Add own readpassphrase function

This removes the libbsd dependency.
Fixed #10.

Makefile

@@ -1,7 +1,7 @@
 CFLAGS = -Wall -Wextra -Werror -Wl,-z,now
 CFLAGS_RELEASE = ${CFLAGS} -O2 -s -D_FORTIFY_SOURCE=2
 CFLAGS_DEBUG = ${CFLAGS} -O0 -g -fsanitize=undefined
-LIBS = -lbsd -lcrypt
+LIBS = -lcrypt
 CC = gcc
 
 all: rdo.c

README.md

@@ -6,9 +6,7 @@ This project aims to be a very slim alternative to both sudo and doas.
 
 If you are on Arch Linux, you can download the package via the [AUR](https://aur.archlinux.org/packages/rdo/).
 
-If you are using any other linux distro, or want to build it yourself, you will first need to install either `libbsd` or `libbsd-dev`, depending on how your package manager calls it.
-
-Then, you can clone and build rdo with the following set of commands:
+You can clone and build rdo with the following set of commands:
 
 ```sh
 git clone https://codeberg.org/sw1tchbl4d3/rdo

rdo.c

@@ -7,7 +7,8 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
-#include <bsd/readpassphrase.h>
+
+#include "readpassphrase.h"
 #include "sessions.h"
 
 #define VERSION "1.4"
@@ -116,7 +117,7 @@ int main(int argc, char** argv) {
 
 	tries = 0;
 	while (tries < 3) {
-		if (!readpassphrase("(rdo) Password: ", password, sizeof(password), RPP_REQUIRE_TTY))
+		if (!readpassphrase("(rdo) Password: ", password, sizeof(password)))
 			err(1, "Could not get passphrase");
 
 		char* hashed_pw = crypt(password, shadowEntry->sp_pwdp);

readpassphrase.h

@@ -0,0 +1,61 @@
+#include <stdio.h>
+#include <unistd.h>
+#include <termios.h>
+#include <fcntl.h>
+
+char* readpassphrase(const char* prompt, char* buf, size_t bufsz) {
+    char stdin_path[256];
+    char tty_link_path[256];
+    int n;
+    int ttyfd = -1;
+
+    struct termios term;
+
+    for (int i = 0; i < 3; i++) {
+        if (tcgetattr(i, &term) == 0) {
+            ttyfd = i;
+            break;
+        }
+    }
+    
+    if (ttyfd < 0)
+        return NULL;
+
+    snprintf(tty_link_path, sizeof(tty_link_path), "/proc/self/fd/%d", ttyfd);
+
+    n = readlink(tty_link_path, stdin_path, sizeof(stdin_path));
+    if (n < 0)
+        return NULL;
+    
+    stdin_path[n] = '\0';
+
+    int fd = open(stdin_path, O_RDWR);
+    if (fd < 0)
+        return NULL;
+
+    term.c_lflag &= ~ECHO;
+    tcsetattr(ttyfd, 0, &term);
+    term.c_lflag |= ECHO;
+
+    if (write(fd, prompt, strlen(prompt)) < 0) {
+        tcsetattr(ttyfd, 0, &term);
+        return NULL;
+    }
+
+    n = read(fd, buf, bufsz);
+    if (n < 0) {
+        tcsetattr(ttyfd, 0, &term);
+        printf("\n");
+        return NULL;
+    }
+
+    buf[n-1] = '\0';
+
+    close(fd);
+    tcsetattr(ttyfd, 0, &term);
+
+    // NOTE: As we disabled echo, the enter sent by the user isn't displayed.
+    printf("\n");
+
+    return buf;
+}