psh: Implement chmod command

The `chmod` command allows to change file access mode bits in a
P1003.2 4.7.7 conformant way. Each mode is either in octal form
like e.g. 0775 or symbolic form e.g. a-rwx,a+Xr,ug+w.

JIRA: RTOS-292

psh/Makefile

@@ -1,7 +1,7 @@
 #
 # Makefile for Phoenix-RTOS psh (Phoenix SHell)
 #
-# Copyright 2018-2023 Phoenix Systems
+# Copyright 2018-2024 Phoenix Systems
 #
 
 NAME := psh
@@ -19,9 +19,9 @@ LOCAL_CFLAGS += -DPSH_SYSEXECWL='"$(PSH_SYSEXECWL)"'
 LOCAL_LDFLAGS := -z stack-size=4096 -z noexecstack
 
 # TODO: search for dirs?
-PSH_ALLCOMMANDS := bind cat cd cp date dd df dmesg echo edit exec hm ifconfig kill \
-ln ls mem mkdir mount nc nslookup ntpclient perf ping pm printenv ps pwd reboot rm \
-rmdir route runfile sync sysexec top touch tty umount uptime wget
+PSH_ALLCOMMANDS := bind cat cd chmod cp date dd df dmesg echo edit exec hm \
+ifconfig kill ln ls mem mkdir mount nc nslookup ntpclient perf ping pm printenv \
+ps pwd reboot rm rmdir runfile route sync sysexec top touch tty umount uptime wget
 PSH_COMMANDS ?= $(PSH_ALLCOMMANDS)
 PSH_INTERNAL_APPLETS := pshapp help $(filter $(PSH_ALLCOMMANDS), $(PSH_COMMANDS))
 

psh/chmod/chmod.c

@@ -0,0 +1,329 @@
+/*
+ * Phoenix-RTOS
+ *
+ * chmod - change file mode
+ *
+ * Copyright 2022-2024 Phoenix Systems
+ * Author: Gerard Swiderski
+ *
+ * This file is part of Phoenix-RTOS.
+ *
+ * %LICENSE%
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <ctype.h>
+#include <dirent.h>
+#include <unistd.h>
+#include <sys/stat.h>
+
+#include "../psh.h"
+
+#define USR_MODES (S_ISUID | S_IRWXU)
+#define GRP_MODES (S_ISGID | S_IRWXG)
+#define EXE_MODES (S_IXUSR | S_IXGRP | S_IXOTH)
+
+#ifdef S_ISVTX
+#define ALL_MODES (USR_MODES | GRP_MODES | S_IRWXO | S_ISVTX)
+#else
+#define ALL_MODES (USR_MODES | GRP_MODES | S_IRWXO)
+#endif
+
+
+#define PATH_MAX 512  // FIXME: shouldn't be here
+
+static struct {
+	char *symbolic;
+	char path[PATH_MAX + 1];
+	struct stat st;
+	int rflag, errors;
+	mode_t octal, u_mask;
+} common;
+
+
+static void psh_chmod_info(void)
+{
+	printf("changes file mode, chmod [-R] <mode> <file>...");
+}
+
+
+static int psh_chmod_help(void)
+{
+	fprintf(stderr, "Usage: chmod [-R] <mode> <file>...\n");
+	return EXIT_FAILURE;
+}
+
+
+static int parsemode(char *symbolic, mode_t *pNewmode, mode_t oldmode)
+{
+	mode_t who, mask, newmode, tmpmask;
+	char action;
+
+	newmode = (oldmode & ALL_MODES);
+	*pNewmode = newmode;
+
+	while (*symbolic != '\0') {
+		who = 0;
+		for (; *symbolic != '\0'; symbolic++) {
+			if (*symbolic == 'a') {
+				who |= ALL_MODES;
+				continue;
+			}
+			else if (*symbolic == 'u') {
+				who |= USR_MODES;
+				continue;
+			}
+			else if (*symbolic == 'g') {
+				who |= GRP_MODES;
+				continue;
+			}
+			else if (*symbolic == 'o') {
+				who |= S_IRWXO;
+				continue;
+			}
+
+			break;
+		}
+
+		if ((*symbolic == '\0') || (*symbolic == ',')) {
+			return psh_chmod_help();
+		}
+
+		while (*symbolic != '\0') {
+			if (*symbolic == ',') {
+				break;
+			}
+
+			switch (*symbolic) {
+				default: return psh_chmod_help();
+				case '+': /* fall-through */
+				case '-': /* fall-through */
+				case '=': action = *symbolic++; break;
+			}
+
+			mask = 0;
+
+			for (; *symbolic != '\0'; symbolic++) {
+				if (*symbolic == 'u') {
+					tmpmask = newmode & S_IRWXU;
+					mask |= tmpmask | (tmpmask << 3) | (tmpmask << 6);
+					symbolic++;
+					break;
+				}
+				else if (*symbolic == 'g') {
+					tmpmask = newmode & S_IRWXG;
+					mask |= tmpmask | (tmpmask >> 3) | (tmpmask << 3);
+					symbolic++;
+					break;
+				}
+				else if (*symbolic == 'o') {
+					tmpmask = newmode & S_IRWXO;
+					mask |= tmpmask | (tmpmask >> 3) | (tmpmask >> 6);
+					symbolic++;
+					break;
+				}
+				else if (*symbolic == 'r') {
+					mask |= S_IRUSR | S_IRGRP | S_IROTH;
+					continue;
+				}
+				else if (*symbolic == 'w') {
+					mask |= S_IWUSR | S_IWGRP | S_IWOTH;
+					continue;
+				}
+				else if (*symbolic == 'x') {
+					mask |= EXE_MODES;
+					continue;
+				}
+				else if (*symbolic == 's') {
+					mask |= S_ISUID | S_ISGID;
+					continue;
+				}
+				else if (*symbolic == 'X') {
+					if (S_ISDIR(oldmode) || (oldmode & EXE_MODES)) {
+						mask |= EXE_MODES;
+					}
+					continue;
+				}
+
+#ifdef S_ISVTX
+				else if (*symbolic == 't') {
+					mask |= S_ISVTX;
+					who |= S_ISVTX;
+					continue;
+				}
+#endif
+
+				break;
+			}
+
+			switch (action) {
+				case '=':
+					if (who) {
+						newmode &= ~who;
+					}
+					else {
+						newmode = 0;
+					}
+					/* fall-through */
+
+				case '+':
+					if (who) {
+						newmode |= who & mask;
+					}
+					else {
+						newmode |= mask & (~common.u_mask);
+					}
+					break;
+
+				case '-':
+					if (who) {
+						newmode &= ~(who & mask);
+					}
+					else {
+						newmode &= ~mask | common.u_mask;
+					}
+					break;
+			}
+		}
+
+		if (*symbolic != '\0') {
+			symbolic++;
+		}
+	}
+
+	*pNewmode = newmode;
+
+	return EXIT_SUCCESS;
+}
+
+
+static int do_chmod(char *name)
+{
+	mode_t mode;
+	DIR *dirp;
+	struct dirent *entp;
+	char *namp;
+
+	if (lstat(name, &common.st)) {
+		perror(name);
+		return EXIT_FAILURE;
+	}
+
+	if (S_ISLNK(common.st.st_mode) && (common.rflag != 0)) {
+		return EXIT_SUCCESS;
+	}
+
+	if (common.symbolic != NULL) {
+		if (parsemode(common.symbolic, &mode, common.st.st_mode) == EXIT_FAILURE) {
+			return -1;
+		}
+	}
+	else {
+		mode = common.octal;
+	}
+
+	if (chmod(name, mode)) {
+		perror(name);
+		common.errors = 1;
+	}
+	else {
+		common.errors = 0;
+	}
+
+	if (S_ISDIR(common.st.st_mode) && (common.rflag != 0)) {
+		dirp = opendir(name);
+		if (dirp == NULL) {
+			perror(name);
+			return EXIT_FAILURE;
+		}
+
+		if (name != common.path) {
+			strncpy(common.path, name, PATH_MAX);
+		}
+
+		/* FIXME: use realloc for common.path, check if we fit into common.path, etc. */
+		namp = common.path + strlen(common.path);
+		*namp++ = '/';
+
+		entp = readdir(dirp);
+		while (entp != NULL) {
+			if (entp->d_name[0] != '.' || (entp->d_name[1] && (entp->d_name[1] != '.' || entp->d_name[2]))) {
+				strcpy(namp, entp->d_name); /* FIXME: strcpy */
+				common.errors |= do_chmod(common.path);
+			}
+
+			entp = readdir(dirp);
+		}
+		closedir(dirp);
+		*(--namp) = '\0';
+	}
+
+	return (common.errors != 0) ? EXIT_FAILURE : EXIT_SUCCESS;
+}
+
+
+static int psh_chmod(int argc, char **argv)
+{
+	int ret, exitCode = EXIT_SUCCESS;
+
+	argc--;
+	argv++;
+
+	memset(&common, 0, sizeof(common));
+
+	if ((argc != 0) && (strcmp(*argv, "-R") == 0)) {
+		argc--;
+		argv++;
+		common.rflag = 1;
+	}
+	else {
+		common.rflag = 0;
+	}
+
+	if (argc-- <= 0) {
+		return psh_chmod_help();
+	}
+
+	common.symbolic = *argv++;
+	if (argc == 0) {
+		return psh_chmod_help();
+	}
+
+	if (isdigit(*common.symbolic)) {
+		common.octal = 0;
+		for (; isdigit(*common.symbolic); common.symbolic++) {
+			common.octal = (common.octal << 3) | (*common.symbolic & 07);
+		}
+
+		if (*common.symbolic) {
+			return psh_chmod_help();
+		}
+
+		common.octal &= ALL_MODES;
+		common.symbolic = NULL;
+	}
+	else {
+		common.u_mask = umask(0);
+	}
+
+	while (argc-- > 0) {
+		ret = do_chmod(*argv++);
+		if (ret < 0) {
+			return EXIT_FAILURE;
+		}
+		else if (ret == EXIT_FAILURE) {
+			exitCode = EXIT_FAILURE;
+		}
+	}
+
+	return exitCode;
+}
+
+
+void __attribute__((constructor)) chmod_registerapp(void)
+{
+	static psh_appentry_t app = { .name = "chmod", .run = psh_chmod, .info = psh_chmod_info };
+	psh_registerapp(&app);
+}