usr.bin: Add initial /etc/passwd parsing

Signed-off-by: Ian Moffett <ian@osmora.org>

3 files changed, 123 insertions, 0 deletions

diff --git a/usr.bin/Makefile b/usr.bin/Makefile
index a2abdf0..4c17ddf 100644
--- a/usr.bin/Makefile
+++ b/usr.bin/Makefile
@@ -18,3 +18,4 @@ all:
 	make -C getconf/ $(ARGS)
 	make -C echo/ $(ARGS)
 	make -C readcore/ $(ARGS)
+	make -C login/ $(ARGS)
diff --git a/usr.bin/login/Makefile b/usr.bin/login/Makefile
new file mode 100644
index 0000000..8b37d4c
--- /dev/null
+++ b/usr.bin/login/Makefile
@@ -0,0 +1,6 @@
+include user.mk
+
+CFILES = $(shell find . -name "*.c")
+
+$(ROOT)/base/usr/bin/login:
+	gcc -Iinclude/ $(CFILES) -o $@ $(INTERNAL_CFLAGS)
diff --git a/usr.bin/login/login.c b/usr.bin/login/login.c
new file mode 100644
index 0000000..11cb668
--- /dev/null
+++ b/usr.bin/login/login.c
@@ -0,0 +1,116 @@
+/*
+ * Copyright (c) 2023-2025 Ian Marco Moffett and the Osmora Team.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice,
+ *    this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of Hyra nor the names of its
+ *    contributors may be used to endorse or promote products derived from
+ *    this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <sys/types.h>
+#include <sys/errno.h>
+#include <stdio.h>
+#include <string.h>
+
+#define USERNAME "root"
+
+/* Row indices for /etc/passwd */
+#define ROW_USERNAME 0
+#define ROW_USERID   2
+#define ROW_GRPID    3
+#define ROW_GECOS    4
+#define ROW_HOME     5
+#define ROW_SHELL    6
+
+/*
+ * Check an /etc/passwd entry against an alias
+ * (username)
+ *
+ * Returns 0 if the entry matches
+ */
+static int
+check_user(char *alias, char *entry)
+{
+    const char *p;
+    size_t row = 0;
+
+    if (alias == NULL || entry == NULL) {
+        return -EINVAL;
+    }
+
+    /* Grab the username */
+    p = strtok(entry, ":");
+    if (p == NULL) {
+        printf("bad /etc/passwd entry @ line 1\n");
+        return -1;
+    }
+
+    /* Iterate through each field */
+    while (p != NULL) {
+        switch (row) {
+        case ROW_USERNAME:
+            printf("username: %s\n", p);
+            break;  /* UNREACHABLE */
+        case ROW_USERID:
+            printf("UID: %s\n", p);
+            break;
+        case ROW_GRPID:
+            printf("GID: %s\n", p);
+            break;
+        case ROW_GECOS:
+            printf("GECOS: %s\n", p);
+            break;
+        case ROW_HOME:
+            printf("HOME: %s\n", p);
+            break;
+        case ROW_SHELL:
+            printf("SHELL: %s\n", p);
+            break;
+        defaukt:
+        }
+
+        p = strtok(NULL, ":");
+        ++row;
+    }
+
+    return 0;
+}
+
+int
+main(void)
+{
+    FILE *fp;
+    char *alias, *p;
+    char entry[256];
+
+    fp = fopen("/etc/passwd", "r");
+    if (fp == NULL) {
+        printf("failed to open /etc/passwd\n");
+        return -1;
+    }
+
+    while (fgets(entry, sizeof(entry), fp) != NULL) {
+        check_user(USERNAME, entry);
+    }
+    return 0;
+}