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

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Also, refactor the hell out of pwd.cpp & grp.cpp
This commit is contained in:
Sergey Bugaev 2020-08-25 17:21:45 +03:00 • committed by Andreas Kling
parent 5fd88e51c5
commit 17109a3a31
4 changed files with 192 additions and 189 deletions
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162
Libraries/LibC/pwd.cpp
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@ -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;
}
static bool parse_pwddb_entry(const String& line)
{
auto parts = line.split_view(':', true);
if (parts.size() != 7) {
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 gid = gid_string.to_uint();
if (!gid.has_value()) {
fprintf(stderr, "getpwent(): Malformed GID on line %u\n", s_line_number);
return false;
}
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 (!__pwdb_stream)
if (!s_stream)
setpwent();
assert(__pwdb_stream);
if (feof(__pwdb_stream))
return nullptr;
while (true) {
if (!s_stream || feof(s_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);
if (parts.size() != 7) {
fprintf(stderr, "getpwent(): Malformed entry on line %u\n", __pwdb_line_number);
goto next_entry;
}
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 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;
}
__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;
if (ferror(s_stream)) {
fprintf(stderr, "getpwent(): Read error: %s\n", strerror(ferror(s_stream)));
return nullptr;
}
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;
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.
}
}
int putpwent(const struct passwd* p, FILE* stream)