LibC: Use AK::String-backed buffers instead of static buffers

Also, refactor the hell out of pwd.cpp & grp.cpp

Libraries/LibC/grp.cpp

@@ -26,54 +26,51 @@
 
 #include <AK/String.h>
 #include <AK/Vector.h>
+#include <errno_numbers.h>
 #include <grp.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
-#include <sys/mman.h>
 #include <unistd.h>
 
 extern "C" {
 
-#define GRDB_STR_MAX_LEN 256
+static FILE* s_stream = nullptr;
+static unsigned s_line_number = 0;
+static struct group s_group;
 
-struct group_with_strings : public group {
-    char name_buffer[GRDB_STR_MAX_LEN];
-    char passwd_buffer[GRDB_STR_MAX_LEN];
-    char* members[32];
-    char members_buffer[32][32];
-};
-
-static FILE* __grdb_stream = nullptr;
-static unsigned __grdb_line_number = 0;
-static struct group_with_strings* __grdb_entry = nullptr;
+static String s_name;
+static String s_passwd;
+static Vector<String> s_members;
+static Vector<const char*> s_members_ptrs;
 
 void setgrent()
 {
-    __grdb_line_number = 0;
-    if (__grdb_stream) {
-        rewind(__grdb_stream);
+    s_line_number = 0;
+    if (s_stream) {
+        rewind(s_stream);
     } else {
-        __grdb_stream = fopen("/etc/group", "r");
-        if (!__grdb_stream) {
+        s_stream = fopen("/etc/group", "r");
+        if (!s_stream) {
             perror("open /etc/group");
         }
-        assert(__grdb_stream);
-        __grdb_entry = (struct group_with_strings*)mmap_with_name(nullptr, getpagesize(), PROT_READ | PROT_WRITE, MAP_ANONYMOUS | MAP_PRIVATE, 0, 0, "setgrent");
     }
 }
 
 void endgrent()
 {
-    __grdb_line_number = 0;
-    if (__grdb_stream) {
-        fclose(__grdb_stream);
-        __grdb_stream = nullptr;
-    }
-    if (__grdb_entry) {
-        munmap(__grdb_entry, getpagesize());
-        __grdb_entry = nullptr;
+    s_line_number = 0;
+    if (s_stream) {
+        fclose(s_stream);
+        s_stream = nullptr;
     }
+
+    memset(&s_group, 0, sizeof(s_group));
+
+    s_name = {};
+    s_passwd = {};
+    s_members = {};
+    s_members_ptrs = {};
 }
 
 struct group* getgrgid(gid_t gid)
@@ -96,52 +93,69 @@ struct group* getgrnam(const char* name)
     return nullptr;
 }
 
-struct group* getgrent()
+static bool parse_grpdb_entry(const String& line)
 {
-    if (!__grdb_stream)
-        setgrent();
-
-    assert(__grdb_stream);
-    if (feof(__grdb_stream))
-        return nullptr;
-
-next_entry:
-    char buffer[1024];
-    ++__grdb_line_number;
-    char* s = fgets(buffer, sizeof(buffer), __grdb_stream);
-    if (!s)
-        return nullptr;
-    assert(__grdb_stream);
-    if (feof(__grdb_stream))
-        return nullptr;
-    String line(s, Chomp);
-    auto parts = line.split(':', true);
+    auto parts = line.split_view(':', true);
     if (parts.size() != 4) {
-        fprintf(stderr, "getgrent(): Malformed entry on line %u: '%s' has %zu parts\n", __grdb_line_number, line.characters(), parts.size());
-        goto next_entry;
+        fprintf(stderr, "getgrent(): Malformed entry on line %u: '%s' has %zu parts\n", s_line_number, line.characters(), parts.size());
+        return false;
     }
-    auto& e_name = parts[0];
-    auto& e_passwd = parts[1];
-    auto& e_gid_string = parts[2];
-    auto& e_members_string = parts[3];
-    auto e_gid = e_gid_string.to_uint();
-    if (!e_gid.has_value()) {
-        fprintf(stderr, "getgrent(): Malformed GID on line %u\n", __grdb_line_number);
-        goto next_entry;
+
+    s_name = parts[0];
+    s_passwd = parts[1];
+
+    auto& gid_string = parts[2];
+    String members_string = parts[3];
+
+    auto gid = gid_string.to_uint();
+    if (!gid.has_value()) {
+        fprintf(stderr, "getgrent(): Malformed GID on line %u\n", s_line_number);
+        return false;
     }
-    auto members = e_members_string.split(',');
-    __grdb_entry->gr_gid = e_gid.value();
-    __grdb_entry->gr_name = __grdb_entry->name_buffer;
-    __grdb_entry->gr_passwd = __grdb_entry->passwd_buffer;
-    for (size_t i = 0; i < members.size(); ++i) {
-        __grdb_entry->members[i] = __grdb_entry->members_buffer[i];
-        strlcpy(__grdb_entry->members_buffer[i], members[i].characters(), sizeof(__grdb_entry->members_buffer[i]));
+
+    s_members = members_string.split(',');
+    s_members_ptrs.clear_with_capacity();
+    s_members_ptrs.ensure_capacity(s_members.size() + 1);
+    for (auto& member : s_members) {
+        s_members_ptrs.append(member.characters());
+    }
+    s_members_ptrs.append(nullptr);
+
+    s_group.gr_gid = gid.value();
+    s_group.gr_name = const_cast<char*>(s_name.characters());
+    s_group.gr_passwd = const_cast<char*>(s_passwd.characters());
+    s_group.gr_mem = const_cast<char**>(s_members_ptrs.data());
+
+    return true;
+}
+
+struct group* getgrent()
+{
+    if (!s_stream)
+        setgrent();
+
+    while (true) {
+        if (!s_stream || feof(s_stream))
+            return nullptr;
+
+        if (ferror(s_stream)) {
+            fprintf(stderr, "getgrent(): Read error: %s\n", strerror(ferror(s_stream)));
+            return nullptr;
+        }
+
+        char buffer[1024];
+        ++s_line_number;
+        char* s = fgets(buffer, sizeof(buffer), s_stream);
+
+        // Silently tolerate an empty line at the end.
+        if ((!s || !s[0]) && feof(s_stream))
+            return nullptr;
+
+        String line(s, Chomp);
+        if (parse_grpdb_entry(line))
+            return &s_group;
+        // Otherwise, proceed to the next line.
     }
-    __grdb_entry->members[members.size()] = nullptr;
-    __grdb_entry->gr_mem = __grdb_entry->members;
-    strlcpy(__grdb_entry->name_buffer, e_name.characters(), GRDB_STR_MAX_LEN);
-    strlcpy(__grdb_entry->passwd_buffer, e_passwd.characters(), GRDB_STR_MAX_LEN);
-    return __grdb_entry;
 }
 
 int initgroups(const char* user, gid_t extra_gid)

Libraries/LibC/netdb.cpp

@@ -41,12 +41,10 @@ extern "C" {
 int h_errno;
 
 static hostent __gethostbyname_buffer;
-static char __gethostbyname_name_buffer[512];
 static in_addr_t __gethostbyname_address;
 static in_addr_t* __gethostbyname_address_list_buffer[2];
 
 static hostent __gethostbyaddr_buffer;
-static char __gethostbyaddr_name_buffer[512];
 static in_addr_t* __gethostbyaddr_address_list_buffer[2];
 
 //Get service entry buffers and file information for the getservent() family of functions
@@ -55,8 +53,8 @@ static const char* services_path = "/etc/services";
 
 static bool fill_getserv_buffers(char* line, ssize_t read);
 static servent __getserv_buffer;
-static char __getserv_name_buffer[512];
-static char __getserv_protocol_buffer[10];
+static String __getserv_name_buffer;
+static String __getserv_protocol_buffer;
 static int __getserv_port_buffer;
 static Vector<ByteBuffer> __getserv_alias_list_buffer;
 static Vector<char*> __getserv_alias_list;
@@ -69,7 +67,7 @@ static const char* protocols_path = "/etc/protocols";
 
 static bool fill_getproto_buffers(char* line, ssize_t read);
 static protoent __getproto_buffer;
-static char __getproto_name_buffer[512];
+static String __getproto_name_buffer;
 static Vector<ByteBuffer> __getproto_alias_list_buffer;
 static Vector<char*> __getproto_alias_list;
 static int __getproto_protocol_buffer;
@@ -98,12 +96,13 @@ static int connect_to_lookup_server()
 
 hostent* gethostbyname(const char* name)
 {
+    static String s_name_buffer;
+
     auto ipv4_address = IPv4Address::from_string(name);
+
     if (ipv4_address.has_value()) {
-        auto ip4_string = ipv4_address.value().to_string();
-        ASSERT(ip4_string.length() < sizeof(__gethostbyname_name_buffer));
-        strlcpy(__gethostbyname_name_buffer, ip4_string.characters(), sizeof(__gethostbyname_name_buffer));
-        __gethostbyname_buffer.h_name = __gethostbyname_name_buffer;
+        s_name_buffer = ipv4_address.value().to_string();
+        __gethostbyname_buffer.h_name = const_cast<char*>(s_name_buffer.characters());
         __gethostbyname_buffer.h_aliases = nullptr;
         __gethostbyname_buffer.h_addrtype = AF_INET;
         new (&__gethostbyname_address) IPv4Address(ipv4_address.value());
@@ -152,9 +151,8 @@ hostent* gethostbyname(const char* name)
     if (rc <= 0)
         return nullptr;
 
-    strlcpy(__gethostbyname_name_buffer, name, sizeof(__gethostbyaddr_name_buffer));
-
-    __gethostbyname_buffer.h_name = __gethostbyname_name_buffer;
+    s_name_buffer = name;
+    __gethostbyname_buffer.h_name = const_cast<char*>(s_name_buffer.characters());
     __gethostbyname_buffer.h_aliases = nullptr;
     __gethostbyname_buffer.h_addrtype = AF_INET;
     __gethostbyname_address_list_buffer[0] = &__gethostbyname_address;
@@ -167,6 +165,8 @@ hostent* gethostbyname(const char* name)
 
 hostent* gethostbyaddr(const void* addr, socklen_t addr_size, int type)
 {
+    static String s_name_buffer;
+
     if (type != AF_INET) {
         errno = EAFNOSUPPORT;
         return nullptr;
@@ -214,11 +214,8 @@ hostent* gethostbyaddr(const void* addr, socklen_t addr_size, int type)
     if (responses.is_empty())
         return nullptr;
 
-    auto& response = responses[0];
-
-    strlcpy(__gethostbyaddr_name_buffer, response.characters(), sizeof(__gethostbyaddr_name_buffer));
-
-    __gethostbyaddr_buffer.h_name = __gethostbyaddr_name_buffer;
+    s_name_buffer = responses[0];
+    __gethostbyaddr_buffer.h_name = const_cast<char*>(s_name_buffer.characters());
     __gethostbyaddr_buffer.h_aliases = nullptr;
     __gethostbyaddr_buffer.h_addrtype = AF_INET;
     // FIXME: Should we populate the hostent's address list here with a sockaddr_in for the provided host?
@@ -275,9 +272,9 @@ struct servent* getservent()
     if (!fill_getserv_buffers(line, read))
         return nullptr;
 
-    __getserv_buffer.s_name = __getserv_name_buffer;
+    __getserv_buffer.s_name = const_cast<char*>(__getserv_name_buffer.characters());
     __getserv_buffer.s_port = __getserv_port_buffer;
-    __getserv_buffer.s_proto = __getserv_protocol_buffer;
+    __getserv_buffer.s_proto = const_cast<char*>(__getserv_protocol_buffer.characters());
 
     __getserv_alias_list.clear();
     for (auto& alias : __getserv_alias_list_buffer) {
@@ -373,12 +370,7 @@ static bool fill_getserv_buffers(char* line, ssize_t read)
         perror("malformed services file: entry");
         return false;
     }
-    if (sizeof(__getserv_name_buffer) >= split_line[0].length() + 1) {
-        strlcpy(__getserv_name_buffer, split_line[0].characters(), sizeof(__getserv_name_buffer));
-    } else {
-        perror("invalid buffer length: service name");
-        return false;
-    }
+    __getserv_name_buffer = split_line[0];
 
     auto port_protocol_split = String(split_line[1]).split('/');
     if (port_protocol_split.size() < 2) {
@@ -396,13 +388,7 @@ static bool fill_getserv_buffers(char* line, ssize_t read)
     port_protocol_split[1].replace("\t", "", true);
     port_protocol_split[1].replace("\n", "", true);
 
-    if (sizeof(__getserv_protocol_buffer) >= port_protocol_split[1].length()) {
-        strlcpy(__getserv_protocol_buffer, port_protocol_split[1].characters(), sizeof(__getserv_protocol_buffer));
-    } else {
-        perror("malformed services file: protocol");
-        return false;
-    }
-
+    __getserv_protocol_buffer = port_protocol_split[1];
     __getserv_alias_list_buffer.clear();
 
     //If there are aliases for the service, we will fill the alias list buffer.
@@ -468,7 +454,7 @@ struct protoent* getprotoent()
     if (!fill_getproto_buffers(line, read))
         return nullptr;
 
-    __getproto_buffer.p_name = __getproto_name_buffer;
+    __getproto_buffer.p_name = const_cast<char*>(__getproto_name_buffer.characters());
     __getproto_buffer.p_proto = __getproto_protocol_buffer;
 
     __getproto_alias_list.clear();
@@ -565,12 +551,7 @@ static bool fill_getproto_buffers(char* line, ssize_t read)
         perror("malformed protocols file: entry");
         return false;
     }
-    if (sizeof(__getproto_name_buffer) >= split_line[0].length() + 1) {
-        strlcpy(__getproto_name_buffer, split_line[0].characters(), sizeof(__getproto_name_buffer));
-    } else {
-        perror("invalid buffer length: protocol name");
-        return false;
-    }
+    __getproto_name_buffer = split_line[0];
 
     auto number = split_line[1].to_int();
     if (!number.has_value())

Libraries/LibC/pwd.cpp

@@ -26,55 +26,53 @@
 
 #include <AK/String.h>
 #include <AK/Vector.h>
+#include <errno_numbers.h>
 #include <pwd.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
-#include <sys/mman.h>
 #include <unistd.h>
 
 extern "C" {
 
-#define PWDB_STR_MAX_LEN 256
+static FILE* s_stream = nullptr;
+static unsigned s_line_number = 0;
+static struct passwd s_passwd_entry;
 
-struct passwd_with_strings : public passwd {
-    char name_buffer[PWDB_STR_MAX_LEN];
-    char passwd_buffer[PWDB_STR_MAX_LEN];
-    char gecos_buffer[PWDB_STR_MAX_LEN];
-    char dir_buffer[PWDB_STR_MAX_LEN];
-    char shell_buffer[PWDB_STR_MAX_LEN];
-};
-
-static FILE* __pwdb_stream = nullptr;
-static unsigned __pwdb_line_number = 0;
-static struct passwd_with_strings* __pwdb_entry = nullptr;
+static String s_name;
+static String s_passwd;
+static String s_gecos;
+static String s_dir;
+static String s_shell;
 
 void setpwent()
 {
-    __pwdb_line_number = 0;
-    if (__pwdb_stream) {
-        rewind(__pwdb_stream);
+    s_line_number = 0;
+    if (s_stream) {
+        rewind(s_stream);
     } else {
-        __pwdb_stream = fopen("/etc/passwd", "r");
-        if (!__pwdb_stream) {
+        s_stream = fopen("/etc/passwd", "r");
+        if (!s_stream) {
             perror("open /etc/passwd");
         }
-        assert(__pwdb_stream);
-        __pwdb_entry = (struct passwd_with_strings*)mmap_with_name(nullptr, getpagesize(), PROT_READ | PROT_WRITE, MAP_ANONYMOUS | MAP_PRIVATE, 0, 0, "setpwent");
     }
 }
 
 void endpwent()
 {
-    __pwdb_line_number = 0;
-    if (__pwdb_stream) {
-        fclose(__pwdb_stream);
-        __pwdb_stream = nullptr;
-    }
-    if (__pwdb_entry) {
-        munmap(__pwdb_entry, getpagesize());
-        __pwdb_entry = nullptr;
+    s_line_number = 0;
+    if (s_stream) {
+        fclose(s_stream);
+        s_stream = nullptr;
     }
+
+    memset(&s_passwd_entry, 0, sizeof(s_passwd_entry));
+
+    s_name = {};
+    s_passwd = {};
+    s_gecos = {};
+    s_dir = {};
+    s_shell = {};
 }
 
 struct passwd* getpwuid(uid_t uid)
@@ -97,61 +95,71 @@ struct passwd* getpwnam(const char* name)
     return nullptr;
 }
 
-struct passwd* getpwent()
+static bool parse_pwddb_entry(const String& line)
 {
-    if (!__pwdb_stream)
-        setpwent();
-
-    assert(__pwdb_stream);
-    if (feof(__pwdb_stream))
-        return nullptr;
-
-next_entry:
-    char buffer[1024];
-    ++__pwdb_line_number;
-    char* s = fgets(buffer, sizeof(buffer), __pwdb_stream);
-    if (!s)
-        return nullptr;
-    assert(__pwdb_stream);
-    if (feof(__pwdb_stream))
-        return nullptr;
-    String line(s, Chomp);
-    auto parts = line.split(':', true);
+    auto parts = line.split_view(':', true);
     if (parts.size() != 7) {
-        fprintf(stderr, "getpwent(): Malformed entry on line %u\n", __pwdb_line_number);
-        goto next_entry;
+        fprintf(stderr, "getpwent(): Malformed entry on line %u\n", s_line_number);
+        return false;
+    }
+
+    s_name = parts[0];
+    s_passwd = parts[1];
+    auto& uid_string = parts[2];
+    auto& gid_string = parts[3];
+    s_gecos = parts[4];
+    s_dir = parts[5];
+    s_shell = parts[6];
+
+    auto uid = uid_string.to_uint();
+    if (!uid.has_value()) {
+        fprintf(stderr, "getpwent(): Malformed UID on line %u\n", s_line_number);
+        return false;
     }
-    auto& e_name = parts[0];
-    auto& e_passwd = parts[1];
-    auto& e_uid_string = parts[2];
-    auto& e_gid_string = parts[3];
-    auto& e_gecos = parts[4];
-    auto& e_dir = parts[5];
-    auto& e_shell = parts[6];
-    auto e_uid = e_uid_string.to_uint();
-    if (!e_uid.has_value()) {
-        fprintf(stderr, "getpwent(): Malformed UID on line %u\n", __pwdb_line_number);
-        goto next_entry;
+    auto gid = gid_string.to_uint();
+    if (!gid.has_value()) {
+        fprintf(stderr, "getpwent(): Malformed GID on line %u\n", s_line_number);
+        return false;
     }
-    auto e_gid = e_gid_string.to_uint();
-    if (!e_gid.has_value()) {
-        fprintf(stderr, "getpwent(): Malformed GID on line %u\n", __pwdb_line_number);
-        goto next_entry;
+
+    s_passwd_entry.pw_name = const_cast<char*>(s_name.characters());
+    s_passwd_entry.pw_passwd = const_cast<char*>(s_passwd.characters());
+    s_passwd_entry.pw_uid = uid.value();
+    s_passwd_entry.pw_gid = gid.value();
+    s_passwd_entry.pw_gecos = const_cast<char*>(s_gecos.characters());
+    s_passwd_entry.pw_dir = const_cast<char*>(s_dir.characters());
+    s_passwd_entry.pw_shell = const_cast<char*>(s_shell.characters());
+
+    return true;
+}
+
+struct passwd* getpwent()
+{
+    if (!s_stream)
+        setpwent();
+
+    while (true) {
+        if (!s_stream || feof(s_stream))
+            return nullptr;
+
+        if (ferror(s_stream)) {
+            fprintf(stderr, "getpwent(): Read error: %s\n", strerror(ferror(s_stream)));
+            return nullptr;
+        }
+
+        char buffer[1024];
+        ++s_line_number;
+        char* s = fgets(buffer, sizeof(buffer), s_stream);
+
+        // Silently tolerate an empty line at the end.
+        if ((!s || !s[0]) && feof(s_stream))
+            return nullptr;
+
+        String line(s, Chomp);
+        if (parse_pwddb_entry(line))
+            return &s_passwd_entry;
+        // Otherwise, proceed to the next line.
     }
-    __pwdb_entry->pw_uid = e_uid.value();
-    __pwdb_entry->pw_gid = e_gid.value();
-    __pwdb_entry->pw_name = __pwdb_entry->name_buffer;
-    __pwdb_entry->pw_passwd = __pwdb_entry->passwd_buffer;
-    __pwdb_entry->pw_gecos = __pwdb_entry->gecos_buffer;
-    __pwdb_entry->pw_dir = __pwdb_entry->dir_buffer;
-    __pwdb_entry->pw_shell = __pwdb_entry->shell_buffer;
-
-    strlcpy(__pwdb_entry->name_buffer, e_name.characters(), PWDB_STR_MAX_LEN);
-    strlcpy(__pwdb_entry->passwd_buffer, e_passwd.characters(), PWDB_STR_MAX_LEN);
-    strlcpy(__pwdb_entry->gecos_buffer, e_gecos.characters(), PWDB_STR_MAX_LEN);
-    strlcpy(__pwdb_entry->dir_buffer, e_dir.characters(), PWDB_STR_MAX_LEN);
-    strlcpy(__pwdb_entry->shell_buffer, e_shell.characters(), PWDB_STR_MAX_LEN);
-    return __pwdb_entry;
 }
 
 int putpwent(const struct passwd* p, FILE* stream)

Libraries/LibC/unistd.cpp

@@ -557,14 +557,14 @@ int set_process_icon(int icon_id)
 
 char* getlogin()
 {
-    static char __getlogin_buffer[256];
-    if (auto* passwd = getpwuid(getuid())) {
-        strlcpy(__getlogin_buffer, passwd->pw_name, sizeof(__getlogin_buffer));
+    static String buffer;
+    if (buffer.is_null()) {
+        if (auto* passwd = getpwuid(getuid())) {
+            buffer = String(passwd->pw_name);
+        }
         endpwent();
-        return __getlogin_buffer;
     }
-    endpwent();
-    return nullptr;
+    return const_cast<char*>(buffer.characters());
 }
 
 int ftruncate(int fd, off_t length)