LibC: implement endpwent(), getpwent() and setpwent()

libc/CMakeLists.txt

@@ -8,6 +8,7 @@ set(LIBC_SOURCES
 	dirent.cpp
 	fcntl.cpp
 	printf_impl.cpp
+	pwd.cpp
 	stdio.cpp
 	stdlib.cpp
 	string.cpp

libc/pwd.cpp

@@ -0,0 +1,113 @@
+#include <BAN/String.h>
+#include <BAN/StringView.h>
+#include <BAN/Vector.h>
+
+#include <ctype.h>
+#include <errno.h>
+#include <pwd.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+static FILE* s_pwent_fp = nullptr;
+static passwd s_pwent_struct;
+
+#define TRY_LIBC(expr, ret) ({ auto&& e = expr; if (e.is_error()) { errno = e.error().get_error_code(); return ret; } e.release_value(); })
+
+static bool open_pwent()
+{
+	if (s_pwent_fp)
+		return true;
+	s_pwent_fp = fopen("/etc/passwd", "r");
+	return s_pwent_fp;    
+}
+
+static void clear_pwent(passwd& passwd)
+{
+	if (passwd.pw_name)
+		free(passwd.pw_name);
+	passwd.pw_name = nullptr;
+	if (passwd.pw_dir)
+		free(passwd.pw_dir);
+	passwd.pw_dir = nullptr;
+	if (passwd.pw_shell)
+		free(passwd.pw_shell);
+	passwd.pw_shell = nullptr;
+}
+
+void endpwent(void)
+{
+	if (!s_pwent_fp)
+		return;
+	fclose(s_pwent_fp);
+	s_pwent_fp = nullptr;
+	clear_pwent(s_pwent_struct);
+}
+
+struct passwd* getpwent(void)
+{
+	if (!s_pwent_fp)
+		if (!open_pwent())
+			return nullptr;
+	clear_pwent(s_pwent_struct);
+	
+	BAN::String line;
+	while (true)
+	{
+		char buffer[128];
+		if (!fgets(buffer, sizeof(buffer), s_pwent_fp))
+			return nullptr;
+		TRY_LIBC(line.append(buffer), nullptr);
+
+		if (line.back() == '\n')
+		{
+			line.pop_back();
+			break;
+		}
+	}
+
+	auto parts = TRY_LIBC(line.sv().split(':', true), nullptr);
+	ASSERT(parts.size() == 7);
+
+	ASSERT(1 <= parts[2].size() && parts[2].size() <= 9);
+	for (char c : parts[2])
+		ASSERT(isdigit(c));
+	ASSERT(1 <= parts[3].size() && parts[3].size() <= 9);
+	for (char c : parts[3])
+		ASSERT(isdigit(c));
+
+	s_pwent_struct.pw_uid = atoi(parts[2].data());
+	s_pwent_struct.pw_gid = atoi(parts[3].data());
+
+	s_pwent_struct.pw_name = (char*)malloc(parts[0].size() + 1);
+	if (!s_pwent_struct.pw_name)
+		return nullptr;
+	memcpy(s_pwent_struct.pw_name, parts[0].data(), parts[0].size());
+	s_pwent_struct.pw_name[parts[0].size()] = '\0';
+
+	s_pwent_struct.pw_dir = (char*)malloc(parts[5].size() + 1);
+	if (!s_pwent_struct.pw_dir)
+		return nullptr;
+	memcpy(s_pwent_struct.pw_dir, parts[5].data(), parts[5].size());
+	s_pwent_struct.pw_dir[parts[5].size()] = '\0';
+
+	s_pwent_struct.pw_shell = (char*)malloc(parts[6].size() + 1);
+	if (!s_pwent_struct.pw_shell)
+		return nullptr;
+	memcpy(s_pwent_struct.pw_shell, parts[6].data(), parts[6].size());
+	s_pwent_struct.pw_shell[parts[6].size()] = '\0';
+
+	return &s_pwent_struct;
+}
+
+struct passwd*	getpwnam(const char* name);
+int				getpwnam_r(const char* name, struct passwd* pwd, char* buffer, size_t bufsize, struct passwd** result);
+struct passwd*	getpwuid(uid_t uid);
+int				getpwuid_r(uid_t uid, struct passwd* pwd, char* buffer, size_t bufsize, struct passwd** result);
+
+void setpwent(void)
+{
+	if (!s_pwent_fp)
+		return;
+	fseek(s_pwent_fp, 0, SEEK_SET);
+}