		// If ref is null, use the file mode creation mask

		if (!m[i].ref) { m[i].ref = M_ALL & ~mask; }

		switch (m[i].op) {

		case '+': { mode |= m[i].ref & m[i].mod; break; }

		case '-': { mode &= (~(m[i].ref & m[i].mod) & 07777); break; }

		case '=': { mode &= ~m[i].ref; mode |= m[i].ref & m[i].mod; break; }

		}

		// If the XIFX flag is set, set execute permission accordingly

		if (m[i].flag == MF_XIFX) {

			if (S_ISDIR(mode) || mode & M_EX) { mode |= m[i].ref & M_EX; }

		} break;

	}

	case MF_COPY: { /* TODO */ }

	case MF_NULL: { goto end; }

	} end:;

	// Set permissions of the file to the calculated mode

	if (chmod(path, mode)) { return 1; }

	// Recurse into directories if R flag is set

	if (Rflag && !ln && S_ISDIR(st.st_mode)) {

		DIR *di; if (!(di = opendir(path))) { return 1; }

		// For each entry in directory, recursively call setmode

		for (struct dirent *de; (de = readdir(di));) {

			if (de->d_name[0] == '.' && (de->d_name[1] == 0 ||

				(de->d_name[1] == '.' && de->d_name[2] == 0))) { continue; }

			char *s = mkpath(path, de->d_name);

			if (setmode(s, m)) { warn("%s: %s", s, serr()); warned = true; }

			free(s);

		}

		closedir(di);

	}

	return 0;

}

/* Allocate and make path from two components */

static inline char *mkpath(const char *path, const char *file) {

	register size_t pl = strlen(path); char *s;

	s = (char *)malloc((pl + strlen(file) + 2) * sizeof (*s));

	strcpy(s, path); if (s[pl - 1] != '/') { s[pl] = '/'; s[++pl] = 0; }

	strcat(s, file); return s;

}

/* Print help information */

static void hlp(void) {

	puts("chmod - change the file modes\n");

	puts("usage: chmod [-R] mode file...\n");

	puts("options:");

	puts("  -R         Recursively change file mode bits");

	puts("  --help     Display help information");

	puts("  --version  Display version information");

}

/* Print version information */

static void ver(void) {

	puts("OMKOV coreutils chmod, version " VERSION);

	puts("Copyright (C) 2020, Jakob Wakeling");

	puts("MIT Licence (https://opensource.org/licenses/MIT)");

}