Merge pull request #1113 from Mathewnd/master

options/posix: implement {get,set,end}usershell

options/posix/generic/unistd-stubs.cpp

@@ -1137,19 +1137,59 @@ int access(const char *path, int mode) {
 	return 0;
 }
 
+namespace {
+	FILE *user_shell_global_file; // Used by setusershell/getusershell/endusershell.
+
+	bool user_shell_open_global_file() {
+		if(!user_shell_global_file) {
+			user_shell_global_file = fopen("/etc/shells", "r");
+			if(!user_shell_global_file) {
+				// if the file cannot be opened, we need to pretend one exists with
+				// these shells:
+				static char shells[] = "/bin/sh\n/bin/csh\n";
+
+				user_shell_global_file = fmemopen(shells, strlen(shells), "r");
+				if(user_shell_global_file == nullptr)
+					return false;
+			}
+		}
+
+		return true;
+	}
+
+	void user_shell_close_global_file() {
+		if(user_shell_global_file) {
+			fclose(user_shell_global_file);
+			user_shell_global_file = nullptr;
+		}
+	}
+}
+
 char *getusershell(void) {
-	__ensure(!"Not implemented");
-	__builtin_unreachable();
+	static char shell[PATH_MAX];
+	if(!user_shell_open_global_file())
+		return nullptr;
+
+	if (fgets(shell, PATH_MAX, user_shell_global_file)){
+		shell[strcspn(shell, "\n")] = '\0';
+		return shell;
+	}
+
+	if(ferror(user_shell_global_file))
+		errno = EIO;
+
+	return nullptr;
 }
 
 void setusershell(void) {
-	__ensure(!"Not implemented");
-	__builtin_unreachable();
+	if(!user_shell_open_global_file())
+		return;
+
+	rewind(user_shell_global_file);
 }
 
 void endusershell(void) {
-	__ensure(!"Not implemented");
-	__builtin_unreachable();
+	user_shell_close_global_file();
 }
 
 int isatty(int fd) {

tests/meson.build

@@ -96,6 +96,7 @@ all_test_cases = [
 	'posix/strdupa',
 	'posix/mkstemp',
 	'posix/waitid',
+        'posix/usershell',
 	'glibc/getopt',
 	'glibc/ffsl-ffsll',
 	'glibc/error_message_count',

tests/posix/usershell.c

@@ -0,0 +1,63 @@
+#include <unistd.h>
+#include <assert.h>
+#include <string.h>
+#include <stdio.h>
+
+static void testfor(const char *expected, char *shell, int *count) {
+	if (strcmp(shell, expected) == 0)
+		*count += 1;
+}
+
+#define BUFFER_SIZE (1024 * 512)
+
+int main(void) {
+	setusershell();
+
+	FILE *f = fopen("/etc/shells", "r");
+	if (f == NULL) {
+		/* /etc/shells file is unreadable, test for the existance of /bin/sh and /bin/csh */
+		char *shell = getusershell();
+		int csh = 0;
+		int sh = 0;
+
+		testfor("/bin/sh", shell, &sh);
+		testfor("/bin/csh", shell, &csh);
+
+		shell = getusershell();
+		assert(shell);
+
+		testfor("/bin/sh", shell, &sh);
+		testfor("/bin/csh", shell, &csh);
+
+		assert(sh == 1 && csh == 1);
+		assert(getusershell() == NULL);
+	} else {
+		/* /etc/shells is there, read the whole file into a buffer and change all '\n's to '\0'. */
+		char buffer[BUFFER_SIZE + 1];
+		int nbytes = fread(buffer, 1, BUFFER_SIZE, f);
+		buffer[nbytes] = '\0';
+
+		for (int i = 0; i < nbytes; ++i) {
+			if (buffer[i] == '\n')
+				buffer[i] = '\0';
+		}
+
+		/* loop through each shell and make sure the result is right */
+		char *shell = buffer;
+		while (shell < &buffer[nbytes]) {
+			char *usershell = getusershell();
+			while (usershell && *usershell == '#')
+				usershell = getusershell();
+
+			while (*shell == '#')
+				shell += strlen(shell) + 1;
+
+			assert(strcmp(shell, usershell) == 0);
+			shell += strlen(shell) + 1;
+		}
+	}
+
+	endusershell();
+
+	return 0;
+}