lib: Add mlibc

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

1 files changed, 284 insertions, 0 deletions

diff --git a/lib/mlibc/options/posix/generic/pwd-stubs.cpp b/lib/mlibc/options/posix/generic/pwd-stubs.cpp
new file mode 100644
index 0000000..5d8f618
--- /dev/null
+++ b/lib/mlibc/options/posix/generic/pwd-stubs.cpp
@@ -0,0 +1,284 @@
+
+#include <errno.h>
+#include <pwd.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <bits/ensure.h>
+
+#include <mlibc/debug.hpp>
+
+namespace {
+	FILE *global_file; // Used by setpwent/getpwent/endpwent.
+
+	bool open_global_file() {
+		if(!global_file) {
+			global_file = fopen("/etc/passwd", "r");
+			if(!global_file) {
+				errno = EIO;
+				return false;
+			}
+		}
+
+		return true;
+	}
+
+	void close_global_file() {
+		if(global_file) {
+			fclose(global_file);
+			global_file = nullptr;
+		}
+	}
+
+	bool extract_entry(frg::string_view line, passwd *entry) {
+		frg::string_view segments[8];
+
+		// Parse the line into 7 or 8 segments.
+		size_t s = 0;
+		int n;
+		for(n = 0; n < 7; n++) {
+			size_t d = line.find_first(':', s);
+			if(d == size_t(-1))
+				break;
+			segments[n] = line.sub_string(s, d - s);
+			s = d + 1;
+		}
+		if(line.find_first(':', s) != size_t(-1))
+			return false;
+		segments[n] = line.sub_string(s, line.size() - s);
+		n++;
+
+		if(n < 7)
+			return false;
+
+		// TODO: Handle strndup() failure.
+		auto name = strndup(segments[0].data(), segments[0].size());
+		__ensure(name);
+
+		auto passwd = strndup(segments[1].data(), segments[1].size());
+		__ensure(passwd);
+
+		auto uid = segments[2].to_number<int>();
+		if(!uid)
+			return false;
+		auto gid = segments[3].to_number<int>();
+		if(!gid)
+			return false;
+
+		auto real_name = strndup(segments[4].data(), segments[4].size());
+		__ensure(real_name);
+		auto dir = strndup(segments[5].data(), segments[5].size());
+		__ensure(dir);
+		auto shell = strndup(segments[6].data(), segments[6].size());
+		__ensure(shell);
+
+		// Chop the newline off the end of shell
+		__ensure(strlen(shell) > 0);
+		shell[strlen(shell) - 1] = '\0';
+
+		entry->pw_name = name;
+		entry->pw_passwd = passwd;
+		entry->pw_uid = *uid;
+		entry->pw_gid = *gid;
+		entry->pw_dir = dir;
+		entry->pw_shell = shell;
+		entry->pw_gecos = real_name;
+		return true;
+	}
+
+	void copy_to_buffer(passwd *pwd, char *buffer, size_t size) {
+		char *pw_dir = stpcpy(buffer, pwd->pw_name) + 1;
+		free(pwd->pw_name);
+		pwd->pw_name = buffer;
+
+		char *pw_shell = stpcpy(pw_dir, pwd->pw_dir) + 1;
+		free(pwd->pw_dir);
+		pwd->pw_dir = pw_dir;
+
+		char *pw_passwd = stpcpy(pw_shell, pwd->pw_shell) + 1;
+		free(pwd->pw_shell);
+		pwd->pw_shell = pw_shell;
+
+		char *end = stpcpy(pw_passwd, pwd->pw_passwd);
+		__ensure(end <= buffer + size);
+		free(pwd->pw_passwd);
+		pwd->pw_passwd = pw_passwd;
+	}
+
+	void clear_entry(passwd *entry) {
+		free(entry->pw_name);
+		free(entry->pw_dir);
+		free(entry->pw_passwd);
+		free(entry->pw_shell);
+		entry->pw_name = nullptr;
+		entry->pw_dir = nullptr;
+		entry->pw_passwd = nullptr;
+		entry->pw_shell = nullptr;
+	}
+}
+
+struct passwd *getpwent(void) {
+	static passwd entry;
+	char line[NSS_BUFLEN_PASSWD];
+
+	if(!open_global_file()) {
+		return nullptr;
+	}
+
+	if (fgets(line, NSS_BUFLEN_PASSWD, global_file)) {
+		clear_entry(&entry);
+		if(!extract_entry(line, &entry)) {
+			errno = EINVAL;	// I suppose this can be a valid errno?
+			return nullptr;
+		}
+		return &entry;
+	}
+
+	if(ferror(global_file)) {
+		errno = EIO;
+	}
+
+	return nullptr;
+}
+
+struct passwd *getpwnam(const char *name) {
+	static passwd entry;
+	auto file = fopen("/etc/passwd", "r");
+	if(!file)
+		return nullptr;
+
+	char line[NSS_BUFLEN_PASSWD];
+	while(fgets(line, NSS_BUFLEN_PASSWD, file)) {
+		clear_entry(&entry);
+		if(!extract_entry(line, &entry))
+			continue;
+		if(!strcmp(entry.pw_name, name)) {
+			fclose(file);
+			return &entry;
+		}
+	}
+
+	int err = errno;
+	if(ferror(file)) {
+		err = EIO;
+	}
+
+	fclose(file);
+	errno = err;
+	return nullptr;
+}
+
+int getpwnam_r(const char *name, struct passwd *pwd, char *buffer, size_t size, struct passwd **result) {
+	*result = nullptr;
+	auto file = fopen("/etc/passwd", "r");
+	if(!file) {
+		return EIO;
+	}
+
+	char line[NSS_BUFLEN_PASSWD];
+	while(fgets(line, NSS_BUFLEN_PASSWD, file)) {
+		if(!extract_entry(line, pwd))
+			continue;
+		if(!strcmp(pwd->pw_name, name)) {
+			fclose(file);
+
+			size_t required_size = strlen(pwd->pw_name) + strlen(pwd->pw_dir)
+				+ strlen(pwd->pw_shell) + strlen(pwd->pw_passwd) + 4;
+			if (size < required_size)
+				return ERANGE;
+
+			copy_to_buffer(pwd, buffer, size);
+			*result = pwd;
+			return 0;
+		}
+	}
+
+	int ret = 0;
+	if(ferror(file)) {
+		ret = EIO;
+	}
+
+	fclose(file);
+	return ret;
+}
+
+struct passwd *getpwuid(uid_t uid) {
+	static passwd entry;
+	auto file = fopen("/etc/passwd", "r");
+	if(!file)
+		return nullptr;
+
+	char line[NSS_BUFLEN_PASSWD];
+	while(fgets(line, NSS_BUFLEN_PASSWD, file)) {
+		clear_entry(&entry);
+		if(!extract_entry(line, &entry))
+			continue;
+		if(entry.pw_uid == uid) {
+			fclose(file);
+			return &entry;
+		}
+	}
+
+	int err = ESRCH;
+	if(ferror(file)) {
+		err = EIO;
+	}
+
+	fclose(file);
+	errno = err;
+	return nullptr;
+}
+
+int getpwuid_r(uid_t uid, struct passwd *pwd, char *buffer, size_t size, struct passwd **result) {
+	*result = nullptr;
+	auto file = fopen("/etc/passwd", "r");
+	if(!file) {
+		return EIO;
+	}
+
+	char line[NSS_BUFLEN_PASSWD];
+	while(fgets(line, NSS_BUFLEN_PASSWD, file)) {
+		if(!extract_entry(line, pwd))
+			continue;
+		if(pwd->pw_uid == uid) {
+			fclose(file);
+
+			size_t required_size = strlen(pwd->pw_name) + strlen(pwd->pw_dir)
+				+ strlen(pwd->pw_shell) + + strlen(pwd->pw_passwd) + 4;
+			if (size < required_size)
+				return ERANGE;
+
+			copy_to_buffer(pwd, buffer, size);
+			*result = pwd;
+			return 0;
+		}
+	}
+
+	int ret = 0;
+	if(ferror(file)) {
+		ret = EIO;
+	}
+
+	fclose(file);
+	return ret;
+}
+
+void setpwent(void) {
+	if(!open_global_file()) {
+		return;
+	}
+	rewind(global_file);
+}
+
+void endpwent(void) {
+	close_global_file();
+}
+
+int putpwent(const struct passwd *, FILE *) {
+	__ensure(!"Not implemented");
+	__builtin_unreachable();
+}
+
+struct passwd *fgetpwent(FILE *) {
+	__ensure(!"Not implemented");
+	__builtin_unreachable();
+}