feat: Implement chwrite command

A narrowed down version of chmod. Recursion must be done in-script.

2 files changed, 63 insertions, 0 deletions

diff --git a/chwrite/Makefile b/chwrite/Makefile
new file mode 100644
index 0000000..c9e0b66
--- /dev/null
+++ b/chwrite/Makefile
@@ -0,0 +1,8 @@
+CFLAGS  = -std=c89 -Wall -O2
+CFLAGS += -D_XOPEN_SOURCE=500
+
+all: chwrite
+
+chwrite: chwrite.o
+
+.PHONY: all
diff --git a/chwrite/chwrite.c b/chwrite/chwrite.c
new file mode 100644
index 0000000..6be8ec8
--- /dev/null
+++ b/chwrite/chwrite.c
@@ -0,0 +1,55 @@
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <errno.h>
+#include <stdio.h>
+
+static void
+help_message(void) {
+    printf(
+        "chwrite [-h|--help]\n"
+        "chwrite +|+w|-|-w FILE...\n"
+        "\n"
+        "Change write permissions for file(s)\n"
+    );
+}
+
+int
+main(int argc, char *argv[]) {
+    int i = 0, f = 0, result = 0;
+    struct stat fs = { 0, };
+    char operation;
+
+    if (argc <= 1) {
+        help_message();
+        return 0;
+    }
+
+    operation = argv[1][0];
+
+    if (operation != '+' && operation != '-') {
+        help_message();
+        return 1;
+    }
+
+    for (i = 2; i < argc; ++i) {
+        f = open(argv[i], 0);
+        if (f == -1)
+            return errno;
+
+        result = fstat(f, &fs);
+        if (result == -1)
+            return errno;
+
+        if (operation == '+')
+            fs.st_mode |=   S_IWUSR;
+        else
+            fs.st_mode &= ~(S_IWUSR | S_IWGRP | S_IWOTH);
+
+        result = fchmod(f, fs.st_mode);
+        if (result == -1)
+            return errno;
+    }
+    return result;
+}