coreutils

chmod: Add chmod utility

Diffstat

3 files changed, 140 insertions, 0 deletions

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 1a008c6..c8c3b54 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -16,6 +16,7 @@ LINK_LIBRARIES(lib)
 
 ADD_EXECUTABLE(basename ${PROJECT_SOURCE_DIR}/src/basename.c)
 ADD_EXECUTABLE(cat      ${PROJECT_SOURCE_DIR}/src/cat.c)
+ADD_EXECUTABLE(chmod    ${PROJECT_SOURCE_DIR}/src/chmod.c)
 ADD_EXECUTABLE(cksum    ${PROJECT_SOURCE_DIR}/src/cksum.c)
 ADD_EXECUTABLE(dirname  ${PROJECT_SOURCE_DIR}/src/dirname.c)
 ADD_EXECUTABLE(echo     ${PROJECT_SOURCE_DIR}/src/echo.c)
diff --git a/README.md b/README.md
index cfc5002..2f5457e 100644
--- a/README.md
+++ b/README.md
@@ -11,6 +11,7 @@ UNIX-like systems.
 | ---------------- | ---------------------------------------- | -------- |
 | basename         | Return non-directory portion of a path   | POSIX    |
 | cat              | Concatenate and print files              | POSIX    |
+| chmod            | Change the file modes                    | POSIX    |
 | cksum            | Write file checksums and sizes           | POSIX    |
 | dirname          | Return the directory portion of a path   | POSIX    |
 | echo             | Write arguments to standard output       | POSIX    |
diff --git a/src/chmod.c b/src/chmod.c
new file mode 100644
index 0000000..c6dc1e0
--- /dev/null
+++ b/src/chmod.c
@@ -0,0 +1,138 @@
+// chmod.c, version 1.0.0
+// OMKOV coreutils implementation of POSIX chmod
+// Copyright (C) 2020, Jakob Wakeling
+// All rights reserved.
+
+/*
+OMKOV Permissive Licence, version 1.0
+
+Permission is hereby granted, free of charge, to any person obtaining a copy of
+this software and associated documentation files (the "Software"), to deal with
+the Software without restriction, including without limitation the rights to
+use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
+the Software, and to permit persons to whom the Software is furnished to do so,
+subject to the following conditions:
+
+* Redistributions of source code must retain the above copyright notice, this
+  list of conditions and the following disclaimers.
+* Redistributions in binary form must reproduce the above copyright notice, this
+  list of conditions and the following disclaimers in the documentation and/or
+  other materials provided with the distribution.
+* Neither the names of the copyright holders, nor the names of its contributors
+  may be used to endorse or promote products derived from this Software without
+  specific prior written permission.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE COPYRIGHT
+HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS WITH THE SOFTWARE.
+*/
+
+/*
+	TODO Handle R flag
+	TODO Handle copying permission
+*/
+
+#include "lib/error.h"
+#include "lib/mode.h"
+#include "lib/optget.h"
+
+#include <sys/stat.h>
+
+#include <errno.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+#define VERSION "1.0.0"
+
+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 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]); }
+	
+	bool warned = false;
+	
+	for (char **p = &av[opt.ind + 1]; *p; ++p) {
+		if (setmode(*p, m)) { warn("%s: %s", *p, serr()); warned = true; }
+	}
+	
+	if (m) { free(m); } return warned;
+}
+
+/* Set the mode of the specified file */
+static inline int setmode(const char *path, chmod_t *m) {
+	// Get current permissions of file
+	struct stat st; if (stat(path, &st)) { return 1; };
+	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; } return 0;
+}
+
+/* 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");
+	return;
+}
+
+/* Print version information */
+static void ver(void) {
+	puts("OMKOV coreutils chmod, version " VERSION);
+	puts("Copyright (C) 2020, Jakob Wakeling");
+	puts("All rights reserved.");
+	puts("OMKOV Permissive Licence (https://www.omkov.net/OLPE)");
+	return;
+}